[PATCH 04/60] KVM: SVM: Inject NMIs when Restricted Injection is active
From: Jörg Rödel <joro@8bytes.org>
Date: 2026-06-08 14:43:12
Also in:
kvm, kvm-riscv, kvmarm, linux-mips, lkml, loongarch
Subsystem:
kernel virtual machine for x86 (kvm/x86), the rest, x86 architecture (32-bit and 64-bit) · Maintainers:
Sean Christopherson, Paolo Bonzini, Linus Torvalds, Thomas Gleixner, Ingo Molnar, Borislav Petkov, Dave Hansen
From: Melody Wang <redacted> When Restricted Injection is active, only #HV exceptions can be injected into the SEV-SNP guest. Detect that, and then follow the #HV doorbell communication from the GHCB specification to inject NMIs. Co-developed-by: Thomas Lendacky <thomas.lendacky@amd.com> Signed-off-by: Thomas Lendacky <thomas.lendacky@amd.com> Signed-off-by: Melody Wang <redacted> Signed-off-by: Joerg Roedel <redacted> --- arch/x86/kvm/svm/sev.c | 19 ++++++++++++++++--- arch/x86/kvm/svm/svm.c | 8 ++++++++ arch/x86/kvm/svm/svm.h | 1 + 3 files changed, 25 insertions(+), 3 deletions(-)
diff --git a/arch/x86/kvm/svm/sev.c b/arch/x86/kvm/svm/sev.c
index f2f40f81ba86..b48745fad8c5 100644
--- a/arch/x86/kvm/svm/sev.c
+++ b/arch/x86/kvm/svm/sev.c@@ -5428,7 +5428,10 @@ static void __sev_snp_inject(enum inject_type type, struct kvm_vcpu *vcpu) return; } - hvdb->events.vector = vcpu->arch.interrupt.nr; + if (type == INJECT_NMI) + hvdb->events.nmi = 1; + else + hvdb->events.vector = vcpu->arch.interrupt.nr; prepare_hv_injection(svm, hvdb);
@@ -5508,10 +5511,17 @@ void sev_snp_cancel_injection(struct kvm_vcpu *vcpu) /* Copy info back into event_inj field (replaces #HV) */ svm->vmcb->control.event_inj = SVM_EVTINJ_VALID; + /* + * KVM only injects a single event each time (prepare_hv_injection), + * so when events.nmi is true, the vector will be zero + */ if (hvdb->events.vector) svm->vmcb->control.event_inj |= hvdb->events.vector | SVM_EVTINJ_TYPE_INTR; + if (hvdb->events.nmi) + svm->vmcb->control.event_inj |= SVM_EVTINJ_TYPE_NMI; + hvdb->events.pending_events = 0; out:
@@ -5537,8 +5547,11 @@ bool sev_snp_blocked(enum inject_type type, struct kvm_vcpu *vcpu) if (!hvdb) return true; - /* Indicate interrupts blocked based on guest acknowledgment */ - blocked = !!hvdb->events.vector; + /* Indicate NMIs and interrupts blocked based on guest acknowledgment */ + if (type == INJECT_NMI) + blocked = hvdb->events.nmi; + else + blocked = !!hvdb->events.vector; unmap_hvdb(vcpu, &hvdb_map);
diff --git a/arch/x86/kvm/svm/svm.c b/arch/x86/kvm/svm/svm.c
index 7253936c460c..5255393986cc 100644
--- a/arch/x86/kvm/svm/svm.c
+++ b/arch/x86/kvm/svm/svm.c@@ -3738,6 +3738,9 @@ static void svm_inject_nmi(struct kvm_vcpu *vcpu) { struct vcpu_svm *svm = to_svm(vcpu); + if (sev_snp_inject(INJECT_NMI, vcpu)) + goto status; + svm->vmcb->control.event_inj = SVM_EVTINJ_VALID | SVM_EVTINJ_TYPE_NMI; if (svm->nmi_l1_to_l2)
@@ -3752,6 +3755,8 @@ static void svm_inject_nmi(struct kvm_vcpu *vcpu) svm->nmi_masked = true; svm_set_iret_intercept(svm); } + +status: ++vcpu->stat.nmi_injections; }
@@ -3968,6 +3973,9 @@ bool svm_nmi_blocked(struct kvm_vcpu *vcpu) if (!gif_set(svm)) return true; + if (sev_snp_is_rinj_active(vcpu)) + return sev_snp_blocked(INJECT_NMI, vcpu); + if (is_guest_mode(vcpu) && nested_exit_on_nmi(svm)) return false;
diff --git a/arch/x86/kvm/svm/svm.h b/arch/x86/kvm/svm/svm.h
index a22ad5de03ea..bb0e5bfdb9a6 100644
--- a/arch/x86/kvm/svm/svm.h
+++ b/arch/x86/kvm/svm/svm.h@@ -57,6 +57,7 @@ extern struct kvm_x86_ops svm_x86_ops __initdata; enum inject_type { INJECT_IRQ, + INJECT_NMI, }; /*
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2.53.0