Commit 05cade71cf3b ("KVM: nSVM: fix SMI injection in guest mode") made
KVM mask SMI if GIF=0 but it didn't do anything to unmask it when GIF is
enabled.
The issue manifests for me as a significantly longer boot time of Windows
guests when running with SMM-enabled OVMF.
This commit fixes it by intercepting STGI instead of requesting immediate
exit if the reason why SMM was masked is GIF.
Fixes: 05cade71cf3b ("KVM: nSVM: fix SMI injection in guest mode")
Signed-off-by: Ladi Prosek <lprosek@xxxxxxxxxx>
---
arch/x86/include/asm/kvm_host.h | 1 +
arch/x86/kvm/svm.c | 16 +++++++++++++++-
arch/x86/kvm/vmx.c | 6 ++++++
arch/x86/kvm/x86.c | 22 ++++++++++++++--------
4 files changed, 36 insertions(+), 9 deletions(-)
diff --git a/arch/x86/include/asm/kvm_host.h b/arch/x86/include/asm/kvm_host.h
index 8700b845f780..7233445a20bd 100644
--- a/arch/x86/include/asm/kvm_host.h
+++ b/arch/x86/include/asm/kvm_host.h
@@ -1065,6 +1065,7 @@ struct kvm_x86_ops {
int (*smi_allowed)(struct kvm_vcpu *vcpu);
int (*pre_enter_smm)(struct kvm_vcpu *vcpu, char *smstate);
int (*pre_leave_smm)(struct kvm_vcpu *vcpu, u64 smbase);
+ int (*enable_smi_window)(struct kvm_vcpu *vcpu);
};
struct kvm_arch_async_pf {
diff --git a/arch/x86/kvm/svm.c b/arch/x86/kvm/svm.c
index a9ef41407bec..1868fe4af4b7 100644
--- a/arch/x86/kvm/svm.c
+++ b/arch/x86/kvm/svm.c
@@ -3179,7 +3179,7 @@ static int stgi_interception(struct vcpu_svm *svm)
/*
* If VGIF is enabled, the STGI intercept is only added to
- * detect the opening of the NMI window; remove it now.
+ * detect the opening of the SMI/NMI window; remove it now.
*/
if (vgif_enabled(svm))
clr_intercept(svm, INTERCEPT_STGI);
@@ -5468,6 +5468,19 @@ static int svm_pre_leave_smm(struct kvm_vcpu *vcpu, u64 smbase)
return ret;
}
+static int enable_smi_window(struct kvm_vcpu *vcpu)
+{
+ struct vcpu_svm *svm = to_svm(vcpu);
+
+ if (!gif_set(svm)) {
+ if (vgif_enabled(svm))
+ set_intercept(svm, INTERCEPT_STGI);
+ /* STGI will cause a vm exit */
+ return 1;
+ }
+ return 0;
+}
+
static struct kvm_x86_ops svm_x86_ops __ro_after_init = {
.cpu_has_kvm_support = has_svm,
.disabled_by_bios = is_disabled,
@@ -5582,6 +5595,7 @@ static struct kvm_x86_ops svm_x86_ops __ro_after_init = {
.smi_allowed = svm_smi_allowed,
.pre_enter_smm = svm_pre_enter_smm,
.pre_leave_smm = svm_pre_leave_smm,
+ .enable_smi_window = enable_smi_window,
};
static int __init svm_init(void)
diff --git a/arch/x86/kvm/vmx.c b/arch/x86/kvm/vmx.c
index c27e9e1de54c..bfafa20af7da 100644
--- a/arch/x86/kvm/vmx.c
+++ b/arch/x86/kvm/vmx.c
@@ -11998,6 +11998,11 @@ static int vmx_pre_leave_smm(struct kvm_vcpu *vcpu, u64 smbase)
return 0;
}
+static int enable_smi_window(struct kvm_vcpu *vcpu)
+{
+ return 0;
+}
+
static struct kvm_x86_ops vmx_x86_ops __ro_after_init = {
.cpu_has_kvm_support = cpu_has_kvm_support,
.disabled_by_bios = vmx_disabled_by_bios,
@@ -12127,6 +12132,7 @@ static struct kvm_x86_ops vmx_x86_ops __ro_after_init = {
.smi_allowed = vmx_smi_allowed,
.pre_enter_smm = vmx_pre_enter_smm,
.pre_leave_smm = vmx_pre_leave_smm,
+ .enable_smi_window = enable_smi_window,
};
static int __init vmx_init(void)
diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
index 283e9f4b7d8b..f6bfe0f08a63 100644
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -6886,17 +6886,23 @@ static int vcpu_enter_guest(struct kvm_vcpu *vcpu)
if (inject_pending_event(vcpu, req_int_win) != 0)
req_immediate_exit = true;
else {
- /* Enable NMI/IRQ window open exits if needed.
+ /* Enable SMI/NMI/IRQ window open exits if needed.
*
- * SMIs have two cases: 1) they can be nested, and
- * then there is nothing to do here because RSM will
- * cause a vmexit anyway; 2) or the SMI can be pending
- * because inject_pending_event has completed the
- * injection of an IRQ or NMI from the previous vmexit,
- * and then we request an immediate exit to inject the SMI.
+ * SMIs have three cases:
+ * 1) They can be nested, and then there is nothing to
+ * do here because RSM will cause a vmexit anyway.
+ * 2) There is an ISA-specific reason why SMI cannot be
+ * injected, and the moment when this changes can be
+ * intercepted.
+ * 3) Or the SMI can be pending because
+ * inject_pending_event has completed the injection
+ * of an IRQ or NMI from the previous vmexit, and
+ * then we request an immediate exit to inject the
+ * SMI.
*/
if (vcpu->arch.smi_pending && !is_smm(vcpu))
- req_immediate_exit = true;
+ if (!kvm_x86_ops->enable_smi_window(vcpu))
+ req_immediate_exit = true;
if (vcpu->arch.nmi_pending)
kvm_x86_ops->enable_nmi_window(vcpu);
if (kvm_cpu_has_injectable_intr(vcpu) || req_int_win)
--
2.13.5
