| Message ID | 20210727210916.1652841-1-pbonzini@redhat.com |
|---|---|
| State | Accepted |
| Commit | fa7a549d321a4189677b0cea86e58d9db7977f7b |
| Headers | show |
| Series | [v3] KVM: x86: accept userspace interrupt only if no event is injected | expand |
On Tue, Jul 27, 2021, Paolo Bonzini wrote: > 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> > --- > arch/x86/kvm/x86.c | 13 +++++++++++-- > 1 file changed, 11 insertions(+), 2 deletions(-) > > diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c > index 4116567f3d44..e5d5c5ed7dd4 100644 > --- a/arch/x86/kvm/x86.c > +++ b/arch/x86/kvm/x86.c > @@ -4358,8 +4358,17 @@ static int kvm_cpu_accept_dm_intr(struct kvm_vcpu *vcpu) > > static int kvm_vcpu_ready_for_interrupt_injection(struct kvm_vcpu *vcpu) > { > - return kvm_arch_interrupt_allowed(vcpu) && > - kvm_cpu_accept_dm_intr(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) && Ha, adding a '(' is one way to fix the indentation. Reviewed-by: Sean Christopherson <seanjc@google.com> > + 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, > -- > 2.27.0 >
28.07.2021 00:09, 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 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> Acked-by: stsp2@yandex.ru
diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c index 4116567f3d44..e5d5c5ed7dd4 100644 --- a/arch/x86/kvm/x86.c +++ b/arch/x86/kvm/x86.c @@ -4358,8 +4358,17 @@ static int kvm_cpu_accept_dm_intr(struct kvm_vcpu *vcpu) static int kvm_vcpu_ready_for_interrupt_injection(struct kvm_vcpu *vcpu) { - return kvm_arch_interrupt_allowed(vcpu) && - kvm_cpu_accept_dm_intr(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_event_needs_reinjection(vcpu) && + !vcpu->arch.exception.pending); } static int kvm_vcpu_ioctl_interrupt(struct kvm_vcpu *vcpu,