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Shutemov" References: <20231027182217.3615211-1-seanjc@google.com> <20231027182217.3615211-3-seanjc@google.com> From: Paolo Bonzini Autocrypt: addr=pbonzini@redhat.com; keydata= xsEhBFRCcBIBDqDGsz4K0zZun3jh+U6Z9wNGLKQ0kSFyjN38gMqU1SfP+TUNQepFHb/Gc0E2 CxXPkIBTvYY+ZPkoTh5xF9oS1jqI8iRLzouzF8yXs3QjQIZ2SfuCxSVwlV65jotcjD2FTN04 hVopm9llFijNZpVIOGUTqzM4U55sdsCcZUluWM6x4HSOdw5F5Utxfp1wOjD/v92Lrax0hjiX DResHSt48q+8FrZzY+AUbkUS+Jm34qjswdrgsC5uxeVcLkBgWLmov2kMaMROT0YmFY6A3m1S P/kXmHDXxhe23gKb3dgwxUTpENDBGcfEzrzilWueOeUWiOcWuFOed/C3SyijBx3Av/lbCsHU Vx6pMycNTdzU1BuAroB+Y3mNEuW56Yd44jlInzG2UOwt9XjjdKkJZ1g0P9dwptwLEgTEd3Fo UdhAQyRXGYO8oROiuh+RZ1lXp6AQ4ZjoyH8WLfTLf5g1EKCTc4C1sy1vQSdzIRu3rBIjAvnC tGZADei1IExLqB3uzXKzZ1BZ+Z8hnt2og9hb7H0y8diYfEk2w3R7wEr+Ehk5NQsT2MPI2QBd wEv1/Aj1DgUHZAHzG1QN9S8wNWQ6K9DqHZTBnI1hUlkp22zCSHK/6FwUCuYp1zcAEQEAAc0j UGFvbG8gQm9uemluaSA8cGJvbnppbmlAcmVkaGF0LmNvbT7CwU0EEwECACMFAlRCcBICGwMH CwkIBwMCAQYVCAIJCgsEFgIDAQIeAQIXgAAKCRB+FRAMzTZpsbceDp9IIN6BIA0Ol7MoB15E 11kRz/ewzryFY54tQlMnd4xxfH8MTQ/mm9I482YoSwPMdcWFAKnUX6Yo30tbLiNB8hzaHeRj jx12K+ptqYbg+cevgOtbLAlL9kNgLLcsGqC2829jBCUTVeMSZDrzS97ole/YEez2qFpPnTV0 VrRWClWVfYh+JfzpXmgyhbkuwUxNFk421s4Ajp3d8nPPFUGgBG5HOxzkAm7xb1cjAuJ+oi/K CHfkuN+fLZl/u3E/fw7vvOESApLU5o0icVXeakfSz0LsygEnekDbxPnE5af/9FEkXJD5EoYG SEahaEtgNrR4qsyxyAGYgZlS70vkSSYJ+iT2rrwEiDlo31MzRo6Ba2FfHBSJ7lcYdPT7bbk9 AO3hlNMhNdUhoQv7M5HsnqZ6unvSHOKmReNaS9egAGdRN0/GPDWr9wroyJ65ZNQsHl9nXBqE AukZNr5oJO5vxrYiAuuTSd6UI/xFkjtkzltG3mw5ao2bBpk/V/YuePrJsnPFHG7NhizrxttB nTuOSCMo45pfHQ+XYd5K1+Cv/NzZFNWscm5htJ0HznY+oOsZvHTyGz3v91pn51dkRYN0otqr bQ4tlFFuVjArBZcapSIe6NV8C4cEiSTOwE0EVEJx7gEIAMeHcVzuv2bp9HlWDp6+RkZe+vtl KwAHplb/WH59j2wyG8V6i33+6MlSSJMOFnYUCCL77bucx9uImI5nX24PIlqT+zasVEEVGSRF m8dgkcJDB7Tps0IkNrUi4yof3B3shR+vMY3i3Ip0e41zKx0CvlAhMOo6otaHmcxr35sWq1Jk tLkbn3wG+fPQCVudJJECvVQ//UAthSSEklA50QtD2sBkmQ14ZryEyTHQ+E42K3j2IUmOLriF dNr9NvE1QGmGyIcbw2NIVEBOK/GWxkS5+dmxM2iD4Jdaf2nSn3jlHjEXoPwpMs0KZsgdU0pP JQzMUMwmB1wM8JxovFlPYrhNT9MAEQEAAcLBMwQYAQIACQUCVEJx7gIbDAAKCRB+FRAMzTZp sadRDqCctLmYICZu4GSnie4lKXl+HqlLanpVMOoFNnWs9oRP47MbE2wv8OaYh5pNR9VVgyhD OG0AU7oidG36OeUlrFDTfnPYYSF/mPCxHttosyt8O5kabxnIPv2URuAxDByz+iVbL+RjKaGM GDph56ZTswlx75nZVtIukqzLAQ5fa8OALSGum0cFi4ptZUOhDNz1onz61klD6z3MODi0sBZN Aj6guB2L/+2ZwElZEeRBERRd/uommlYuToAXfNRdUwrwl9gRMiA0WSyTb190zneRRDfpSK5d usXnM/O+kr3Dm+Ui+UioPf6wgbn3T0o6I5BhVhs4h4hWmIW7iNhPjX1iybXfmb1gAFfjtHfL xRUr64svXpyfJMScIQtBAm0ihWPltXkyITA92ngCmPdHa6M1hMh4RDX+Jf1fiWubzp1voAg0 JBrdmNZSQDz0iKmSrx8xkoXYfA3bgtFN8WJH2xgFL28XnqY4M6dLhJwV3z08tPSRqYFm4NMP dRsn0/7oymhneL8RthIvjDDQ5ktUjMe8LtHr70OZE/TT88qvEdhiIVUogHdo4qBrk41+gGQh b906Dudw5YhTJFU3nC6bbF2nrLlB4C/XSiH76ZvqzV0Z/cAMBo5NF/w= In-Reply-To: <20231027182217.3615211-3-seanjc@google.com> X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: redhat.com Content-Language: en-US Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit X-Rspamd-Server: rspam08 X-Rspamd-Queue-Id: B20CDC0022 X-Stat-Signature: 88jxt51si8o3dm8b8fqft1xrbjey4rk4 X-Rspam-User: X-HE-Tag: 1698683453-418198 X-HE-Meta: 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 PhEJaVbd 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 X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On 10/27/23 20:21, Sean Christopherson wrote: > Move the assertion on the in-progress invalidation count from the primary > MMU's notifier path to KVM's common notification path, i.e. assert that > the count doesn't go negative even when the invalidation is coming from > KVM itself. > > Opportunistically convert the assertion to a KVM_BUG_ON(), i.e. kill only > the affected VM, not the entire kernel. A corrupted count is fatal to the > VM, e.g. the non-zero (negative) count will cause mmu_invalidate_retry() > to block any and all attempts to install new mappings. But it's far from > guaranteed that an end() without a start() is fatal or even problematic to > anything other than the target VM, e.g. the underlying bug could simply be > a duplicate call to end(). And it's much more likely that a missed > invalidation, i.e. a potential use-after-free, would manifest as no > notification whatsoever, not an end() without a start(). Reviewed-by: Paolo Bonzini > Signed-off-by: Sean Christopherson > --- > virt/kvm/kvm_main.c | 3 +-- > 1 file changed, 1 insertion(+), 2 deletions(-) > > diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c > index 0524933856d4..5a97e6c7d9c2 100644 > --- a/virt/kvm/kvm_main.c > +++ b/virt/kvm/kvm_main.c > @@ -833,6 +833,7 @@ void kvm_mmu_invalidate_end(struct kvm *kvm, unsigned long start, > * in conjunction with the smp_rmb in mmu_invalidate_retry(). > */ > kvm->mmu_invalidate_in_progress--; > + KVM_BUG_ON(kvm->mmu_invalidate_in_progress < 0, kvm); > } > > static void kvm_mmu_notifier_invalidate_range_end(struct mmu_notifier *mn, > @@ -863,8 +864,6 @@ static void kvm_mmu_notifier_invalidate_range_end(struct mmu_notifier *mn, > */ > if (wake) > rcuwait_wake_up(&kvm->mn_memslots_update_rcuwait); > - > - BUG_ON(kvm->mmu_invalidate_in_progress < 0); > } > > static int kvm_mmu_notifier_clear_flush_young(struct mmu_notifier *mn,