tree 9c2701d94781bef81439a33f42507e89dcf2f28b
parent 5ef1d8c1ddbf696e47b226e11888eaf8d9e8e807
parent d02c357e5bfa7dfd618b7b3015624beb71f58f1f
author Paolo Bonzini <pbonzini@redhat.com> 1710001126 -0500
committer Paolo Bonzini <pbonzini@redhat.com> 1710002526 -0500

Merge tag 'kvm-x86-fixes-6.8-2' of https://github.com/kvm-x86/linux into HEAD

KVM x86 fixes for 6.8, round 2:

 - When emulating an atomic access, mark the gfn as dirty in the memslot
   to fix a bug where KVM could fail to mark the slot as dirty during live
   migration, ultimately resulting in guest data corruption due to a dirty
   page not being re-copied from the source to the target.

 - Check for mmu_notifier invalidation events before faulting in the pfn,
   and before acquiring mmu_lock, to avoid unnecessary work and lock
   contention.  Contending mmu_lock is especially problematic on preemptible
   kernels, as KVM may yield mmu_lock in response to the contention, which
   severely degrades overall performance due to vCPUs making it difficult
   for the task that triggered invalidation to make forward progress.

   Note, due to another kernel bug, this fix isn't limited to preemtible
   kernels, as any kernel built with CONFIG_PREEMPT_DYNAMIC=y will yield
   contended rwlocks and spinlocks.

   https://lore.kernel.org/all/20240110214723.695930-1-seanjc@google.com