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RE: [PATCH 5/7] xen/arm: pmap: Add missing ISB in arch_pmap_map()
- To: Julien Grall <julien@xxxxxxx>, "xen-devel@xxxxxxxxxxxxxxxxxxxx" <xen-devel@xxxxxxxxxxxxxxxxxxxx>
- From: Henry Wang <Henry.Wang@xxxxxxx>
- Date: Tue, 20 Jun 2023 03:07:06 +0000
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- Cc: Luca Fancellu <Luca.Fancellu@xxxxxxx>, "michal.orzel@xxxxxxx" <michal.orzel@xxxxxxx>, Julien Grall <jgrall@xxxxxxxxxx>, Stefano Stabellini <sstabellini@xxxxxxxxxx>, Bertrand Marquis <Bertrand.Marquis@xxxxxxx>, Volodymyr Babchuk <Volodymyr_Babchuk@xxxxxxxx>
- Delivery-date: Tue, 20 Jun 2023 03:07:52 +0000
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- Thread-topic: [PATCH 5/7] xen/arm: pmap: Add missing ISB in arch_pmap_map()
Hi Julien,
> -----Original Message-----
> Subject: [PATCH 5/7] xen/arm: pmap: Add missing ISB in arch_pmap_map()
>
> From: Julien Grall <jgrall@xxxxxxxxxx>
>
> Per the Arm Arm, (Armv7 DDI406C.d A3.8.3 and Armv8 DDI 0487J.a B2.3.12):
>
> "The DMB and DSB memory barriers affect reads and writes to the memory
> system generated by load/store instructions and data or unified cache
> maintenance operations being executed by the processor. Instruction
> fetches or accesses caused by a hardware translation table access are
> not explicit accesses."
>
> Note that second sentence is not part of the newer Armv8 spec. But the
> interpretation is not much different.
>
> As the entry created by arch_pmap_map() will be used soon after
> pmap_map() returns, we want to ensure the DSB in write_pte() has
> completed. So add an ISB.
>
> Fixes: 4f17357b52f6 ("xen/arm: add Persistent Map (PMAP) infrastructure")
> Signed-off-by: Julien Grall <jgrall@xxxxxxxxxx>
Reviewed-by: Henry Wang <Henry.Wang@xxxxxxx>
I've also tested this patch on top of today's staging by our internal CI, and
this
patch looks good, so:
Tested-by: Henry Wang <Henry.Wang@xxxxxxx>
Kind regards,
Henry
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