From: "H. Peter Anvin" <hpa@zytor.com>
To: Anthony Liguori <anthony@codemonkey.ws>
Cc: Linda Wang <lwang@redhat.com>,
Thomas Gleixner <tglx@linutronix.de>,
"H. Peter Anvin" <hpa@linux.intel.com>,
Qemu devel <qemu-devel@nongnu.org>,
Ingo Molnar <mingo@kernel.org>
Subject: Re: [Qemu-devel] [PATCH] x86: Implement SMEP and SMAP
Date: Wed, 26 Sep 2012 13:10:59 -0700 [thread overview]
Message-ID: <50636153.3070200@zytor.com> (raw)
In-Reply-To: <873924wokp.fsf@codemonkey.ws>
On 09/26/2012 12:50 PM, Anthony Liguori wrote:
>
> The patch looks good except for these two chunks. This would break live
> migration from a new QEMU to an old one because CPUs are currently not
> versioned.
>
> If you just remove these two chunks, the patch can be applied and you
> can still test with:
>
> qemu-system-x86_64 -cpu qemu64,+smep,+smap
>
> We're working vcpu versioning and will hopefully have it in place for
> 1.3. If we get there, we can enable these features unconditionally and
> add the appropriate backwards compatibility code.
>
OK. I had to add a chunk to up the minimum CPUID level to 7 if any of
the level 7 features were enabled, however.
>
> scripts/checkpatch.pl will complain about lack of curly braces with ifs.
>
> I know this file does not use them consistently. Since you have to
> respin anyway, please run checkpatch and fixup the errors.
>
Actually, several of the files are very consistent about *not* using
them. I'll respin the patch, but it ain't pretty.
-hpa
prev parent reply other threads:[~2012-09-26 20:11 UTC|newest]
Thread overview: 3+ messages / expand[flat|nested] mbox.gz Atom feed top
2012-09-26 18:30 [Qemu-devel] [PATCH] x86: Implement SMEP and SMAP H. Peter Anvin
2012-09-26 19:50 ` Anthony Liguori
2012-09-26 20:10 ` H. Peter Anvin [this message]
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