2020-04-23 02:27:58

by Sean Christopherson

Subject: [PATCH 10/13] KVM: x86: WARN on injected+pending exception even in nested case

WARN if a pending exception is coincident with an injected exception
before calling check_nested_events() so that the WARN will fire even if
inject_pending_event() bails early because check_nested_events() detects
the conflict. Bailing early isn't problematic (quite the opposite), but
suppressing the WARN is undesirable as it could mask a bug elsewhere in
KVM.

Signed-off-by: Sean Christopherson <[email protected]>
---
arch/x86/kvm/x86.c | 4 +++-
1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
index 6af873b7e0ae..7c49a7dc601f 100644
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -7693,6 +7693,9 @@ static int inject_pending_event(struct kvm_vcpu *vcpu)
kvm_x86_ops.set_irq(vcpu);
}

+ WARN_ON_ONCE(vcpu->arch.exception.injected &&
+ vcpu->arch.exception.pending);
+
/*
* Call check_nested_events() even if we reinjected a previous event
* in order for caller to determine if it should require immediate-exit
@@ -7711,7 +7714,6 @@ static int inject_pending_event(struct kvm_vcpu *vcpu)
vcpu->arch.exception.has_error_code,
vcpu->arch.exception.error_code);

- WARN_ON_ONCE(vcpu->arch.exception.injected);
vcpu->arch.exception.pending = false;
vcpu->arch.exception.injected = true;

--
2.26.0

2020-04-28 22:07:30

by Jim Mattson

Subject: Re: [PATCH 10/13] KVM: x86: WARN on injected+pending exception even in nested case

On Wed, Apr 22, 2020 at 7:26 PM Sean Christopherson
<[email protected]> wrote:
>
> WARN if a pending exception is coincident with an injected exception
> before calling check_nested_events() so that the WARN will fire even if
> inject_pending_event() bails early because check_nested_events() detects
> the conflict. Bailing early isn't problematic (quite the opposite), but
> suppressing the WARN is undesirable as it could mask a bug elsewhere in
> KVM.
>
> Signed-off-by: Sean Christopherson <[email protected]>
Reviewed-by: Jim Mattson <[email protected]>