Once an exception has been injected, any side effects related to the exception (such as setting CR2 or DR6) have been taked place. Therefore, once KVM sets the VM-entry interruption information field or the AMD EVENTINJ field, the next VM-entry must deliver that exception.
Pending interrupts are processed after injected exceptions, so in theory it would not be a problem to use KVM_INTERRUPT when an injected exception is present. However, DOSEMU is using run->ready_for_interrupt_injection to detect interrupt windows and then using KVM_SET_SREGS/KVM_SET_REGS to inject the interrupt manually. For this to work, the interrupt window must be delayed after the completion of the previous event injection.
Cc: stable@vger.kernel.org Reported-by: Stas Sergeev stsp2@yandex.ru Tested-by: Stas Sergeev stsp2@yandex.ru Fixes: 71cc849b7093 ("KVM: x86: Fix split-irqchip vs interrupt injection window request") Signed-off-by: Paolo Bonzini pbonzini@redhat.com (cherry picked from commit 043264d97e9ab74cc9661c8b1f9c00c8ce24cad9) --- arch/x86/kvm/x86.c | 12 +++++++++++- 1 file changed, 11 insertions(+), 1 deletion(-)
diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c index 4116567f3d44..5e921f1e00db 100644 --- a/arch/x86/kvm/x86.c +++ b/arch/x86/kvm/x86.c @@ -4358,8 +4358,18 @@ static int kvm_cpu_accept_dm_intr(struct kvm_vcpu *vcpu)
static int kvm_vcpu_ready_for_interrupt_injection(struct kvm_vcpu *vcpu) { + /* + * Do not cause an interrupt window exit if an exception + * is pending or an event needs reinjection; userspace + * might want to inject the interrupt manually using KVM_SET_REGS + * or KVM_SET_SREGS. For that to work, we must be at an + * instruction boundary and with no events half-injected. + */ return kvm_arch_interrupt_allowed(vcpu) && - kvm_cpu_accept_dm_intr(vcpu); + kvm_cpu_accept_dm_intr(vcpu) && + !kvm_event_needs_reinjection(vcpu) + !vcpu->arch.exception.pending; + }
static int kvm_vcpu_ioctl_interrupt(struct kvm_vcpu *vcpu,