From: David Woodhouse <dwmw2@infradead.org>
To: Richard Weinberger <richard@sigma-star.at>
Cc: mingo@kernel.org, luto@kernel.org, arjan@linux.intel.com,
bp@alien8.de, dan.j.williams@intel.com,
dave.hansen@linux.intel.com, gregkh@linuxfoundation.org,
jpoimboe@redhat.com, torvalds@linux-foundation.org,
peterz@infradead.org, tglx@linutronix.de,
arjan.van.de.ven@intel.com, dave.hansen@intel.com,
jmattson@google.com, karahmed@amazon.de, kvm@vger.kernel.org,
pbonzini@redhat.com, rkrcmar@redhat.com, sironi@amazon.de,
linux-kernel@vger.kernel.org
Subject: Re: Revert "x86/speculation: Simplify indirect_branch_prediction_barrier()" crashes KVM guest
Date: Thu, 15 Feb 2018 23:28:30 +0000 [thread overview]
Message-ID: <1518737310.7876.10.camel@infradead.org> (raw)
In-Reply-To: <1753460.Vme2X1QhPT@blindfold>
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On Fri, 2018-02-16 at 00:12 +0100, Richard Weinberger wrote:
>
> [ 2.791518] Code: 8b 45 00 49 8b 7d 08 49 83 c5 18 31 d2 31 f6 ff
> d0 49 8b 45 00 48 85 c0 75 e9 eb b1 b9 49 00 00 00 b8 01 00 00 00 ba
> 00 00 00 00 <0f> 30 e9 68 fd ff ff 9c 58 0f 1f 44 00 00 48 89 c5 fa
> 66 0f 1f
23: b9 49 00 00 00 mov $0x49,%ecx
28: b8 01 00 00 00 mov $0x1,%eax
2d: ba 00 00 00 00 mov $0x0,%edx
32: 0f 30 wrmsr
The faulting instruction is the wrmsr itself. That shouldn't happen; if
the CPUID bit indicates that the MSR exists, then it should exist.
The reverted patch did use the C __wrmsr() macro which contained a
fixup for this GP# but it was just a side-effect of the "cleanup" — it
wasn't intentional because that really shouldn't happen. That looks
like a qemu bug as first glance.
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next prev parent reply other threads:[~2018-02-15 23:28 UTC|newest]
Thread overview: 3+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-02-15 23:12 Revert "x86/speculation: Simplify indirect_branch_prediction_barrier()" crashes KVM guest Richard Weinberger
2018-02-15 23:28 ` David Woodhouse [this message]
2018-02-15 23:45 ` Richard Weinberger
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