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| * KVM: PPC: Book3S HV: Allow userspace to set the desired SMT modePaul Mackerras2017-06-191-11/+60
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | This allows userspace to set the desired virtual SMT (simultaneous multithreading) mode for a VM, that is, the number of VCPUs that get assigned to each virtual core. Previously, the virtual SMT mode was fixed to the number of threads per subcore, and if userspace wanted to have fewer vcpus per vcore, then it would achieve that by using a sparse CPU numbering. This had the disadvantage that the vcpu numbers can get quite large, particularly for SMT1 guests on a POWER8 with 8 threads per core. With this patch, userspace can set its desired virtual SMT mode and then use contiguous vcpu numbering. On POWER8, where the threading mode is "strict", the virtual SMT mode must be less than or equal to the number of threads per subcore. On POWER9, which implements a "loose" threading mode, the virtual SMT mode can be any power of 2 between 1 and 8, even though there is effectively one thread per subcore, since the threads are independent and can all be in different partitions. Signed-off-by: Paul Mackerras <paulus@ozlabs.org>
| * KVM: PPC: Book3S HV: Context-switch HFSCR between host and guest on POWER9Paul Mackerras2017-06-191-0/+10
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | This adds code to allow us to use a different value for the HFSCR (Hypervisor Facilities Status and Control Register) when running the guest from that which applies in the host. The reason for doing this is to allow us to trap the msgsndp instruction and related operations in future so that they can be virtualized. We also save the value of HFSCR when a hypervisor facility unavailable interrupt occurs, because the high byte of HFSCR indicates which facility the guest attempted to access. We save and restore the host value on guest entry/exit because some bits of it affect host userspace execution. We only do all this on POWER9, not on POWER8, because we are not intending to virtualize any of the facilities controlled by HFSCR on POWER8. In particular, the HFSCR bit that controls execution of msgsndp and related operations does not exist on POWER8. The HFSCR doesn't exist at all on POWER7. Signed-off-by: Paul Mackerras <paulus@ozlabs.org>
| * KVM: PPC: Book3S HV: Don't let VCPU sleep if it has a doorbell pendingPaul Mackerras2017-06-191-3/+22
| | | | | | | | | | | | | | | | | | | | | | | | | | | | It is possible, through a narrow race condition, for a VCPU to exit the guest with a H_CEDE hypercall while it has a doorbell interrupt pending. In this case, the H_CEDE should return immediately, but in fact it puts the VCPU to sleep until some other interrupt becomes pending or a prod is received (via another VCPU doing H_PROD). This fixes it by checking the DPDES (Directed Privileged Doorbell Exception Status) bit for the thread along with the other interrupt pending bits. Signed-off-by: Paul Mackerras <paulus@ozlabs.org>
| * KVM: PPC: Book3S HV: Enable guests to use large decrementer mode on POWER9Paul Mackerras2017-06-191-0/+6
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | This allows userspace (e.g. QEMU) to enable large decrementer mode for the guest when running on a POWER9 host, by setting the LPCR_LD bit in the guest LPCR value. With this, the guest exit code saves 64 bits of the guest DEC value on exit. Other places that use the guest DEC value check the LPCR_LD bit in the guest LPCR value, and if it is set, omit the 32-bit sign extension that would otherwise be done. This doesn't change the DEC emulation used by PR KVM because PR KVM is not supported on POWER9 yet. This is partly based on an earlier patch by Oliver O'Halloran. Signed-off-by: Paul Mackerras <paulus@ozlabs.org>
* | Merge branch 'smp-hotplug-for-linus' of ↵Linus Torvalds2017-07-031-7/+7
|\ \ | |/ |/| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip Pull SMP hotplug updates from Thomas Gleixner: "This update is primarily a cleanup of the CPU hotplug locking code. The hotplug locking mechanism is an open coded RWSEM, which allows recursive locking. The main problem with that is the recursive nature as it evades the full lockdep coverage and hides potential deadlocks. The rework replaces the open coded RWSEM with a percpu RWSEM and establishes full lockdep coverage that way. The bulk of the changes fix up recursive locking issues and address the now fully reported potential deadlocks all over the place. Some of these deadlocks have been observed in the RT tree, but on mainline the probability was low enough to hide them away." * 'smp-hotplug-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (37 commits) cpu/hotplug: Constify attribute_group structures powerpc: Only obtain cpu_hotplug_lock if called by rtasd ARM/hw_breakpoint: Fix possible recursive locking for arch_hw_breakpoint_init cpu/hotplug: Remove unused check_for_tasks() function perf/core: Don't release cred_guard_mutex if not taken cpuhotplug: Link lock stacks for hotplug callbacks acpi/processor: Prevent cpu hotplug deadlock sched: Provide is_percpu_thread() helper cpu/hotplug: Convert hotplug locking to percpu rwsem s390: Prevent hotplug rwsem recursion arm: Prevent hotplug rwsem recursion arm64: Prevent cpu hotplug rwsem recursion kprobes: Cure hotplug lock ordering issues jump_label: Reorder hotplug lock and jump_label_lock perf/tracing/cpuhotplug: Fix locking order ACPI/processor: Use cpu_hotplug_disable() instead of get_online_cpus() PCI: Replace the racy recursion prevention PCI: Use cpu_hotplug_disable() instead of get_online_cpus() perf/x86/intel: Drop get_online_cpus() in intel_snb_check_microcode() x86/perf: Drop EXPORT of perf_check_microcode ...
| * KVM/PPC/Book3S HV: Use cpuhp_setup_state_nocalls_cpuslocked()Sebastian Andrzej Siewior2017-05-261-7/+7
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | kvmppc_alloc_host_rm_ops() holds get_online_cpus() while invoking cpuhp_setup_state_nocalls(). cpuhp_setup_state_nocalls() invokes get_online_cpus() as well. This is correct, but prevents the conversion of the hotplug locking to a percpu rwsem. Use cpuhp_setup_state_nocalls_cpuslocked() to avoid the nested call. Convert *_online_cpus() to the new interfaces while at it. Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de> Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Acked-by: Ingo Molnar <mingo@kernel.org> Cc: Paul E. McKenney <paulmck@linux.vnet.ibm.com> Cc: kvm@vger.kernel.org Cc: Peter Zijlstra <peterz@infradead.org> Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org> Cc: Steven Rostedt <rostedt@goodmis.org> Cc: kvm-ppc@vger.kernel.org Cc: Michael Ellerman <mpe@ellerman.id.au> Cc: linuxppc-dev@lists.ozlabs.org Cc: Alexander Graf <agraf@suse.com> Link: http://lkml.kernel.org/r/20170524081547.809616236@linutronix.de
* | KVM: PPC: Book3S HV: Ignore timebase offset on POWER9 DD1Paul Mackerras2017-06-161-0/+8
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | POWER9 DD1 has an erratum where writing to the TBU40 register, which is used to apply an offset to the timebase, can cause the timebase to lose counts. This results in the timebase on some CPUs getting out of sync with other CPUs, which then results in misbehaviour of the timekeeping code. To work around the problem, we make KVM ignore the timebase offset for all guests on POWER9 DD1 machines. This means that live migration cannot be supported on POWER9 DD1 machines. Cc: stable@vger.kernel.org # v4.10+ Signed-off-by: Paul Mackerras <paulus@ozlabs.org>
* | KVM: PPC: Book3S HV: Preserve userspace HTM state properlyPaul Mackerras2017-06-151-0/+21
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | If userspace attempts to call the KVM_RUN ioctl when it has hardware transactional memory (HTM) enabled, the values that it has put in the HTM-related SPRs TFHAR, TFIAR and TEXASR will get overwritten by guest values. To fix this, we detect this condition and save those SPR values in the thread struct, and disable HTM for the task. If userspace goes to access those SPRs or the HTM facility in future, a TM-unavailable interrupt will occur and the handler will reload those SPRs and re-enable HTM. If userspace has started a transaction and suspended it, we would currently lose the transactional state in the guest entry path and would almost certainly get a "TM Bad Thing" interrupt, which would cause the host to crash. To avoid this, we detect this case and return from the KVM_RUN ioctl with an EINVAL error, with the KVM exit reason set to KVM_EXIT_FAIL_ENTRY. Fixes: b005255e12a3 ("KVM: PPC: Book3S HV: Context-switch new POWER8 SPRs", 2014-01-08) Cc: stable@vger.kernel.org # v3.14+ Signed-off-by: Paul Mackerras <paulus@ozlabs.org>
* | KVM: PPC: Book3S HV: Restore critical SPRs to host values on guest exitPaul Mackerras2017-06-151-2/+9
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | This restores several special-purpose registers (SPRs) to sane values on guest exit that were missed before. TAR and VRSAVE are readable and writable by userspace, and we need to save and restore them to prevent the guest from potentially affecting userspace execution (not that TAR or VRSAVE are used by any known program that run uses the KVM_RUN ioctl). We save/restore these in kvmppc_vcpu_run_hv() rather than on every guest entry/exit. FSCR affects userspace execution in that it can prohibit access to certain facilities by userspace. We restore it to the normal value for the task on exit from the KVM_RUN ioctl. IAMR is normally 0, and is restored to 0 on guest exit. However, with a radix host on POWER9, it is set to a value that prevents the kernel from executing user-accessible memory. On POWER9, we save IAMR on guest entry and restore it on guest exit to the saved value rather than 0. On POWER8 we continue to set it to 0 on guest exit. PSPB is normally 0. We restore it to 0 on guest exit to prevent userspace taking advantage of the guest having set it non-zero (which would allow userspace to set its SMT priority to high). UAMOR is normally 0. We restore it to 0 on guest exit to prevent the AMR from being used as a covert channel between userspace processes, since the AMR is not context-switched at present. Fixes: b005255e12a3 ("KVM: PPC: Book3S HV: Context-switch new POWER8 SPRs", 2014-01-08) Cc: stable@vger.kernel.org # v3.14+ Signed-off-by: Paul Mackerras <paulus@ozlabs.org>
* | KVM: PPC: Book3S HV: Context-switch EBB registers properlyPaul Mackerras2017-06-131-0/+15
|/ | | | | | | | | | | | | | | | | | | | | | | | | | | | | This adds code to save the values of three SPRs (special-purpose registers) used by userspace to control event-based branches (EBBs), which are essentially interrupts that get delivered directly to userspace. These registers are loaded up with guest values when entering the guest, and their values are saved when exiting the guest, but we were not saving the host values and restoring them before going back to userspace. On POWER8 this would only affect userspace programs which explicitly request the use of EBBs and also use the KVM_RUN ioctl, since the only source of EBBs on POWER8 is the PMU, and there is an explicit enable bit in the PMU registers (and those PMU registers do get properly context-switched between host and guest). On POWER9 there is provision for externally-generated EBBs, and these are not subject to the control in the PMU registers. Since these registers only affect userspace, we can save them when we first come in from userspace and restore them before returning to userspace, rather than saving/restoring the host values on every guest entry/exit. Similarly, we don't need to worry about their values on offline secondary threads since they execute in the context of the idle task, which never executes in userspace. Fixes: b005255e12a3 ("KVM: PPC: Book3S HV: Context-switch new POWER8 SPRs", 2014-01-08) Cc: stable@vger.kernel.org # v3.14+ Signed-off-by: Paul Mackerras <paulus@ozlabs.org>
* Merge remote-tracking branch 'remotes/powerpc/topic/xive' into kvm-ppc-nextPaul Mackerras2017-04-281-21/+48
|\ | | | | | | | | | | | | | | | | This merges in the powerpc topic/xive branch to bring in the code for the in-kernel XICS interrupt controller emulation to use the new XIVE (eXternal Interrupt Virtualization Engine) hardware in the POWER9 chip directly, rather than via a XICS emulation in firmware. Signed-off-by: Paul Mackerras <paulus@ozlabs.org>
| * KVM: PPC: Book3S HV: Native usage of the XIVE interrupt controllerBenjamin Herrenschmidt2017-04-271-12/+39
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | This patch makes KVM capable of using the XIVE interrupt controller to provide the standard PAPR "XICS" style hypercalls. It is necessary for proper operations when the host uses XIVE natively. This has been lightly tested on an actual system, including PCI pass-through with a TG3 device. Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org> [mpe: Cleanup pr_xxx(), unsplit pr_xxx() strings, etc., fix build failures by adding KVM_XIVE which depends on KVM_XICS and XIVE, and adding empty stubs for the kvm_xive_xxx() routines, fixup subject, integrate fixes from Paul for building PR=y HV=n] Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
| * powerpc/kvm: Massage order of #includeBenjamin Herrenschmidt2017-04-101-9/+9
| | | | | | | | | | | | | | We traditionally have linux/ before asm/ Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org> Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
* | KVM: PPC: Book3S HV: Avoid preemptibility warning in module initializationDenis Kirjanov2017-04-281-1/+1
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | With CONFIG_DEBUG_PREEMPT, get_paca() produces the following warning in kvmppc_book3s_init_hv() since it calls debug_smp_processor_id(). There is no real issue with the xics_phys field. If paca->kvm_hstate.xics_phys is non-zero on one cpu, it will be non-zero on them all. Therefore this is not fixing any actual problem, just the warning. [ 138.521188] BUG: using smp_processor_id() in preemptible [00000000] code: modprobe/5596 [ 138.521308] caller is .kvmppc_book3s_init_hv+0x184/0x350 [kvm_hv] [ 138.521404] CPU: 5 PID: 5596 Comm: modprobe Not tainted 4.11.0-rc3-00022-gc7e790c #1 [ 138.521509] Call Trace: [ 138.521563] [c0000007d018b810] [c0000000023eef10] .dump_stack+0xe4/0x150 (unreliable) [ 138.521694] [c0000007d018b8a0] [c000000001f6ec04] .check_preemption_disabled+0x134/0x150 [ 138.521829] [c0000007d018b940] [d00000000a010274] .kvmppc_book3s_init_hv+0x184/0x350 [kvm_hv] [ 138.521963] [c0000007d018ba00] [c00000000191d5cc] .do_one_initcall+0x5c/0x1c0 [ 138.522082] [c0000007d018bad0] [c0000000023e9494] .do_init_module+0x84/0x240 [ 138.522201] [c0000007d018bb70] [c000000001aade18] .load_module+0x1f68/0x2a10 [ 138.522319] [c0000007d018bd20] [c000000001aaeb30] .SyS_finit_module+0xc0/0xf0 [ 138.522439] [c0000007d018be30] [c00000000191baec] system_call+0x38/0xfc Signed-off-by: Denis Kirjanov <kda@linux-powerpc.org> Signed-off-by: Paul Mackerras <paulus@ozlabs.org>
* | KVM: PPC: Book3S HV: Use common error handling code in kvmppc_clr_passthru_irq()Markus Elfring2017-04-201-5/+3
|/ | | | | | | | Add a jump target so that a bit of exception handling can be better reused at the end of this function. Signed-off-by: Markus Elfring <elfring@users.sourceforge.net> Signed-off-by: Paul Mackerras <paulus@ozlabs.org>
* sched/headers: Prepare for new header dependencies before moving code to ↵Ingo Molnar2017-03-021-0/+1
| | | | | | | | | | | | | | | | | | | | <linux/sched/stat.h> We are going to split <linux/sched/stat.h> out of <linux/sched.h>, which will have to be picked up from other headers and a couple of .c files. Create a trivial placeholder <linux/sched/stat.h> file that just maps to <linux/sched.h> to make this patch obviously correct and bisectable. Include the new header in the files that are going to need it. Acked-by: Linus Torvalds <torvalds@linux-foundation.org> Cc: Mike Galbraith <efault@gmx.de> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: linux-kernel@vger.kernel.org Signed-off-by: Ingo Molnar <mingo@kernel.org>
* sched/headers: Prepare to move signal wakeup & sigpending methods from ↵Ingo Molnar2017-03-021-1/+1
| | | | | | | | | | | | | <linux/sched.h> into <linux/sched/signal.h> Fix up affected files that include this signal functionality via sched.h. Acked-by: Linus Torvalds <torvalds@linux-foundation.org> Cc: Mike Galbraith <efault@gmx.de> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: linux-kernel@vger.kernel.org Signed-off-by: Ingo Molnar <mingo@kernel.org>
* KVM: PPC: Book3S HV: Outline of KVM-HV HPT resizing implementationDavid Gibson2017-01-311-0/+25
| | | | | | | | | | | | | | This adds a not yet working outline of the HPT resizing PAPR extension. Specifically it adds the necessary ioctl() functions, their basic steps, the work function which will handle preparation for the resize, and synchronization between these, the guest page fault path and guest HPT update path. The actual guts of the implementation isn't here yet, so for now the calls will always fail. Signed-off-by: David Gibson <david@gibson.dropbear.id.au> Signed-off-by: Paul Mackerras <paulus@ozlabs.org>
* KVM: PPC: Book3S HV: Allow KVM_PPC_ALLOCATE_HTAB ioctl() to change HPT sizeDavid Gibson2017-01-311-4/+1
| | | | | | | | | | | | | | | | | | | | | | | | The KVM_PPC_ALLOCATE_HTAB ioctl() is used to set the size of hashed page table (HPT) that userspace expects a guest VM to have, and is also used to clear that HPT when necessary (e.g. guest reboot). At present, once the ioctl() is called for the first time, the HPT size can never be changed thereafter - it will be cleared but always sized as from the first call. With upcoming HPT resize implementation, we're going to need to allow userspace to resize the HPT at reset (to change it back to the default size if the guest changed it). So, we need to allow this ioctl() to change the HPT size. This patch also updates Documentation/virtual/kvm/api.txt to reflect the new behaviour. In fact the documentation was already slightly incorrect since 572abd5 "KVM: PPC: Book3S HV: Don't fall back to smaller HPT size in allocation ioctl" Signed-off-by: David Gibson <david@gibson.dropbear.id.au> Signed-off-by: Paul Mackerras <paulus@ozlabs.org>
* KVM: PPC: Book3S HV: Split HPT allocation from activationDavid Gibson2017-01-311-3/+14
| | | | | | | | | | | | | | | | | | | | | | | | | | Currently, kvmppc_alloc_hpt() both allocates a new hashed page table (HPT) and sets it up as the active page table for a VM. For the upcoming HPT resize implementation we're going to want to allocate HPTs separately from activating them. So, split the allocation itself out into kvmppc_allocate_hpt() and perform the activation with a new kvmppc_set_hpt() function. Likewise we split kvmppc_free_hpt(), which just frees the HPT, from kvmppc_release_hpt() which unsets it as an active HPT, then frees it. We also move the logic to fall back to smaller HPT sizes if the first try fails into the single caller which used that behaviour, kvmppc_hv_setup_htab_rma(). This introduces a slight semantic change, in that previously if the initial attempt at CMA allocation failed, we would fall back to attempting smaller sizes with the page allocator. Now, we try first CMA, then the page allocator at each size. As far as I can tell this change should be harmless. To match, we make kvmppc_free_hpt() just free the actual HPT itself. The call to kvmppc_free_lpid() that was there, we move to the single caller. Signed-off-by: David Gibson <david@gibson.dropbear.id.au> Signed-off-by: Paul Mackerras <paulus@ozlabs.org>
* KVM: PPC: Book3S HV: Gather HPT related variables into sub-structureDavid Gibson2017-01-311-1/+1
| | | | | | | | | | | Currently, the powerpc kvm_arch structure contains a number of variables tracking the state of the guest's hashed page table (HPT) in KVM HV. This patch gathers them all together into a single kvm_hpt_info substructure. This makes life more convenient for the upcoming HPT resizing implementation. Signed-off-by: David Gibson <david@gibson.dropbear.id.au> Signed-off-by: Paul Mackerras <paulus@ozlabs.org>
* Merge remote-tracking branch 'remotes/powerpc/topic/ppc-kvm' into kvm-ppc-nextPaul Mackerras2017-01-311-24/+181
|\ | | | | | | | | | | | | | | This merges in the POWER9 radix MMU host and guest support, which was put into a topic branch because it touches both powerpc and KVM code. Signed-off-by: Paul Mackerras <paulus@ozlabs.org>
| * KVM: PPC: Book3S HV: Enable radix guest supportPaul Mackerras2017-01-311-25/+63
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | This adds a few last pieces of the support for radix guests: * Implement the backends for the KVM_PPC_CONFIGURE_V3_MMU and KVM_PPC_GET_RMMU_INFO ioctls for radix guests * On POWER9, allow secondary threads to be on/off-lined while guests are running. * Set up LPCR and the partition table entry for radix guests. * Don't allocate the rmap array in the kvm_memory_slot structure on radix. * Don't try to initialize the HPT for radix guests, since they don't have an HPT. * Take out the code that prevents the HV KVM module from initializing on radix hosts. At this stage, we only support radix guests if the host is running in radix mode, and only support HPT guests if the host is running in HPT mode. Thus a guest cannot switch from one mode to the other, which enables some simplifications. Signed-off-by: Paul Mackerras <paulus@ozlabs.org> Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
| * KVM: PPC: Book3S HV: Invalidate TLB on radix guest vcpu movementPaul Mackerras2017-01-311-0/+45
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | With radix, the guest can do TLB invalidations itself using the tlbie (global) and tlbiel (local) TLB invalidation instructions. Linux guests use local TLB invalidations for translations that have only ever been accessed on one vcpu. However, that doesn't mean that the translations have only been accessed on one physical cpu (pcpu) since vcpus can move around from one pcpu to another. Thus a tlbiel might leave behind stale TLB entries on a pcpu where the vcpu previously ran, and if that task then moves back to that previous pcpu, it could see those stale TLB entries and thus access memory incorrectly. The usual symptom of this is random segfaults in userspace programs in the guest. To cope with this, we detect when a vcpu is about to start executing on a thread in a core that is a different core from the last time it executed. If that is the case, then we mark the core as needing a TLB flush and then send an interrupt to any thread in the core that is currently running a vcpu from the same guest. This will get those vcpus out of the guest, and the first one to re-enter the guest will do the TLB flush. The reason for interrupting the vcpus executing on the old core is to cope with the following scenario: CPU 0 CPU 1 CPU 4 (core 0) (core 0) (core 1) VCPU 0 runs task X VCPU 1 runs core 0 TLB gets entries from task X VCPU 0 moves to CPU 4 VCPU 0 runs task X Unmap pages of task X tlbiel (still VCPU 1) task X moves to VCPU 1 task X runs task X sees stale TLB entries That is, as soon as the VCPU starts executing on the new core, it could unmap and tlbiel some page table entries, and then the task could migrate to one of the VCPUs running on the old core and potentially see stale TLB entries. Since the TLB is shared between all the threads in a core, we only use the bit of kvm->arch.need_tlb_flush corresponding to the first thread in the core. To ensure that we don't have a window where we can miss a flush, this moves the clearing of the bit from before the actual flush to after it. This way, two threads might both do the flush, but we prevent the situation where one thread can enter the guest before the flush is finished. Signed-off-by: Paul Mackerras <paulus@ozlabs.org> Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
| * KVM: PPC: Book3S HV: Implement dirty page logging for radix guestsPaul Mackerras2017-01-311-6/+25
| | | | | | | | | | | | | | | | | | | | | | | | | | | | This adds code to keep track of dirty pages when requested (that is, when memslot->dirty_bitmap is non-NULL) for radix guests. We use the dirty bits in the PTEs in the second-level (partition-scoped) page tables, together with a bitmap of pages that were dirty when their PTE was invalidated (e.g., when the page was paged out). This bitmap is stored in the first half of the memslot->dirty_bitmap area, and kvm_vm_ioctl_get_dirty_log_hv() now uses the second half for the bitmap that gets returned to userspace. Signed-off-by: Paul Mackerras <paulus@ozlabs.org> Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
| * KVM: PPC: Book3S HV: Page table construction and page faults for radix guestsPaul Mackerras2017-01-311-1/+16
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | This adds the code to construct the second-level ("partition-scoped" in architecturese) page tables for guests using the radix MMU. Apart from the PGD level, which is allocated when the guest is created, the rest of the tree is all constructed in response to hypervisor page faults. As well as hypervisor page faults for missing pages, we also get faults for reference/change (RC) bits needing to be set, as well as various other error conditions. For now, we only set the R or C bit in the guest page table if the same bit is set in the host PTE for the backing page. This code can take advantage of the guest being backed with either transparent or ordinary 2MB huge pages, and insert 2MB page entries into the guest page tables. There is no support for 1GB huge pages yet. Signed-off-by: Paul Mackerras <paulus@ozlabs.org> Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
| * KVM: PPC: Book3S HV: Set process table for HPT guests on POWER9Paul Mackerras2017-01-311-4/+31
| | | | | | | | | | | | | | | | | | This adds the implementation of the KVM_PPC_CONFIGURE_V3_MMU ioctl for HPT guests on POWER9. With this, we can return 1 for the KVM_CAP_PPC_MMU_HASH_V3 capability. Signed-off-by: Paul Mackerras <paulus@ozlabs.org> Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
| * KVM: PPC: Book3S HV: Add userspace interfaces for POWER9 MMUPaul Mackerras2017-01-311-0/+13
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | This adds two capabilities and two ioctls to allow userspace to find out about and configure the POWER9 MMU in a guest. The two capabilities tell userspace whether KVM can support a guest using the radix MMU, or using the hashed page table (HPT) MMU with a process table and segment tables. (Note that the MMUs in the POWER9 processor cores do not use the process and segment tables when in HPT mode, but the nest MMU does). The KVM_PPC_CONFIGURE_V3_MMU ioctl allows userspace to specify whether a guest will use the radix MMU or the HPT MMU, and to specify the size and location (in guest space) of the process table. The KVM_PPC_GET_RMMU_INFO ioctl gives userspace information about the radix MMU. It returns a list of supported radix tree geometries (base page size and number of bits indexed at each level of the radix tree) and the encoding used to specify the various page sizes for the TLB invalidate entry instruction. Initially, both capabilities return 0 and the ioctls return -EINVAL, until the necessary infrastructure for them to operate correctly is added. Signed-off-by: Paul Mackerras <paulus@ozlabs.org> Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
* | KVM: PPC: Book3S HV: Fix H_PROD to actually wake the target vcpuPaul Mackerras2017-01-271-8/+5
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | The H_PROD hypercall is supposed to wake up an idle vcpu. We have an implementation, but because Linux doesn't use it except when doing cpu hotplug, it was never tested properly. AIX does use it, and reported it broken. It turns out we were waking the wrong vcpu (the one doing H_PROD, not the target of the prod) and we weren't handling the case where the target needs an IPI to wake it. Fix it by using the existing kvmppc_fast_vcpu_kick_hv() function, which is intended for this kind of thing, and by using the target vcpu not the current vcpu. We were also not looking at the prodded flag when checking whether a ceded vcpu should wake up, so this adds checks for the prodded flag alongside the checks for pending exceptions. Signed-off-by: Paul Mackerras <paulus@ozlabs.org>
* | KVM: PPC: Book3S HV: Don't try to signal cpu -1Paul Mackerras2017-01-271-1/+2
|/ | | | | | | | | | | | | | | | | | | If the target vcpu for kvmppc_fast_vcpu_kick_hv() is not running on any CPU, then we will have vcpu->arch.thread_cpu == -1, and as it happens, kvmppc_fast_vcpu_kick_hv will call kvmppc_ipi_thread with -1 as the cpu argument. Although this is not meaningful, in the past, before commit 1704a81ccebc ("KVM: PPC: Book3S HV: Use msgsnd for IPIs to other cores on POWER9", 2016-11-18), it was harmless because CPU -1 is not in the same core as any real CPU thread. On a POWER9, however, we don't do the "same core" check, so we were trying to do a msgsnd to thread -1, which is invalid. To avoid this, we add a check to see that vcpu->arch.thread_cpu is >= 0 before calling kvmppc_ipi_thread() with it. Since vcpu->arch.thread_vcpu can change asynchronously, we use READ_ONCE to ensure that the value we check is the same value that we use as the argument to kvmppc_ipi_thread(). Fixes: 1704a81ccebc ("KVM: PPC: Book3S HV: Use msgsnd for IPIs to other cores on POWER9") Signed-off-by: Paul Mackerras <paulus@ozlabs.org>
* ktime: Cleanup ktime_set() usageThomas Gleixner2016-12-251-2/+1
| | | | | | | | | | ktime_set(S,N) was required for the timespec storage type and is still useful for situations where a Seconds and Nanoseconds part of a time value needs to be converted. For anything where the Seconds argument is 0, this is pointless and can be replaced with a simple assignment. Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Cc: Peter Zijlstra <peterz@infradead.org>
* Replace <asm/uaccess.h> with <linux/uaccess.h> globallyLinus Torvalds2016-12-241-1/+1
| | | | | | | | | | | | | This was entirely automated, using the script by Al: PATT='^[[:blank:]]*#[[:blank:]]*include[[:blank:]]*<asm/uaccess.h>' sed -i -e "s!$PATT!#include <linux/uaccess.h>!" \ $(git grep -l "$PATT"|grep -v ^include/linux/uaccess.h) to do the replacement at the end of the merge window. Requested-by: Al Viro <viro@zeniv.linux.org.uk> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* Merge tag 'for-linus' of git://git.kernel.org/pub/scm/virt/kvm/kvmLinus Torvalds2016-12-131-64/+190
|\ | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Pull KVM updates from Paolo Bonzini: "Small release, the most interesting stuff is x86 nested virt improvements. x86: - userspace can now hide nested VMX features from guests - nested VMX can now run Hyper-V in a guest - support for AVX512_4VNNIW and AVX512_FMAPS in KVM - infrastructure support for virtual Intel GPUs. PPC: - support for KVM guests on POWER9 - improved support for interrupt polling - optimizations and cleanups. s390: - two small optimizations, more stuff is in flight and will be in 4.11. ARM: - support for the GICv3 ITS on 32bit platforms" * tag 'for-linus' of git://git.kernel.org/pub/scm/virt/kvm/kvm: (94 commits) arm64: KVM: pmu: Reset PMSELR_EL0.SEL to a sane value before entering the guest KVM: arm/arm64: timer: Check for properly initialized timer on init KVM: arm/arm64: vgic-v2: Limit ITARGETSR bits to number of VCPUs KVM: x86: Handle the kthread worker using the new API KVM: nVMX: invvpid handling improvements KVM: nVMX: check host CR3 on vmentry and vmexit KVM: nVMX: introduce nested_vmx_load_cr3 and call it on vmentry KVM: nVMX: propagate errors from prepare_vmcs02 KVM: nVMX: fix CR3 load if L2 uses PAE paging and EPT KVM: nVMX: load GUEST_EFER after GUEST_CR0 during emulated VM-entry KVM: nVMX: generate MSR_IA32_CR{0,4}_FIXED1 from guest CPUID KVM: nVMX: fix checks on CR{0,4} during virtual VMX operation KVM: nVMX: support restore of VMX capability MSRs KVM: nVMX: generate non-true VMX MSRs based on true versions KVM: x86: Do not clear RFLAGS.TF when a singlestep trap occurs. KVM: x86: Add kvm_skip_emulated_instruction and use it. KVM: VMX: Move skip_emulated_instruction out of nested_vmx_check_vmcs12 KVM: VMX: Reorder some skip_emulated_instruction calls KVM: x86: Add a return value to kvm_emulate_cpuid KVM: PPC: Book3S: Move prototypes for KVM functions into kvm_ppc.h ...
| * KVM: PPC: Book3S HV: Comment style and print format fixupsSuraj Jitindar Singh2016-11-281-1/+2
| | | | | | | | | | | | | | | | | | Fix comment block to match kernel comment style. Fix print format from signed to unsigned. Signed-off-by: Suraj Jitindar Singh <sjitindarsingh@gmail.com> Signed-off-by: Paul Mackerras <paulus@ozlabs.org>
| * KVM: PPC: Book3S HV: Add check for module parameter halt_poll_nsSuraj Jitindar Singh2016-11-281-3/+2
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | The kvm module parameter halt_poll_ns defines the global maximum halt polling interval and can be dynamically changed by writing to the /sys/module/kvm/parameters/halt_poll_ns sysfs file. However in kvm-hv this module parameter value is only ever checked when we grow the current polling interval for the given vcore. This means that if we decrease the halt_poll_ns value below the current polling interval we won't see any effect unless we try to grow the polling interval above the new max at some point or it happens to be shrunk below the halt_poll_ns value. Update the halt polling code so that we always check for a new module param value of halt_poll_ns and set the current halt polling interval to it if it's currently greater than the new max. This means that it's redundant to also perform this check in the grow_halt_poll_ns() function now. Signed-off-by: Suraj Jitindar Singh <sjitindarsingh@gmail.com> Signed-off-by: Paul Mackerras <paulus@ozlabs.org>
| * KVM: PPC: Book3S HV: Use generic kvm module parametersSuraj Jitindar Singh2016-11-281-23/+6
| | | | | | | | | | | | | | | | | | | | | | | | The previous patch exported the variables which back the module parameters of the generic kvm module. Now use these variables in the kvm-hv module so that any change to the generic module parameters will also have the same effect for the kvm-hv module. This removes the duplication of the kvm module parameters which was redundant and should reduce confusion when tuning them. Signed-off-by: Suraj Jitindar Singh <sjitindarsingh@gmail.com> Signed-off-by: Paul Mackerras <paulus@ozlabs.org>
| * KVM: PPC: Book3S HV: Update kvmppc_set_arch_compat() for ISA v3.00Suraj Jitindar Singh2016-11-241-15/+28
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | The function kvmppc_set_arch_compat() is used to determine the value of the processor compatibility register (PCR) for a guest running in a given compatibility mode. There is currently no support for v3.00 of the ISA. Add support for v3.00 of the ISA which adds an ISA v2.07 compatilibity mode to the PCR. We also add a check to ensure the processor we are running on is capable of emulating the chosen processor (for example a POWER7 cannot emulate a POWER8, similarly with a POWER8 and a POWER9). Based on work by: Paul Mackerras <paulus@ozlabs.org> [paulus@ozlabs.org - moved dummy PCR_ARCH_300 definition here; set guest_pcr_bit when arch_compat == 0, added comment.] Signed-off-by: Suraj Jitindar Singh <sjitindarsingh@gmail.com> Signed-off-by: Paul Mackerras <paulus@ozlabs.org>
| * KVM: PPC: Book3S HV: Treat POWER9 CPU threads as independent subcoresPaul Mackerras2016-11-241-12/+37
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | With POWER9, each CPU thread has its own MMU context and can be in the host or a guest independently of the other threads; there is still however a restriction that all threads must use the same type of address translation, either radix tree or hashed page table (HPT). Since we only support HPT guests on a HPT host at this point, we can treat the threads as being independent, and avoid all of the work of coordinating the CPU threads. To make this simpler, we introduce a new threads_per_vcore() function that returns 1 on POWER9 and threads_per_subcore on POWER7/8, and use that instead of threads_per_subcore or threads_per_core in various places. This also changes the value of the KVM_CAP_PPC_SMT capability on POWER9 systems from 4 to 1, so that userspace will not try to create VMs with multiple vcpus per vcore. (If userspace did create a VM that thought it was in an SMT mode, the VM might try to use the msgsndp instruction, which will not work as expected. In future it may be possible to trap and emulate msgsndp in order to allow VMs to think they are in an SMT mode, if only for the purpose of allowing migration from POWER8 systems.) With all this, we can now run guests on POWER9 as long as the host is running with HPT translation. Since userspace currently has no way to request radix tree translation for the guest, the guest has no choice but to use HPT translation. Signed-off-by: Paul Mackerras <paulus@ozlabs.org>
| * KVM: PPC: Book3S HV: Enable hypervisor virtualization interrupts while in guestPaul Mackerras2016-11-241-2/+9
| | | | | | | | | | | | | | | | | | | | | | | | The new XIVE interrupt controller on POWER9 can direct external interrupts to the hypervisor or the guest. The interrupts directed to the hypervisor are controlled by an LPCR bit called LPCR_HVICE, and come in as a "hypervisor virtualization interrupt". This sets the LPCR bit so that hypervisor virtualization interrupts can occur while we are in the guest. We then also need to cope with exiting the guest because of a hypervisor virtualization interrupt. Signed-off-by: Paul Mackerras <paulus@ozlabs.org>
| * KVM: PPC: Book3S HV: Use OPAL XICS emulation on POWER9Paul Mackerras2016-11-241-2/+26
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | POWER9 includes a new interrupt controller, called XIVE, which is quite different from the XICS interrupt controller on POWER7 and POWER8 machines. KVM-HV accesses the XICS directly in several places in order to send and clear IPIs and handle interrupts from PCI devices being passed through to the guest. In order to make the transition to XIVE easier, OPAL firmware will include an emulation of XICS on top of XIVE. Access to the emulated XICS is via OPAL calls. The one complication is that the EOI (end-of-interrupt) function can now return a value indicating that another interrupt is pending; in this case, the XIVE will not signal an interrupt in hardware to the CPU, and software is supposed to acknowledge the new interrupt without waiting for another interrupt to be delivered in hardware. This adapts KVM-HV to use the OPAL calls on machines where there is no XICS hardware. When there is no XICS, we look for a device-tree node with "ibm,opal-intc" in its compatible property, which is how OPAL indicates that it provides XICS emulation. In order to handle the EOI return value, kvmppc_read_intr() has become kvmppc_read_one_intr(), with a boolean variable passed by reference which can be set by the EOI functions to indicate that another interrupt is pending. The new kvmppc_read_intr() keeps calling kvmppc_read_one_intr() until there are no more interrupts to process. The return value from kvmppc_read_intr() is the largest non-zero value of the returns from kvmppc_read_one_intr(). Signed-off-by: Paul Mackerras <paulus@ozlabs.org>
| * KVM: PPC: Book3S HV: Use msgsnd for IPIs to other cores on POWER9Paul Mackerras2016-11-241-1/+10
| | | | | | | | | | | | | | | | | | On POWER9, the msgsnd instruction is able to send interrupts to other cores, as well as other threads on the local core. Since msgsnd is generally simpler and faster than sending an IPI via the XICS, we use msgsnd for all IPIs sent by KVM on POWER9. Signed-off-by: Paul Mackerras <paulus@ozlabs.org>
| * KVM: PPC: Book3S HV: Adapt TLB invalidations to work on POWER9Paul Mackerras2016-11-241-1/+16
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | POWER9 adds new capabilities to the tlbie (TLB invalidate entry) and tlbiel (local tlbie) instructions. Both instructions get a set of new parameters (RIC, PRS and R) which appear as bits in the instruction word. The tlbiel instruction now has a second register operand, which contains a PID and/or LPID value if needed, and should otherwise contain 0. This adapts KVM-HV's usage of tlbie and tlbiel to work on POWER9 as well as older processors. Since we only handle HPT guests so far, we need RIC=0 PRS=0 R=0, which ends up with the same instruction word as on previous processors, so we don't need to conditionally execute different instructions depending on the processor. The local flush on first entry to a guest in book3s_hv_rmhandlers.S is a loop which depends on the number of TLB sets. Rather than using feature sections to set the number of iterations based on which CPU we're on, we now work out this number at VM creation time and store it in the kvm_arch struct. That will make it possible to get the number from the device tree in future, which will help with compatibility with future processors. Since mmu_partition_table_set_entry() does a global flush of the whole LPID, we don't need to do the TLB flush on first entry to the guest on each processor. Therefore we don't set all bits in the tlb_need_flush bitmap on VM startup on POWER9. Signed-off-by: Paul Mackerras <paulus@ozlabs.org>
| * KVM: PPC: Book3S HV: Add new POWER9 guest-accessible SPRsPaul Mackerras2016-11-241-0/+12
| | | | | | | | | | | | | | | | | | | | | | | | | | | | This adds code to handle two new guest-accessible special-purpose registers on POWER9: TIDR (thread ID register) and PSSCR (processor stop status and control register). They are context-switched between host and guest, and the guest values can be read and set via the one_reg interface. The PSSCR contains some fields which are guest-accessible and some which are only accessible in hypervisor mode. We only allow the guest-accessible fields to be read or set by userspace. Signed-off-by: Paul Mackerras <paulus@ozlabs.org>
| * KVM: PPC: Book3S HV: Set partition table rather than SDR1 on POWER9Paul Mackerras2016-11-241-6/+30
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | On POWER9, the SDR1 register (hashed page table base address) is no longer used, and instead the hardware reads the HPT base address and size from the partition table. The partition table entry also contains the bits that specify the page size for the VRMA mapping, which were previously in the LPCR. The VPM0 bit of the LPCR is now reserved; the processor now always uses the VRMA (virtual real-mode area) mechanism for guest real-mode accesses in HPT mode, and the RMO (real-mode offset) mechanism has been dropped. When entering or exiting the guest, we now only have to set the LPIDR (logical partition ID register), not the SDR1 register. There is also no requirement now to transition via a reserved LPID value. Signed-off-by: Paul Mackerras <paulus@ozlabs.org>
| * KVM: PPC: Book3S HV: Save/restore XER in checkpointed register statePaul Mackerras2016-11-211-0/+6
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | When switching from/to a guest that has a transaction in progress, we need to save/restore the checkpointed register state. Although XER is part of the CPU state that gets checkpointed, the code that does this saving and restoring doesn't save/restore XER. This fixes it by saving and restoring the XER. To allow userspace to read/write the checkpointed XER value, we also add a new ONE_REG specifier. The visible effect of this bug is that the guest may see its XER value being corrupted when it uses transactions. Fixes: e4e38121507a ("KVM: PPC: Book3S HV: Add transactional memory support") Fixes: 0a8eccefcb34 ("KVM: PPC: Book3S HV: Add missing code for transaction reclaim on guest exit") Cc: stable@vger.kernel.org # v3.15+ Signed-off-by: Paul Mackerras <paulus@ozlabs.org> Reviewed-by: Thomas Huth <thuth@redhat.com> Signed-off-by: Paul Mackerras <paulus@ozlabs.org>
| * KVM: PPC: Book3S HV: Add a per vcpu cache for recently page faulted MMIO entriesYongji Xie2016-11-211-0/+9
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | This keeps a per vcpu cache for recently page faulted MMIO entries. On a page fault, if the entry exists in the cache, we can avoid some time-consuming paths, for example, looking up HPT, locking HPTE twice and searching mmio gfn from memslots, then directly call kvmppc_hv_emulate_mmio(). In current implenment, we limit the size of cache to four. We think it's enough to cover the high-frequency MMIO HPTEs in most case. For example, considering the case of using virtio device, for virtio legacy devices, one HPTE could handle notifications from up to 1024 (64K page / 64 byte Port IO register) devices, so one cache entry is enough; for virtio modern devices, we always need one HPTE to handle notification for each device because modern device would use a 8M MMIO register to notify host instead of Port IO register, typically the system's configuration should not exceed four virtio devices per vcpu, four cache entry is also enough in this case. Of course, if needed, we could also modify the macro to a module parameter in the future. Signed-off-by: Yongji Xie <xyjxie@linux.vnet.ibm.com> Signed-off-by: Paul Mackerras <paulus@ozlabs.org>
| * KVM: PPC: Book3S HV: Use list_move_tail instead of list_del/list_add_tailWei Yongjun2016-11-211-2/+1
| | | | | | | | | | | | | | Using list_move_tail() instead of list_del() + list_add_tail(). Signed-off-by: Wei Yongjun <weiyongjun1@huawei.com> Signed-off-by: Paul Mackerras <paulus@ozlabs.org>
* | KVM/PPC/Book3S HV: Convert to hotplug state machineAnna-Maria Gleixner2016-12-021-37/+11
|/ | | | | | | | | | | | | | | | | | | | Install the callbacks via the state machine. Signed-off-by: Anna-Maria Gleixner <anna-maria@linutronix.de> Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de> Cc: kvm@vger.kernel.org Cc: Radim Krčmář <rkrcmar@redhat.com> Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org> Cc: linuxppc-dev@lists.ozlabs.org Cc: kvm-ppc@vger.kernel.org Cc: Paul Mackerras <paulus@samba.org> Cc: rt@linutronix.de Cc: Michael Ellerman <mpe@ellerman.id.au> Cc: Paolo Bonzini <pbonzini@redhat.com> Cc: Alexander Graf <agraf@suse.com> Link: http://lkml.kernel.org/r/20161126231350.10321-18-bigeasy@linutronix.de Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
* KVM: PPC: Book3S HV: Take out virtual core piggybacking codePaul Mackerras2016-09-271-125/+3
| | | | | | | | | | | | | | | | | This takes out the code that arranges to run two (or more) virtual cores on a single subcore when possible, that is, when both vcores are from the same VM, the VM is configured with one CPU thread per virtual core, and all the per-subcore registers have the same value in each vcore. Since the VTB (virtual timebase) is a per-subcore register, and will almost always differ between vcores, this code is disabled on POWER8 machines, meaning that it is only usable on POWER7 machines (which don't have VTB). Given the tiny number of POWER7 machines which have firmware that allows them to run HV KVM, the benefit of simplifying the code outweighs the loss of this feature on POWER7 machines. Tested-by: Thomas Huth <thuth@redhat.com> Signed-off-by: Paul Mackerras <paulus@ozlabs.org>
* KVM: PPC: Book3S: Treat VTB as a per-subcore register, not per-threadPaul Mackerras2016-09-271-3/+11
| | | | | | | | | | | | | | | | | | | | | | | | POWER8 has one virtual timebase (VTB) register per subcore, not one per CPU thread. The HV KVM code currently treats VTB as a per-thread register, which can lead to spurious soft lockup messages from guests which use the VTB as the time source for the soft lockup detector. (CPUs before POWER8 did not have the VTB register.) For HV KVM, this fixes the problem by making only the primary thread in each virtual core save and restore the VTB value. With this, the VTB state becomes part of the kvmppc_vcore structure. This also means that "piggybacking" of multiple virtual cores onto one subcore is not possible on POWER8, because then the virtual cores would share a single VTB register. PR KVM emulates a VTB register, which is per-vcpu because PR KVM has no notion of CPU threads or SMT. For PR KVM we move the VTB state into the kvmppc_vcpu_book3s struct. Cc: stable@vger.kernel.org # v3.14+ Reported-by: Thomas Huth <thuth@redhat.com> Tested-by: Thomas Huth <thuth@redhat.com> Signed-off-by: Paul Mackerras <paulus@ozlabs.org>
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