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McKenney" , Kunwu Chan , Kunwu Chan , syzbot+208f7f3e5f59c11aeb90@syzkaller.appspotmail.com Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: quoted-printable On Tue, Nov 10, 2026, David Woodhouse wrote: > On Thu, 2026-11-05 at 02:00 +0000, David Woodhouse wrote: > > From: David Woodhouse > >=20 > > Based on v7.4-rc1 (kvm/next doesn't have the atomic SRCU flavour yet), > > this series: > >=20 > > =C2=A0=E2=80=A2 Converts the GPC to use atomic SRCU, ditching the rwloc= k which was a > > =C2=A0=C2=A0 scaling and latency problem, and which PREEMPT_RT hated be= cause it > > =C2=A0=C2=A0 turned the rwlock into a sleeping lock=C2=B9. > >=20 > > =C2=A0=E2=80=A2 Fixes the pre-existing bugs which torture-testing that = conversion > > =C2=A0=C2=A0 shook out: a guest-reachable dirty ring overflow from the = hypercall > > =C2=A0=C2=A0 page write (128 pushes of the same gfn against 64 reserved= entries, > > =C2=A0=C2=A0 without PML), and a lost TLB flush request in record_steal= _time(). > >=20 > > =C2=A0=E2=80=A2 Adds KVM_XEN_VCPU_ATTR_TYPE_WRITE_HYPERCALL_PAGE, for V= MMs which > > =C2=A0=C2=A0 intercept the guest's MSR write and need to replay it from= host > > =C2=A0=C2=A0 context=C2=B2. > >=20 > > =C2=A0=E2=80=A2 Cleans up the intentional lack of dirty-tracking of Xen= shinfo and > > =C2=A0=C2=A0 vcpu_info pages (Sean). > >=20 > > =C2=A0=E2=80=A2 Converts steal-time / preempted status to use gfn_to_pf= n_cache. > > =C2=A0=C2=A0 (Carsten) > >=20 >=20 > I love it when sashiko-bot finds things which my own local runs don't. > I'm still iterating on the latter part of the series; I think it > probably makes sense to merge the first half (patches 1-9 above), and > the nested parts (below) can come later. >=20 > Sean, what do you think? Ya, I'm definitely in favor of that. Even if Sashiko didn't find anything,= I think I'd want to grab the GUEST_USES_PFN stuff separately.