From: Avi Kivity <avi@redhat.com>
To: "Yang, Wei Y" <wei.y.yang@intel.com>
Cc: "kvm@vger.kernel.org" <kvm@vger.kernel.org>,
"Li, Xin" <xin.li@intel.com>,
"Tian, Kevin" <kevin.tian@intel.com>,
"Shan, Haitao" <haitao.shan@intel.com>
Subject: Re: [PATCH v2] Enable CPU SMEP feature for KVM
Date: Sun, 22 May 2011 11:11:04 +0300 [thread overview]
Message-ID: <4DD8C518.7010606@redhat.com> (raw)
In-Reply-To: <5D8008F58939784290FAB48F54975198419FB02D33@shsmsx502.ccr.corp.intel.com>
On 05/22/2011 11:08 AM, Yang, Wei Y wrote:
> > This patch matches with "[PATCH v2] Enable CPU SMEP feature support for QEMU-KVM", no changes since v1.
> >
> > Enable newly documented SMEP (Supervisor Mode Execution Protection) CPU feature in KVM module.
> >
> > Intel new CPU supports SMEP (Supervisor Mode Execution Protection). SMEP prevents kernel from executing code in application. Updated Intel SDM describes this CPU feature. The document will be published soon.
> >
> > This patch is based on Fenghua's SMEP patch series, as referred by: https://lkml.org/lkml/2011/5/17/523
> > This patch enables guests' usage of SMEP.
> > Currently, we don't enable this feature for guests with shadow page tables.
>
> > Why not? I see nothing that conflicts with shadow.
>
> We don't need to enable it for shadow page table, because shadow has mask against guest/shadow PTE, which may cause problem. Let's keep shadow as it is because it's already very complex. Assume SMEP machines should have EPT.
>
I don't understand why. Can you elaborate?
Shadow implements the U bit, which is all that is needed by SMEP as far
as I can tell.
> > update walk_addr_generic() to fault if SMEP is enabled and fetching
>
> Comments above.
>
> > from a user page
>
Needs to be done even from EPT, in case walk_addr_generic() is invoked
by the emulator.
--
I have a truly marvellous patch that fixes the bug which this
signature is too narrow to contain.
next prev parent reply other threads:[~2011-05-22 8:11 UTC|newest]
Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top
2011-05-22 5:23 [PATCH v2] Enable CPU SMEP feature for KVM Yang, Wei Y
2011-05-22 6:50 ` Avi Kivity
2011-05-22 8:08 ` Yang, Wei Y
2011-05-22 8:11 ` Avi Kivity [this message]
[not found] ` <BANLkTikGwL2zYU303riyeJ-aSZ311es+bA@mail.gmail.com>
2011-05-24 7:38 ` Avi Kivity
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