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authorOliver Upton <oupton@google.com>2020-02-07 13:36:05 +0300
committerPaolo Bonzini <pbonzini@redhat.com>2020-02-12 14:34:09 +0300
commit684c0422da71da0cd81319c90b8099b563b13da4 (patch)
tree149e0e42b2faea4c31780c9c6641afbf89be552b /arch
parent307f1cfa269657c63cfe2c932386fcc24684d9dd (diff)
downloadlinux-684c0422da71da0cd81319c90b8099b563b13da4.tar.xz
KVM: nVMX: Handle pending #DB when injecting INIT VM-exit
SDM 27.3.4 states that the 'pending debug exceptions' VMCS field will be populated if a VM-exit caused by an INIT signal takes priority over a debug-trap. Emulate this behavior when synthesizing an INIT signal VM-exit into L1. Fixes: 4b9852f4f389 ("KVM: x86: Fix INIT signal handling in various CPU states") Signed-off-by: Oliver Upton <oupton@google.com> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Diffstat (limited to 'arch')
-rw-r--r--arch/x86/kvm/vmx/nested.c28
1 files changed, 28 insertions, 0 deletions
diff --git a/arch/x86/kvm/vmx/nested.c b/arch/x86/kvm/vmx/nested.c
index 657c2eda357c..1586aaae3a6f 100644
--- a/arch/x86/kvm/vmx/nested.c
+++ b/arch/x86/kvm/vmx/nested.c
@@ -3575,6 +3575,33 @@ static void nested_vmx_inject_exception_vmexit(struct kvm_vcpu *vcpu,
nested_vmx_vmexit(vcpu, EXIT_REASON_EXCEPTION_NMI, intr_info, exit_qual);
}
+/*
+ * Returns true if a debug trap is pending delivery.
+ *
+ * In KVM, debug traps bear an exception payload. As such, the class of a #DB
+ * exception may be inferred from the presence of an exception payload.
+ */
+static inline bool vmx_pending_dbg_trap(struct kvm_vcpu *vcpu)
+{
+ return vcpu->arch.exception.pending &&
+ vcpu->arch.exception.nr == DB_VECTOR &&
+ vcpu->arch.exception.payload;
+}
+
+/*
+ * Certain VM-exits set the 'pending debug exceptions' field to indicate a
+ * recognized #DB (data or single-step) that has yet to be delivered. Since KVM
+ * represents these debug traps with a payload that is said to be compatible
+ * with the 'pending debug exceptions' field, write the payload to the VMCS
+ * field if a VM-exit is delivered before the debug trap.
+ */
+static void nested_vmx_update_pending_dbg(struct kvm_vcpu *vcpu)
+{
+ if (vmx_pending_dbg_trap(vcpu))
+ vmcs_writel(GUEST_PENDING_DBG_EXCEPTIONS,
+ vcpu->arch.exception.payload);
+}
+
static int vmx_check_nested_events(struct kvm_vcpu *vcpu, bool external_intr)
{
struct vcpu_vmx *vmx = to_vmx(vcpu);
@@ -3587,6 +3614,7 @@ static int vmx_check_nested_events(struct kvm_vcpu *vcpu, bool external_intr)
test_bit(KVM_APIC_INIT, &apic->pending_events)) {
if (block_nested_events)
return -EBUSY;
+ nested_vmx_update_pending_dbg(vcpu);
clear_bit(KVM_APIC_INIT, &apic->pending_events);
nested_vmx_vmexit(vcpu, EXIT_REASON_INIT_SIGNAL, 0, 0);
return 0;