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[35.185.214.157]) by smtp.gmail.com with ESMTPSA id j6-20020a17090a588600b001c699d77503sm3584376pji.2.2022.03.29.12.23.08 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Tue, 29 Mar 2022 12:23:08 -0700 (PDT) Date: Tue, 29 Mar 2022 19:23:04 +0000 From: Sean Christopherson To: Chao Peng Cc: kvm@vger.kernel.org, linux-kernel@vger.kernel.org, linux-mm@kvack.org, linux-fsdevel@vger.kernel.org, linux-api@vger.kernel.org, qemu-devel@nongnu.org, Paolo Bonzini , Jonathan Corbet , Vitaly Kuznetsov , Wanpeng Li , Jim Mattson , Joerg Roedel , Thomas Gleixner , Ingo Molnar , Borislav Petkov , x86@kernel.org, "H . Peter Anvin" , Hugh Dickins , Jeff Layton , "J . Bruce Fields" , Andrew Morton , Mike Rapoport , Steven Price , "Maciej S . Szmigiero" , Vlastimil Babka , Vishal Annapurve , Yu Zhang , "Kirill A . Shutemov" , luto@kernel.org, jun.nakajima@intel.com, dave.hansen@intel.com, ak@linux.intel.com, david@redhat.com Subject: Re: [PATCH v5 11/13] KVM: Zap existing KVM mappings when pages changed in the private fd Message-ID: References: <20220310140911.50924-1-chao.p.peng@linux.intel.com> <20220310140911.50924-12-chao.p.peng@linux.intel.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20220310140911.50924-12-chao.p.peng@linux.intel.com> Precedence: bulk List-ID: X-Mailing-List: linux-api@vger.kernel.org On Thu, Mar 10, 2022, Chao Peng wrote: > diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c > index 67349421eae3..52319f49d58a 100644 > --- a/virt/kvm/kvm_main.c > +++ b/virt/kvm/kvm_main.c > @@ -841,8 +841,43 @@ static int kvm_init_mmu_notifier(struct kvm *kvm) > #endif /* CONFIG_MMU_NOTIFIER && KVM_ARCH_WANT_MMU_NOTIFIER */ > > #ifdef CONFIG_MEMFILE_NOTIFIER > +static void kvm_memfile_notifier_handler(struct memfile_notifier *notifier, > + pgoff_t start, pgoff_t end) > +{ > + int idx; > + struct kvm_memory_slot *slot = container_of(notifier, > + struct kvm_memory_slot, > + notifier); > + struct kvm_gfn_range gfn_range = { > + .slot = slot, > + .start = start - (slot->private_offset >> PAGE_SHIFT), > + .end = end - (slot->private_offset >> PAGE_SHIFT), > + .may_block = true, > + }; > + struct kvm *kvm = slot->kvm; > + > + gfn_range.start = max(gfn_range.start, slot->base_gfn); > + gfn_range.end = min(gfn_range.end, slot->base_gfn + slot->npages); > + > + if (gfn_range.start >= gfn_range.end) > + return; > + > + idx = srcu_read_lock(&kvm->srcu); > + KVM_MMU_LOCK(kvm); > + kvm_unmap_gfn_range(kvm, &gfn_range); > + kvm_flush_remote_tlbs(kvm); This should check the result of kvm_unmap_gfn_range() and flush only if necessary. kvm->mmu_notifier_seq needs to be incremented, otherwise KVM will incorrectly install a SPTE if the mapping is zapped between retrieving the pfn in faultin and installing it after acquire mmu_lock. > + KVM_MMU_UNLOCK(kvm); > + srcu_read_unlock(&kvm->srcu, idx); > +} > + > +static struct memfile_notifier_ops kvm_memfile_notifier_ops = { > + .invalidate = kvm_memfile_notifier_handler, > + .fallocate = kvm_memfile_notifier_handler, > +}; > + > static inline int kvm_memfile_register(struct kvm_memory_slot *slot) > { > + slot->notifier.ops = &kvm_memfile_notifier_ops; > return memfile_register_notifier(file_inode(slot->private_file), > &slot->notifier, > &slot->pfn_ops); > @@ -1963,6 +1998,7 @@ int __kvm_set_memory_region(struct kvm *kvm, > new->private_file = file; > new->private_offset = mem->flags & KVM_MEM_PRIVATE ? > region_ext->private_offset : 0; > + new->kvm = kvm; > > r = kvm_set_memslot(kvm, old, new, change); > if (!r) > -- > 2.17.1 >