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Subject: Re: [PATCH v3] KVM: x86: accept userspace interrupt only if no event
 is injected
To:     Paolo Bonzini <pbonzini@redhat.com>, linux-kernel@vger.kernel.org,
        kvm@vger.kernel.org
Cc:     seanjc@google.com, stable@vger.kernel.org
References: <20210727210916.1652841-1-pbonzini@redhat.com>
From:   stsp <stsp2@yandex.ru>
Message-ID: <2b157da6-39a5-4dbb-037f-7abf33a5e0b3@yandex.ru>
Date:   Fri, 6 Aug 2021 20:59:03 +0300
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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