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Subject[RFC PATCH v2 24/33] KVM: SVM: Do not report support for SMM for an SEV-ES guest
Date
From: Tom Lendacky <thomas.lendacky@amd.com>

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@amd.com>
---
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
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