KVM: x86: Add KVM_GET/SET_VCPU_EVENTS

This new IOCTL exports all yet user-invisible states related to
exceptions, interrupts, and NMIs. Together with appropriate user space
changes, this fixes sporadic problems of vmsave/restore, live migration
and system reset.

[avi: future-proof abi by adding a flags field]

Signed-off-by: Jan Kiszka <jan.kiszka@siemens.com>
Signed-off-by: Avi Kivity <avi@redhat.com>

1 files changed, 22 insertions, 0 deletions

diff --git a/arch/x86/kvm/svm.c b/arch/x86/kvm/svm.c
index 34b700f9e498..3de0b37ec038 100644
--- a/arch/x86/kvm/svm.c
+++ b/arch/x86/kvm/svm.c
@@ -2499,6 +2499,26 @@ static int svm_nmi_allowed(struct kvm_vcpu *vcpu)
                 !(svm->vcpu.arch.hflags & HF_NMI_MASK);
 }
 
+static bool svm_get_nmi_mask(struct kvm_vcpu *vcpu)
+{
+        struct vcpu_svm *svm = to_svm(vcpu);
+
+        return !!(svm->vcpu.arch.hflags & HF_NMI_MASK);
+}
+
+static void svm_set_nmi_mask(struct kvm_vcpu *vcpu, bool masked)
+{
+        struct vcpu_svm *svm = to_svm(vcpu);
+
+        if (masked) {
+                svm->vcpu.arch.hflags |= HF_NMI_MASK;
+                svm->vmcb->control.intercept |= (1UL << INTERCEPT_IRET);
+        } else {
+                svm->vcpu.arch.hflags &= ~HF_NMI_MASK;
+                svm->vmcb->control.intercept &= ~(1UL << INTERCEPT_IRET);
+        }
+}
+
 static int svm_interrupt_allowed(struct kvm_vcpu *vcpu)
 {
         struct vcpu_svm *svm = to_svm(vcpu);
@@ -2946,6 +2966,8 @@ static struct kvm_x86_ops svm_x86_ops = {
         .queue_exception = svm_queue_exception,
         .interrupt_allowed = svm_interrupt_allowed,
         .nmi_allowed = svm_nmi_allowed,
+        .get_nmi_mask = svm_get_nmi_mask,
+        .set_nmi_mask = svm_set_nmi_mask,
         .enable_nmi_window = enable_nmi_window,
         .enable_irq_window = enable_irq_window,
         .update_cr8_intercept = update_cr8_intercept,