[PATCH 5/6] KVM: SVM: Inject MCEs when restricted injection is active

Melody Wang
2024-08-07T01:04:47Z

When restricted injection is active, only #HV exceptions can be injected into
the SEV-SNP guest.

Detect that restricted injection feature is active for the guest, and then
follow the #HV doorbell communication from the GHCB specification to inject the
MCEs.

Co-developed-by: Thomas Lendacky <thomas.lendacky@amd.com>
Signed-off-by: Thomas Lendacky <thomas.lendacky@amd.com>
Signed-off-by: Melody Wang <huibo.wang@amd.com>
---
arch/x86/include/asm/kvm-x86-ops.h | 1 +
arch/x86/include/asm/kvm_host.h | 1 +
arch/x86/kvm/svm/sev.c | 16 ++++++++++++++--
arch/x86/kvm/svm/svm.c | 17 +++++++++++++++++
arch/x86/kvm/svm/svm.h | 2 ++
arch/x86/kvm/vmx/main.c | 1 +
arch/x86/kvm/vmx/vmx.c | 5 +++++
arch/x86/kvm/vmx/x86_ops.h | 1 +
arch/x86/kvm/x86.c | 7 +++++++
9 files changed, 49 insertions(+), 2 deletions(-)

diff --git a/arch/x86/include/asm/kvm-x86-ops.h b/arch/x86/include/asm/kvm-x86-ops.h
index 68ad4f923664..9e5764a8e031 100644
--- a/arch/x86/include/asm/kvm-x86-ops.h
+++ b/arch/x86/include/asm/kvm-x86-ops.h
@@ -76,6 +76,7 @@ KVM_X86_OP(inject_exception)
KVM_X86_OP(cancel_injection)
KVM_X86_OP(interrupt_allowed)
KVM_X86_OP(nmi_allowed)
+KVM_X86_OP_OPTIONAL(mce_allowed)
KVM_X86_OP(get_nmi_mask)
KVM_X86_OP(set_nmi_mask)
KVM_X86_OP(enable_nmi_window)
diff --git a/arch/x86/include/asm/kvm_host.h b/arch/x86/include/asm/kvm_host.h
index 94e7b5a4fafe..cb1608a69144 100644
--- a/arch/x86/include/asm/kvm_host.h
+++ b/arch/x86/include/asm/kvm_host.h
@@ -1715,6 +1715,7 @@ struct kvm_x86_ops {
void (*cancel_injection)(struct kvm_vcpu *vcpu);
int (*interrupt_allowed)(struct kvm_vcpu *vcpu, bool for_injection);
int (*nmi_allowed)(struct kvm_vcpu *vcpu, bool for_injection);
+ int (*mce_allowed)(struct kvm_vcpu *vcpu);
bool (*get_nmi_mask)(struct kvm_vcpu *vcpu);
void (*set_nmi_mask)(struct kvm_vcpu *vcpu, bool masked);
/* Whether or not a virtual NMI is pending in hardware. */
diff --git a/arch/x86/kvm/svm/sev.c b/arch/x86/kvm/svm/sev.c
index 7f9f35e0e092..87c493bad93a 100644
--- a/arch/x86/kvm/svm/sev.c
+++ b/arch/x86/kvm/svm/sev.c
@@ -5071,6 +5071,8 @@ static bool __sev_snp_inject(enum inject_type type, struct kvm_vcpu *vcpu)

if (type == INJECT_NMI)
hvdb->events.nmi = 1;
+ else if (type == INJECT_MCE)
+ hvdb->events.mce = 1;
else
hvdb->events.vector = vcpu->arch.interrupt.nr;

@@ -5088,6 +5090,11 @@ bool sev_snp_queue_exception(struct kvm_vcpu *vcpu)
if (!sev_snp_is_rinj_active(vcpu))
return false;

+ if (vcpu->arch.exception.vector == MC_VECTOR) {
+ if (__sev_snp_inject(INJECT_MCE, vcpu))
+ return true;
+ }
+
/*
* Restricted injection is enabled, only #HV is supported.
* If the vector is not HV_VECTOR, do not inject the exception,
@@ -5152,7 +5159,7 @@ void sev_snp_cancel_injection(struct kvm_vcpu *vcpu)

/*
* KVM only injects a single event each time (prepare_hv_injection),
- * so when events.nmi is true, the vector will be zero
+ * so when events.nmi is true, the mce and vector will be zero
*/
if (hvdb->events.vector)
svm->vmcb->control.event_inj |= hvdb->events.vector |
@@ -5161,6 +5168,9 @@ void sev_snp_cancel_injection(struct kvm_vcpu *vcpu)
if (hvdb->events.nmi)
svm->vmcb->control.event_inj |= SVM_EVTINJ_TYPE_NMI;

+ if (hvdb->events.mce)
+ svm->vmcb->control.event_inj |= MC_VECTOR | SVM_EVTINJ_TYPE_EXEPT;
+
hvdb->events.pending_events = 0;

out:
@@ -5178,9 +5188,11 @@ bool sev_snp_blocked(enum inject_type type, struct kvm_vcpu *vcpu)
if (!hvdb)
return true;

- /* Indicate NMIs and interrupts blocked based on guest acknowledgment */
+ /* Indicate NMIs, MCEs and interrupts blocked based on guest acknowledgment */
if (type == INJECT_NMI)
blocked = hvdb->events.nmi;
+ else if (type == INJECT_MCE)
+ blocked = hvdb->events.mce;
else
blocked = !!hvdb->events.vector;

diff --git a/arch/x86/kvm/svm/svm.c b/arch/x86/kvm/svm/svm.c
index d9c572344f0c..1c13c5da6eea 100644
--- a/arch/x86/kvm/svm/svm.c
+++ b/arch/x86/kvm/svm/svm.c
@@ -3867,6 +3867,22 @@ static int svm_interrupt_allowed(struct kvm_vcpu *vcpu, bool for_injection)
return 1;
}

+bool svm_mce_blocked(struct kvm_vcpu *vcpu)
+{
+ if (sev_snp_is_rinj_active(vcpu))
+ return sev_snp_blocked(INJECT_MCE, vcpu);
+
+ return false;
+}
+
+static int svm_mce_allowed(struct kvm_vcpu *vcpu)
+{
+ if (svm_mce_blocked(vcpu))
+ return 0;
+
+ return 1;
+}
+
static void svm_enable_irq_window(struct kvm_vcpu *vcpu)
{
struct vcpu_svm *svm = to_svm(vcpu);
@@ -5066,6 +5082,7 @@ static struct kvm_x86_ops svm_x86_ops __initdata = {
.cancel_injection = svm_cancel_injection,
.interrupt_allowed = svm_interrupt_allowed,
.nmi_allowed = svm_nmi_allowed,
+ .mce_allowed = svm_mce_allowed,
.get_nmi_mask = svm_get_nmi_mask,
.set_nmi_mask = svm_set_nmi_mask,
.enable_nmi_window = svm_enable_nmi_window,
diff --git a/arch/x86/kvm/svm/svm.h b/arch/x86/kvm/svm/svm.h
index f60ff6229ff4..0cf32954589f 100644
--- a/arch/x86/kvm/svm/svm.h
+++ b/arch/x86/kvm/svm/svm.h
@@ -44,6 +44,7 @@ extern int lbrv;
enum inject_type {
INJECT_IRQ,
INJECT_NMI,
+ INJECT_MCE,
};

/*
@@ -602,6 +603,7 @@ void svm_set_cr4(struct kvm_vcpu *vcpu, unsigned long cr4);
void disable_nmi_singlestep(struct vcpu_svm *svm);
bool svm_smi_blocked(struct kvm_vcpu *vcpu);
bool svm_nmi_blocked(struct kvm_vcpu *vcpu);
+bool svm_mce_blocked(struct kvm_vcpu *vcpu);
bool svm_interrupt_blocked(struct kvm_vcpu *vcpu);
void svm_set_gif(struct vcpu_svm *svm, bool value);
int svm_invoke_exit_handler(struct kvm_vcpu *vcpu, u64 exit_code);
diff --git a/arch/x86/kvm/vmx/main.c b/arch/x86/kvm/vmx/main.c
index 0bf35ebe8a1b..c3a49a3b7f21 100644
--- a/arch/x86/kvm/vmx/main.c
+++ b/arch/x86/kvm/vmx/main.c
@@ -84,6 +84,7 @@ struct kvm_x86_ops vt_x86_ops __initdata = {
.cancel_injection = vmx_cancel_injection,
.interrupt_allowed = vmx_interrupt_allowed,
.nmi_allowed = vmx_nmi_allowed,
+ .mce_allowed = vmx_mce_allowed,
.get_nmi_mask = vmx_get_nmi_mask,
.set_nmi_mask = vmx_set_nmi_mask,
.enable_nmi_window = vmx_enable_nmi_window,
diff --git a/arch/x86/kvm/vmx/vmx.c b/arch/x86/kvm/vmx/vmx.c
index f18c2d8c7476..b3dce5d95329 100644
--- a/arch/x86/kvm/vmx/vmx.c
+++ b/arch/x86/kvm/vmx/vmx.c
@@ -5093,6 +5093,11 @@ int vmx_interrupt_allowed(struct kvm_vcpu *vcpu, bool for_injection)
return !vmx_interrupt_blocked(vcpu);
}

+int vmx_mce_allowed(struct kvm_vcpu *vcpu)
+{
+ return 1;
+}
+
int vmx_set_tss_addr(struct kvm *kvm, unsigned int addr)
{
void __user *ret;
diff --git a/arch/x86/kvm/vmx/x86_ops.h b/arch/x86/kvm/vmx/x86_ops.h
index ce3221cd1d01..b2b1a3bb4eb3 100644
--- a/arch/x86/kvm/vmx/x86_ops.h
+++ b/arch/x86/kvm/vmx/x86_ops.h
@@ -92,6 +92,7 @@ void vmx_inject_exception(struct kvm_vcpu *vcpu);
void vmx_cancel_injection(struct kvm_vcpu *vcpu);
int vmx_interrupt_allowed(struct kvm_vcpu *vcpu, bool for_injection);
int vmx_nmi_allowed(struct kvm_vcpu *vcpu, bool for_injection);
+int vmx_mce_allowed(struct kvm_vcpu *vcpu);
bool vmx_get_nmi_mask(struct kvm_vcpu *vcpu);
void vmx_set_nmi_mask(struct kvm_vcpu *vcpu, bool masked);
void vmx_enable_nmi_window(struct kvm_vcpu *vcpu);
diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
index ef3d3511e4af..e926fc9d82e6 100644
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -10487,12 +10487,19 @@ static int kvm_check_and_inject_events(struct kvm_vcpu *vcpu,
}
}

+ if (vcpu->arch.exception.vector == MC_VECTOR) {
+ r = static_call(kvm_x86_mce_allowed)(vcpu);
+ if (!r)
+ goto out_except;
+ }
+
kvm_inject_exception(vcpu);

vcpu->arch.exception.pending = false;
vcpu->arch.exception.injected = true;

can_inject = false;
+out_except:
}

/* Don't inject interrupts if the user asked to avoid doing so */
--
2.34.1