On 20/10/2023 2:14 am, Henry Wang wrote:
> Hi all,
>
>> On Oct 20, 2023, at 07:48, Andrew Cooper <andrew.coop...@citrix.com> wrote:
>>
>> On 18/10/2023 9:02 am, Tamas K Lengyel wrote:
>>> When mapping in the shared_info page to a fork the m2p entry wasn't set
>>> resulting in the shared_info being reset even when the fork reset was called
>>> with only reset_state and not reset_memory. This results in an extra
>>> unnecessary TLB flush.
>>>
>>> Fixes: 1a0000ac775 ("mem_sharing: map shared_info page to same gfn during
>>> fork")
>>> Signed-off-by: Tamas K Lengyel <ta...@tklengyel.com>
>>> ---
>>> xen/arch/x86/mm/mem_sharing.c | 2 ++
>>> 1 file changed, 2 insertions(+)
>>>
>>> diff --git a/xen/arch/x86/mm/mem_sharing.c b/xen/arch/x86/mm/mem_sharing.c
>>> index 94b6b782ef..142258f16a 100644
>>> --- a/xen/arch/x86/mm/mem_sharing.c
>>> +++ b/xen/arch/x86/mm/mem_sharing.c
>>> @@ -1847,6 +1847,8 @@ static int copy_special_pages(struct domain *cd,
>>> struct domain *d)
>>> p2m_ram_rw, p2m->default_access, -1);
>>> if ( rc )
>>> return rc;
>>> +
>>> + set_gpfn_from_mfn(mfn_x(new_mfn), gfn_x(old_gfn));
>>> }
>>> }
>>>
>> Acked-by: Andrew Cooper <andrew.coop...@citrix.com>
>>
>> CC Henry. This needs a view about a release ack.
>>
>> Cons: it's been broken since Xen 4.14 and we're very deep into the 4.18
>> code freeze.
>>
>> Pros: it's a bug and would clearly qualify for backport, and is in a
>> niche feature so isn't plausibly going to adversely affect other users.
> Given the fact that it will be backported anyway, I had the same discussion
> with Juergen
> in his thread [1]. So if we can bear the risk of delaying merging this patch
> for a week,
> would it be ok to wait for the release and backport this patch to the stable
> tree? Thanks!
>
> [1]
> https://lore.kernel.org/xen-devel/83e6dcf6-926c-43a6-94d2-eb3b2c444...@arm.com/
>
> Kind regards,
> Henry
That's fine. I'll pull this into my next branch for when the 4.19 tree
opens.
~Andrew
