KVM: x86: advertise KVM_CAP_X86_SMM
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
--
RFC->v1: depend on support for real mode CS base above 1M
diff --git a/arch/x86/include/asm/kvm_host.h b/arch/x86/include/asm/kvm_host.h
index 661888a..60f8623 100644
--- a/arch/x86/include/asm/kvm_host.h
+++ b/arch/x86/include/asm/kvm_host.h
@@ -701,6 +701,7 @@
int (*hardware_setup)(void); /* __init */
void (*hardware_unsetup)(void); /* __exit */
bool (*cpu_has_accelerated_tpr)(void);
+ bool (*cpu_has_high_real_mode_segbase)(void);
void (*cpuid_update)(struct kvm_vcpu *vcpu);
/* Create, but do not attach this VCPU */
diff --git a/arch/x86/kvm/svm.c b/arch/x86/kvm/svm.c
index 6ff1faf..6807531 100644
--- a/arch/x86/kvm/svm.c
+++ b/arch/x86/kvm/svm.c
@@ -4080,6 +4080,11 @@
return false;
}
+static bool svm_has_high_real_mode_segbase(void)
+{
+ return true;
+}
+
static u64 svm_get_mt_mask(struct kvm_vcpu *vcpu, gfn_t gfn, bool is_mmio)
{
return 0;
@@ -4353,6 +4358,7 @@
.hardware_enable = svm_hardware_enable,
.hardware_disable = svm_hardware_disable,
.cpu_has_accelerated_tpr = svm_cpu_has_accelerated_tpr,
+ .cpu_has_high_real_mode_segbase = svm_has_high_real_mode_segbase,
.vcpu_create = svm_create_vcpu,
.vcpu_free = svm_free_vcpu,
diff --git a/arch/x86/kvm/vmx.c b/arch/x86/kvm/vmx.c
index b1f13ff..e53800e 100644
--- a/arch/x86/kvm/vmx.c
+++ b/arch/x86/kvm/vmx.c
@@ -8139,6 +8139,11 @@
local_irq_enable();
}
+static bool vmx_has_high_real_mode_segbase(void)
+{
+ return enable_unrestricted_guest || emulate_invalid_guest_state;
+}
+
static bool vmx_mpx_supported(void)
{
return (vmcs_config.vmexit_ctrl & VM_EXIT_CLEAR_BNDCFGS) &&
@@ -10296,6 +10301,7 @@
.hardware_enable = hardware_enable,
.hardware_disable = hardware_disable,
.cpu_has_accelerated_tpr = report_flexpriority,
+ .cpu_has_high_real_mode_segbase = vmx_has_high_real_mode_segbase,
.vcpu_create = vmx_create_vcpu,
.vcpu_free = vmx_free_vcpu,
diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
index ef923b3..6b6b8ed 100644
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -2890,6 +2890,17 @@
#endif
r = 1;
break;
+ case KVM_CAP_X86_SMM:
+ /* SMBASE is usually relocated above 1M on modern chipsets,
+ * and SMM handlers might indeed rely on 4G segment limits,
+ * so do not report SMM to be available if real mode is
+ * emulated via vm86 mode. Still, do not go to great lengths
+ * to avoid userspace's usage of the feature, because it is a
+ * fringe case that is not enabled except via specific settings
+ * of the module parameters.
+ */
+ r = kvm_x86_ops->cpu_has_high_real_mode_segbase();
+ break;
case KVM_CAP_COALESCED_MMIO:
r = KVM_COALESCED_MMIO_PAGE_OFFSET;
break;
@@ -4283,6 +4294,10 @@
for (i = j = 0; i < ARRAY_SIZE(emulated_msrs); i++) {
switch (emulated_msrs[i]) {
+ case MSR_IA32_SMBASE:
+ if (!kvm_x86_ops->cpu_has_high_real_mode_segbase())
+ continue;
+ break;
default:
break;
}
