From: "Radim Krčmář" <rkrcmar@redhat.com>
To: Laszlo Ersek <lersek@redhat.com>
Cc: linux-kernel@vger.kernel.org, kvm@vger.kernel.org,
Paolo Bonzini <pbonzini@redhat.com>
Subject: Re: [PATCH 0/2] KVM: x86: emulate fxsave and fxrstor
Date: Thu, 27 Oct 2016 18:41:00 +0200 [thread overview]
Message-ID: <20161027164059.GG4212@potion> (raw)
In-Reply-To: <0e5108b0-15f0-56c1-b9e5-626ecff644d7@redhat.com>
2016-10-26 23:40+0200, Laszlo Ersek:
> On 10/26/16 22:50, Radim Krčmář wrote:
>> [1/2] adds the emulation (and could be split into two patches if you'd like),
>> [2/2] just refactors the code.
>>
>> This should fix an issue that users are hitting. Laszlo found several reports:
>> - https://bugs.launchpad.net/qemu/+bug/1623276
>> - https://bugzilla.proxmox.com/show_bug.cgi?id=1182
>> - https://bugs.archlinux.org/task/50778
>>
>> I have only tested it with a simple kvm-unit-tests, though. Reproducing the
>> iPXE issue is on the way ...
>>
>>
>> Radim Krčmář (2):
>> KVM: x86: emulate fxsave and fxrstor
>> KVM: x86: save one bit in ctxt->d
>>
>> arch/x86/kvm/emulate.c | 110 ++++++++++++++++++++++++++++++++++++++++++-------
>> 1 file changed, 94 insertions(+), 16 deletions(-)
>>
>
> I was just about to post iPXE patches that would disable the FXSAVE /
> FXRSTOR instructions in the CONFIG=qemu build (*), but you beat me to it
> with the KVM emulation code ;)
>
> (*) If you look at the iPXE commit that added them, they are a
> workaround for a Tivoli VMM bug; i.e., irrelevant for QEMU/KVM guests.
>
> ... Actually, those iPXE patches that conditionalize FXSAVE / FXRSTOR
> may still make sense -- we can rebuild iPXE, and bundle the refreshed
> binaries with QEMU v2.7.1, and swiftly at that. Whereas the KVM patches
> could take more time to propagate to users?... Not sure. What do you
> guys think?
This series won't get into 4.9, so it would take almost half a year
before the kernel trickles into experimental distros. And updating
QEMU/iPXE isn't as dangerous as updating kernel, so I like the idea.
I am just tempted to drop a KVM patch with positive diffstat that fixes
something that doesn't really need fixing anymore. :)
next prev parent reply other threads:[~2016-10-27 16:41 UTC|newest]
Thread overview: 9+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-10-26 20:50 [PATCH 0/2] KVM: x86: emulate fxsave and fxrstor Radim Krčmář
2016-10-26 20:50 ` [PATCH 1/2] " Radim Krčmář
2016-10-27 0:17 ` Bandan Das
2016-10-27 16:34 ` Radim Krčmář
2016-10-28 3:29 ` Bandan Das
2016-10-26 20:50 ` [PATCH 2/2] KVM: x86: save one bit in ctxt->d Radim Krčmář
2016-10-26 21:40 ` [PATCH 0/2] KVM: x86: emulate fxsave and fxrstor Laszlo Ersek
2016-10-27 16:41 ` Radim Krčmář [this message]
2016-10-27 17:01 ` Laszlo Ersek
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