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There is no need to setup this kicker IPI if we are never going
to use the paravirtualized ticketlock mechanism.
Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
Reviewed-by: David Vrabel <david.vrabel@citrix.com>
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Before this patch we would patch all of the pv_lock_ops sites
using alternative assembler. Then later in the bootup cycle
change the unlock_kick and lock_spinning to the Xen specific -
without re patching.
That meant that for the core of the kernel we would be running
with the baremetal version of unlock_kick and lock_spinning while
for modules we would have the proper Xen specific slowpaths.
As most of the module uses some API from the core kernel that ended
up with slowpath lockers waiting forever to be kicked (b/c they
would be using the Xen specific slowpath logic). And the
kick never came b/c the unlock path that was taken was the
baremetal one.
On PV we do not have the problem as we initialise before the
alternative code kicks in.
The fix is to make the updating of the pv_lock_ops function
be done before the alternative code starts patching.
Note that this patch fixes issues discovered by commit
f10cd522c5fbfec9ae3cc01967868c9c2401ed23.
("xen: disable PV spinlocks on HVM") wherein it mentioned
PV spinlocks cannot possibly work with the current code because they are
enabled after pvops patching has already been done, and because PV
spinlocks use a different data structure than native spinlocks so we
cannot switch between them dynamically.
The first problem is solved by this patch.
The second problem has been solved by commit
816434ec4a674fcdb3c2221a6dffdc8f34020550
(Merge branch 'x86-spinlocks-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip)
P.S.
There is still the commit 70dd4998cb85f0ecd6ac892cc7232abefa432efb
(xen/spinlock: Disable IRQ spinlock (PV) allocation on PVHVM) to
revert but that can be done later after all other bugs have been
fixed.
Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
Reviewed-by: David Vrabel <david.vrabel@citrix.com>
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As we are using the generic ticketlock structs and these
old structures are not needed anymore.
Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
Reviewed-by: David Vrabel <david.vrabel@citrix.com>
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The xen_lock_spinning has a check for the kicker interrupts
and if it is not initialized it will spin normally (not enter
the slowpath).
But for PVHVM case we would initialize the kicker interrupt
before the CPU came online. This meant that if the booting
CPU used a spinlock and went in the slowpath - it would
enter the slowpath and block forever. The forever part because
during bootup: the spinlock would be taken _before_ the CPU
sets itself to be online (more on this further), and we enter
to poll on the event channel forever.
The bootup CPU (see commit fc78d343fa74514f6fd117b5ef4cd27e4ac30236
"xen/smp: initialize IPI vectors before marking CPU online"
for details) and the CPU that started the bootup consult
the cpu_online_mask to determine whether the booting CPU should
get an IPI. The booting CPU has to set itself in this mask via:
set_cpu_online(smp_processor_id(), true);
However, if the spinlock is taken before this (and it is) and
it polls on an event channel - it will never be woken up as
the kernel will never send an IPI to an offline CPU.
Note that the PVHVM logic in sending IPIs is using the HVM
path which has numerous checks using the cpu_online_mask
and cpu_active_mask. See above mention git commit for details.
Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
Reviewed-by: David Vrabel <david.vrabel@citrix.com>
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Linux 3.11-rc7
As we need the git commit 28817e9de4f039a1a8c1fe1df2fa2df524626b9e
Author: Chuck Anderson <chuck.anderson@oracle.com>
Date: Tue Aug 6 15:12:19 2013 -0700
xen/smp: initialize IPI vectors before marking CPU online
* tag 'v3.11-rc7': (443 commits)
Linux 3.11-rc7
ARC: [lib] strchr breakage in Big-endian configuration
VFS: collect_mounts() should return an ERR_PTR
bfs: iget_locked() doesn't return an ERR_PTR
efs: iget_locked() doesn't return an ERR_PTR()
proc: kill the extra proc_readfd_common()->dir_emit_dots()
cope with potentially long ->d_dname() output for shmem/hugetlb
usb: phy: fix build breakage
USB: OHCI: add missing PCI PM callbacks to ohci-pci.c
staging: comedi: bug-fix NULL pointer dereference on failed attach
lib/lz4: correct the LZ4 license
memcg: get rid of swapaccount leftovers
nilfs2: fix issue with counting number of bio requests for BIO_EOPNOTSUPP error detection
nilfs2: remove double bio_put() in nilfs_end_bio_write() for BIO_EOPNOTSUPP error
drivers/platform/olpc/olpc-ec.c: initialise earlier
ipv4: expose IPV4_DEVCONF
ipv6: handle Redirect ICMP Message with no Redirected Header option
be2net: fix disabling TX in be_close()
Revert "ACPI / video: Always call acpi_video_init_brightness() on init"
Revert "genetlink: fix family dump race"
...
Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
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git://git.kernel.org/pub/scm/linux/kernel/git/xen/tip
Pull Xen bug-fixes from Konrad Rzeszutek Wilk:
- On ARM did not have balanced calls to get/put_cpu.
- Fix to make tboot + Xen + Linux correctly.
- Fix events VCPU binding issues.
- Fix a vCPU online race where IPIs are sent to not-yet-online vCPU.
* tag 'stable/for-linus-3.11-rc6-tag' of git://git.kernel.org/pub/scm/linux/kernel/git/xen/tip:
xen/smp: initialize IPI vectors before marking CPU online
xen/events: mask events when changing their VCPU binding
xen/events: initialize local per-cpu mask for all possible events
x86/xen: do not identity map UNUSABLE regions in the machine E820
xen/arm: missing put_cpu in xen_percpu_init
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An older PVHVM guest (v3.0 based) crashed during vCPU hot-plug with:
kernel BUG at drivers/xen/events.c:1328!
RCU has detected that a CPU has not entered a quiescent state within the
grace period. It needs to send the CPU a reschedule IPI if it is not
offline. rcu_implicit_offline_qs() does this check:
/*
* If the CPU is offline, it is in a quiescent state. We can
* trust its state not to change because interrupts are disabled.
*/
if (cpu_is_offline(rdp->cpu)) {
rdp->offline_fqs++;
return 1;
}
Else the CPU is online. Send it a reschedule IPI.
The CPU is in the middle of being hot-plugged and has been marked online
(!cpu_is_offline()). See start_secondary():
set_cpu_online(smp_processor_id(), true);
...
per_cpu(cpu_state, smp_processor_id()) = CPU_ONLINE;
start_secondary() then waits for the CPU bringing up the hot-plugged CPU to
mark it as active:
/*
* Wait until the cpu which brought this one up marked it
* online before enabling interrupts. If we don't do that then
* we can end up waking up the softirq thread before this cpu
* reached the active state, which makes the scheduler unhappy
* and schedule the softirq thread on the wrong cpu. This is
* only observable with forced threaded interrupts, but in
* theory it could also happen w/o them. It's just way harder
* to achieve.
*/
while (!cpumask_test_cpu(smp_processor_id(), cpu_active_mask))
cpu_relax();
/* enable local interrupts */
local_irq_enable();
The CPU being hot-plugged will be marked active after it has been fully
initialized by the CPU managing the hot-plug. In the Xen PVHVM case
xen_smp_intr_init() is called to set up the hot-plugged vCPU's
XEN_RESCHEDULE_VECTOR.
The hot-plugging CPU is marked online, not marked active and does not have
its IPI vectors set up. rcu_implicit_offline_qs() sees the hot-plugging
cpu is !cpu_is_offline() and tries to send it a reschedule IPI:
This will lead to:
kernel BUG at drivers/xen/events.c:1328!
xen_send_IPI_one()
xen_smp_send_reschedule()
rcu_implicit_offline_qs()
rcu_implicit_dynticks_qs()
force_qs_rnp()
force_quiescent_state()
__rcu_process_callbacks()
rcu_process_callbacks()
__do_softirq()
call_softirq()
do_softirq()
irq_exit()
xen_evtchn_do_upcall()
because xen_send_IPI_one() will attempt to use an uninitialized IRQ for
the XEN_RESCHEDULE_VECTOR.
There is at least one other place that has caused the same crash:
xen_smp_send_reschedule()
wake_up_idle_cpu()
add_timer_on()
clocksource_watchdog()
call_timer_fn()
run_timer_softirq()
__do_softirq()
call_softirq()
do_softirq()
irq_exit()
xen_evtchn_do_upcall()
xen_hvm_callback_vector()
clocksource_watchdog() uses cpu_online_mask to pick the next CPU to handle
a watchdog timer:
/*
* Cycle through CPUs to check if the CPUs stay synchronized
* to each other.
*/
next_cpu = cpumask_next(raw_smp_processor_id(), cpu_online_mask);
if (next_cpu >= nr_cpu_ids)
next_cpu = cpumask_first(cpu_online_mask);
watchdog_timer.expires += WATCHDOG_INTERVAL;
add_timer_on(&watchdog_timer, next_cpu);
This resulted in an attempt to send an IPI to a hot-plugging CPU that
had not initialized its reschedule vector. One option would be to make
the RCU code check to not check for CPU offline but for CPU active.
As becoming active is done after a CPU is online (in older kernels).
But Srivatsa pointed out that "the cpu_active vs cpu_online ordering has been
completely reworked - in the online path, cpu_active is set *before* cpu_online,
and also, in the cpu offline path, the cpu_active bit is reset in the CPU_DYING
notification instead of CPU_DOWN_PREPARE." Drilling in this the bring-up
path: "[brought up CPU].. send out a CPU_STARTING notification, and in response
to that, the scheduler sets the CPU in the cpu_active_mask. Again, this mask
is better left to the scheduler alone, since it has the intelligence to use it
judiciously."
The conclusion was that:
"
1. At the IPI sender side:
It is incorrect to send an IPI to an offline CPU (cpu not present in
the cpu_online_mask). There are numerous places where we check this
and warn/complain.
2. At the IPI receiver side:
It is incorrect to let the world know of our presence (by setting
ourselves in global bitmasks) until our initialization steps are complete
to such an extent that we can handle the consequences (such as
receiving interrupts without crashing the sender etc.)
" (from Srivatsa)
As the native code enables the interrupts at some point we need to be
able to service them. In other words a CPU must have valid IPI vectors
if it has been marked online.
It doesn't need to handle the IPI (interrupts may be disabled) but needs
to have valid IPI vectors because another CPU may find it in cpu_online_mask
and attempt to send it an IPI.
This patch will change the order of the Xen vCPU bring-up functions so that
Xen vectors have been set up before start_secondary() is called.
It also will not continue to bring up a Xen vCPU if xen_smp_intr_init() fails
to initialize it.
Orabug 13823853
Signed-off-by Chuck Anderson <chuck.anderson@oracle.com>
Acked-by: Srivatsa S. Bhat <srivatsa.bhat@linux.vnet.ibm.com>
Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
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If there are UNUSABLE regions in the machine memory map, dom0 will
attempt to map them 1:1 which is not permitted by Xen and the kernel
will crash.
There isn't anything interesting in the UNUSABLE region that the dom0
kernel needs access to so we can avoid making the 1:1 mapping and
treat it as RAM.
We only do this for dom0, as that is where tboot case shows up.
A PV domU could have an UNUSABLE region in its pseudo-physical map
and would need to be handled in another patch.
This fixes a boot failure on hosts with tboot.
tboot marks a region in the e820 map as unusable and the dom0 kernel
would attempt to map this region and Xen does not permit unusable
regions to be mapped by guests.
(XEN) 0000000000000000 - 0000000000060000 (usable)
(XEN) 0000000000060000 - 0000000000068000 (reserved)
(XEN) 0000000000068000 - 000000000009e000 (usable)
(XEN) 0000000000100000 - 0000000000800000 (usable)
(XEN) 0000000000800000 - 0000000000972000 (unusable)
tboot marked this region as unusable.
(XEN) 0000000000972000 - 00000000cf200000 (usable)
(XEN) 00000000cf200000 - 00000000cf38f000 (reserved)
(XEN) 00000000cf38f000 - 00000000cf3ce000 (ACPI data)
(XEN) 00000000cf3ce000 - 00000000d0000000 (reserved)
(XEN) 00000000e0000000 - 00000000f0000000 (reserved)
(XEN) 00000000fe000000 - 0000000100000000 (reserved)
(XEN) 0000000100000000 - 0000000630000000 (usable)
Signed-off-by: David Vrabel <david.vrabel@citrix.com>
[v1: Altered the patch and description with domU's with UNUSABLE regions]
Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
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git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip into stable/for-linus-3.12
* 'x86/spinlocks' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
x86/kvm/guest: Fix sparse warning: "symbol 'klock_waiting' was not declared as static"
kvm: Paravirtual ticketlocks support for linux guests running on KVM hypervisor
kvm guest: Add configuration support to enable debug information for KVM Guests
kvm uapi: Add KICK_CPU and PV_UNHALT definition to uapi
xen, pvticketlock: Allow interrupts to be enabled while blocking
x86, ticketlock: Add slowpath logic
jump_label: Split jumplabel ratelimit
x86, pvticketlock: When paravirtualizing ticket locks, increment by 2
x86, pvticketlock: Use callee-save for lock_spinning
xen, pvticketlocks: Add xen_nopvspin parameter to disable xen pv ticketlocks
xen, pvticketlock: Xen implementation for PV ticket locks
xen: Defer spinlock setup until boot CPU setup
x86, ticketlock: Collapse a layer of functions
x86, ticketlock: Don't inline _spin_unlock when using paravirt spinlocks
x86, spinlock: Replace pv spinlocks with pv ticketlocks
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If interrupts were enabled when taking the spinlock, we can leave them
enabled while blocking to get the lock.
If we can enable interrupts while waiting for the lock to become
available, and we take an interrupt before entering the poll,
and the handler takes a spinlock which ends up going into
the slow state (invalidating the per-cpu "lock" and "want" values),
then when the interrupt handler returns the event channel will
remain pending so the poll will return immediately, causing it to
return out to the main spinlock loop.
Signed-off-by: Jeremy Fitzhardinge <jeremy@goop.org>
Link: http://lkml.kernel.org/r/1376058122-8248-12-git-send-email-raghavendra.kt@linux.vnet.ibm.com
Reviewed-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
Signed-off-by: Raghavendra K T <raghavendra.kt@linux.vnet.ibm.com>
Acked-by: Ingo Molnar <mingo@kernel.org>
Signed-off-by: H. Peter Anvin <hpa@linux.intel.com>
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Maintain a flag in the LSB of the ticket lock tail which indicates
whether anyone is in the lock slowpath and may need kicking when
the current holder unlocks. The flags are set when the first locker
enters the slowpath, and cleared when unlocking to an empty queue (ie,
no contention).
In the specific implementation of lock_spinning(), make sure to set
the slowpath flags on the lock just before blocking. We must do
this before the last-chance pickup test to prevent a deadlock
with the unlocker:
Unlocker Locker
test for lock pickup
-> fail
unlock
test slowpath
-> false
set slowpath flags
block
Whereas this works in any ordering:
Unlocker Locker
set slowpath flags
test for lock pickup
-> fail
block
unlock
test slowpath
-> true, kick
If the unlocker finds that the lock has the slowpath flag set but it is
actually uncontended (ie, head == tail, so nobody is waiting), then it
clears the slowpath flag.
The unlock code uses a locked add to update the head counter. This also
acts as a full memory barrier so that its safe to subsequently
read back the slowflag state, knowing that the updated lock is visible
to the other CPUs. If it were an unlocked add, then the flag read may
just be forwarded from the store buffer before it was visible to the other
CPUs, which could result in a deadlock.
Unfortunately this means we need to do a locked instruction when
unlocking with PV ticketlocks. However, if PV ticketlocks are not
enabled, then the old non-locked "add" is the only unlocking code.
Note: this code relies on gcc making sure that unlikely() code is out of
line of the fastpath, which only happens when OPTIMIZE_SIZE=n. If it
doesn't the generated code isn't too bad, but its definitely suboptimal.
Thanks to Srivatsa Vaddagiri for providing a bugfix to the original
version of this change, which has been folded in.
Thanks to Stephan Diestelhorst for commenting on some code which relied
on an inaccurate reading of the x86 memory ordering rules.
Signed-off-by: Jeremy Fitzhardinge <jeremy@goop.org>
Link: http://lkml.kernel.org/r/1376058122-8248-11-git-send-email-raghavendra.kt@linux.vnet.ibm.com
Signed-off-by: Srivatsa Vaddagiri <vatsa@linux.vnet.ibm.com>
Reviewed-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
Cc: Stephan Diestelhorst <stephan.diestelhorst@amd.com>
Signed-off-by: Raghavendra K T <raghavendra.kt@linux.vnet.ibm.com>
Acked-by: Ingo Molnar <mingo@kernel.org>
Signed-off-by: H. Peter Anvin <hpa@linux.intel.com>
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Although the lock_spinning calls in the spinlock code are on the
uncommon path, their presence can cause the compiler to generate many
more register save/restores in the function pre/postamble, which is in
the fast path. To avoid this, convert it to using the pvops callee-save
calling convention, which defers all the save/restores until the actual
function is called, keeping the fastpath clean.
Signed-off-by: Jeremy Fitzhardinge <jeremy@goop.org>
Link: http://lkml.kernel.org/r/1376058122-8248-8-git-send-email-raghavendra.kt@linux.vnet.ibm.com
Reviewed-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
Tested-by: Attilio Rao <attilio.rao@citrix.com>
Signed-off-by: Raghavendra K T <raghavendra.kt@linux.vnet.ibm.com>
Acked-by: Ingo Molnar <mingo@kernel.org>
Signed-off-by: H. Peter Anvin <hpa@linux.intel.com>
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Signed-off-by: Jeremy Fitzhardinge <jeremy@goop.org>
Link: http://lkml.kernel.org/r/1376058122-8248-7-git-send-email-raghavendra.kt@linux.vnet.ibm.com
Reviewed-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
Signed-off-by: Raghavendra K T <raghavendra.kt@linux.vnet.ibm.com>
Acked-by: Ingo Molnar <mingo@kernel.org>
Signed-off-by: H. Peter Anvin <hpa@linux.intel.com>
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Replace the old Xen implementation of PV spinlocks with and implementation
of xen_lock_spinning and xen_unlock_kick.
xen_lock_spinning simply registers the cpu in its entry in lock_waiting,
adds itself to the waiting_cpus set, and blocks on an event channel
until the channel becomes pending.
xen_unlock_kick searches the cpus in waiting_cpus looking for the one
which next wants this lock with the next ticket, if any. If found,
it kicks it by making its event channel pending, which wakes it up.
We need to make sure interrupts are disabled while we're relying on the
contents of the per-cpu lock_waiting values, otherwise an interrupt
handler could come in, try to take some other lock, block, and overwrite
our values.
Signed-off-by: Jeremy Fitzhardinge <jeremy@goop.org>
Link: http://lkml.kernel.org/r/1376058122-8248-6-git-send-email-raghavendra.kt@linux.vnet.ibm.com
Reviewed-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
[ Raghavendra: use function + enum instead of macro, cmpxchg for zero status reset
Reintroduce break since we know the exact vCPU to send IPI as suggested by Konrad.]
Signed-off-by: Raghavendra K T <raghavendra.kt@linux.vnet.ibm.com>
Acked-by: Ingo Molnar <mingo@kernel.org>
Signed-off-by: H. Peter Anvin <hpa@linux.intel.com>
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There's no need to do it at very early init, and doing it there
makes it impossible to use the jump_label machinery.
Signed-off-by: Jeremy Fitzhardinge <jeremy@goop.org>
Link: http://lkml.kernel.org/r/1376058122-8248-5-git-send-email-raghavendra.kt@linux.vnet.ibm.com
Reviewed-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
Signed-off-by: Raghavendra K T <raghavendra.kt@linux.vnet.ibm.com>
Acked-by: Ingo Molnar <mingo@kernel.org>
Signed-off-by: H. Peter Anvin <hpa@linux.intel.com>
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Rather than outright replacing the entire spinlock implementation in
order to paravirtualize it, keep the ticket lock implementation but add
a couple of pvops hooks on the slow patch (long spin on lock, unlocking
a contended lock).
Ticket locks have a number of nice properties, but they also have some
surprising behaviours in virtual environments. They enforce a strict
FIFO ordering on cpus trying to take a lock; however, if the hypervisor
scheduler does not schedule the cpus in the correct order, the system can
waste a huge amount of time spinning until the next cpu can take the lock.
(See Thomas Friebel's talk "Prevent Guests from Spinning Around"
http://www.xen.org/files/xensummitboston08/LHP.pdf for more details.)
To address this, we add two hooks:
- __ticket_spin_lock which is called after the cpu has been
spinning on the lock for a significant number of iterations but has
failed to take the lock (presumably because the cpu holding the lock
has been descheduled). The lock_spinning pvop is expected to block
the cpu until it has been kicked by the current lock holder.
- __ticket_spin_unlock, which on releasing a contended lock
(there are more cpus with tail tickets), it looks to see if the next
cpu is blocked and wakes it if so.
When compiled with CONFIG_PARAVIRT_SPINLOCKS disabled, a set of stub
functions causes all the extra code to go away.
Results:
=======
setup: 32 core machine with 32 vcpu KVM guest (HT off) with 8GB RAM
base = 3.11-rc
patched = base + pvspinlock V12
+-----------------+----------------+--------+
dbench (Throughput in MB/sec. Higher is better)
+-----------------+----------------+--------+
| base (stdev %)|patched(stdev%) | %gain |
+-----------------+----------------+--------+
| 15035.3 (0.3) |15150.0 (0.6) | 0.8 |
| 1470.0 (2.2) | 1713.7 (1.9) | 16.6 |
| 848.6 (4.3) | 967.8 (4.3) | 14.0 |
| 652.9 (3.5) | 685.3 (3.7) | 5.0 |
+-----------------+----------------+--------+
pvspinlock shows benefits for overcommit ratio > 1 for PLE enabled cases,
and undercommits results are flat
Signed-off-by: Jeremy Fitzhardinge <jeremy@goop.org>
Link: http://lkml.kernel.org/r/1376058122-8248-2-git-send-email-raghavendra.kt@linux.vnet.ibm.com
Reviewed-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
Tested-by: Attilio Rao <attilio.rao@citrix.com>
[ Raghavendra: Changed SPIN_THRESHOLD, fixed redefinition of arch_spinlock_t]
Signed-off-by: Raghavendra K T <raghavendra.kt@linux.vnet.ibm.com>
Acked-by: Ingo Molnar <mingo@kernel.org>
Signed-off-by: H. Peter Anvin <hpa@linux.intel.com>
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disabled for multicalls
m2p_remove_override() calls get_balloon_scratch_page() in
MULTI_update_va_mapping() even though it already has pointer to this page from
the earlier call (in scratch_page). This second call doesn't have a matching
put_balloon_scratch_page() thus not restoring preempt count back. (Also, there
is no put_balloon_scratch_page() in the error path.)
In addition, the second multicall uses __xen_mc_entry() which does not disable
interrupts. Rearrange xen_mc_* calls to keep interrupts off while performing
multicalls.
This commit fixes a regression introduced by:
commit ee0726407feaf504dff304fb603652fb2d778b42
Author: Stefano Stabellini <stefano.stabellini@eu.citrix.com>
Date: Tue Jul 23 17:23:54 2013 +0000
xen/m2p: use GNTTABOP_unmap_and_replace to reinstate the original mapping
Signed-off-by: Boris Ostrovsky <boris.ostrovsky@oracle.com>
Reviewed-by: Stefano Stabellini <stefano.stabellini@eu.citrix.com>
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kernel use callback linked in panic_notifier_list to notice others when panic
happens.
NORET_TYPE void panic(const char * fmt, ...){
...
atomic_notifier_call_chain(&panic_notifier_list, 0, buf);
}
When Xen becomes aware of this, it will call xen_reboot(SHUTDOWN_crash) to
send out an event with reason code - SHUTDOWN_crash.
xen_panic_handler_init() is defined to register on panic_notifier_list but
we only call it in xen_arch_setup which only be called by PV, this patch is
necessary for PVHVM.
Without this patch, setting 'on_crash=coredump-restart' in PVHVM guest config
file won't lead a vmcore to be generate when the guest panics. It can be
reproduced with 'echo c > /proc/sysrq-trigger'.
Signed-off-by: Vaughan Cao <vaughan.cao@oracle.com>
Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
Acked-by: Joe Jin <joe.jin@oracle.com>
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GNTTABOP_unmap_grant_ref unmaps a grant and replaces it with a 0
mapping instead of reinstating the original mapping.
Doing so separately would be racy.
To unmap a grant and reinstate the original mapping atomically we use
GNTTABOP_unmap_and_replace.
GNTTABOP_unmap_and_replace doesn't work with GNTMAP_contains_pte, so
don't use it for kmaps. GNTTABOP_unmap_and_replace zeroes the mapping
passed in new_addr so we have to reinstate it, however that is a
per-cpu mapping only used for balloon scratch pages, so we can be sure that
it's not going to be accessed while the mapping is not valid.
Signed-off-by: Stefano Stabellini <stefano.stabellini@eu.citrix.com>
Reviewed-by: David Vrabel <david.vrabel@citrix.com>
Acked-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
CC: alex@alex.org.uk
CC: dcrisan@flexiant.com
[v1: Konrad fixed up the conflicts]
Conflicts:
arch/x86/xen/p2m.c
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During early setup, when the reserved regions and MMIO holes are being
setup as 1:1 in the p2m, clear any mappings instead of making them 1:1
(execept for the ISA region which is expected to be mapped).
This fixes a regression introduced in 3.5 by 83d51ab473dd (xen/setup:
update VA mapping when releasing memory during setup) which caused
hosts with tboot to fail to boot.
tboot marks a region in the e820 map as unusable and the dom0 kernel
would attempt to map this region and Xen does not permit unusable
regions to be mapped by guests.
(XEN) 0000000000000000 - 0000000000060000 (usable)
(XEN) 0000000000060000 - 0000000000068000 (reserved)
(XEN) 0000000000068000 - 000000000009e000 (usable)
(XEN) 0000000000100000 - 0000000000800000 (usable)
(XEN) 0000000000800000 - 0000000000972000 (unusable)
tboot marked this region as unusable.
(XEN) 0000000000972000 - 00000000cf200000 (usable)
(XEN) 00000000cf200000 - 00000000cf38f000 (reserved)
(XEN) 00000000cf38f000 - 00000000cf3ce000 (ACPI data)
(XEN) 00000000cf3ce000 - 00000000d0000000 (reserved)
(XEN) 00000000e0000000 - 00000000f0000000 (reserved)
(XEN) 00000000fe000000 - 0000000100000000 (reserved)
(XEN) 0000000100000000 - 0000000630000000 (usable)
Signed-off-by: David Vrabel <david.vrabel@citrix.com>
Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
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If CONFIG_PREEMPT is enabled then xen_enable_irq() (and
xen_restore_fl()) could be preempted and rescheduled on a different
VCPU in between the clear of the mask and the check for pending
events. This may result in events being lost as the upcall will check
for pending events on the wrong VCPU.
Fix this by disabling preemption around the unmask and check for
events.
Signed-off-by: David Vrabel <david.vrabel@citrix.com>
Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
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In m2p_remove_override() when removing the grant map from the kernel
mapping and replacing with a mapping to the original page, the grant
unmap will already have flushed the TLB and it is not necessary to do
it again after updating the mapping.
Signed-off-by: David Vrabel <david.vrabel@citrix.com>
Cc: Stefano Stabellini <stefano.stabellini@eu.citrix.com>
Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
Reviewed-by: Stefano Stabellini <stefano.stabellini@eu.citrix.com>
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This is based on a patch that Zhenzhong Duan had sent - which
was missing some of the remaining pieces. The kernel has the
logic to handle Xen-type-exceptions using the paravirt interface
in the assembler code (see PARAVIRT_ADJUST_EXCEPTION_FRAME -
pv_irq_ops.adjust_exception_frame and and INTERRUPT_RETURN -
pv_cpu_ops.iret).
That means the nmi handler (and other exception handlers) use
the hypervisor iret.
The other changes that would be neccessary for this would
be to translate the NMI_VECTOR to one of the entries on the
ipi_vector and make xen_send_IPI_mask_allbutself use different
events.
Fortunately for us commit 1db01b4903639fcfaec213701a494fe3fb2c490b
(xen: Clean up apic ipi interface) implemented this and we piggyback
on the cleanup such that the apic IPI interface will pass the right
vector value for NMI.
With this patch we can trigger NMIs within a PV guest (only tested
x86_64).
For this to work with normal PV guests (not initial domain)
we need the domain to be able to use the APIC ops - they are
already implemented to use the Xen event channels. For that
to be turned on in a PV domU we need to remove the masking
of X86_FEATURE_APIC.
Incidentally that means kgdb will also now work within
a PV guest without using the 'nokgdbroundup' workaround.
Note that the 32-bit version is different and this patch
does not enable that.
CC: Lisa Nguyen <lisa@xenapiadmin.com>
CC: Ben Guthro <benjamin.guthro@citrix.com>
CC: Zhenzhong Duan <zhenzhong.duan@oracle.com>
Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
[v1: Fixed up per David Vrabel comments]
Reviewed-by: Ben Guthro <benjamin.guthro@citrix.com>
Reviewed-by: David Vrabel <david.vrabel@citrix.com>
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The __cpuinit type of throwaway sections might have made sense
some time ago when RAM was more constrained, but now the savings
do not offset the cost and complications. For example, the fix in
commit 5e427ec2d0 ("x86: Fix bit corruption at CPU resume time")
is a good example of the nasty type of bugs that can be created
with improper use of the various __init prefixes.
After a discussion on LKML[1] it was decided that cpuinit should go
the way of devinit and be phased out. Once all the users are gone,
we can then finally remove the macros themselves from linux/init.h.
Note that some harmless section mismatch warnings may result, since
notify_cpu_starting() and cpu_up() are arch independent (kernel/cpu.c)
are flagged as __cpuinit -- so if we remove the __cpuinit from
arch specific callers, we will also get section mismatch warnings.
As an intermediate step, we intend to turn the linux/init.h cpuinit
content into no-ops as early as possible, since that will get rid
of these warnings. In any case, they are temporary and harmless.
This removes all the arch/x86 uses of the __cpuinit macros from
all C files. x86 only had the one __CPUINIT used in assembly files,
and it wasn't paired off with a .previous or a __FINIT, so we can
delete it directly w/o any corresponding additional change there.
[1] https://lkml.org/lkml/2013/5/20/589
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Cc: x86@kernel.org
Acked-by: Ingo Molnar <mingo@kernel.org>
Acked-by: Thomas Gleixner <tglx@linutronix.de>
Acked-by: H. Peter Anvin <hpa@linux.intel.com>
Signed-off-by: Paul Gortmaker <paul.gortmaker@windriver.com>
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git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip
Pull timer core updates from Thomas Gleixner:
"The timer changes contain:
- posix timer code consolidation and fixes for odd corner cases
- sched_clock implementation moved from ARM to core code to avoid
duplication by other architectures
- alarm timer updates
- clocksource and clockevents unregistration facilities
- clocksource/events support for new hardware
- precise nanoseconds RTC readout (Xen feature)
- generic support for Xen suspend/resume oddities
- the usual lot of fixes and cleanups all over the place
The parts which touch other areas (ARM/XEN) have been coordinated with
the relevant maintainers. Though this results in an handful of
trivial to solve merge conflicts, which we preferred over nasty cross
tree merge dependencies.
The patches which have been committed in the last few days are bug
fixes plus the posix timer lot. The latter was in akpms queue and
next for quite some time; they just got forgotten and Frederic
collected them last minute."
* 'timers-core-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (59 commits)
hrtimer: Remove unused variable
hrtimers: Move SMP function call to thread context
clocksource: Reselect clocksource when watchdog validated high-res capability
posix-cpu-timers: don't account cpu timer after stopped thread runtime accounting
posix_timers: fix racy timer delta caching on task exit
posix-timers: correctly get dying task time sample in posix_cpu_timer_schedule()
selftests: add basic posix timers selftests
posix_cpu_timers: consolidate expired timers check
posix_cpu_timers: consolidate timer list cleanups
posix_cpu_timer: consolidate expiry time type
tick: Sanitize broadcast control logic
tick: Prevent uncontrolled switch to oneshot mode
tick: Make oneshot broadcast robust vs. CPU offlining
x86: xen: Sync the CMOS RTC as well as the Xen wallclock
x86: xen: Sync the wallclock when the system time is set
timekeeping: Indicate that clock was set in the pvclock gtod notifier
timekeeping: Pass flags instead of multiple bools to timekeeping_update()
xen: Remove clock_was_set() call in the resume path
hrtimers: Support resuming with two or more CPUs online (but stopped)
timer: Fix jiffies wrap behavior of round_jiffies_common()
...
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git://git.kernel.org/pub/scm/linux/kernel/git/frederic/linux-dynticks into timers/core
Frederic sayed: "Most of these patches have been hanging around for
several month now, in -mmotm for a significant chunk. They already
missed a few releases."
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
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Adjustments to Xen's persistent clock via update_persistent_clock()
don't actually persist, as the Xen wallclock is a software only clock
and modifications to it do not modify the underlying CMOS RTC.
The x86_platform.set_wallclock hook is there to keep the hardware RTC
synchronized. On a guest this is pointless.
On Dom0 we can use the native implementaion which actually updates the
hardware RTC, but we still need to keep the software emulation of RTC
for the guests up to date. The subscription to the pvclock_notifier
allows us to emulate this easily. The notifier is called at every tick
and when the clock was set.
Right now we only use that notifier when the clock was set, but due to
the fact that it is called periodically from the timekeeping update
code, we can utilize it to emulate the NTP driven drift compensation
of update_persistant_clock() for the Xen wall (software) clock.
Add a 11 minutes periodic update to the pvclock_gtod notifier callback
to achieve that. The static variable 'next' which maintains that 11
minutes update cycle is protected by the core code serialization so
there is no need to add a Xen specific serialization mechanism.
[ tglx: Massaged changelog and added a few comments ]
Signed-off-by: David Vrabel <david.vrabel@citrix.com>
Cc: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
Cc: John Stultz <john.stultz@linaro.org>
Cc: <xen-devel@lists.xen.org>
Link: http://lkml.kernel.org/r/1372329348-20841-6-git-send-email-david.vrabel@citrix.com
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
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Currently the Xen wallclock is only updated every 11 minutes if NTP is
synchronized to its clock source (using the sync_cmos_clock() work).
If a guest is started before NTP is synchronized it may see an
incorrect wallclock time.
Use the pvclock_gtod notifier chain to receive a notification when the
system time has changed and update the wallclock to match.
This chain is called on every timer tick and we want to avoid an extra
(expensive) hypercall on every tick. Because dom0 has historically
never provided a very accurate wallclock and guests do not expect one,
we can do this simply: the wallclock is only updated if the clock was
set.
Signed-off-by: David Vrabel <david.vrabel@citrix.com>
Cc: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
Cc: John Stultz <john.stultz@linaro.org>
Cc: <xen-devel@lists.xen.org>
Link: http://lkml.kernel.org/r/1372329348-20841-5-git-send-email-david.vrabel@citrix.com
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
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All the virtualized platforms (KVM, lguest and Xen) have persistent
wallclocks that have more than one second of precision.
read_persistent_wallclock() and update_persistent_wallclock() allow
for nanosecond precision but their implementation on x86 with
x86_platform.get/set_wallclock() only allows for one second precision.
This means guests may see a wallclock time that is off by up to 1
second.
Make set_wallclock() and get_wallclock() take a struct timespec
parameter (which allows for nanosecond precision) so KVM and Xen
guests may start with a more accurate wallclock time and a Xen dom0
can maintain a more accurate wallclock for guests.
Signed-off-by: David Vrabel <david.vrabel@citrix.com>
Signed-off-by: John Stultz <john.stultz@linaro.org>
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git://git.kernel.org/pub/scm/linux/kernel/git/konrad/xen
Pull Xen bugfixes from Konrad Rzeszutek Wilk:
- Fix memory leak when CPU hotplugging.
- Compile bugs with various #ifdefs
- Fix state changes in Xen PCI front not dealing well with new
toolstack.
- Cleanups in code (use pr_*, fix 80 characters splits, etc)
- Long standing bug in double-reporting the steal time
* tag 'stable/for-linus-3.11-rc0-tag-two' of git://git.kernel.org/pub/scm/linux/kernel/git/konrad/xen:
xen/time: remove blocked time accounting from xen "clockchip"
xen: Convert printks to pr_<level>
xen: ifdef CONFIG_HIBERNATE_CALLBACKS xen_*_suspend
xen/pcifront: Deal with toolstack missing 'XenbusStateClosing' state.
xen/time: Free onlined per-cpu data structure if we want to online it again.
xen/time: Check that the per_cpu data structure has data before freeing.
xen/time: Don't leak interrupt name when offlining.
xen/time: Encapsulate the struct clock_event_device in another structure.
xen/spinlock: Don't leak interrupt name when offlining.
xen/smp: Don't leak interrupt name when offlining.
xen/smp: Set the per-cpu IRQ number to a valid default.
xen/smp: Introduce a common structure to contain the IRQ name and interrupt line.
xen/smp: Coalesce the free_irq calls in one function.
xen-pciback: fix error return code in pcistub_irq_handler_switch()
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... because the "clock_event_device framework" already accounts for idle
time through the "event_handler" function pointer in
xen_timer_interrupt().
The patch is intended as the completion of [1]. It should fix the double
idle times seen in PV guests' /proc/stat [2]. It should be orthogonal to
stolen time accounting (the removed code seems to be isolated).
The approach may be completely misguided.
[1] https://lkml.org/lkml/2011/10/6/10
[2] http://lists.xensource.com/archives/html/xen-devel/2010-08/msg01068.html
John took the time to retest this patch on top of v3.10 and reported:
"idle time is correctly incremented for pv and hvm for the normal
case, nohz=off and nohz=idle." so lets put this patch in.
CC: stable@vger.kernel.org
Signed-off-by: Laszlo Ersek <lersek@redhat.com>
Signed-off-by: John Haxby <john.haxby@oracle.com>
Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
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If the per-cpu time data structure has been onlined already and
we are trying to online it again, then free the previous copy
before blindly over-writting it.
A developer naturally should not call this function multiple times
but just in case.
Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
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We don't check whether the per_cpu data structure has actually
been freed in the past. This checks it and if it has been freed
in the past then just continues on without double-freeing.
Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
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When the user does:
echo 0 > /sys/devices/system/cpu/cpu1/online
echo 1 > /sys/devices/system/cpu/cpu1/online
kmemleak reports:
kmemleak: 7 new suspected memory leaks (see /sys/kernel/debug/kmemleak)
One of the leaks is from xen/time:
unreferenced object 0xffff88003fa51280 (size 32):
comm "swapper/0", pid 1, jiffies 4294667339 (age 1027.789s)
hex dump (first 32 bytes):
74 69 6d 65 72 31 00 00 00 00 00 00 00 00 00 00 timer1..........
00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................
backtrace:
[<ffffffff81660721>] kmemleak_alloc+0x21/0x50
[<ffffffff81190aac>] __kmalloc_track_caller+0xec/0x2a0
[<ffffffff812fe1bb>] kvasprintf+0x5b/0x90
[<ffffffff812fe228>] kasprintf+0x38/0x40
[<ffffffff81041ec1>] xen_setup_timer+0x51/0xf0
[<ffffffff8166339f>] xen_cpu_up+0x5f/0x3e8
[<ffffffff8166bbf5>] _cpu_up+0xd1/0x14b
[<ffffffff8166bd48>] cpu_up+0xd9/0xec
[<ffffffff81ae6e4a>] smp_init+0x4b/0xa3
[<ffffffff81ac4981>] kernel_init_freeable+0xdb/0x1e6
[<ffffffff8165ce39>] kernel_init+0x9/0xf0
[<ffffffff8167edfc>] ret_from_fork+0x7c/0xb0
[<ffffffffffffffff>] 0xffffffffffffffff
This patch fixes it by stashing away the 'name' in the per-cpu
data structure and freeing it when offlining the CPU.
Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
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We don't do any code movement. We just encapsulate the struct clock_event_device
in a new structure which contains said structure and a pointer to
a char *name. The 'name' will be used in 'xen/time: Don't leak interrupt
name when offlining'.
Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
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When the user does:
echo 0 > /sys/devices/system/cpu/cpu1/online
echo 1 > /sys/devices/system/cpu/cpu1/online
kmemleak reports:
kmemleak: 7 new suspected memory leaks (see /sys/kernel/debug/kmemleak)
unreferenced object 0xffff88003fa51260 (size 32):
comm "swapper/0", pid 1, jiffies 4294667339 (age 1027.789s)
hex dump (first 32 bytes):
73 70 69 6e 6c 6f 63 6b 31 00 00 00 00 00 00 00 spinlock1.......
00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................
backtrace:
[<ffffffff81660721>] kmemleak_alloc+0x21/0x50
[<ffffffff81190aac>] __kmalloc_track_caller+0xec/0x2a0
[<ffffffff812fe1bb>] kvasprintf+0x5b/0x90
[<ffffffff812fe228>] kasprintf+0x38/0x40
[<ffffffff81663789>] xen_init_lock_cpu+0x61/0xbe
[<ffffffff816633a6>] xen_cpu_up+0x66/0x3e8
[<ffffffff8166bbf5>] _cpu_up+0xd1/0x14b
[<ffffffff8166bd48>] cpu_up+0xd9/0xec
[<ffffffff81ae6e4a>] smp_init+0x4b/0xa3
[<ffffffff81ac4981>] kernel_init_freeable+0xdb/0x1e6
[<ffffffff8165ce39>] kernel_init+0x9/0xf0
[<ffffffff8167edfc>] ret_from_fork+0x7c/0xb0
[<ffffffffffffffff>] 0xffffffffffffffff
Instead of doing it like the "xen/smp: Don't leak interrupt name when offlining"
patch did (which has a per-cpu structure which contains both the
IRQ number and char*) we use a per-cpu pointers to a *char.
The reason is that the "__this_cpu_read(lock_kicker_irq);" macro
blows up with "__bad_size_call_parameter()" as the size of the
returned structure is not within the parameters of what it expects
and optimizes for.
Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
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When the user does:
echo 0 > /sys/devices/system/cpu/cpu1/online
echo 1 > /sys/devices/system/cpu/cpu1/online
kmemleak reports:
kmemleak: 7 new suspected memory leaks (see /sys/kernel/debug/kmemleak)
unreferenced object 0xffff88003fa51240 (size 32):
comm "swapper/0", pid 1, jiffies 4294667339 (age 1027.789s)
hex dump (first 32 bytes):
72 65 73 63 68 65 64 31 00 00 00 00 00 00 00 00 resched1........
00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................
backtrace:
[<ffffffff81660721>] kmemleak_alloc+0x21/0x50
[<ffffffff81190aac>] __kmalloc_track_caller+0xec/0x2a0
[<ffffffff812fe1bb>] kvasprintf+0x5b/0x90
[<ffffffff812fe228>] kasprintf+0x38/0x40
[<ffffffff81047ed1>] xen_smp_intr_init+0x41/0x2c0
[<ffffffff816636d3>] xen_cpu_up+0x393/0x3e8
[<ffffffff8166bbf5>] _cpu_up+0xd1/0x14b
[<ffffffff8166bd48>] cpu_up+0xd9/0xec
[<ffffffff81ae6e4a>] smp_init+0x4b/0xa3
[<ffffffff81ac4981>] kernel_init_freeable+0xdb/0x1e6
[<ffffffff8165ce39>] kernel_init+0x9/0xf0
[<ffffffff8167edfc>] ret_from_fork+0x7c/0xb0
[<ffffffffffffffff>] 0xffffffffffffffff
This patch fixes some of it by using the 'struct xen_common_irq->name'
field to stash away the char so that it can be freed when
the interrupt line is destroyed.
Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
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When we free it we want to make sure to set it to a default
value of -1 so that we don't double-free it (in case somebody
calls us twice).
Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
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line.
This patch adds a new structure to contain the common two things
that each of the per-cpu interrupts need:
- an interrupt number,
- and the name of the interrupt (to be added in 'xen/smp: Don't leak
interrupt name when offlining').
This allows us to carry the tuple of the per-cpu interrupt data structure
and expand it as we need in the future.
Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
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There are two functions that do a bunch of 'free_irq' on
the per_cpu IRQ. Instead of having duplicate code just move
it to one function.
This is just code movement.
Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
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git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip
Pull x86 FPU changes from Ingo Molnar:
"There are two bigger changes in this tree:
- Add an [early-use-]safe static_cpu_has() variant and other
robustness improvements, including the new X86_DEBUG_STATIC_CPU_HAS
configurable debugging facility, motivated by recent obscure FPU
code bugs, by Borislav Petkov
- Reimplement FPU detection code in C and drop the old asm code, by
Peter Anvin."
* 'x86-fpu-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
x86, fpu: Use static_cpu_has_safe before alternatives
x86: Add a static_cpu_has_safe variant
x86: Sanity-check static_cpu_has usage
x86, cpu: Add a synthetic, always true, cpu feature
x86: Get rid of ->hard_math and all the FPU asm fu
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Reimplement FPU detection code in C and drop old, not-so-recommended
detection method in asm. Move all the relevant stuff into i387.c where
it conceptually belongs. Finally drop cpuinfo_x86.hard_math.
[ hpa: huge thanks to Borislav for taking my original concept patch
and productizing it ]
[ Boris, note to self: do not use static_cpu_has before alternatives! ]
Signed-off-by: H. Peter Anvin <hpa@zytor.com>
Link: http://lkml.kernel.org/r/1367244262-29511-2-git-send-email-bp@alien8.de
Link: http://lkml.kernel.org/r/1365436666-9837-2-git-send-email-bp@alien8.de
Signed-off-by: Borislav Petkov <bp@suse.de>
Signed-off-by: H. Peter Anvin <hpa@linux.intel.com>
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The xen_play_dead is an undead function. When the vCPU is told to
offline it ends up calling xen_play_dead wherin it calls the
VCPUOP_down hypercall which offlines the vCPU. However, when the
vCPU is onlined back, it resumes execution right after
VCPUOP_down hypercall.
That was OK (albeit the API for play_dead assumes that the CPU
stays dead and never returns) but with commit 4b0c0f294
(tick: Cleanup NOHZ per cpu data on cpu down) that is no longer safe
as said commit resets the ts->inidle which at the start of the
cpu_idle loop was set.
The net effect is that we get this warn:
Broke affinity for irq 16
installing Xen timer for CPU 1
cpu 1 spinlock event irq 48
------------[ cut here ]------------
WARNING: at /home/konrad/linux-linus/kernel/time/tick-sched.c:935 tick_nohz_idle_exit+0x195/0x1b0()
Modules linked in: dm_multipath dm_mod xen_evtchn iscsi_boot_sysfs
CPU: 1 PID: 0 Comm: swapper/1 Not tainted 3.10.0-rc3upstream-00068-gdcdbe33 #1
Hardware name: BIOSTAR Group N61PB-M2S/N61PB-M2S, BIOS 6.00 PG 09/03/2009
ffffffff8193b448 ffff880039da5e60 ffffffff816707c8 ffff880039da5ea0
ffffffff8108ce8b ffff880039da4010 ffff88003fa8e500 ffff880039da4010
0000000000000001 ffff880039da4000 ffff880039da4010 ffff880039da5eb0
Call Trace:
[<ffffffff816707c8>] dump_stack+0x19/0x1b
[<ffffffff8108ce8b>] warn_slowpath_common+0x6b/0xa0
[<ffffffff8108ced5>] warn_slowpath_null+0x15/0x20
[<ffffffff810e4745>] tick_nohz_idle_exit+0x195/0x1b0
[<ffffffff810da755>] cpu_startup_entry+0x205/0x250
[<ffffffff81661070>] cpu_bringup_and_idle+0x13/0x15
---[ end trace 915c8c486004dda1 ]---
b/c ts_inidle is set to zero. Thomas suggested that we just add a workaround
to call tick_nohz_idle_enter before returning from xen_play_dead() - and
that is what this patch does and fixes the issue.
We also add the stable part b/c git commit 4b0c0f294 is on the stable
tree.
CC: stable@vger.kernel.org
Suggested-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
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Commit f447d56d36af18c5104ff29dcb1327c0c0ac3634 introduced the
implementation of the PV apic ipi interface. But there were some
odd things (it seems none of which cause really any issue but
maybe they should be cleaned up anyway):
- xen_send_IPI_mask_allbutself (and by that xen_send_IPI_allbutself)
ignore the passed in vector and only use the CALL_FUNCTION_SINGLE
vector. While xen_send_IPI_all and xen_send_IPI_mask use the vector.
- physflat_send_IPI_allbutself is declared unnecessarily. It is never
used.
This patch tries to clean up those things.
Signed-off-by: Stefan Bader <stefan.bader@canonical.com>
Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
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git://git.kernel.org/pub/scm/linux/kernel/git/konrad/xen
Pull Xen bug-fixes from Konrad Rzeszutek Wilk:
- More fixes in the vCPU PVHVM hotplug path.
- Add more documentation.
- Fix various ARM related issues in the Xen generic drivers.
- Updates in the xen-pciback driver per Bjorn's updates.
- Mask the x2APIC feature for PV guests.
* tag 'stable/for-linus-3.10-rc0-tag-two' of git://git.kernel.org/pub/scm/linux/kernel/git/konrad/xen:
xen/pci: Used cached MSI-X capability offset
xen/pci: Use PCI_MSIX_TABLE_BIR, not PCI_MSIX_FLAGS_BIRMASK
xen: clear IRQ_NOAUTOEN and IRQ_NOREQUEST
xen: mask x2APIC feature in PV
xen: SWIOTLB is only used on x86
xen/spinlock: Fix check from greater than to be also be greater or equal to.
xen/smp/pvhvm: Don't point per_cpu(xen_vpcu, 33 and larger) to shared_info
xen/vcpu: Document the xen_vcpu_info and xen_vcpu
xen/vcpu/pvhvm: Fix vcpu hotplugging hanging.
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On x2apic enabled pvm, doing sysrq+l, got NULL pointer dereference as below.
SysRq : Show backtrace of all active CPUs
BUG: unable to handle kernel NULL pointer dereference at (null)
IP: [<ffffffff8125e3cb>] memcpy+0xb/0x120
Call Trace:
[<ffffffff81039633>] ? __x2apic_send_IPI_mask+0x73/0x160
[<ffffffff8103973e>] x2apic_send_IPI_all+0x1e/0x20
[<ffffffff8103498c>] arch_trigger_all_cpu_backtrace+0x6c/0xb0
[<ffffffff81501be4>] ? _raw_spin_lock_irqsave+0x34/0x50
[<ffffffff8131654e>] sysrq_handle_showallcpus+0xe/0x10
[<ffffffff8131616d>] __handle_sysrq+0x7d/0x140
[<ffffffff81316230>] ? __handle_sysrq+0x140/0x140
[<ffffffff81316287>] write_sysrq_trigger+0x57/0x60
[<ffffffff811ca996>] proc_reg_write+0x86/0xc0
[<ffffffff8116dd8e>] vfs_write+0xce/0x190
[<ffffffff8116e3e5>] sys_write+0x55/0x90
[<ffffffff8150a242>] system_call_fastpath+0x16/0x1b
That's because apic points to apic_x2apic_cluster or apic_x2apic_phys
but the basic element like cpumask isn't initialized.
Mask x2APIC feature in pvm to avoid overwrite of apic pointer,
update commit message per Konrad's suggestion.
Signed-off-by: Zhenzhong Duan <zhenzhong.duan@oracle.com>
Tested-by: Tamon Shiose <tamon.shiose@oracle.com>
Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
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During review of git commit cb9c6f15f318aa3aeb62fe525aa5c6dcf6eee159
("xen/spinlock: Check against default value of -1 for IRQ line.")
Stefano pointed out a bug in the patch. Unfortunatly due to vacation
timing the fix was not applied and this patch fixes it up.
Acked-by: Stefano Stabellini <stefano.stabellini@eu.citrix.com>
Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
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As it will point to some data, but not event channel data (the
shared_info has an array limited to 32).
This means that for PVHVM guests with more than 32 VCPUs without
the usage of VCPUOP_register_info any interrupts to VCPUs
larger than 32 would have gone unnoticed during early bootup.
That is OK, as during early bootup, in smp_init we end up calling
the hotplug mechanism (xen_hvm_cpu_notify) which makes the
VCPUOP_register_vcpu_info call for all VCPUs and we can receive
interrupts on VCPUs 33 and further.
This is just a cleanup.
Acked-by: Stefano Stabellini <stefano.stabellini@eu.citrix.com>
Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
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They are important structures and it is not clear at first
look what they are for.
The xen_vcpu is a pointer. By default it points to the shared_info
structure (at the CPU offset location). However if the
VCPUOP_register_vcpu_info hypercall is implemented we can make the
xen_vcpu pointer point to a per-CPU location.
Acked-by: Stefano Stabellini <stefano.stabellini@eu.citrix.com>
[v1: Added comments from Ian Campbell]
Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
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If a user did:
echo 0 > /sys/devices/system/cpu/cpu1/online
echo 1 > /sys/devices/system/cpu/cpu1/online
we would (this a build with DEBUG enabled) get to:
smpboot: ++++++++++++++++++++=_---CPU UP 1
.. snip..
smpboot: Stack at about ffff880074c0ff44
smpboot: CPU1: has booted.
and hang. The RCU mechanism would kick in an try to IPI the CPU1
but the IPIs (and all other interrupts) would never arrive at the
CPU1. At first glance at least. A bit digging in the hypervisor
trace shows that (using xenanalyze):
[vla] d4v1 vec 243 injecting
0.043163027 --|x d4v1 intr_window vec 243 src 5(vector) intr f3
] 0.043163639 --|x d4v1 vmentry cycles 1468
] 0.043164913 --|x d4v1 vmexit exit_reason PENDING_INTERRUPT eip ffffffff81673254
0.043164913 --|x d4v1 inj_virq vec 243 real
[vla] d4v1 vec 243 injecting
0.043164913 --|x d4v1 intr_window vec 243 src 5(vector) intr f3
] 0.043165526 --|x d4v1 vmentry cycles 1472
] 0.043166800 --|x d4v1 vmexit exit_reason PENDING_INTERRUPT eip ffffffff81673254
0.043166800 --|x d4v1 inj_virq vec 243 real
[vla] d4v1 vec 243 injecting
there is a pending event (subsequent debugging shows it is the IPI
from the VCPU0 when smpboot.c on VCPU1 has done
"set_cpu_online(smp_processor_id(), true)") and the guest VCPU1 is
interrupted with the callback IPI (0xf3 aka 243) which ends up calling
__xen_evtchn_do_upcall.
The __xen_evtchn_do_upcall seems to do *something* but not acknowledge
the pending events. And the moment the guest does a 'cli' (that is the
ffffffff81673254 in the log above) the hypervisor is invoked again to
inject the IPI (0xf3) to tell the guest it has pending interrupts.
This repeats itself forever.
The culprit was the per_cpu(xen_vcpu, cpu) pointer. At the bootup
we set each per_cpu(xen_vcpu, cpu) to point to the
shared_info->vcpu_info[vcpu] but later on use the VCPUOP_register_vcpu_info
to register per-CPU structures (xen_vcpu_setup).
This is used to allow events for more than 32 VCPUs and for performance
optimizations reasons.
When the user performs the VCPU hotplug we end up calling the
the xen_vcpu_setup once more. We make the hypercall which returns
-EINVAL as it does not allow multiple registration calls (and
already has re-assigned where the events are being set). We pick
the fallback case and set per_cpu(xen_vcpu, cpu) to point to the
shared_info->vcpu_info[vcpu] (which is a good fallback during bootup).
However the hypervisor is still setting events in the register
per-cpu structure (per_cpu(xen_vcpu_info, cpu)).
As such when the events are set by the hypervisor (such as timer one),
and when we iterate in __xen_evtchn_do_upcall we end up reading stale
events from the shared_info->vcpu_info[vcpu] instead of the
per_cpu(xen_vcpu_info, cpu) structures. Hence we never acknowledge the
events that the hypervisor has set and the hypervisor keeps on reminding
us to ack the events which we never do.
The fix is simple. Don't on the second time when xen_vcpu_setup is
called over-write the per_cpu(xen_vcpu, cpu) if it points to
per_cpu(xen_vcpu_info).
Acked-by: Stefano Stabellini <stefano.stabellini@eu.citrix.com>
CC: stable@vger.kernel.org
Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
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