From: Avi Kivity <avi@redhat.com>
To: "Tian, Kevin" <kevin.tian@intel.com>
Cc: "Yang, Wei Y" <wei.y.yang@intel.com>,
"kvm@vger.kernel.org" <kvm@vger.kernel.org>,
"Li, Xin" <xin.li@intel.com>
Subject: Re: [Patch v3] Enable CPU SMEP feature for KVM
Date: Fri, 27 May 2011 11:47:51 +0300 [thread overview]
Message-ID: <4DDF6537.6040101@redhat.com> (raw)
In-Reply-To: <625BA99ED14B2D499DC4E29D8138F1505C9C008A5E@shsmsx502.ccr.corp.intel.com>
On 05/27/2011 05:56 AM, Tian, Kevin wrote:
> > From: Yang, Wei Y
> > Sent: Thursday, May 26, 2011 9:29 PM
> >
> > This patchset enables a new CPU feature SMEP (Supervisor Mode Execution
> > Protection) in KVM. SMEP prevents kernel from executing code in application.
> > Updated Intel SDM describes this CPU feature. The document will be published
> > soon.
> >
> > This patchset is based on Fenghua's SMEP patch series, as referred by:
> > https://lkml.org/lkml/2011/5/17/523
> >
> > Changes since v2: enable SMEP for spt mode.
>
> another change in this version is to avoid adding SMEP to cr4_guest_owned_bits,
> because architecturally it's required to flush TLB when CR4.SMEP is changed
> which has to be emulated.
That is actually a good change since it allows us to query SMEP without
a vmcs_readl(GUEST_CR4).
> Also based on your comment SMEP is now permitted based on cpuid setting. One pending
> issue though is check_cr_write in emulation path. We changed cr4_reserved_bits
> to vcpu specific instead of global, but check_cr_write doesn't provide a vcpu parameter.
> Looks the whole emulation logic avoids using vcpu context to be neutral. Avi, do you
> have any suggestion for a clean change here? Add cr_reserved_bits array into
> emulation context instead of hard-coding?
We can have a ->cpuid() callback so we can query it dynamically. cr4
writes will be emulated very rarely, after all.
--
I have a truly marvellous patch that fixes the bug which this
signature is too narrow to contain.
next prev parent reply other threads:[~2011-05-27 8:47 UTC|newest]
Thread overview: 8+ messages / expand[flat|nested] mbox.gz Atom feed top
2011-05-26 13:28 [Patch v3] Enable CPU SMEP feature for KVM Yang, Wei Y
2011-05-27 2:56 ` Tian, Kevin
2011-05-27 8:47 ` Avi Kivity [this message]
2011-05-27 8:45 ` Avi Kivity
2011-05-29 5:16 ` Li, Xin
2011-05-29 6:42 ` Avi Kivity
2011-05-29 7:15 ` Li, Xin
2011-05-29 7:20 ` Avi Kivity
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