linux-kernel - [PATCH 02/18] KVM: x86: hyper-v: Introduce helpers to check if VSM is exposed to guest

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Message-ID: <20240609154945.55332-3-nsaenz@amazon.com>
Date: Sun, 9 Jun 2024 15:49:30 +0000
From: Nicolas Saenz Julienne <nsaenz@...zon.com>
To: <linux-kernel@...r.kernel.org>, <kvm@...r.kernel.org>
CC: <pbonzini@...hat.com>, <seanjc@...gle.com>, <vkuznets@...hat.com>,
	<linux-doc@...r.kernel.org>, <linux-hyperv@...r.kernel.org>,
	<linux-arch@...r.kernel.org>, <linux-trace-kernel@...r.kernel.org>,
	<graf@...zon.de>, <dwmw2@...radead.org>, <paul@...zon.com>,
	<nsaenz@...zon.com>, <mlevitsk@...hat.com>, <jgowans@...zon.com>,
	<corbet@....net>, <decui@...rosoft.com>, <tglx@...utronix.de>,
	<mingo@...hat.com>, <bp@...en8.de>, <dave.hansen@...ux.intel.com>,
	<x86@...nel.org>, <amoorthy@...gle.com>
Subject: [PATCH 02/18] KVM: x86: hyper-v: Introduce helpers to check if VSM is exposed to guest

Introduce a helper function to check if the guest exposes the VSM CPUID
bit.

Signed-off-by: Nicolas Saenz Julienne <nsaenz@...zon.com>
---
 arch/x86/kvm/hyperv.h             | 10 ++++++++++
 include/asm-generic/hyperv-tlfs.h |  1 +
 2 files changed, 11 insertions(+)

diff --git a/arch/x86/kvm/hyperv.h b/arch/x86/kvm/hyperv.h
index 923e64903da9a..d007d2203e0e4 100644
--- a/arch/x86/kvm/hyperv.h
+++ b/arch/x86/kvm/hyperv.h
@@ -265,6 +265,12 @@ static inline void kvm_hv_nested_transtion_tlb_flush(struct kvm_vcpu *vcpu,
 }
 
 int kvm_hv_vcpu_flush_tlb(struct kvm_vcpu *vcpu);
+static inline bool kvm_hv_cpuid_vsm_enabled(struct kvm_vcpu *vcpu)
+{
+	struct kvm_vcpu_hv *hv_vcpu = to_hv_vcpu(vcpu);
+
+	return hv_vcpu && (hv_vcpu->cpuid_cache.features_ebx & HV_ACCESS_VSM);
+}
 #else /* CONFIG_KVM_HYPERV */
 static inline void kvm_hv_setup_tsc_page(struct kvm *kvm,
 					 struct pvclock_vcpu_time_info *hv_clock) {}
@@ -322,6 +328,10 @@ static inline u32 kvm_hv_get_vpindex(struct kvm_vcpu *vcpu)
 	return vcpu->vcpu_idx;
 }
 static inline void kvm_hv_nested_transtion_tlb_flush(struct kvm_vcpu *vcpu, bool tdp_enabled) {}
+static inline bool kvm_hv_cpuid_vsm_enabled(struct kvm_vcpu *vcpu)
+{
+	return false;
+}
 #endif /* CONFIG_KVM_HYPERV */
 
 #endif /* __ARCH_X86_KVM_HYPERV_H__ */
diff --git a/include/asm-generic/hyperv-tlfs.h b/include/asm-generic/hyperv-tlfs.h
index 814207e7c37fc..ffac04bbd0c19 100644
--- a/include/asm-generic/hyperv-tlfs.h
+++ b/include/asm-generic/hyperv-tlfs.h
@@ -89,6 +89,7 @@
 #define HV_ACCESS_STATS				BIT(8)
 #define HV_DEBUGGING				BIT(11)
 #define HV_CPU_MANAGEMENT			BIT(12)
+#define HV_ACCESS_VSM				BIT(16)
 #define HV_ENABLE_EXTENDED_HYPERCALLS		BIT(20)
 #define HV_ISOLATION				BIT(22)
 
-- 
2.40.1