From: Xiao Guangrong <xiaoguangrong@linux.vnet.ibm.com>
To: Takuya Yoshikawa <yoshikawa.takuya@oss.ntt.co.jp>
Cc: Avi Kivity <avi@redhat.com>,
Marcelo Tosatti <mtosatti@redhat.com>,
LKML <linux-kernel@vger.kernel.org>, KVM <kvm@vger.kernel.org>
Subject: Re: [PATCH v2 3/3] KVM: remove dummy pages
Date: Thu, 26 Jul 2012 17:35:13 +0800 [thread overview]
Message-ID: <50110F51.3050903@linux.vnet.ibm.com> (raw)
In-Reply-To: <20120726182033.e127e9e6.yoshikawa.takuya@oss.ntt.co.jp>
On 07/26/2012 05:20 PM, Takuya Yoshikawa wrote:
> On Thu, 26 Jul 2012 11:56:15 +0300
> Avi Kivity <avi@redhat.com> wrote:
>
>> Since my comments are better done as a separate patch, I applied all
>> three patches. Thanks!
>
> Is this patch really safe for all architectures?
>
> IS_ERR_VALUE() casts -MAX_ERRNO to unsigned long and then does comparison.
> Isn't it possible to conflict with valid pfns?
>
See IS_ERR_VALUE():
#define IS_ERR_VALUE(x) unlikely((x) >= (unsigned long)-MAX_ERRNO)
The minimal value of the error code is:
0xffff f001 on 32-bit and 0x ffff ffff ffff f001 on 64-bit,
it is fair larger that a valid pfn (for the pfn, the most top of 12 bits
are always 0).
Note, PAE is a special case, but only 64G physical memory is valid,
0xffff f001 is also suitable for that.
next prev parent reply other threads:[~2012-07-26 9:35 UTC|newest]
Thread overview: 9+ messages / expand[flat|nested] mbox.gz Atom feed top
2012-07-26 3:56 [PATCH v2 0/3] KVM: remove dummy pages Xiao Guangrong
2012-07-26 3:57 ` [PATCH v2 1/3] KVM: MMU: use kvm_release_pfn_clean to release pfn Xiao Guangrong
2012-07-26 3:58 ` [PATCH v2 2/3] KVM: use kvm_release_page_clean to release the page Xiao Guangrong
2012-07-26 3:58 ` [PATCH v2 3/3] KVM: remove dummy pages Xiao Guangrong
2012-07-26 8:56 ` Avi Kivity
2012-07-26 9:20 ` Takuya Yoshikawa
2012-07-26 9:35 ` Xiao Guangrong [this message]
2012-07-26 9:52 ` Takuya Yoshikawa
2012-07-26 9:25 ` Xiao Guangrong
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