From: Avi Kivity <avi@redhat.com>
To: "Yang, Wei Y" <wei.y.yang@intel.com>
Cc: "kvm@vger.kernel.org" <kvm@vger.kernel.org>
Subject: Re: [Patch v4 4/4] Add instruction fetch checking when walking guest page table
Date: Sun, 29 May 2011 16:58:35 +0300 [thread overview]
Message-ID: <4DE2510B.2090106@redhat.com> (raw)
In-Reply-To: <5D8008F58939784290FAB48F5497519844E9278013@shsmsx502.ccr.corp.intel.com>
On 05/29/2011 02:42 PM, Yang, Wei Y wrote:
> This patch adds instruction fetch checking when walking guest page table.
>
>
>
> + /* check if the kernel is fetching from user page */
> + if (unlikely((pte_access& PT_USER_MASK)&&
> + kvm_read_cr4_bits(vcpu, X86_CR4_SMEP)))
> + if (fetch_fault&& !user_fault)
> + eperm = true;
> +
pte_access is a union of ACC_*_MASK values, so this should be
ACC_USER_MASK (though the values are the same).
The difference is that bit 0 is execute permission, while in ptes bit 63
is the no-execute permission.
--
error compiling committee.c: too many arguments to function
prev parent reply other threads:[~2011-05-29 13:58 UTC|newest]
Thread overview: 2+ messages / expand[flat|nested] mbox.gz Atom feed top
2011-05-29 11:42 [Patch v4 4/4] Add instruction fetch checking when walking guest page table Yang, Wei Y
2011-05-29 13:58 ` Avi Kivity [this message]
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