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KVM: SVM: detect opening of SMI window using STGI intercept

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Commit 05cade71cf ("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: 05cade71cf ("KVM: nSVM: fix SMI injection in guest mode")
Signed-off-by: Ladi Prosek <lprosek@redhat.com>
Signed-off-by: Radim Krčmář <rkrcmar@redhat.com>
This commit is contained in:
Ladi Prosek 2017-10-17 16:02:39 +02:00 committed by Radim Krčmář
parent 9b8ebbdb74
commit cc3d967f7e
4 changed files with 36 additions and 9 deletions
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1
arch/x86/include/asm/kvm_host.h
View File

@ -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 {

16
arch/x86/kvm/svm.c
View File

@ -3187,7 +3187,7 @@ 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);
@ -5476,6 +5476,19 @@ 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,
@ -5590,6 +5603,7 @@ 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)

6
arch/x86/kvm/vmx.c
View File

@ -11973,6 +11973,11 @@ 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,
@ -12102,6 +12107,7 @@ 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)

22
arch/x86/kvm/x86.c
View File

@ -6892,17 +6892,23 @@ 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)