From: Michal Orzel <michal.orzel@amd.com>
To: Julien Grall <julien@xen.org>, <xen-devel@lists.xenproject.org>
Cc: <Luca.Fancellu@arm.com>, Julien Grall <jgrall@amazon.com>,
"Stefano Stabellini" <sstabellini@kernel.org>,
Bertrand Marquis <bertrand.marquis@arm.com>,
Volodymyr Babchuk <Volodymyr_Babchuk@epam.com>
Subject: Re: [PATCH v7 3/5] xen/arm64: mm: Introduce helpers to prepare/enable/disable the identity mapping
Date: Mon, 17 Apr 2023 09:55:54 +0200 [thread overview]
Message-ID: <3a011582-f6e4-9c28-509c-1d552e7ff903@amd.com> (raw)
In-Reply-To: <20230416143211.72227-4-julien@xen.org>
On 16/04/2023 16:32, Julien Grall wrote:
>
>
> From: Julien Grall <jgrall@amazon.com>
>
> In follow-up patches we will need to have part of Xen identity mapped in
> order to safely switch the TTBR.
>
> On some platform, the identity mapping may have to start at 0. If we always
> keep the identity region mapped, NULL pointer dereference would lead to
> access to valid mapping.
>
> It would be possible to relocate Xen to avoid clashing with address 0.
> However the identity mapping is only meant to be used in very limited
> places. Therefore it would be better to keep the identity region invalid
> for most of the time.
>
> Two new external helpers are introduced:
> - arch_setup_page_tables() will setup the page-tables so it is
> easy to create the mapping afterwards.
> - update_identity_mapping() will create/remove the identity mapping
>
> Signed-off-by: Julien Grall <jgrall@amazon.com>
Reviewed-by: Michal Orzel <michal.orzel@amd.com>
~Michal
next prev parent reply other threads:[~2023-04-17 7:56 UTC|newest]
Thread overview: 21+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-04-16 14:32 [PATCH v7 0/5] xen/arm: Don't switch TTBR while the MMU is on Julien Grall
2023-04-16 14:32 ` [PATCH v7 1/5] xen/arm32: head: Widen the use of the temporary mapping Julien Grall
2023-04-18 13:51 ` Bertrand Marquis
2023-06-10 18:49 ` Julien Grall
2023-04-16 14:32 ` [PATCH v7 2/5] xen/arm64: Rework the memory layout Julien Grall
2023-04-17 4:58 ` Henry Wang
2023-04-17 7:21 ` Luca Fancellu
2023-04-17 7:28 ` Michal Orzel
2023-04-19 18:38 ` Julien Grall
2023-04-18 13:53 ` Bertrand Marquis
2023-04-18 13:58 ` Bertrand Marquis
2023-04-16 14:32 ` [PATCH v7 3/5] xen/arm64: mm: Introduce helpers to prepare/enable/disable the identity mapping Julien Grall
2023-04-17 4:59 ` Henry Wang
2023-04-17 7:46 ` Luca Fancellu
2023-04-17 7:55 ` Michal Orzel [this message]
2023-04-18 13:57 ` Bertrand Marquis
2023-04-16 14:32 ` [PATCH v7 4/5] xen/arm64: mm: Rework switch_ttbr() Julien Grall
2023-04-17 4:59 ` Henry Wang
2023-04-16 14:32 ` [PATCH v7 5/5] xen/arm64: smpboot: Directly switch to the runtime page-tables Julien Grall
2023-04-17 4:59 ` Henry Wang
2023-04-19 18:42 ` [PATCH v7 0/5] xen/arm: Don't switch TTBR while the MMU is on Julien Grall
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