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, DOSBox 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: [email protected]
Reported-by: Stas Sergeev <[email protected]>
Tested-by: Stas Sergeev <[email protected]>
Fixes: 71cc849b7093 ("KVM: x86: Fix split-irqchip vs interrupt injection window request")
Signed-off-by: Paolo Bonzini <[email protected]>
---
arch/x86/kvm/x86.c | 3 +++
1 file changed, 3 insertions(+)
diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
index fe3aaf195292..7fbab29b3569 100644
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -4342,6 +4342,9 @@ static int kvm_vcpu_ioctl_set_lapic(struct kvm_vcpu *vcpu,
static int kvm_cpu_accept_dm_intr(struct kvm_vcpu *vcpu)
{
+ if (kvm_event_needs_reinjection(vcpu))
+ return false;
+
/*
* We can accept userspace's request for interrupt injection
* as long as we have a place to store the interrupt number.
--
2.27.0
15.07.2021 00:38, Paolo Bonzini пишет:
> Once an exception has been injected, any side effects related to
> the exception (such as setting CR2 or DR6) have been taked
"taken"? Probably a typo.
> 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, DOSBox
dosemu2 to be precise.
> 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: [email protected]
> Reported-by: Stas Sergeev <[email protected]>
> Tested-by: Stas Sergeev <[email protected]>
> Fixes: 71cc849b7093 ("KVM: x86: Fix split-irqchip vs interrupt injection window request")
> Signed-off-by: Paolo Bonzini <[email protected]>
> ---
> arch/x86/kvm/x86.c | 3 +++
> 1 file changed, 3 insertions(+)
>
> diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
> index fe3aaf195292..7fbab29b3569 100644
> --- a/arch/x86/kvm/x86.c
> +++ b/arch/x86/kvm/x86.c
> @@ -4342,6 +4342,9 @@ static int kvm_vcpu_ioctl_set_lapic(struct kvm_vcpu *vcpu,
>
> static int kvm_cpu_accept_dm_intr(struct kvm_vcpu *vcpu)
> {
> + if (kvm_event_needs_reinjection(vcpu))
> + return false;
> +
kvm_event_needs_reinjection() seems
to miss exception.pending check.
Don't we need it too?
Also perhaps a comment would be good
to have to avoid it from disappearing again,
as obviously kvm devs tend to overlook
the possibility of injecting interrupts by hands.
On 16/07/21 09:27, stsp wrote:
>> + if (kvm_event_needs_reinjection(vcpu))
>> + return false;
>> +
>
> kvm_event_needs_reinjection() seems
> to miss exception.pending check.
> Don't we need it too?
Yes, good point.
Paolo