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From: David Dunn <daviddunn@google.com>
To: kvm@vger.kernel.org, pbonzini@redhat.com,
	like.xu.linux@gmail.com, jmattson@google.com,
	cloudliang@tencent.com
Cc: daviddunn@google.com
Subject: [PATCH v2 1/3] Provide VM capability to disable PMU virtualization for individual VMs
Date: Fri, 21 Jan 2022 00:29:50 +0000	[thread overview]
Message-ID: <20220121002952.241015-2-daviddunn@google.com> (raw)
In-Reply-To: <20220121002952.241015-1-daviddunn@google.com>

KVM_PMU_CONFIG_DISABLE can be used to disable PMU virtualization on
individual x86 VMs.  PMU configuration must be done prior to creating
VCPUs.

To enable future extension, KVM_CAP_PMU_CONFIG reports available
settings when queried via check_extension.

Since KVM_GET_SUPPORTED_CPUID reports the maximal CPUID information
based on module parameters, usermode will need to adjust CPUID when
disabling PMU virtualization on individual VMs.

Signed-off-by: David Dunn <daviddunn@google.com>
---
 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              | 12 ++++++++++++
 include/uapi/linux/kvm.h        |  4 ++++
 tools/include/uapi/linux/kvm.h  |  4 ++++
 6 files changed, 23 insertions(+), 2 deletions(-)

diff --git a/arch/x86/include/asm/kvm_host.h b/arch/x86/include/asm/kvm_host.h
index 682ad02a4e58..5cdcd4a7671b 100644
--- a/arch/x86/include/asm/kvm_host.h
+++ b/arch/x86/include/asm/kvm_host.h
@@ -1232,6 +1232,7 @@ 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 466d18fc0c5d..2c5868d77268 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 55518b7d3b96..42a98635bea5 100644
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -4326,6 +4326,9 @@ 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_CONFIG:
+		r = enable_pmu ? KVM_PMU_CONFIG_VALID : 0;
+		break;
 	}
 	default:
 		break;
@@ -5937,6 +5940,14 @@ 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_CONFIG:
+		r = -EINVAL;
+		if (!enable_pmu || kvm->created_vcpus > 0 ||
+		    cap->args[0] & ~KVM_PMU_CONFIG_VALID)
+			break;
+		kvm->arch.enable_pmu = !(cap->args[0] & KVM_PMU_CONFIG_DISABLE);
+		r = 0;
+		break;
 	default:
 		r = -EINVAL;
 		break;
@@ -11562,6 +11573,7 @@ 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 9563d294f181..57a1280fa43b 100644
--- a/include/uapi/linux/kvm.h
+++ b/include/uapi/linux/kvm.h
@@ -1133,6 +1133,7 @@ struct kvm_ppc_resize_hpt {
 #define KVM_CAP_VM_MOVE_ENC_CONTEXT_FROM 206
 #define KVM_CAP_VM_GPA_BITS 207
 #define KVM_CAP_XSAVE2 208
+#define KVM_CAP_PMU_CONFIG 209
 
 #ifdef KVM_CAP_IRQ_ROUTING
 
@@ -1972,6 +1973,9 @@ struct kvm_dirty_gfn {
 #define KVM_BUS_LOCK_DETECTION_OFF             (1 << 0)
 #define KVM_BUS_LOCK_DETECTION_EXIT            (1 << 1)
 
+#define KVM_PMU_CONFIG_DISABLE                 (1 << 0)
+#define KVM_PMU_CONFIG_VALID                   (KVM_PMU_CONFIG_DISABLE)
+
 /**
  * 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 9563d294f181..57a1280fa43b 100644
--- a/tools/include/uapi/linux/kvm.h
+++ b/tools/include/uapi/linux/kvm.h
@@ -1133,6 +1133,7 @@ struct kvm_ppc_resize_hpt {
 #define KVM_CAP_VM_MOVE_ENC_CONTEXT_FROM 206
 #define KVM_CAP_VM_GPA_BITS 207
 #define KVM_CAP_XSAVE2 208
+#define KVM_CAP_PMU_CONFIG 209
 
 #ifdef KVM_CAP_IRQ_ROUTING
 
@@ -1972,6 +1973,9 @@ struct kvm_dirty_gfn {
 #define KVM_BUS_LOCK_DETECTION_OFF             (1 << 0)
 #define KVM_BUS_LOCK_DETECTION_EXIT            (1 << 1)
 
+#define KVM_PMU_CONFIG_DISABLE                 (1 << 0)
+#define KVM_PMU_CONFIG_VALID                   (KVM_PMU_CONFIG_DISABLE)
+
 /**
  * struct kvm_stats_header - Header of per vm/vcpu binary statistics data.
  * @flags: Some extra information for header, always 0 for now.
-- 
2.35.0.rc0.227.g00780c9af4-goog


  reply	other threads:[~2022-01-21  0:30 UTC|newest]

Thread overview: 5+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2022-01-21  0:29 [PATCH v2 0/3] Provide VM capability to disable PMU virtualization for individual VMs David Dunn
2022-01-21  0:29 ` David Dunn [this message]
2022-01-21  6:59   ` [PATCH v2 1/3] " Like Xu
2022-01-21  0:29 ` [PATCH v2 2/3] selftests: introduce function to create test VM without vcpus David Dunn
2022-01-21  0:29 ` [PATCH v2 3/3] selftests: Verify disabling PMU via KVM_CAP_CONFIG_PMU David Dunn

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