diff options
Diffstat (limited to 'Documentation/virt/kvm')
| -rw-r--r-- | Documentation/virt/kvm/api.rst | 40 | ||||
| -rw-r--r-- | Documentation/virt/kvm/devices/arm-vgic-v3.rst | 77 |
2 files changed, 109 insertions, 8 deletions
diff --git a/Documentation/virt/kvm/api.rst b/Documentation/virt/kvm/api.rst index 544fb11351d9..6aa40ee05a4a 100644 --- a/Documentation/virt/kvm/api.rst +++ b/Documentation/virt/kvm/api.rst @@ -2006,7 +2006,7 @@ frequency is KHz. If the KVM_CAP_VM_TSC_CONTROL capability is advertised, this can also be used as a vm ioctl to set the initial tsc frequency of subsequently -created vCPUs. +created vCPUs. Note, the vm ioctl is only allowed prior to creating vCPUs. For TSC protected Confidential Computing (CoCo) VMs where TSC frequency is configured once at VM scope and remains unchanged during VM's @@ -7851,6 +7851,7 @@ Valid bits in args[0] are:: #define KVM_X86_DISABLE_EXITS_HLT (1 << 1) #define KVM_X86_DISABLE_EXITS_PAUSE (1 << 2) #define KVM_X86_DISABLE_EXITS_CSTATE (1 << 3) + #define KVM_X86_DISABLE_EXITS_APERFMPERF (1 << 4) Enabling this capability on a VM provides userspace with a way to no longer intercept some instructions for improved latency in some @@ -7861,6 +7862,28 @@ all such vmexits. Do not enable KVM_FEATURE_PV_UNHALT if you disable HLT exits. +Virtualizing the ``IA32_APERF`` and ``IA32_MPERF`` MSRs requires more +than just disabling APERF/MPERF exits. While both Intel and AMD +document strict usage conditions for these MSRs--emphasizing that only +the ratio of their deltas over a time interval (T0 to T1) is +architecturally defined--simply passing through the MSRs can still +produce an incorrect ratio. + +This erroneous ratio can occur if, between T0 and T1: + +1. The vCPU thread migrates between logical processors. +2. Live migration or suspend/resume operations take place. +3. Another task shares the vCPU's logical processor. +4. C-states lower than C0 are emulated (e.g., via HLT interception). +5. The guest TSC frequency doesn't match the host TSC frequency. + +Due to these complexities, KVM does not automatically associate this +passthrough capability with the guest CPUID bit, +``CPUID.6:ECX.APERFMPERF[bit 0]``. Userspace VMMs that deem this +mechanism adequate for virtualizing the ``IA32_APERF`` and +``IA32_MPERF`` MSRs must set the guest CPUID bit explicitly. + + 7.14 KVM_CAP_S390_HPAGE_1M -------------------------- @@ -8387,7 +8410,7 @@ core crystal clock frequency, if a non-zero CPUID 0x15 is exposed to the guest. 7.36 KVM_CAP_DIRTY_LOG_RING/KVM_CAP_DIRTY_LOG_RING_ACQ_REL ---------------------------------------------------------- -:Architectures: x86, arm64 +:Architectures: x86, arm64, riscv :Type: vm :Parameters: args[0] - size of the dirty log ring @@ -8599,7 +8622,7 @@ ENOSYS for the others. When enabled, KVM will exit to userspace with KVM_EXIT_SYSTEM_EVENT of type KVM_SYSTEM_EVENT_SUSPEND to process the guest suspend request. -7.37 KVM_CAP_ARM_WRITABLE_IMP_ID_REGS +7.42 KVM_CAP_ARM_WRITABLE_IMP_ID_REGS ------------------------------------- :Architectures: arm64 @@ -8628,6 +8651,17 @@ given VM. When this capability is enabled, KVM resets the VCPU when setting MP_STATE_INIT_RECEIVED through IOCTL. The original MP_STATE is preserved. +7.43 KVM_CAP_ARM_CACHEABLE_PFNMAP_SUPPORTED +------------------------------------------- + +:Architectures: arm64 +:Target: VM +:Parameters: None + +This capability indicate to the userspace whether a PFNMAP memory region +can be safely mapped as cacheable. This relies on the presence of +force write back (FWB) feature support on the hardware. + 8. Other capabilities. ====================== diff --git a/Documentation/virt/kvm/devices/arm-vgic-v3.rst b/Documentation/virt/kvm/devices/arm-vgic-v3.rst index e860498b1e35..ff02102f7141 100644 --- a/Documentation/virt/kvm/devices/arm-vgic-v3.rst +++ b/Documentation/virt/kvm/devices/arm-vgic-v3.rst @@ -78,6 +78,8 @@ Groups: -ENXIO The group or attribute is unknown/unsupported for this device or hardware support is missing. -EFAULT Invalid user pointer for attr->addr. + -EBUSY Attempt to write a register that is read-only after + initialization ======= ============================================================= @@ -120,6 +122,12 @@ Groups: Note that distributor fields are not banked, but return the same value regardless of the mpidr used to access the register. + Userspace is allowed to write the following register fields prior to + initialization of the VGIC: + + * GICD_IIDR.Revision + * GICD_TYPER2.nASSGIcap + GICD_IIDR.Revision is updated when the KVM implementation is changed in a way directly observable by the guest or userspace. Userspace should read GICD_IIDR from KVM and write back the read value to confirm its expected @@ -128,6 +136,12 @@ Groups: behavior. + GICD_TYPER2.nASSGIcap allows userspace to control the support of SGIs + without an active state. At VGIC creation the field resets to the + maximum capability of the system. Userspace is expected to read the field + to determine the supported value(s) before writing to the field. + + The GICD_STATUSR and GICR_STATUSR registers are architecturally defined such that a write of a clear bit has no effect, whereas a write with a set bit clears that value. To allow userspace to freely set the values of these two @@ -202,16 +216,69 @@ Groups: KVM_DEV_ARM_VGIC_GRP_CPU_SYSREGS accesses the CPU interface registers for the CPU specified by the mpidr field. - CPU interface registers access is not implemented for AArch32 mode. - Error -ENXIO is returned when accessed in AArch32 mode. + The available registers are: + + =============== ==================================================== + ICC_PMR_EL1 + ICC_BPR0_EL1 + ICC_AP0R0_EL1 + ICC_AP0R1_EL1 when the host implements at least 6 bits of priority + ICC_AP0R2_EL1 when the host implements 7 bits of priority + ICC_AP0R3_EL1 when the host implements 7 bits of priority + ICC_AP1R0_EL1 + ICC_AP1R1_EL1 when the host implements at least 6 bits of priority + ICC_AP1R2_EL1 when the host implements 7 bits of priority + ICC_AP1R3_EL1 when the host implements 7 bits of priority + ICC_BPR1_EL1 + ICC_CTLR_EL1 + ICC_SRE_EL1 + ICC_IGRPEN0_EL1 + ICC_IGRPEN1_EL1 + =============== ==================================================== + + When EL2 is available for the guest, these registers are also available: + + ============= ==================================================== + ICH_AP0R0_EL2 + ICH_AP0R1_EL2 when the host implements at least 6 bits of priority + ICH_AP0R2_EL2 when the host implements 7 bits of priority + ICH_AP0R3_EL2 when the host implements 7 bits of priority + ICH_AP1R0_EL2 + ICH_AP1R1_EL2 when the host implements at least 6 bits of priority + ICH_AP1R2_EL2 when the host implements 7 bits of priority + ICH_AP1R3_EL2 when the host implements 7 bits of priority + ICH_HCR_EL2 + ICC_SRE_EL2 + ICH_VTR_EL2 + ICH_VMCR_EL2 + ICH_LR0_EL2 + ICH_LR1_EL2 + ICH_LR2_EL2 + ICH_LR3_EL2 + ICH_LR4_EL2 + ICH_LR5_EL2 + ICH_LR6_EL2 + ICH_LR7_EL2 + ICH_LR8_EL2 + ICH_LR9_EL2 + ICH_LR10_EL2 + ICH_LR11_EL2 + ICH_LR12_EL2 + ICH_LR13_EL2 + ICH_LR14_EL2 + ICH_LR15_EL2 + ============= ==================================================== + + CPU interface registers are only described using the AArch64 + encoding. Errors: - ======= ===================================================== - -ENXIO Getting or setting this register is not yet supported + ======= ================================================= + -ENXIO Getting or setting this register is not supported -EBUSY VCPU is running -EINVAL Invalid mpidr or register value supplied - ======= ===================================================== + ======= ================================================= KVM_DEV_ARM_VGIC_GRP_NR_IRQS |