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Re: [PATCH 3/7] xen/arm64: head: Add missing isb in setup_fixmap()
Hi,
On 21/06/2023 11:13, Michal Orzel wrote:
On 21/06/2023 12:02, Julien Grall wrote:
Hi,
On 21/06/2023 10:33, Michal Orzel wrote:
On 19/06/2023 19:01, Julien Grall wrote:
From: Julien Grall <jgrall@xxxxxxxxxx>
On older version of the Arm Arm (ARM DDI 0487E.a, B2-125) there were
the following paragraph:
"DMB and DSB instructions affect reads and writes to the memory system
generated by Load/Store instructions and data or unified cache
maintenance instructions being executed by the PE. Instruction fetches
or accesses caused by a hardware translation table access are not
explicit accesses."
Newer revision (e.g. ARM DDI 0487J.a) doesn't have the second sentence
(it might be somewhere else in the Arm Arm). But the interpretation is
not much different.
In setup_fixmap(), we write the fixmap area and may be used soon after,
for instance, to write to the UART. IOW, there could be hardware
translation table access. So we need to ensure the 'dsb' has completed
before continuing. Therefore add an 'isb'.
Fixes: 2b11c3646105 ("xen/arm64: head: Remove 1:1 mapping as soon as it is not
used")
Signed-off-by: Julien Grall <jgrall@xxxxxxxxxx>
Reviewed-by: Michal Orzel <michal.orzel@xxxxxxx>
I'm happy with the whole series but I do not see a point in flooding each patch
with my tag
since you already got two (from Henry and Luca).
Thanks. To clarify, shall I add it in each patch or only this one?
Whatever you prefer. If you care about my tag and want to have more than two,
feel free to add it to
all the patches.
Ok. I will not then because I need to add the ack manually.
Cheers,
--
Julien Grall
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