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Re: [PATCH v3] x86/gnttab: do not implement GNTTABOP_cache_flush
- To: Roger Pau Monne <roger.pau@xxxxxxxxxx>, xen-devel@xxxxxxxxxxxxxxxxxxxx
- From: Julien Grall <julien@xxxxxxx>
- Date: Wed, 21 May 2025 17:10:42 +0100
- Cc: Oleksii Kurochko <oleksii.kurochko@xxxxxxxxx>, Community Manager <community.manager@xxxxxxxxxxxxxx>, Andrew Cooper <andrew.cooper3@xxxxxxxxxx>, Anthony PERARD <anthony.perard@xxxxxxxxxx>, Michal Orzel <michal.orzel@xxxxxxx>, Jan Beulich <jbeulich@xxxxxxxx>, Stefano Stabellini <sstabellini@xxxxxxxxxx>, Bertrand Marquis <bertrand.marquis@xxxxxxx>, Volodymyr Babchuk <Volodymyr_Babchuk@xxxxxxxx>
- Delivery-date: Wed, 21 May 2025 16:10:56 +0000
- List-id: Xen developer discussion <xen-devel.lists.xenproject.org>
Hi Roger,
On 21/05/2025 10:12, Roger Pau Monne wrote:
The current underlying implementation of GNTTABOP_cache_flush on x86 won't
work as expected. The provided {clean,invalidate}_dcache_va_range()
helpers only do a local pCPU cache flush, so the cache of previous pCPUs
where the vCPU might have run are not flushed.
However instead of attempting to fix this, make the GNTTABOP_cache_flush
operation only available to ARM. There are no known users on x86, the
implementation is broken, and other architectures don't have grant-table
support yet.
With that operation not implemented on x86, the related
{clean,invalidate}_dcache_va_range() helpers can also be removed.
Fixes: f62dc81c2df7 ("x86: introduce more cache maintenance operations")
Fixes: 18e8d22fe750 ("introduce GNTTABOP_cache_flush")
Signed-off-by: Roger Pau Monné <roger.pau@xxxxxxxxxx>
Reviewed-by: Jan Beulich <jbeulich@xxxxxxxx>
Reviewed-By: Oleksii Kurochko<oleksii.kurochko@xxxxxxxxx>
Acked-by: Julien Grall <jgrall@xxxxxxxxxx>
Cheers,
--
Julien Grall
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