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Sun, 5 Nov 2023 16:32:06 +0000 (UTC) From: Paolo Bonzini To: Paolo Bonzini , Marc Zyngier , Oliver Upton , Huacai Chen , Michael Ellerman , Anup Patel , Paul Walmsley , Palmer Dabbelt , Albert Ou , Sean Christopherson , Alexander Viro , Christian Brauner , "Matthew Wilcox (Oracle)" , Andrew Morton Cc: kvm@vger.kernel.org, linux-arm-kernel@lists.infradead.org, kvmarm@lists.linux.dev, linux-mips@vger.kernel.org, linuxppc-dev@lists.ozlabs.org, kvm-riscv@lists.infradead.org, linux-riscv@lists.infradead.org, linux-fsdevel@vger.kernel.org, linux-mm@kvack.org, linux-kernel@vger.kernel.org, Xiaoyao Li , Xu Yilun , Chao Peng , Fuad Tabba , Jarkko Sakkinen , Anish Moorthy , David Matlack , Yu Zhang , Isaku Yamahata , =?UTF-8?q?Micka=C3=ABl=20Sala=C3=BCn?= , Vlastimil Babka , Vishal Annapurve , Ackerley Tng , Maciej Szmigiero , David Hildenbrand , Quentin Perret , Michael Roth , Wang , Liam Merwick , Isaku Yamahata , "Kirill A. Shutemov" Subject: [PATCH 11/34] KVM: Drop .on_unlock() mmu_notifier hook Date: Sun, 5 Nov 2023 17:30:14 +0100 Message-ID: <20231105163040.14904-12-pbonzini@redhat.com> In-Reply-To: <20231105163040.14904-1-pbonzini@redhat.com> References: <20231105163040.14904-1-pbonzini@redhat.com> MIME-Version: 1.0 Content-Type: text/plain Content-Transfer-Encoding: 8bit X-Scanned-By: MIMEDefang 3.4.1 on 10.11.54.6 X-Rspamd-Queue-Id: 83158120011 X-Rspam-User: X-Rspamd-Server: rspam02 X-Stat-Signature: 336aoy5mukh6bfkjzf7hhom4pca4sbch X-HE-Tag: 1699201940-910371 X-HE-Meta: U2FsdGVkX1+pCXwypJ0iKHKwzqBrEe5QJRJRfJ1Te5S92EeEDDKWJBaGCULMFQA9SXyofGhRCLcfoWL3GQnMm6HoQYUKdpCFA2Q0eSQQL3yMd7355FFOc5QmDxo/O06nvVUp4gFay8q6igbG4G31WWRcY5SsXq7PlGTQjY+FYxY8eN+pj9M45AnSNKC+WQlQxTBH8nO3NGgV+Tj9tEczf+52SmI5C3sUAzOIB54hvXKMkBQ6CNHdSjp1aZBwscJPFekD5YtRMivVM5NYQETH8Ch0x6l/Bux01nPuzO/R2OKRNtxdpQsN0Hh4gLXxcbjmKHL/25Oa5Ojxvzh3YqAJ5Y4sBSjmQA+mdeeev+InFQidnKOCnJL1FDq1c/8QAREZN6Fh7T7QlKNQES1H+9Yy7hHSlxuDRcVCMURRlSlutxShGMH61jYVijpWCJAS/4sIBa1qd6YzYaXz4pZr8HQBolKpWq/Ie9LQU7BePK7IH0v5iU6Qe5YRNSwnLrwb5JMYoOLJh2mloHMXD36dtWB4Ym0YcK4K5u/q7NDZPjtXMLFuMSC719VsfVEhMlZ6TSOgB50ifxIxTl2FQqybXiJ4SoSJ3C5xZvDEfxkEsSfLSCx+lCgedYrkjbFHbRp2kylbEWBX4sQKJ5jxpbp9JHo97nguMbwiEkFAKjCHSO+T2MX2avFey+08utiwlurZw9sCIj6jC8GxtMsHh9qFNZytz2l2R/yXHFnTMwAZK2RClQ5Z3RksioYPTbE1s8+d3k5V1ZkYkJqe3w/KyWs9kklzNo9ITtaB/uPzIQrrUFbQFWBzGdkdjp6upRn5xM2rS9yNkNCH4CKV3OcCZI5XO9HEy1jEeAunvShWa+IhYvqFUP1KBznK6XALODlcUuzsX+EA7+orK0IN6UVyg1W0m86EL4lFGPz/q2MgQ5mWPXrqeH0+zORDfLmDGGIvAFa/1JgrY05ANG3x7rcZjNx+Whs bRnUjOwI KhDJ1D8RQHqd9iLGs6jFgM3b0kOzCem9gU1nXM12ATeKeE5ZCT9arkeQ1hgBbpvEbqKRJCSMO4bXTG02T1FbuwDzACD9M/WV1K3cXQNF7C31fOTqrkKw4GA0dqBngMJQ47XDAerxjyPVUr8kMZlbweHjxO22IWrOb36cAJkD8KDFUe1gnDX8372rpMLIWf14eqvD6rylO+t+4ntlNSB98YBkE+ZTVzcbmdE97TWcf9burhcH2DODi6Q5LqfbIAC/68fmfk2l8JdcVhUEcdzBe+f3zswKaG5g7+sLoDksF2/7bvTbku0CjMi4JHcUx9YEpBAdjrORIDAmlkxW+ITHDwgH82z/CmbkiOOfgtagvf9+zuY6vvzwrLC4RiFwpCLYViYRNtKgRMLgu1yo= 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: From: Sean Christopherson Drop the .on_unlock() mmu_notifer hook now that it's no longer used for notifying arch code that memory has been reclaimed. Adding .on_unlock() and invoking it *after* dropping mmu_lock was a terrible idea, as doing so resulted in .on_lock() and .on_unlock() having divergent and asymmetric behavior, and set future developers up for failure, i.e. all but asked for bugs where KVM relied on using .on_unlock() to try to run a callback while holding mmu_lock. Opportunistically add a lockdep assertion in kvm_mmu_invalidate_end() to guard against future bugs of this nature. Reported-by: Isaku Yamahata Link: https://lore.kernel.org/all/20230802203119.GB2021422@ls.amr.corp.intel.com Signed-off-by: Sean Christopherson Reviewed-by: Paolo Bonzini Reviewed-by: Fuad Tabba Tested-by: Fuad Tabba Message-Id: <20231027182217.3615211-12-seanjc@google.com> Signed-off-by: Paolo Bonzini --- virt/kvm/kvm_main.c | 11 +---------- 1 file changed, 1 insertion(+), 10 deletions(-) diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c index e18a7f152c0b..7f3291dec7a6 100644 --- a/virt/kvm/kvm_main.c +++ b/virt/kvm/kvm_main.c @@ -544,7 +544,6 @@ static inline struct kvm *mmu_notifier_to_kvm(struct mmu_notifier *mn) typedef bool (*gfn_handler_t)(struct kvm *kvm, struct kvm_gfn_range *range); typedef void (*on_lock_fn_t)(struct kvm *kvm); -typedef void (*on_unlock_fn_t)(struct kvm *kvm); struct kvm_mmu_notifier_range { /* @@ -556,7 +555,6 @@ struct kvm_mmu_notifier_range { union kvm_mmu_notifier_arg arg; gfn_handler_t handler; on_lock_fn_t on_lock; - on_unlock_fn_t on_unlock; bool flush_on_ret; bool may_block; }; @@ -663,11 +661,8 @@ static __always_inline kvm_mn_ret_t __kvm_handle_hva_range(struct kvm *kvm, if (range->flush_on_ret && r.ret) kvm_flush_remote_tlbs(kvm); - if (r.found_memslot) { + if (r.found_memslot) KVM_MMU_UNLOCK(kvm); - if (!IS_KVM_NULL_FN(range->on_unlock)) - range->on_unlock(kvm); - } srcu_read_unlock(&kvm->srcu, idx); @@ -687,7 +682,6 @@ static __always_inline int kvm_handle_hva_range(struct mmu_notifier *mn, .arg = arg, .handler = handler, .on_lock = (void *)kvm_null_fn, - .on_unlock = (void *)kvm_null_fn, .flush_on_ret = true, .may_block = false, }; @@ -706,7 +700,6 @@ static __always_inline int kvm_handle_hva_range_no_flush(struct mmu_notifier *mn .end = end, .handler = handler, .on_lock = (void *)kvm_null_fn, - .on_unlock = (void *)kvm_null_fn, .flush_on_ret = false, .may_block = false, }; @@ -813,7 +806,6 @@ static int kvm_mmu_notifier_invalidate_range_start(struct mmu_notifier *mn, .end = range->end, .handler = kvm_mmu_unmap_gfn_range, .on_lock = kvm_mmu_invalidate_begin, - .on_unlock = (void *)kvm_null_fn, .flush_on_ret = true, .may_block = mmu_notifier_range_blockable(range), }; @@ -891,7 +883,6 @@ static void kvm_mmu_notifier_invalidate_range_end(struct mmu_notifier *mn, .end = range->end, .handler = (void *)kvm_null_fn, .on_lock = kvm_mmu_invalidate_end, - .on_unlock = (void *)kvm_null_fn, .flush_on_ret = false, .may_block = mmu_notifier_range_blockable(range), }; -- 2.39.1