From: Julien Grall <julien@xen.org>
To: Henry Wang <Henry.Wang@arm.com>,
"sstabellini@kernel.org" <sstabellini@kernel.org>,
"xen-devel@lists.xenproject.org" <xen-devel@lists.xenproject.org>
Cc: Wei Chen <Wei.Chen@arm.com>, Penny Zheng <Penny.Zheng@arm.com>,
Bertrand Marquis <Bertrand.Marquis@arm.com>
Subject: Re: Discussion of Xenheap problems on AArch64
Date: Wed, 21 Apr 2021 10:03:37 +0100 [thread overview]
Message-ID: <cdde98ca-4183-c92b-adca-801330992fc5@xen.org> (raw)
In-Reply-To: <PA4PR08MB6253F49C13ED56811BA5B64E92479@PA4PR08MB6253.eurprd08.prod.outlook.com>
On 21/04/2021 07:28, Henry Wang wrote:
> Hi,
Hi Henry,
>
> We are trying to implement the static memory allocation on AArch64. Part of
> this feature is the reserved heap memory allocation, where a specific range of
> memory is reserved only for heap. In the development process, we found a
> pitfall in current AArch64 setup_xenheap_mappings() function.
>
> According to a previous discussion in community
> https://lore.kernel.org/xen-devel/20190216134456.10681-1-peng.fan@nxp.com/,
> on AArch64, bootmem is initialized after setup_xenheap_mappings(),
> setup_xenheap_mappings() may try to allocate memory before memory has been
> handed over to the boot allocator. If the reserved heap memory allocation is
> introduced, either of below 2 cases will trigger a crash:
>
> 1. If the reserved heap memory is at the end of the memory block list and the
> gap between reserved and unreserved memory is bigger than 512GB, when we setup
> mappings from the beginning of the memory block list, we will get OOM caused
> by lack of pages in boot allocator. This is because the memory that is reserved
> for heap has not been mapped and added to the boot allocator.
>
> 2. If we add the memory that is reserved for heap to boot allocator first, and
> then setup mappings for banks in the memory block list, we may get a page which
> has not been setup mapping, causing a data abort.
There are a few issues with setup_xenheap_mappings(). I have been
reworking the code on my spare time and started to upstream bits of it.
A PoC can be found here:
https://xenbits.xen.org/gitweb/?p=people/julieng/xen-unstable.git;a=shortlog;h=refs/heads/pt/dev
Cheers,
--
Julien Grall
next prev parent reply other threads:[~2021-04-21 9:03 UTC|newest]
Thread overview: 15+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-04-21 6:28 Discussion of Xenheap problems on AArch64 Henry Wang
2021-04-21 9:03 ` Julien Grall [this message]
2021-04-21 9:32 ` Henry Wang
2021-04-25 20:19 ` Julien Grall
2021-04-27 6:29 ` Henry Wang
2021-04-28 9:28 ` Henry Wang
2021-04-28 12:46 ` Julien Grall
2021-05-07 4:06 ` Henry Wang
2021-05-10 16:58 ` Julien Grall
2021-05-11 1:11 ` Henry Wang
2021-05-13 18:18 ` Julien Grall
2021-05-14 4:35 ` Henry Wang
2021-05-15 19:11 ` Julien Grall
2021-05-17 6:38 ` Henry Wang
2021-05-18 14:09 ` Julien Grall
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