diff options
Diffstat (limited to 'Documentation/virtual')
| -rw-r--r-- | Documentation/virtual/kvm/api.txt | 33 | ||||
| -rw-r--r-- | Documentation/virtual/kvm/hypercalls.txt | 66 | ||||
| -rw-r--r-- | Documentation/virtual/kvm/msr.txt | 32 | ||||
| -rw-r--r-- | Documentation/virtual/kvm/ppc-pv.txt | 22 |
4 files changed, 133 insertions, 20 deletions
diff --git a/Documentation/virtual/kvm/api.txt b/Documentation/virtual/kvm/api.txt index bf33aaa4c59f..f6ec3a92e621 100644 --- a/Documentation/virtual/kvm/api.txt +++ b/Documentation/virtual/kvm/api.txt @@ -857,7 +857,8 @@ struct kvm_userspace_memory_region { }; /* for kvm_memory_region::flags */ -#define KVM_MEM_LOG_DIRTY_PAGES 1UL +#define KVM_MEM_LOG_DIRTY_PAGES (1UL << 0) +#define KVM_MEM_READONLY (1UL << 1) This ioctl allows the user to create or modify a guest physical memory slot. When changing an existing slot, it may be moved in the guest @@ -873,14 +874,17 @@ It is recommended that the lower 21 bits of guest_phys_addr and userspace_addr be identical. This allows large pages in the guest to be backed by large pages in the host. -The flags field supports just one flag, KVM_MEM_LOG_DIRTY_PAGES, which -instructs kvm to keep track of writes to memory within the slot. See -the KVM_GET_DIRTY_LOG ioctl. +The flags field supports two flag, KVM_MEM_LOG_DIRTY_PAGES, which instructs +kvm to keep track of writes to memory within the slot. See KVM_GET_DIRTY_LOG +ioctl. The KVM_CAP_READONLY_MEM capability indicates the availability of the +KVM_MEM_READONLY flag. When this flag is set for a memory region, KVM only +allows read accesses. Writes will be posted to userspace as KVM_EXIT_MMIO +exits. -When the KVM_CAP_SYNC_MMU capability, changes in the backing of the memory -region are automatically reflected into the guest. For example, an mmap() -that affects the region will be made visible immediately. Another example -is madvise(MADV_DROP). +When the KVM_CAP_SYNC_MMU capability is available, changes in the backing of +the memory region are automatically reflected into the guest. For example, an +mmap() that affects the region will be made visible immediately. Another +example is madvise(MADV_DROP). It is recommended to use this API instead of the KVM_SET_MEMORY_REGION ioctl. The KVM_SET_MEMORY_REGION does not allow fine grained control over memory @@ -1946,6 +1950,19 @@ the guest using the specified gsi pin. The irqfd is removed using the KVM_IRQFD_FLAG_DEASSIGN flag, specifying both kvm_irqfd.fd and kvm_irqfd.gsi. +With KVM_CAP_IRQFD_RESAMPLE, KVM_IRQFD supports a de-assert and notify +mechanism allowing emulation of level-triggered, irqfd-based +interrupts. When KVM_IRQFD_FLAG_RESAMPLE is set the user must pass an +additional eventfd in the kvm_irqfd.resamplefd field. When operating +in resample mode, posting of an interrupt through kvm_irq.fd asserts +the specified gsi in the irqchip. When the irqchip is resampled, such +as from an EOI, the gsi is de-asserted and the user is notifed via +kvm_irqfd.resamplefd. It is the user's responsibility to re-queue +the interrupt if the device making use of it still requires service. +Note that closing the resamplefd is not sufficient to disable the +irqfd. The KVM_IRQFD_FLAG_RESAMPLE is only necessary on assignment +and need not be specified with KVM_IRQFD_FLAG_DEASSIGN. + 4.76 KVM_PPC_ALLOCATE_HTAB Capability: KVM_CAP_PPC_ALLOC_HTAB diff --git a/Documentation/virtual/kvm/hypercalls.txt b/Documentation/virtual/kvm/hypercalls.txt new file mode 100644 index 000000000000..ea113b5d87a4 --- /dev/null +++ b/Documentation/virtual/kvm/hypercalls.txt @@ -0,0 +1,66 @@ +Linux KVM Hypercall: +=================== +X86: + KVM Hypercalls have a three-byte sequence of either the vmcall or the vmmcall + instruction. The hypervisor can replace it with instructions that are + guaranteed to be supported. + + Up to four arguments may be passed in rbx, rcx, rdx, and rsi respectively. + The hypercall number should be placed in rax and the return value will be + placed in rax. No other registers will be clobbered unless explicitly stated + by the particular hypercall. + +S390: + R2-R7 are used for parameters 1-6. In addition, R1 is used for hypercall + number. The return value is written to R2. + + S390 uses diagnose instruction as hypercall (0x500) along with hypercall + number in R1. + + PowerPC: + It uses R3-R10 and hypercall number in R11. R4-R11 are used as output registers. + Return value is placed in R3. + + KVM hypercalls uses 4 byte opcode, that are patched with 'hypercall-instructions' + property inside the device tree's /hypervisor node. + For more information refer to Documentation/virtual/kvm/ppc-pv.txt + +KVM Hypercalls Documentation +=========================== +The template for each hypercall is: +1. Hypercall name. +2. Architecture(s) +3. Status (deprecated, obsolete, active) +4. Purpose + +1. KVM_HC_VAPIC_POLL_IRQ +------------------------ +Architecture: x86 +Status: active +Purpose: Trigger guest exit so that the host can check for pending +interrupts on reentry. + +2. KVM_HC_MMU_OP +------------------------ +Architecture: x86 +Status: deprecated. +Purpose: Support MMU operations such as writing to PTE, +flushing TLB, release PT. + +3. KVM_HC_FEATURES +------------------------ +Architecture: PPC +Status: active +Purpose: Expose hypercall availability to the guest. On x86 platforms, cpuid +used to enumerate which hypercalls are available. On PPC, either device tree +based lookup ( which is also what EPAPR dictates) OR KVM specific enumeration +mechanism (which is this hypercall) can be used. + +4. KVM_HC_PPC_MAP_MAGIC_PAGE +------------------------ +Architecture: PPC +Status: active +Purpose: To enable communication between the hypervisor and guest there is a +shared page that contains parts of supervisor visible register state. +The guest can map this shared page to access its supervisor register through +memory using this hypercall. diff --git a/Documentation/virtual/kvm/msr.txt b/Documentation/virtual/kvm/msr.txt index 730471048583..6d470ae7b073 100644 --- a/Documentation/virtual/kvm/msr.txt +++ b/Documentation/virtual/kvm/msr.txt @@ -34,9 +34,12 @@ MSR_KVM_WALL_CLOCK_NEW: 0x4b564d00 time information and check that they are both equal and even. An odd version indicates an in-progress update. - sec: number of seconds for wallclock. + sec: number of seconds for wallclock at time of boot. - nsec: number of nanoseconds for wallclock. + nsec: number of nanoseconds for wallclock at time of boot. + + In order to get the current wallclock time, the system_time from + MSR_KVM_SYSTEM_TIME_NEW needs to be added. Note that although MSRs are per-CPU entities, the effect of this particular MSR is global. @@ -82,20 +85,25 @@ MSR_KVM_SYSTEM_TIME_NEW: 0x4b564d01 time at the time this structure was last updated. Unit is nanoseconds. - tsc_to_system_mul: a function of the tsc frequency. One has - to multiply any tsc-related quantity by this value to get - a value in nanoseconds, besides dividing by 2^tsc_shift + tsc_to_system_mul: multiplier to be used when converting + tsc-related quantity to nanoseconds - tsc_shift: cycle to nanosecond divider, as a power of two, to - allow for shift rights. One has to shift right any tsc-related - quantity by this value to get a value in nanoseconds, besides - multiplying by tsc_to_system_mul. + tsc_shift: shift to be used when converting tsc-related + quantity to nanoseconds. This shift will ensure that + multiplication with tsc_to_system_mul does not overflow. + A positive value denotes a left shift, a negative value + a right shift. - With this information, guests can derive per-CPU time by - doing: + The conversion from tsc to nanoseconds involves an additional + right shift by 32 bits. With this information, guests can + derive per-CPU time by doing: time = (current_tsc - tsc_timestamp) - time = (time * tsc_to_system_mul) >> tsc_shift + if (tsc_shift >= 0) + time <<= tsc_shift; + else + time >>= -tsc_shift; + time = (time * tsc_to_system_mul) >> 32 time = time + system_time flags: bits in this field indicate extended capabilities diff --git a/Documentation/virtual/kvm/ppc-pv.txt b/Documentation/virtual/kvm/ppc-pv.txt index 4911cf95c67e..4cd076febb02 100644 --- a/Documentation/virtual/kvm/ppc-pv.txt +++ b/Documentation/virtual/kvm/ppc-pv.txt @@ -174,3 +174,25 @@ following: That way we can inject an arbitrary amount of code as replacement for a single instruction. This allows us to check for pending interrupts when setting EE=1 for example. + +Hypercall ABIs in KVM on PowerPC +================================= +1) KVM hypercalls (ePAPR) + +These are ePAPR compliant hypercall implementation (mentioned above). Even +generic hypercalls are implemented here, like the ePAPR idle hcall. These are +available on all targets. + +2) PAPR hypercalls + +PAPR hypercalls are needed to run server PowerPC PAPR guests (-M pseries in QEMU). +These are the same hypercalls that pHyp, the POWER hypervisor implements. Some of +them are handled in the kernel, some are handled in user space. This is only +available on book3s_64. + +3) OSI hypercalls + +Mac-on-Linux is another user of KVM on PowerPC, which has its own hypercall (long +before KVM). This is supported to maintain compatibility. All these hypercalls get +forwarded to user space. This is only useful on book3s_32, but can be used with +book3s_64 as well. |
