From: stsp <stsp2@yandex.ru>
To: Paolo Bonzini <pbonzini@redhat.com>, Jim Mattson <jmattson@google.com>
Cc: Sean Christopherson <seanjc@google.com>,
kvm@vger.kernel.org, David Woodhouse <dwmw@amazon.co.uk>,
"ntsironis@arrikto.com" <ntsironis@arrikto.com>
Subject: Re: exception vs SIGALRM race (was: Re: guest/host mem out of sync on core2duo?)
Date: Wed, 7 Jul 2021 01:22:38 +0300 [thread overview]
Message-ID: <eadbc511-3270-8a8e-a2d8-a8eb1fccb8c0@yandex.ru> (raw)
In-Reply-To: <1501d6d3-4dab-3eca-1d82-1e1954e293e1@redhat.com>
06.07.2021 19:28, Paolo Bonzini пишет:
> On 29/06/21 00:27, Jim Mattson wrote:
>>> static int kvm_vcpu_ready_for_interrupt_injection(struct kvm_vcpu
>>> *vcpu)
>>> {
>>> return kvm_arch_interrupt_allowed(vcpu) &&
>>> kvm_cpu_accept_dm_intr(vcpu);
>>> }
>> It looks like Paolo may have broken this in commit 71cc849b7093
>> ("KVM: x86: Fix split-irqchip vs interrupt injection window request").
>> The commit message seems focused only on
>> vcpu->arch.interrupt.injected. Perhaps he overlooked
>> vcpu->arch.exception.injected.
>
> I was expecting the exception to be injected first and the interrupt
> second.
> But something like this should fix it:
>
> diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
> index 21877ad2214e..dddff682c9c2 100644
> --- a/arch/x86/kvm/x86.c
> +++ b/arch/x86/kvm/x86.c
> @@ -4277,6 +4277,9 @@ 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.
>
> I'll figure out a selftest to better understand what's going on. In
> the meanwhile
> Stas can test it!
I confirm that this works, thanks.
Sadly the problematic patch was
CCed to -stable, and is now present
in all kernels, like ubuntu's 5.8.0-55-generic.
Since AFAICT it didn't contain the
important/security fix, I think it
shouldn't have been CCed to -stable.
Can we revert it from -stable?
That will mean a relatively quick
fix for most of current users.
next prev parent reply other threads:[~2021-07-06 22:22 UTC|newest]
Thread overview: 36+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-06-12 22:49 guest/host mem out of sync on core2duo? stsp
2021-06-13 12:36 ` stsp
2021-06-14 17:06 ` Sean Christopherson
2021-06-14 17:32 ` stsp
2021-06-17 14:42 ` Sean Christopherson
2021-06-18 15:59 ` stsp
2021-06-18 21:07 ` Jim Mattson
2021-06-18 21:55 ` stsp
2021-06-18 22:06 ` Jim Mattson
2021-06-18 22:26 ` stsp
2021-06-18 22:32 ` Sean Christopherson
2021-06-19 0:11 ` stsp
2021-06-19 0:54 ` Sean Christopherson
2021-06-19 9:18 ` stsp
2021-06-21 2:34 ` exception vs SIGALRM race (was: Re: guest/host mem out of sync on core2duo?) stsp
2021-06-21 22:33 ` Jim Mattson
2021-06-21 23:32 ` stsp
2021-06-22 0:27 ` stsp
2021-06-28 21:47 ` Jim Mattson
2021-06-28 21:50 ` stsp
2021-06-28 22:00 ` stsp
2021-06-28 22:27 ` Jim Mattson
2021-07-06 16:28 ` Paolo Bonzini
2021-07-06 22:22 ` stsp [this message]
2021-07-06 23:41 ` Paolo Bonzini
2021-06-23 23:38 ` exception vs SIGALRM race (with test-case now!) stsp
2021-06-24 0:11 ` stsp
2021-06-24 0:25 ` stsp
2021-06-24 18:05 ` exception vs SIGALRM race on core2 CPUs (with qemu-based test-case this time!) stsp
2021-06-24 18:07 ` stsp
2021-06-25 23:35 ` exception vs SIGALRM race on core2 CPUs (with fix!) stsp
2021-06-26 0:15 ` Jim Mattson
2021-06-26 0:35 ` stsp
2021-06-26 21:50 ` stsp
2021-06-27 12:13 ` stsp
2021-06-26 14:03 ` exception vs SIGALRM race (another patch) stsp
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