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Re: [PATCH Linux v3 6/6] xen: Add new Xen pv-op pte_get_and_clear.
- To: Juergen Gross <jgross@xxxxxxxx>, Kevin Lampis <kevin.lampis@xxxxxxxxxx>, xen-devel@xxxxxxxxxxxxxxxxxxxx
- From: Andrew Cooper <andrew.cooper3@xxxxxxxxxx>
- Date: Fri, 9 Oct 2026 12:33:42 +0100
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- Cc: Andrew Cooper <andrew.cooper3@xxxxxxxxxx>, jbeulich@xxxxxxxx, teddy.astie@xxxxxxxxxx
- Delivery-date: Fri, 09 Oct 2026 11:33:55 +0000
- List-id: Xen developer discussion <xen-devel.lists.xenproject.org>
On 09/10/2026 9:27 am, Juergen Gross wrote:
> On 01.10.26 19:47, Kevin Lampis wrote:
>> If Xen supports XENFEAT_mmu_pt_update_swap then for performance reasons
>> call mmu_update with the new MMU_PT_UPDATE_SWAP flag instead of
>> native_ptep_get_and_clear().
>>
>> Signed-off-by: Kevin Lampis <kevin.lampis@xxxxxxxxxx>
>
> Reviewed-by: Juergen Gross <jgross@xxxxxxxx>
>
> I will take this patch when the Xen side has gone in.
"for performance reasons" is of little use to people reading the patch.
Can I suggest instead:
"If Xen supports XENFEAT_mmu_pt_update_swap, use the new
MMU_PT_UPDATE_SWAP instead of native_ptep_get_and_clear(). This avoids
the the pagetable write trapping for emulation."
?
~Andrew
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