From: Avi Kivity <avi@redhat.com>
To: Ingo Molnar <mingo@elte.hu>
Cc: "Yang, Wei Y" <wei.y.yang@intel.com>,
Pekka Enberg <penberg@cs.helsinki.fi>,
"kvm@vger.kernel.org" <kvm@vger.kernel.org>
Subject: Re: [Patch v5 1/4] Remove SMEP bit from CR4_RESERVED_BITS
Date: Mon, 30 May 2011 10:49:13 +0300 [thread overview]
Message-ID: <4DE34BF9.20106@redhat.com> (raw)
In-Reply-To: <20110530074033.GB27557@elte.hu>
On 05/30/2011 10:40 AM, Ingo Molnar wrote:
> * Yang, Wei Y<wei.y.yang@intel.com> wrote:
>
> > This patch removes SMEP bit from CR4_RESERVED_BITS.
>
> I'm wondering, what is the best-practice way for tools/kvm/ to set
> SMEP for the guest kernel automatically, even if the guest kernel
> itsef has not requested SMEP?
>
> The portion i'm worried about are old KVM versions that have the SMEP
> bit in CR4_RESERVED_BITS and reject it. So we cannot just
> unilaterally add SMEP to every cr4 write of the guest.
tools/kvm doesn't see cr4 writes at all. The only way to do this is in
kvm itself.
> Is there a way
> to query whether the host KVM version supports SMEP setting in cr4?
>
KVM_GET_SUPPORTED_CPUID (it returns whether both the host cpu and kvm
support smep; if one of them doesn't, you'll see smep disabled).
--
I have a truly marvellous patch that fixes the bug which this
signature is too narrow to contain.
next prev parent reply other threads:[~2011-05-30 7:49 UTC|newest]
Thread overview: 12+ messages / expand[flat|nested] mbox.gz Atom feed top
2011-05-30 3:01 [Patch v5 1/4] Remove SMEP bit from CR4_RESERVED_BITS Yang, Wei Y
2011-05-30 7:40 ` Ingo Molnar
2011-05-30 7:49 ` Avi Kivity [this message]
2011-05-30 8:05 ` Ingo Molnar
2011-05-30 8:43 ` Avi Kivity
2011-05-30 8:52 ` Ingo Molnar
2011-05-30 8:53 ` Avi Kivity
2011-05-30 8:57 ` Ingo Molnar
2011-05-30 9:00 ` Avi Kivity
2011-06-01 7:18 ` Tian, Kevin
2011-06-01 7:46 ` Ingo Molnar
2011-06-01 7:55 ` Avi Kivity
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