Hi Julien,
> -----Original Message-----
> Subject: [PATCH 3/7] xen/arm64: head: Add missing isb in setup_fixmap()
>
> From: Julien Grall <jgr...@amazon.com>
>
> 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 <jgr...@amazon.com>
Reviewed-by: Henry Wang <henry.w...@arm.com>
I've also tested this patch on top of today's staging by our internal CI, which
includes some arm64 emulated platforms and also real hardware, and this patch
looks good, so:
Tested-by: Henry Wang <henry.w...@arm.com>
Kind regards,
Henry
