diff options
Diffstat (limited to 'Documentation/virtual/kvm/api.txt')
| -rw-r--r-- | Documentation/virtual/kvm/api.txt | 135 |
1 files changed, 124 insertions, 11 deletions
diff --git a/Documentation/virtual/kvm/api.txt b/Documentation/virtual/kvm/api.txt index d6b3ff51a14f..1c7958b57fe9 100644 --- a/Documentation/virtual/kvm/api.txt +++ b/Documentation/virtual/kvm/api.txt @@ -3480,7 +3480,7 @@ encrypted VMs. Currently, this ioctl is used for issuing Secure Encrypted Virtualization (SEV) commands on AMD Processors. The SEV commands are defined in -Documentation/virtual/kvm/amd-memory-encryption.txt. +Documentation/virtual/kvm/amd-memory-encryption.rst. 4.111 KVM_MEMORY_ENCRYPT_REG_REGION @@ -3516,6 +3516,38 @@ Returns: 0 on success; -1 on error This ioctl can be used to unregister the guest memory region registered with KVM_MEMORY_ENCRYPT_REG_REGION ioctl above. +4.113 KVM_HYPERV_EVENTFD + +Capability: KVM_CAP_HYPERV_EVENTFD +Architectures: x86 +Type: vm ioctl +Parameters: struct kvm_hyperv_eventfd (in) + +This ioctl (un)registers an eventfd to receive notifications from the guest on +the specified Hyper-V connection id through the SIGNAL_EVENT hypercall, without +causing a user exit. SIGNAL_EVENT hypercall with non-zero event flag number +(bits 24-31) still triggers a KVM_EXIT_HYPERV_HCALL user exit. + +struct kvm_hyperv_eventfd { + __u32 conn_id; + __s32 fd; + __u32 flags; + __u32 padding[3]; +}; + +The conn_id field should fit within 24 bits: + +#define KVM_HYPERV_CONN_ID_MASK 0x00ffffff + +The acceptable values for the flags field are: + +#define KVM_HYPERV_EVENTFD_DEASSIGN (1 << 0) + +Returns: 0 on success, + -EINVAL if conn_id or flags is outside the allowed range + -ENOENT on deassign if the conn_id isn't registered + -EEXIST on assign if the conn_id is already registered + 5. The kvm_run structure ------------------------ @@ -3873,7 +3905,7 @@ in userspace. __u64 kvm_dirty_regs; union { struct kvm_sync_regs regs; - char padding[1024]; + char padding[SYNC_REGS_SIZE_BYTES]; } s; If KVM_CAP_SYNC_REGS is defined, these fields allow userspace to access @@ -4078,6 +4110,46 @@ Once this is done the KVM_REG_MIPS_VEC_* and KVM_REG_MIPS_MSA_* registers can be accessed, and the Config5.MSAEn bit is accessible via the KVM API and also from the guest. +6.74 KVM_CAP_SYNC_REGS +Architectures: s390, x86 +Target: s390: always enabled, x86: vcpu +Parameters: none +Returns: x86: KVM_CHECK_EXTENSION returns a bit-array indicating which register +sets are supported (bitfields defined in arch/x86/include/uapi/asm/kvm.h). + +As described above in the kvm_sync_regs struct info in section 5 (kvm_run): +KVM_CAP_SYNC_REGS "allow[s] userspace to access certain guest registers +without having to call SET/GET_*REGS". This reduces overhead by eliminating +repeated ioctl calls for setting and/or getting register values. This is +particularly important when userspace is making synchronous guest state +modifications, e.g. when emulating and/or intercepting instructions in +userspace. + +For s390 specifics, please refer to the source code. + +For x86: +- the register sets to be copied out to kvm_run are selectable + by userspace (rather that all sets being copied out for every exit). +- vcpu_events are available in addition to regs and sregs. + +For x86, the 'kvm_valid_regs' field of struct kvm_run is overloaded to +function as an input bit-array field set by userspace to indicate the +specific register sets to be copied out on the next exit. + +To indicate when userspace has modified values that should be copied into +the vCPU, the all architecture bitarray field, 'kvm_dirty_regs' must be set. +This is done using the same bitflags as for the 'kvm_valid_regs' field. +If the dirty bit is not set, then the register set values will not be copied +into the vCPU even if they've been modified. + +Unused bitfields in the bitarrays must be set to zero. + +struct kvm_sync_regs { + struct kvm_regs regs; + struct kvm_sregs sregs; + struct kvm_vcpu_events events; +}; + 7. Capabilities that can be enabled on VMs ------------------------------------------ @@ -4286,6 +4358,26 @@ enables QEMU to build error log and branch to guest kernel registered machine check handling routine. Without this capability KVM will branch to guests' 0x200 interrupt vector. +7.13 KVM_CAP_X86_DISABLE_EXITS + +Architectures: x86 +Parameters: args[0] defines which exits are disabled +Returns: 0 on success, -EINVAL when args[0] contains invalid exits + +Valid bits in args[0] are + +#define KVM_X86_DISABLE_EXITS_MWAIT (1 << 0) +#define KVM_X86_DISABLE_EXITS_HLT (1 << 1) + +Enabling this capability on a VM provides userspace with a way to no +longer intercept some instructions for improved latency in some +workloads, and is suggested when vCPUs are associated to dedicated +physical CPUs. More bits can be added in the future; userspace can +just pass the KVM_CHECK_EXTENSION result to KVM_ENABLE_CAP to disable +all such vmexits. + +Do not enable KVM_FEATURE_PV_UNHALT if you disable HLT exits. + 8. Other capabilities. ---------------------- @@ -4398,15 +4490,6 @@ reserved. Both registers and addresses are 64-bits wide. It will be possible to run 64-bit or 32-bit guest code. -8.8 KVM_CAP_X86_GUEST_MWAIT - -Architectures: x86 - -This capability indicates that guest using memory monotoring instructions -(MWAIT/MWAITX) to stop the virtual CPU will not cause a VM exit. As such time -spent while virtual CPU is halted in this way will then be accounted for as -guest running time on the host (as opposed to e.g. HLT). - 8.9 KVM_CAP_ARM_USER_IRQ Architectures: arm, arm64 @@ -4483,3 +4566,33 @@ Parameters: none This capability indicates if the flic device will be able to get/set the AIS states for migration via the KVM_DEV_FLIC_AISM_ALL attribute and allows to discover this without having to create a flic device. + +8.14 KVM_CAP_S390_PSW + +Architectures: s390 + +This capability indicates that the PSW is exposed via the kvm_run structure. + +8.15 KVM_CAP_S390_GMAP + +Architectures: s390 + +This capability indicates that the user space memory used as guest mapping can +be anywhere in the user memory address space, as long as the memory slots are +aligned and sized to a segment (1MB) boundary. + +8.16 KVM_CAP_S390_COW + +Architectures: s390 + +This capability indicates that the user space memory used as guest mapping can +use copy-on-write semantics as well as dirty pages tracking via read-only page +tables. + +8.17 KVM_CAP_S390_BPB + +Architectures: s390 + +This capability indicates that kvm will implement the interfaces to handle +reset, migration and nested KVM for branch prediction blocking. The stfle +facility 82 should not be provided to the guest without this capability. |