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

[Tom Lendacky]

From: Tom Lendacky <thomas.lenda...@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.lenda...@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