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Tue, 27 Aug 2024 08:49:23 -0700 (PDT) Received: from mnissler.ba.rivosinc.com ([64.71.180.162]) by smtp.gmail.com with ESMTPSA id 98e67ed59e1d1-2d5eb9037a2sm14624478a91.13.2024.08.27.08.49.22 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Tue, 27 Aug 2024 08:49:22 -0700 (PDT) From: Mattias Nissler To: qemu-devel@nongnu.org, jag.raman@oracle.com Cc: Elena Ufimtseva , john.levon@nutanix.com, Thanos Makatos , Mattias Nissler Subject: [PATCH v12 3/3] vfio-user: Fix memory region reference accounting Date: Tue, 27 Aug 2024 08:49:01 -0700 Message-Id: <20240827154902.607926-4-mnissler@rivosinc.com> X-Mailer: git-send-email 2.34.1 In-Reply-To: <20240827154902.607926-1-mnissler@rivosinc.com> References: <20240827154902.607926-1-mnissler@rivosinc.com> MIME-Version: 1.0 Received-SPF: pass client-ip=2607:f8b0:4864:20::534; envelope-from=mnissler@rivosinc.com; helo=mail-pg1-x534.google.com X-Spam_score_int: -18 X-Spam_score: -1.9 X-Spam_bar: - X-Spam_report: (-1.9 / 5.0 requ) BAYES_00=-1.9, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, RCVD_IN_DNSWL_NONE=-0.0001, SPF_HELO_NONE=0.001, SPF_PASS=-0.001, T_SCC_BODY_TEXT_LINE=-0.01 autolearn=ham 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 The memory regions created for DMA regions where leaking the original reference the object is initialized with. This happened since we insert the memory region as a subregion, but don't keep the reference obtained when creating the object. Thus, drop the reference after inserting the DMA memory region into the address space. This fixes auto-shutdown behavior: Due to the leaked references, the memory regions would never be released, and indirectly keep the VFU object as their owner alive. Thus, vfu_object_finalize didn't get invoked, and qemu wouldn't terminate. With this fix, this is now working as originally intended. Signed-off-by: Mattias Nissler --- hw/remote/vfio-user-obj.c | 8 ++++++++ 1 file changed, 8 insertions(+) diff --git a/hw/remote/vfio-user-obj.c b/hw/remote/vfio-user-obj.c index 0e93d7a7b4..d347a96e39 100644 --- a/hw/remote/vfio-user-obj.c +++ b/hw/remote/vfio-user-obj.c @@ -394,6 +394,14 @@ static void dma_register(vfu_ctx_t *vfu_ctx, vfu_dma_info_t *info) memory_region_add_subregion(dma_as->root, (hwaddr)iov->iov_base, subregion); + /* + * Insertion into the address space grabbed a reference to keep the memory + * region alive. However, the memory region object was created with an + * original reference count of 1, so we must unref since we don't keep that + * reference. + */ + memory_region_unref(subregion); + trace_vfu_dma_register((uint64_t)iov->iov_base, iov->iov_len); }