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From: Vitaly Kuznetsov <vkuznets@redhat.com>
To: kvm@vger.kernel.org, Paolo Bonzini <pbonzini@redhat.com>
Cc: Sean Christopherson <seanjc@google.com>,
	Wanpeng Li <wanpengli@tencent.com>,
	Jim Mattson <jmattson@google.com>,
	Siddharth Chandrasekaran <sidcha@amazon.de>,
	linux-kernel@vger.kernel.org
Subject: [PATCH 03/30] KVM: x86: hyper-v: Cache guest CPUID leaves determining features availability
Date: Mon, 19 Apr 2021 18:01:00 +0200
Message-ID: <20210419160127.192712-4-vkuznets@redhat.com> (raw)
In-Reply-To: <20210419160127.192712-1-vkuznets@redhat.com>

Limiting exposed Hyper-V features requires a fast way to check if the
particular feature is exposed in guest visible CPUIDs or not. To aboid
looping through all CPUID entries on every hypercall/MSR access cache
the required leaves on CPUID update.

Signed-off-by: Vitaly Kuznetsov <vkuznets@redhat.com>
---
 arch/x86/include/asm/kvm_host.h |  8 ++++++
 arch/x86/kvm/hyperv.c           | 49 ++++++++++++++++++++++++++-------
 2 files changed, 47 insertions(+), 10 deletions(-)

diff --git a/arch/x86/include/asm/kvm_host.h b/arch/x86/include/asm/kvm_host.h
index dc40897c41bc..6525d2716b09 100644
--- a/arch/x86/include/asm/kvm_host.h
+++ b/arch/x86/include/asm/kvm_host.h
@@ -531,6 +531,14 @@ struct kvm_vcpu_hv {
 	DECLARE_BITMAP(stimer_pending_bitmap, HV_SYNIC_STIMER_COUNT);
 	cpumask_t tlb_flush;
 	bool enforce_cpuid;
+	struct {
+		u32 features_eax; /* HYPERV_CPUID_FEATURES.EAX */
+		u32 features_ebx; /* HYPERV_CPUID_FEATURES.EBX */
+		u32 features_edx; /* HYPERV_CPUID_FEATURES.EDX */
+		u32 enlightenments_eax; /* HYPERV_CPUID_ENLIGHTMENT_INFO.EAX */
+		u32 enlightenments_ebx; /* HYPERV_CPUID_ENLIGHTMENT_INFO.EBX */
+		u32 syndbg_cap_eax; /* HYPERV_CPUID_SYNDBG_PLATFORM_CAPABILITIES.EAX */
+	} cpuid_cache;
 };
 
 /* Xen HVM per vcpu emulation context */
diff --git a/arch/x86/kvm/hyperv.c b/arch/x86/kvm/hyperv.c
index 557897c453a9..ccb298cfc933 100644
--- a/arch/x86/kvm/hyperv.c
+++ b/arch/x86/kvm/hyperv.c
@@ -273,15 +273,10 @@ static int synic_set_msr(struct kvm_vcpu_hv_synic *synic,
 
 static bool kvm_hv_is_syndbg_enabled(struct kvm_vcpu *vcpu)
 {
-	struct kvm_cpuid_entry2 *entry;
-
-	entry = kvm_find_cpuid_entry(vcpu,
-				     HYPERV_CPUID_SYNDBG_PLATFORM_CAPABILITIES,
-				     0);
-	if (!entry)
-		return false;
+	struct kvm_vcpu_hv *hv_vcpu = to_hv_vcpu(vcpu);
 
-	return entry->eax & HV_X64_SYNDBG_CAP_ALLOW_KERNEL_DEBUGGING;
+	return hv_vcpu->cpuid_cache.syndbg_cap_eax &
+		HV_X64_SYNDBG_CAP_ALLOW_KERNEL_DEBUGGING;
 }
 
 static int kvm_hv_syndbg_complete_userspace(struct kvm_vcpu *vcpu)
@@ -1801,12 +1796,46 @@ static u64 kvm_hv_send_ipi(struct kvm_vcpu *vcpu, u64 ingpa, u64 outgpa,
 void kvm_hv_set_cpuid(struct kvm_vcpu *vcpu)
 {
 	struct kvm_cpuid_entry2 *entry;
+	struct kvm_vcpu_hv *hv_vcpu = to_hv_vcpu(vcpu);
 
 	entry = kvm_find_cpuid_entry(vcpu, HYPERV_CPUID_INTERFACE, 0);
-	if (entry && entry->eax == HYPERV_CPUID_SIGNATURE_EAX)
+	if (entry && entry->eax == HYPERV_CPUID_SIGNATURE_EAX) {
 		vcpu->arch.hyperv_enabled = true;
-	else
+	} else {
 		vcpu->arch.hyperv_enabled = false;
+		return;
+	}
+
+	if (!to_hv_vcpu(vcpu) && kvm_hv_vcpu_init(vcpu))
+		return;
+
+	hv_vcpu = to_hv_vcpu(vcpu);
+
+	entry = kvm_find_cpuid_entry(vcpu, HYPERV_CPUID_FEATURES, 0);
+	if (entry) {
+		hv_vcpu->cpuid_cache.features_eax = entry->eax;
+		hv_vcpu->cpuid_cache.features_ebx = entry->ebx;
+		hv_vcpu->cpuid_cache.features_edx = entry->edx;
+	} else {
+		hv_vcpu->cpuid_cache.features_eax = 0;
+		hv_vcpu->cpuid_cache.features_ebx = 0;
+		hv_vcpu->cpuid_cache.features_edx = 0;
+	}
+
+	entry = kvm_find_cpuid_entry(vcpu, HYPERV_CPUID_ENLIGHTMENT_INFO, 0);
+	if (entry) {
+		hv_vcpu->cpuid_cache.enlightenments_eax = entry->eax;
+		hv_vcpu->cpuid_cache.enlightenments_ebx = entry->ebx;
+	} else {
+		hv_vcpu->cpuid_cache.enlightenments_eax = 0;
+		hv_vcpu->cpuid_cache.enlightenments_ebx = 0;
+	}
+
+	entry = kvm_find_cpuid_entry(vcpu, HYPERV_CPUID_SYNDBG_PLATFORM_CAPABILITIES, 0);
+	if (entry)
+		hv_vcpu->cpuid_cache.syndbg_cap_eax = entry->eax;
+	else
+		hv_vcpu->cpuid_cache.syndbg_cap_eax = 0;
 }
 
 int kvm_hv_set_enforce_cpuid(struct kvm_vcpu *vcpu, bool enforce)
-- 
2.30.2


  parent reply index

Thread overview: 31+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-04-19 16:00 [PATCH 00/30] KVM: x86: hyper-v: Fine-grained access check to Hyper-V hypercalls and MSRs Vitaly Kuznetsov
2021-04-19 16:00 ` [PATCH 01/30] asm-generic/hyperv: add HV_STATUS_ACCESS_DENIED definition Vitaly Kuznetsov
2021-04-19 16:00 ` [PATCH 02/30] KVM: x86: hyper-v: Introduce KVM_CAP_HYPERV_ENFORCE_CPUID Vitaly Kuznetsov
2021-04-19 16:01 ` Vitaly Kuznetsov [this message]
2021-04-19 16:01 ` [PATCH 04/30] KVM: x86: hyper-v: Prepare to check access to Hyper-V MSRs Vitaly Kuznetsov
2021-04-19 16:01 ` [PATCH 05/30] KVM: x86: hyper-v: Honor HV_MSR_HYPERCALL_AVAILABLE privilege bit Vitaly Kuznetsov
2021-04-19 16:01 ` [PATCH 06/30] KVM: x86: hyper-v: Honor HV_MSR_VP_RUNTIME_AVAILABLE " Vitaly Kuznetsov
2021-04-19 16:01 ` [PATCH 07/30] KVM: x86: hyper-v: Honor HV_MSR_TIME_REF_COUNT_AVAILABLE " Vitaly Kuznetsov
2021-04-19 16:01 ` [PATCH 08/30] KVM: x86: hyper-v: Honor HV_MSR_VP_INDEX_AVAILABLE " Vitaly Kuznetsov
2021-04-19 16:01 ` [PATCH 09/30] KVM: x86: hyper-v: Honor HV_MSR_RESET_AVAILABLE " Vitaly Kuznetsov
2021-04-19 16:01 ` [PATCH 10/30] KVM: x86: hyper-v: Honor HV_MSR_REFERENCE_TSC_AVAILABLE " Vitaly Kuznetsov
2021-04-19 16:01 ` [PATCH 11/30] KVM: x86: hyper-v: Honor HV_MSR_SYNIC_AVAILABLE " Vitaly Kuznetsov
2021-04-19 16:01 ` [PATCH 12/30] KVM: x86: hyper-v: Honor HV_MSR_SYNTIMER_AVAILABLE " Vitaly Kuznetsov
2021-04-19 16:01 ` [PATCH 13/30] KVM: x86: hyper-v: Honor HV_MSR_APIC_ACCESS_AVAILABLE " Vitaly Kuznetsov
2021-04-19 16:01 ` [PATCH 14/30] KVM: x86: hyper-v: Honor HV_ACCESS_FREQUENCY_MSRS " Vitaly Kuznetsov
2021-04-19 16:01 ` [PATCH 15/30] KVM: x86: hyper-v: Honor HV_ACCESS_REENLIGHTENMENT " Vitaly Kuznetsov
2021-04-19 16:01 ` [PATCH 16/30] KVM: x86: hyper-v: Honor HV_FEATURE_GUEST_CRASH_MSR_AVAILABLE " Vitaly Kuznetsov
2021-04-19 16:01 ` [PATCH 17/30] KVM: x86: hyper-v: Honor HV_FEATURE_DEBUG_MSRS_AVAILABLE " Vitaly Kuznetsov
2021-04-19 16:01 ` [PATCH 18/30] KVM: x86: hyper-v: Inverse the default in hv_check_msr_access() Vitaly Kuznetsov
2021-04-19 16:01 ` [PATCH 19/30] KVM: x86: hyper-v: Honor HV_STIMER_DIRECT_MODE_AVAILABLE privilege bit Vitaly Kuznetsov
2021-04-19 16:01 ` [PATCH 20/30] KVM: x86: hyper-v: Prepare to check access to Hyper-V hypercalls Vitaly Kuznetsov
2021-04-19 16:01 ` [PATCH 21/30] KVM: x86: hyper-v: Check access to HVCALL_NOTIFY_LONG_SPIN_WAIT hypercall Vitaly Kuznetsov
2021-04-19 16:01 ` [PATCH 22/30] KVM: x86: hyper-v: Honor HV_POST_MESSAGES privilege bit Vitaly Kuznetsov
2021-04-19 16:01 ` [PATCH 23/30] KVM: x86: hyper-v: Honor HV_SIGNAL_EVENTS " Vitaly Kuznetsov
2021-04-19 16:01 ` [PATCH 24/30] KVM: x86: hyper-v: Honor HV_DEBUGGING " Vitaly Kuznetsov
2021-04-19 16:01 ` [PATCH 25/30] KVM: x86: hyper-v: Honor HV_X64_REMOTE_TLB_FLUSH_RECOMMENDED bit Vitaly Kuznetsov
2021-04-19 16:01 ` [PATCH 26/30] KVM: x86: hyper-v: Honor HV_X64_CLUSTER_IPI_RECOMMENDED bit Vitaly Kuznetsov
2021-04-19 16:01 ` [PATCH 27/30] KVM: x86: hyper-v: Honor HV_X64_EX_PROCESSOR_MASKS_RECOMMENDED bit Vitaly Kuznetsov
2021-04-19 16:01 ` [PATCH 28/30] KVM: selftests: move Hyper-V MSR definitions to hyperv.h Vitaly Kuznetsov
2021-04-19 16:01 ` [PATCH 29/30] KVM: selftests: Move evmcs.h to x86_64/ Vitaly Kuznetsov
2021-04-19 16:01 ` [PATCH 30/30] KVM: selftests: Introduce hyperv_features test Vitaly Kuznetsov

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