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Re: [Qemu-devel] [PATCH] linux-user: Fix page_find_alloc for 32-bit use
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From: |
Jan Kiszka |
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Subject: |
Re: [Qemu-devel] [PATCH] linux-user: Fix page_find_alloc for 32-bit use on 64-bit hosts |
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Date: |
Wed, 23 Jul 2008 16:42:05 +0200 |
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User-agent: |
Mozilla/5.0 (X11; U; Linux i686 (x86_64); de; rv:1.8.1.12) Gecko/20080226 SUSE/2.0.0.12-1.1 Thunderbird/2.0.0.12 Mnenhy/0.7.5.666 |
Paul Brook wrote:
> On Sunday 13 July 2008, Jan Kiszka wrote:
>> page_find_alloc, used e.g. for TB allocation, is not safe on 64-bit
>> hosts for 32-bit guests. Patch below fixes this by requesting new pages
>> only from the guest-reachable address range.
>
> I'm pretty sure this is wrong. The structures allocated by page_find_alloc do
> not need to be accessible by the guest. In fact it's better if they are
> outside the guest address space.
Bet we have "addr = h2g(p);" in page_find_alloc(), ie. we expect to
retrieve a valid guest address (for use with page_set_flag). Something
is borken here, but you can surely better tell us what precisely than
I'm able to.
Jan
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