From: Sean Christopherson <seanjc@google.com>
To: David Matlack <dmatlack@google.com>
Cc: David Edmondson <dme@dme.org>,
linux-kernel@vger.kernel.org, Wanpeng Li <wanpengli@tencent.com>,
Jim Mattson <jmattson@google.com>, Borislav Petkov <bp@alien8.de>,
Vitaly Kuznetsov <vkuznets@redhat.com>,
Joerg Roedel <joro@8bytes.org>,
kvm@vger.kernel.org, Paolo Bonzini <pbonzini@redhat.com>,
Thomas Gleixner <tglx@linutronix.de>,
x86@kernel.org, Ingo Molnar <mingo@redhat.com>,
"H. Peter Anvin" <hpa@zytor.com>
Subject: Re: [PATCH v2 0/2] kvm: x86: Convey the exit reason to user-space on emulation failure
Date: Fri, 9 Jul 2021 16:08:32 +0000 [thread overview]
Message-ID: <YOh0gNxRJ67Lbo7g@google.com> (raw)
In-Reply-To: <YOdhhcjXEHUaMIFc@google.com>
On Thu, Jul 08, 2021, David Matlack wrote:
> On Thu, Jul 08, 2021 at 09:13:38PM +0100, David Edmondson wrote:
> > On Thursday, 2021-07-08 at 18:38:18 UTC, David Matlack wrote:
> > > On Thu, Jul 08, 2021 at 03:17:40PM +0100, David Edmondson wrote:
> > >> I can't cite an example of where this has definitively led in a
> > >> direction that helped solve a problem, but we do sometimes see emulation
> > >> failures reported in situations where we are not able to reproduce the
> > >> failures on demand and the existing information provided at the time of
> > >> failure is either insufficient or suspect.
> > >>
> > >> Given that, I'm left casting about for data that can be made available
> > >> to assist in postmortem analysis of the failures.
> > >
> > > Understood, thanks for the context. My only concern would be that
> > > userspace APIs are difficult to change once they exist.
> >
> > Agreed.
> >
> > > If it turns out knowing the exit reason does not help with debugging
> > > emulation failures we'd still be stuck with exporting it on every
> > > emulation failure.
I can think of multiple cases where knowing why KVM emulated in the first place
would be helpful, e.g. a failure on EPT misconfig (MMIO) exit could be a simple
"drat, KVM doesn't handle SSE instructions", whereas a failure on a descriptor
table exit (for UMIP emulation) would be a completely different mess.
next prev parent reply other threads:[~2021-07-09 16:08 UTC|newest]
Thread overview: 13+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-07-06 10:12 [PATCH v2 0/2] kvm: x86: Convey the exit reason to user-space on emulation failure David Edmondson
2021-07-06 10:12 ` [PATCH v2 1/2] KVM: x86: Add kvm_x86_ops.get_exit_reason David Edmondson
2021-07-06 10:12 ` [PATCH v2 2/2] KVM: x86: On emulation failure, convey the exit reason to userspace David Edmondson
2021-07-09 15:47 ` Sean Christopherson
2021-07-12 15:34 ` David Edmondson
2021-07-07 23:20 ` [PATCH v2 0/2] kvm: x86: Convey the exit reason to user-space on emulation failure David Matlack
2021-07-08 14:17 ` David Edmondson
2021-07-08 18:38 ` David Matlack
2021-07-08 20:13 ` David Edmondson
2021-07-08 20:35 ` David Matlack
2021-07-09 16:08 ` Sean Christopherson [this message]
2021-07-07 23:22 ` David Matlack
2021-07-08 14:20 ` David Edmondson
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