[RFC PATCH v2 24/33] KVM: SVM: Do not report support for SMM for an SEV-ES guest

[Tom Lendacky]

From: Tom Lendacky <thomas.lendacky@xxxxxxx>

SEV-ES guests do not currently support SMM. Update the has_emulated_msr()
kvm_x86_ops function to take a struct kvm parameter so that the capability
can be reported at a VM level.

Since this op is also called during KVM initialization and before a struct
kvm instance is available, comments will be added to each implementation
of has_emulated_msr() to indicate the kvm parameter can be null.

Signed-off-by: Tom Lendacky <thomas.lendacky@xxxxxxx>
---
 arch/x86/include/asm/kvm_host.h |  2 +-
 arch/x86/kvm/svm/svm.c          | 11 ++++++++++-
 arch/x86/kvm/vmx/vmx.c          |  6 +++++-
 arch/x86/kvm/x86.c              |  4 ++--
 4 files changed, 18 insertions(+), 5 deletions(-)

diff --git a/arch/x86/include/asm/kvm_host.h b/arch/x86/include/asm/kvm_host.h
index 44da687855e0..30f1300a05c0 100644
--- a/arch/x86/include/asm/kvm_host.h
+++ b/arch/x86/include/asm/kvm_host.h
@@ -1062,7 +1062,7 @@ struct kvm_x86_ops {
 	void (*hardware_disable)(void);
 	void (*hardware_unsetup)(void);
 	bool (*cpu_has_accelerated_tpr)(void);
-	bool (*has_emulated_msr)(u32 index);
+	bool (*has_emulated_msr)(struct kvm *kvm, u32 index);
 	void (*vcpu_after_set_cpuid)(struct kvm_vcpu *vcpu);
 
 	unsigned int vm_size;
diff --git a/arch/x86/kvm/svm/svm.c b/arch/x86/kvm/svm/svm.c
index 7082432db161..de44f7f2b7a8 100644
--- a/arch/x86/kvm/svm/svm.c
+++ b/arch/x86/kvm/svm/svm.c
@@ -3934,12 +3934,21 @@ static bool svm_cpu_has_accelerated_tpr(void)
 	return false;
 }
 
-static bool svm_has_emulated_msr(u32 index)
+/*
+ * The kvm parameter can be NULL (module initialization, or invocation before
+ * VM creation). Be sure to check the kvm parameter before using it.
+ */
+static bool svm_has_emulated_msr(struct kvm *kvm, u32 index)
 {
 	switch (index) {
 	case MSR_IA32_MCG_EXT_CTL:
 	case MSR_IA32_VMX_BASIC ... MSR_IA32_VMX_VMFUNC:
 		return false;
+	case MSR_IA32_SMBASE:
+		/* SEV-ES guests do not support SMM, so report false */
+		if (kvm && sev_es_guest(kvm))
+			return false;
+		break;
 	default:
 		break;
 	}
diff --git a/arch/x86/kvm/vmx/vmx.c b/arch/x86/kvm/vmx/vmx.c
index 4551a7e80ebc..4fb4f488d4e1 100644
--- a/arch/x86/kvm/vmx/vmx.c
+++ b/arch/x86/kvm/vmx/vmx.c
@@ -6372,7 +6372,11 @@ static void vmx_handle_exit_irqoff(struct kvm_vcpu *vcpu)
 		handle_exception_nmi_irqoff(vmx);
 }
 
-static bool vmx_has_emulated_msr(u32 index)
+/*
+ * The kvm parameter can be NULL (module initialization, or invocation before
+ * VM creation). Be sure to check the kvm parameter before using it.
+ */
+static bool vmx_has_emulated_msr(struct kvm *kvm, u32 index)
 {
 	switch (index) {
 	case MSR_IA32_SMBASE:
diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
index 39c8d9a311d4..20fabf578ab7 100644
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -3690,7 +3690,7 @@ int kvm_vm_ioctl_check_extension(struct kvm *kvm, long ext)
 		 * fringe case that is not enabled except via specific settings
 		 * of the module parameters.
 		 */
-		r = kvm_x86_ops.has_emulated_msr(MSR_IA32_SMBASE);
+		r = kvm_x86_ops.has_emulated_msr(kvm, MSR_IA32_SMBASE);
 		break;
 	case KVM_CAP_VAPIC:
 		r = !kvm_x86_ops.cpu_has_accelerated_tpr();
@@ -5688,7 +5688,7 @@ static void kvm_init_msr_list(void)
 	}
 
 	for (i = 0; i < ARRAY_SIZE(emulated_msrs_all); i++) {
-		if (!kvm_x86_ops.has_emulated_msr(emulated_msrs_all[i]))
+		if (!kvm_x86_ops.has_emulated_msr(NULL, emulated_msrs_all[i]))
 			continue;
 
 		emulated_msrs[num_emulated_msrs++] = emulated_msrs_all[i];
-- 
2.28.0