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>

3 files changed, 129 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,
diff --git a/arch/x86/kvm/vmx.c b/arch/x86/kvm/vmx.c
index 22fcd27a0b58..778f059ae423 100644
--- a/arch/x86/kvm/vmx.c
+++ b/arch/x86/kvm/vmx.c
@@ -2639,6 +2639,34 @@ static int vmx_nmi_allowed(struct kvm_vcpu *vcpu)
                                 GUEST_INTR_STATE_NMI));
 }
 
+static bool vmx_get_nmi_mask(struct kvm_vcpu *vcpu)
+{
+        if (!cpu_has_virtual_nmis())
+                return to_vmx(vcpu)->soft_vnmi_blocked;
+        else
+                return !!(vmcs_read32(GUEST_INTERRUPTIBILITY_INFO) &
+                          GUEST_INTR_STATE_NMI);
+}
+
+static void vmx_set_nmi_mask(struct kvm_vcpu *vcpu, bool masked)
+{
+        struct vcpu_vmx *vmx = to_vmx(vcpu);
+
+        if (!cpu_has_virtual_nmis()) {
+                if (vmx->soft_vnmi_blocked != masked) {
+                        vmx->soft_vnmi_blocked = masked;
+                        vmx->vnmi_blocked_time = 0;
+                }
+        } else {
+                if (masked)
+                        vmcs_set_bits(GUEST_INTERRUPTIBILITY_INFO,
+                                      GUEST_INTR_STATE_NMI);
+                else
+                        vmcs_clear_bits(GUEST_INTERRUPTIBILITY_INFO,
+                                        GUEST_INTR_STATE_NMI);
+        }
+}
+
 static int vmx_interrupt_allowed(struct kvm_vcpu *vcpu)
 {
         return (vmcs_readl(GUEST_RFLAGS) & X86_EFLAGS_IF) &&
@@ -3985,6 +4013,8 @@ static struct kvm_x86_ops vmx_x86_ops = {
         .queue_exception = vmx_queue_exception,
         .interrupt_allowed = vmx_interrupt_allowed,
         .nmi_allowed = vmx_nmi_allowed,
+        .get_nmi_mask = vmx_get_nmi_mask,
+        .set_nmi_mask = vmx_set_nmi_mask,
         .enable_nmi_window = enable_nmi_window,
         .enable_irq_window = enable_irq_window,
         .update_cr8_intercept = update_cr8_intercept,
diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
index ba8958dca3c4..35eea30821d6 100644
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -1342,6 +1342,7 @@ int kvm_dev_ioctl_check_extension(long ext)
         case KVM_CAP_SET_IDENTITY_MAP_ADDR:
         case KVM_CAP_XEN_HVM:
         case KVM_CAP_ADJUST_CLOCK:
+        case KVM_CAP_VCPU_EVENTS:
                 r = 1;
                 break;
         case KVM_CAP_COALESCED_MMIO:
@@ -1883,6 +1884,61 @@ static int kvm_vcpu_ioctl_x86_set_mce(struct kvm_vcpu *vcpu,
         return 0;
 }
 
+static void kvm_vcpu_ioctl_x86_get_vcpu_events(struct kvm_vcpu *vcpu,
+                                               struct kvm_vcpu_events *events)
+{
+        vcpu_load(vcpu);
+
+        events->exception.injected = vcpu->arch.exception.pending;
+        events->exception.nr = vcpu->arch.exception.nr;
+        events->exception.has_error_code = vcpu->arch.exception.has_error_code;
+        events->exception.error_code = vcpu->arch.exception.error_code;
+
+        events->interrupt.injected = vcpu->arch.interrupt.pending;
+        events->interrupt.nr = vcpu->arch.interrupt.nr;
+        events->interrupt.soft = vcpu->arch.interrupt.soft;
+
+        events->nmi.injected = vcpu->arch.nmi_injected;
+        events->nmi.pending = vcpu->arch.nmi_pending;
+        events->nmi.masked = kvm_x86_ops->get_nmi_mask(vcpu);
+
+        events->sipi_vector = vcpu->arch.sipi_vector;
+
+        events->flags = 0;
+
+        vcpu_put(vcpu);
+}
+
+static int kvm_vcpu_ioctl_x86_set_vcpu_events(struct kvm_vcpu *vcpu,
+                                              struct kvm_vcpu_events *events)
+{
+        if (events->flags)
+                return -EINVAL;
+
+        vcpu_load(vcpu);
+
+        vcpu->arch.exception.pending = events->exception.injected;
+        vcpu->arch.exception.nr = events->exception.nr;
+        vcpu->arch.exception.has_error_code = events->exception.has_error_code;
+        vcpu->arch.exception.error_code = events->exception.error_code;
+
+        vcpu->arch.interrupt.pending = events->interrupt.injected;
+        vcpu->arch.interrupt.nr = events->interrupt.nr;
+        vcpu->arch.interrupt.soft = events->interrupt.soft;
+        if (vcpu->arch.interrupt.pending && irqchip_in_kernel(vcpu->kvm))
+                kvm_pic_clear_isr_ack(vcpu->kvm);
+
+        vcpu->arch.nmi_injected = events->nmi.injected;
+        vcpu->arch.nmi_pending = events->nmi.pending;
+        kvm_x86_ops->set_nmi_mask(vcpu, events->nmi.masked);
+
+        vcpu->arch.sipi_vector = events->sipi_vector;
+
+        vcpu_put(vcpu);
+
+        return 0;
+}
+
 long kvm_arch_vcpu_ioctl(struct file *filp,
                          unsigned int ioctl, unsigned long arg)
 {
@@ -2040,6 +2096,27 @@ long kvm_arch_vcpu_ioctl(struct file *filp,
                 r = kvm_vcpu_ioctl_x86_set_mce(vcpu, &mce);
                 break;
         }
+        case KVM_GET_VCPU_EVENTS: {
+                struct kvm_vcpu_events events;
+
+                kvm_vcpu_ioctl_x86_get_vcpu_events(vcpu, &events);
+
+                r = -EFAULT;
+                if (copy_to_user(argp, &events, sizeof(struct kvm_vcpu_events)))
+                        break;
+                r = 0;
+                break;
+        }
+        case KVM_SET_VCPU_EVENTS: {
+                struct kvm_vcpu_events events;
+
+                r = -EFAULT;
+                if (copy_from_user(&events, argp, sizeof(struct kvm_vcpu_events)))
+                        break;
+
+                r = kvm_vcpu_ioctl_x86_set_vcpu_events(vcpu, &events);
+                break;
+        }
         default:
                 r = -EINVAL;
         }