| Message ID | 20220215014806.4102669-2-daviddunn@google.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | KVM: x86: Provide per VM capability for disabling PMU virtualization | expand |
On Tue, Feb 15, 2022, David Dunn wrote: > Add a new capability, KVM_CAP_PMU_CAPABILITY, that takes a bitmask of > settings/features to allow userspace to configure PMU virtualization on > a per-VM basis. For now, support a single flag, KVM_CAP_PMU_DISABLE, > to allow disabling PMU virtualization for a VM even when KVM is configured > with enable_pmu=true a module level. > > To keep KVM simple, disallow changing VM's PMU configuration after vCPUs > have been created. > > Signed-off-by: David Dunn <daviddunn@google.com> > --- A few nits, otherwise Reviewed-by: Sean Christopherson <seanjc@google.com> Somewhat off-topic, looking at this got me looking at vmx_get_perf_capabilities(). We really should cache the result of its RDMSR. And I believe emulation of WRMSR from the guest to MSR_IA32_PERF_CAPABILITIES is missing a guest_cpuid_has() check. > Documentation/virt/kvm/api.rst | 22 ++++++++++++++++++++++ > arch/x86/include/asm/kvm_host.h | 1 + > arch/x86/kvm/svm/pmu.c | 2 +- > arch/x86/kvm/vmx/pmu_intel.c | 2 +- > arch/x86/kvm/x86.c | 17 +++++++++++++++++ > include/uapi/linux/kvm.h | 3 +++ > tools/include/uapi/linux/kvm.h | 3 +++ > 7 files changed, 48 insertions(+), 2 deletions(-) > > diff --git a/Documentation/virt/kvm/api.rst b/Documentation/virt/kvm/api.rst > index a4267104db50..df836965b347 100644 > --- a/Documentation/virt/kvm/api.rst > +++ b/Documentation/virt/kvm/api.rst > @@ -7561,3 +7561,25 @@ The argument to KVM_ENABLE_CAP is also a bitmask, and must be a subset > of the result of KVM_CHECK_EXTENSION. KVM will forward to userspace > the hypercalls whose corresponding bit is in the argument, and return > ENOSYS for the others. > + > +8.35 KVM_CAP_PMU_CAPABILITY > +--------------------------- > + > +:Capability KVM_CAP_PMU_CAPABILITY > +:Architectures: x86 > +:Type: vm > +:Parameters: arg[0] is bitmask of PMU virtualization capabilities. Referring to "DISABLE" as a capabilitiy is rather odd, but I don't have a better suggestion. > +:Returns 0 on success, -EINVAL when arg[0] contains invalid bits > + > +This capability alters PMU virtualization in KVM. > + > +Calling KVM_CHECK_EXTENSION for this capability returns a bitmask of > +PMU virtualization capabilities that can be adjusted on a VM. > + > +The argument to KVM_ENABLE_CAP is also a bitmask and selects specific > +PMU virtualization capabilities to be applied to the VM. This can > +only be invoked on a VM prior to the creation of VCPUs. > + > +At this time, KVM_CAP_PMU_DISABLE is the only capability. Setting > +this capability will disable PMU virtualization for that VM. Usermode > +should adjust CPUID leaf 0xA to reflect that the PMU is disabled. > diff --git a/arch/x86/include/asm/kvm_host.h b/arch/x86/include/asm/kvm_host.h > index 10815b672a26..61e9050a3488 100644 > --- a/arch/x86/include/asm/kvm_host.h > +++ b/arch/x86/include/asm/kvm_host.h > @@ -1233,6 +1233,7 @@ struct kvm_arch { > hpa_t hv_root_tdp; > spinlock_t hv_root_tdp_lock; > #endif > + bool enable_pmu; Doesn''t really matter, but I'd prefer we put this up among the many other bools, e.g. diff --git a/arch/x86/include/asm/kvm_host.h b/arch/x86/include/asm/kvm_host.h index 4bb0d3be2055..b57d40419ddd 100644 --- a/arch/x86/include/asm/kvm_host.h +++ b/arch/x86/include/asm/kvm_host.h @@ -1150,6 +1150,7 @@ struct kvm_arch { bool guest_can_read_msr_platform_info; bool exception_payload_enabled; + bool enable_pmu; bool bus_lock_detection_enabled; /* * If exit_on_emulation_error is set, and the in-kernel instruction @@ -1233,7 +1234,6 @@ struct kvm_arch { hpa_t hv_root_tdp; spinlock_t hv_root_tdp_lock; #endif - bool enable_pmu; }; struct kvm_vm_stat { > }; > > struct kvm_vm_stat { > diff --git a/arch/x86/kvm/svm/pmu.c b/arch/x86/kvm/svm/pmu.c > index 5aa45f13b16d..d4de52409335 100644 > --- a/arch/x86/kvm/svm/pmu.c > +++ b/arch/x86/kvm/svm/pmu.c > @@ -101,7 +101,7 @@ static inline struct kvm_pmc *get_gp_pmc_amd(struct kvm_pmu *pmu, u32 msr, > { > struct kvm_vcpu *vcpu = pmu_to_vcpu(pmu); > > - if (!enable_pmu) > + if (!vcpu->kvm->arch.enable_pmu) > return NULL; > > switch (msr) { > diff --git a/arch/x86/kvm/vmx/pmu_intel.c b/arch/x86/kvm/vmx/pmu_intel.c > index 03fab48b149c..4e5b1eeeb77c 100644 > --- a/arch/x86/kvm/vmx/pmu_intel.c > +++ b/arch/x86/kvm/vmx/pmu_intel.c > @@ -487,7 +487,7 @@ static void intel_pmu_refresh(struct kvm_vcpu *vcpu) > pmu->reserved_bits = 0xffffffff00200000ull; > > entry = kvm_find_cpuid_entry(vcpu, 0xa, 0); > - if (!entry || !enable_pmu) > + if (!entry || !vcpu->kvm->arch.enable_pmu) > return; > eax.full = entry->eax; > edx.full = entry->edx; > diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c > index eaa3b5b89c5e..0803a1388bbf 100644 > --- a/arch/x86/kvm/x86.c > +++ b/arch/x86/kvm/x86.c > @@ -110,6 +110,8 @@ static u64 __read_mostly cr4_reserved_bits = CR4_RESERVED_BITS; > > #define KVM_EXIT_HYPERCALL_VALID_MASK (1 << KVM_HC_MAP_GPA_RANGE) > > +#define KVM_CAP_PMU_VALID_MASK KVM_CAP_PMU_DISABLE > + > #define KVM_X2APIC_API_VALID_FLAGS (KVM_X2APIC_API_USE_32BIT_IDS | \ > KVM_X2APIC_API_DISABLE_BROADCAST_QUIRK) > > @@ -4331,6 +4333,9 @@ int kvm_vm_ioctl_check_extension(struct kvm *kvm, long ext) > if (r < sizeof(struct kvm_xsave)) > r = sizeof(struct kvm_xsave); > break; > + case KVM_CAP_PMU_CAPABILITY: > + r = enable_pmu ? KVM_CAP_PMU_VALID_MASK : 0; > + break; > } > default: > break; > @@ -6005,6 +6010,17 @@ int kvm_vm_ioctl_enable_cap(struct kvm *kvm, > kvm->arch.exit_on_emulation_error = cap->args[0]; > r = 0; > break; > + case KVM_CAP_PMU_CAPABILITY: > + r = -EINVAL; > + if (!enable_pmu || (cap->args[0] & ~KVM_CAP_PMU_VALID_MASK)) > + break; I'd prefer another newline here, the other case statements are just bad influences :-) > + mutex_lock(&kvm->lock); > + if (!kvm->created_vcpus) { > + kvm->arch.enable_pmu = !(cap->args[0] & KVM_CAP_PMU_DISABLE); > + r = 0; > + } > + mutex_unlock(&kvm->lock); > + break; > default: > r = -EINVAL; > break;
diff --git a/Documentation/virt/kvm/api.rst b/Documentation/virt/kvm/api.rst index a4267104db50..df836965b347 100644 --- a/Documentation/virt/kvm/api.rst +++ b/Documentation/virt/kvm/api.rst @@ -7561,3 +7561,25 @@ The argument to KVM_ENABLE_CAP is also a bitmask, and must be a subset of the result of KVM_CHECK_EXTENSION. KVM will forward to userspace the hypercalls whose corresponding bit is in the argument, and return ENOSYS for the others. + +8.35 KVM_CAP_PMU_CAPABILITY +--------------------------- + +:Capability KVM_CAP_PMU_CAPABILITY +:Architectures: x86 +:Type: vm +:Parameters: arg[0] is bitmask of PMU virtualization capabilities. +:Returns 0 on success, -EINVAL when arg[0] contains invalid bits + +This capability alters PMU virtualization in KVM. + +Calling KVM_CHECK_EXTENSION for this capability returns a bitmask of +PMU virtualization capabilities that can be adjusted on a VM. + +The argument to KVM_ENABLE_CAP is also a bitmask and selects specific +PMU virtualization capabilities to be applied to the VM. This can +only be invoked on a VM prior to the creation of VCPUs. + +At this time, KVM_CAP_PMU_DISABLE is the only capability. Setting +this capability will disable PMU virtualization for that VM. Usermode +should adjust CPUID leaf 0xA to reflect that the PMU is disabled. diff --git a/arch/x86/include/asm/kvm_host.h b/arch/x86/include/asm/kvm_host.h index 10815b672a26..61e9050a3488 100644 --- a/arch/x86/include/asm/kvm_host.h +++ b/arch/x86/include/asm/kvm_host.h @@ -1233,6 +1233,7 @@ struct kvm_arch { hpa_t hv_root_tdp; spinlock_t hv_root_tdp_lock; #endif + bool enable_pmu; }; struct kvm_vm_stat { diff --git a/arch/x86/kvm/svm/pmu.c b/arch/x86/kvm/svm/pmu.c index 5aa45f13b16d..d4de52409335 100644 --- a/arch/x86/kvm/svm/pmu.c +++ b/arch/x86/kvm/svm/pmu.c @@ -101,7 +101,7 @@ static inline struct kvm_pmc *get_gp_pmc_amd(struct kvm_pmu *pmu, u32 msr, { struct kvm_vcpu *vcpu = pmu_to_vcpu(pmu); - if (!enable_pmu) + if (!vcpu->kvm->arch.enable_pmu) return NULL; switch (msr) { diff --git a/arch/x86/kvm/vmx/pmu_intel.c b/arch/x86/kvm/vmx/pmu_intel.c index 03fab48b149c..4e5b1eeeb77c 100644 --- a/arch/x86/kvm/vmx/pmu_intel.c +++ b/arch/x86/kvm/vmx/pmu_intel.c @@ -487,7 +487,7 @@ static void intel_pmu_refresh(struct kvm_vcpu *vcpu) pmu->reserved_bits = 0xffffffff00200000ull; entry = kvm_find_cpuid_entry(vcpu, 0xa, 0); - if (!entry || !enable_pmu) + if (!entry || !vcpu->kvm->arch.enable_pmu) return; eax.full = entry->eax; edx.full = entry->edx; diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c index eaa3b5b89c5e..0803a1388bbf 100644 --- a/arch/x86/kvm/x86.c +++ b/arch/x86/kvm/x86.c @@ -110,6 +110,8 @@ static u64 __read_mostly cr4_reserved_bits = CR4_RESERVED_BITS; #define KVM_EXIT_HYPERCALL_VALID_MASK (1 << KVM_HC_MAP_GPA_RANGE) +#define KVM_CAP_PMU_VALID_MASK KVM_CAP_PMU_DISABLE + #define KVM_X2APIC_API_VALID_FLAGS (KVM_X2APIC_API_USE_32BIT_IDS | \ KVM_X2APIC_API_DISABLE_BROADCAST_QUIRK) @@ -4331,6 +4333,9 @@ int kvm_vm_ioctl_check_extension(struct kvm *kvm, long ext) if (r < sizeof(struct kvm_xsave)) r = sizeof(struct kvm_xsave); break; + case KVM_CAP_PMU_CAPABILITY: + r = enable_pmu ? KVM_CAP_PMU_VALID_MASK : 0; + break; } default: break; @@ -6005,6 +6010,17 @@ int kvm_vm_ioctl_enable_cap(struct kvm *kvm, kvm->arch.exit_on_emulation_error = cap->args[0]; r = 0; break; + case KVM_CAP_PMU_CAPABILITY: + r = -EINVAL; + if (!enable_pmu || (cap->args[0] & ~KVM_CAP_PMU_VALID_MASK)) + break; + mutex_lock(&kvm->lock); + if (!kvm->created_vcpus) { + kvm->arch.enable_pmu = !(cap->args[0] & KVM_CAP_PMU_DISABLE); + r = 0; + } + mutex_unlock(&kvm->lock); + break; default: r = -EINVAL; break; @@ -11591,6 +11607,7 @@ int kvm_arch_init_vm(struct kvm *kvm, unsigned long type) raw_spin_unlock_irqrestore(&kvm->arch.tsc_write_lock, flags); kvm->arch.guest_can_read_msr_platform_info = true; + kvm->arch.enable_pmu = enable_pmu; #if IS_ENABLED(CONFIG_HYPERV) spin_lock_init(&kvm->arch.hv_root_tdp_lock); diff --git a/include/uapi/linux/kvm.h b/include/uapi/linux/kvm.h index 5191b57e1562..3d6046295755 100644 --- a/include/uapi/linux/kvm.h +++ b/include/uapi/linux/kvm.h @@ -1134,6 +1134,7 @@ struct kvm_ppc_resize_hpt { #define KVM_CAP_VM_GPA_BITS 207 #define KVM_CAP_XSAVE2 208 #define KVM_CAP_SYS_ATTRIBUTES 209 +#define KVM_CAP_PMU_CAPABILITY 210 #ifdef KVM_CAP_IRQ_ROUTING @@ -1970,6 +1971,8 @@ struct kvm_dirty_gfn { #define KVM_BUS_LOCK_DETECTION_OFF (1 << 0) #define KVM_BUS_LOCK_DETECTION_EXIT (1 << 1) +#define KVM_CAP_PMU_DISABLE (1 << 0) + /** * struct kvm_stats_header - Header of per vm/vcpu binary statistics data. * @flags: Some extra information for header, always 0 for now. diff --git a/tools/include/uapi/linux/kvm.h b/tools/include/uapi/linux/kvm.h index 5191b57e1562..3d6046295755 100644 --- a/tools/include/uapi/linux/kvm.h +++ b/tools/include/uapi/linux/kvm.h @@ -1134,6 +1134,7 @@ struct kvm_ppc_resize_hpt { #define KVM_CAP_VM_GPA_BITS 207 #define KVM_CAP_XSAVE2 208 #define KVM_CAP_SYS_ATTRIBUTES 209 +#define KVM_CAP_PMU_CAPABILITY 210 #ifdef KVM_CAP_IRQ_ROUTING @@ -1970,6 +1971,8 @@ struct kvm_dirty_gfn { #define KVM_BUS_LOCK_DETECTION_OFF (1 << 0) #define KVM_BUS_LOCK_DETECTION_EXIT (1 << 1) +#define KVM_CAP_PMU_DISABLE (1 << 0) + /** * struct kvm_stats_header - Header of per vm/vcpu binary statistics data. * @flags: Some extra information for header, always 0 for now.
Add a new capability, KVM_CAP_PMU_CAPABILITY, that takes a bitmask of settings/features to allow userspace to configure PMU virtualization on a per-VM basis. For now, support a single flag, KVM_CAP_PMU_DISABLE, to allow disabling PMU virtualization for a VM even when KVM is configured with enable_pmu=true a module level. To keep KVM simple, disallow changing VM's PMU configuration after vCPUs have been created. Signed-off-by: David Dunn <daviddunn@google.com> --- Documentation/virt/kvm/api.rst | 22 ++++++++++++++++++++++ arch/x86/include/asm/kvm_host.h | 1 + arch/x86/kvm/svm/pmu.c | 2 +- arch/x86/kvm/vmx/pmu_intel.c | 2 +- arch/x86/kvm/x86.c | 17 +++++++++++++++++ include/uapi/linux/kvm.h | 3 +++ tools/include/uapi/linux/kvm.h | 3 +++ 7 files changed, 48 insertions(+), 2 deletions(-)