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Fri, 03 Mar 2023 02:39:54 -0800 (PST) From: Chuang Xu To: qemu-devel@nongnu.org Cc: dgilbert@redhat.com, quintela@redhat.com, pbonzini@redhat.com, peterx@redhat.com, david@redhat.com, philmd@linaro.org, zhouyibo@bytedance.com, Chuang Xu Subject: [PATCH v6 4/5] memory: Add sanity check in address_space_to_flatview Date: Fri, 3 Mar 2023 18:39:34 +0800 Message-Id: <20230303103935.370903-5-xuchuangxclwt@bytedance.com> X-Mailer: git-send-email 2.20.1 In-Reply-To: <20230303103935.370903-1-xuchuangxclwt@bytedance.com> References: <20230303103935.370903-1-xuchuangxclwt@bytedance.com> MIME-Version: 1.0 Received-SPF: pass client-ip=2607:f8b0:4864:20::52c; envelope-from=xuchuangxclwt@bytedance.com; helo=mail-pg1-x52c.google.com X-Spam_score_int: -5 X-Spam_score: -0.6 X-Spam_bar: / X-Spam_report: (-0.6 / 5.0 requ) BAYES_00=-1.9, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, DKIM_VALID_EF=-0.1, FROM_LOCAL_NOVOWEL=0.5, HK_RANDOM_ENVFROM=0.001, HK_RANDOM_FROM=0.999, RCVD_IN_DNSWL_NONE=-0.0001, SPF_HELO_NONE=0.001, SPF_PASS=-0.001 autolearn=no autolearn_force=no X-Spam_action: no action X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: qemu-devel-bounces+incoming=patchwork.ozlabs.org@nongnu.org Sender: qemu-devel-bounces+incoming=patchwork.ozlabs.org@nongnu.org Before using any flatview, sanity check whether BQL or rcu is held. And if we're during a memory region transaction, try to immediately update mappings, or the map can be invalid. Signed-off-by: Chuang Xu --- include/exec/memory.h | 23 +++++++++++++++++++++++ softmmu/memory.c | 5 +++++ 2 files changed, 28 insertions(+) diff --git a/include/exec/memory.h b/include/exec/memory.h index 2e602a2fad..84b531c6ff 100644 --- a/include/exec/memory.h +++ b/include/exec/memory.h @@ -27,6 +27,7 @@ #include "qemu/notify.h" #include "qom/object.h" #include "qemu/rcu.h" +#include "qemu/main-loop.h" #define RAM_ADDR_INVALID (~(ram_addr_t)0) @@ -1095,8 +1096,30 @@ struct FlatView { MemoryRegion *root; }; +bool memory_region_transaction_in_progress(void); + +void memory_region_transaction_do_commit(void); + static inline FlatView *address_space_to_flatview(AddressSpace *as) { + if (qemu_mutex_iothread_locked()) { + /* We exclusively own the flatview now.. */ + if (memory_region_transaction_in_progress()) { + /* + * Fetch the flatview within a transaction in-progress, it + * means current_map may not be the latest, we need to update + * immediately to make sure the caller won't see obsolete + * mapping. + */ + memory_region_transaction_do_commit(); + } + + /* No further protection needed to access current_map */ + return as->current_map; + } + + /* Otherwise we must have had the RCU lock or something went wrong */ + assert(rcu_read_is_locked()); return qatomic_rcu_read(&as->current_map); } diff --git a/softmmu/memory.c b/softmmu/memory.c index b89abf400e..1834e14cc8 100644 --- a/softmmu/memory.c +++ b/softmmu/memory.c @@ -1130,6 +1130,11 @@ void memory_region_transaction_commit(void) } } +bool memory_region_transaction_in_progress(void) +{ + return memory_region_transaction_depth != 0; +} + static void memory_region_destructor_none(MemoryRegion *mr) { }