On Wed, Dec 15, 2021, Paolo Bonzini wrote: > On 12/15/21 02:15, Sean Christopherson wrote: > > Patches 01-03 implement a bug fix by ensuring KVM zaps both valid and > > invalid roots when unmapping a gfn range (including the magic "all" range). > > Failure to zap invalid roots means KVM doesn't honor the mmu_notifier's > > requirement that all references are dropped. > > > > set_nx_huge_pages() is the most blatant offender, as it doesn't elevate > > mm_users and so a VM's entire mm can be released, but the same underlying > > bug exists for any "unmap" command from the mmu_notifier in combination > > with a memslot update. E.g. if KVM is deleting a memslot, and a > > mmu_notifier hook acquires mmu_lock while it's dropped by > > kvm_mmu_zap_all_fast(), the mmu_notifier hook will see the to-be-deleted > > memslot but won't zap entries from the invalid roots. > > > > Patch 04 is cleanup to reuse the common iterator for walking _only_ > > invalid roots. > > > > Sean Christopherson (4): > > KVM: x86/mmu: Use common TDP MMU zap helper for MMU notifier unmap > > hook > > KVM: x86/mmu: Move "invalid" check out of kvm_tdp_mmu_get_root() > > KVM: x86/mmu: Zap _all_ roots when unmapping gfn range in TDP MMU > > KVM: x86/mmu: Use common iterator for walking invalid TDP MMU roots > > > > arch/x86/kvm/mmu/tdp_mmu.c | 116 +++++++++++++++++-------------------- > > arch/x86/kvm/mmu/tdp_mmu.h | 3 - > > 2 files changed, 53 insertions(+), 66 deletions(-) > > > > Queued 1-3 for 5.16 and 4 for 5.17. Actually, can you please unqueue patch 4? I think we can actually kill off kvm_tdp_mmu_zap_invalidated_roots() entirely. I don't know if that code will be ready for 5.17, but if it is then this patch is unnecesary. And if not, it shouldn't be difficult to re-queue this a bit later. Thanks!
