On Fri, Oct 20, 2023 at 6:57 AM Andrew Cooper <[email protected]> wrote: > > On 20/10/2023 2:14 am, Henry Wang wrote: > > Hi all, > > > >> On Oct 20, 2023, at 07:48, Andrew Cooper <[email protected]> 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 <[email protected]> > >>> --- > >>> 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 <[email protected]> > >> > >> 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/[email protected]/ > > > > Kind regards, > > Henry > > That's fine. I'll pull this into my next branch for when the 4.19 tree > opens.
Thanks, I agree that backporting is perfectly fine for this one. Tamas
