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Thu, 12 Jan 2023 16:27:55 -0800 From: Fan Ni To: "qemu-devel@nongnu.org" CC: "jonathan.cameron@huawei.com" , "linux-cxl@vger.kernel.org" , "alison.schofield@intel.com" , "dave@stgolabs.net" , Adam Manzanares , "bwidawsk@kernel.org" , "gregory.price@memverge.com" , "hchkuo@avery-design.com.tw" , "cbrowy@avery-design.com" , "ira.weiny@intel.com" , Fan Ni Subject: [RFC] cxl-host: Fix committed check for passthrough decoder Thread-Topic: [RFC] cxl-host: Fix committed check for passthrough decoder Thread-Index: AQHZJuXhSxTSwCcfWUCp6ChLVpTS/Q== Date: Fri, 13 Jan 2023 00:27:55 +0000 Message-ID: <20230113002727.11411-1-fan.ni@samsung.com> Accept-Language: en-US Content-Language: en-US X-MS-Has-Attach: X-MS-TNEF-Correlator: x-originating-ip: [105.128.2.176] MIME-Version: 1.0 X-CFilter-Loop: Reflected X-Brightmail-Tracker: H4sIAAAAAAAAA+NgFjrAKsWRmVeSWpSXmKPExsWy7djX87q9Sw8kG3TdZbG4+/gCm0Xz5MWM Ft3nNzBarL65htGioekRi0XL7vdMFvufPmexWLXwGpvF+VmnWCyO9+5gceDyuDB5AqvH4gZX j5Yjb4GMPS+ZPDat6mTz2PjxP7vHk2ubmTymzq73+LxJLoAzissmJTUnsyy1SN8ugSvj/O3J LAVd/BUbb09lbmBcx9PFyMkhIWAiMaH3IyOILSSwklFi/eLMLkYuILuVSeLcx2vMMEVd+44y QSTWMkq83XeIEcL5xCjx/NhEZghnGaPErkWrmEBa2AQUJfZ1bWcDsUUEjCWOHV4CVsQssItF 4uOMG2BzhQVcJNb93Q9V5CnRfOIaK4StJ7F0/2Wwo1gEVCXa570Fqufg4BUwl7g9JQYkzCgg JvH91BqwXcwC4hK3nsxngjhVUGLR7D1QZ4tJ/Nv1kA3CVpS4//0lO0S9nsSNqVPYIGxtiWUL X4PV8wL1npz5hAWiXlLi4IobLCA3Swg84JD4dWI7I8gNEkA3r/rrCFEjLTF9zWWo+mKJ0zNf MkPUNzBKrLtzgxUiYS2x8M96qEP5JP7+egQ1h1eio01oAqPSLCQvzEJy3iwk581Cct4CRpZV jOKlxcW56anFhnmp5XrFibnFpXnpesn5uZsYgYns9L/DuTsYd9z6qHeIkYmD8RCjBAezkgjv nqP7k4V4UxIrq1KL8uOLSnNSiw8xSnOwKInzdm+dnywkkJ5YkpqdmlqQWgSTZeLglGpgqmx+ yecr658j+U3/dMaX03afWLqZs14k7bd1+ffOoDrIZeX3qA1X9YOiHe7OrnXLNZxgMSvvTPot 4Qru6J96snsP5ynJL3/+PaXR6qvSee5vYgtXn61KNWCR4Nt00uetrYXlYRfTN1nzjavSzpyq rAj8MkcqVWS6RXzeSw3tww0v5hf9f9A05dWKM5d8WJyKHHNnv5l7f27d9VtC+0qnbQnnCj2y z/7aDSXJ6M3Zy4PEVr/s6PbSPldtYSztXzPtYPK8Hhs5V7XQ40n3NWdtdNJ64Pt+hVjbpiM2 pZzHzZ/E9k2RNLwY8fvi2rnM6/gWreC4VN3FuPv15fSlVcucvhkzfjbZ9GXF/uQnE7pXKrEU ZyQaajEXFScCAPW+t4HTAwAA X-Brightmail-Tracker: H4sIAAAAAAAAA+NgFtrFIsWRmVeSWpSXmKPExsWS2cA0Ubdn6YFkg3fHlS3uPr7AZtE8eTGj Rff5DYwWq2+uYbRoaHrEYtGy+z2Txf6nz1ksVi28xmZxftYpFovjvTtYHLg8LkyewOqxuMHV o+XIWyBjz0smj02rOtk8Nn78z+7x5NpmJo+ps+s9Pm+SC+CM4rJJSc3JLEst0rdL4Mo4f3sy S0EXf8XG21OZGxjX8XQxcnJICJhIdO07ygRiCwmsZpQ4vy20i5ELyP7EKLG3+z0ThLOMUeLM 5t1sIFVsAooS+7q2g9kiAsYSxw4vYQYpYhbYxSLxccYNZpCEsICLxLq/+6GKPCWaT1xjhbD1 JJbuv8wIYrMIqEq0z3sLVM/BwStgLnF7SgxImFFATOL7qTVgFzELiEvcejKfCeJSAYkle84z Q9iiEi8f/2OFsBUl7n9/yQ5RrydxY+oUNghbW2LZwtdg9bwCghInZz5hgaiXlDi44gbLBEbR WUhWzELSPgtJ+ywk7QsYWVYxipcWF+emVxQb56WW6xUn5haX5qXrJefnbmIERu/pf4djdjDe u/VR7xAjEwfjIUYJDmYlEd49R/cnC/GmJFZWpRblxxeV5qQWH2KU5mBREuf1iJ0YLySQnliS mp2aWpBaBJNl4uCUamBSnjn1JPeSd68WC23f9Knpnvn1sv+ZC13u3zFKue9//mhzutyHpE96 MnFcfCtcRDseC4pHzL/ieSs7gvMml1DHaSOtnMtLmFmc+rQKz+ZdLbY2kZo9bcn50mmMe0/Y T+WNabOWNlpZEROr/Lo6MNTkwVSx5Zu3PD5a7fu+eyOv0oM9quK1IWslpp9bbfPit/u77ZPi 7FdHbVhva3BAvO3yF4/8q9uXiXjpyUmqiuaGhzv3ySXe9l7LH7Li773mLX5L87RC+xivehdL Npw6t/0X7x+VqcdeL5SskKxmPVbbYst1duqdE5m+K4TKrnx4pre2cburmnHfrqqPdl6Orqdd p9n/4/m9Y1Lp94tNz6KUWIozEg21mIuKEwGkApMOTQMAAA== X-CMS-MailID: 20230113002756uscas1p2b602bff26576110407491f67eff5e065 CMS-TYPE: 301P X-CMS-RootMailID: 20230113002756uscas1p2b602bff26576110407491f67eff5e065 References: Received-SPF: pass client-ip=211.189.100.12; envelope-from=fan.ni@samsung.com; helo=mailout2.w2.samsung.com X-Spam_score_int: -70 X-Spam_score: -7.1 X-Spam_bar: ------- X-Spam_report: (-7.1 / 5.0 requ) BAYES_00=-1.9, DKIMWL_WL_HIGH=-0.001, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, DKIM_VALID_EF=-0.1, RCVD_IN_DNSWL_HI=-5, RCVD_IN_MSPIKE_H3=0.001, RCVD_IN_MSPIKE_WL=0.001, SPF_HELO_PASS=-0.001, SPF_PASS=-0.001 autolearn=ham autolearn_force=no X-Spam_action: no action X-Mailman-Approved-At: Thu, 12 Jan 2023 21:10:18 -0500 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+qemu-devel=archiver.kernel.org@nongnu.org Sender: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org For passthrough decoder (a decoder hosted by a cxl component with only one downstream port), its cache_mem_registers field COMMITTED (see spec 2.0 8.2.5.12 - CXL HDM Decoder Capability Structure) will not be set by the current Linux CXL driver. Without the fix, for a cxl topology setup with a single HB and single root port, the memdev read/write requests cannot be passed to the device successfully as the function cxl_hdm_find_target will fail the decoder COMMITTED check and return directly, which causes read/write not being directed to cxl type3 device. Before the fix, a segfault is observed when trying using cxl memory for htop command through 'numactl --membind' after converting cxl memory into normal RAM. Detailed steps to reproduce the issue with the cxl setup where there is only one HB and a memdev is directly attached to the only root port of the HB are listed as below, 1. cxl create-region region0 2. ndctl create-namespace -m dax -r region0 3. daxctl reconfigure-device --mode=system-ram --no-online dax0.0 4. daxctl online-memory dax0.0 5. numactl --membind=1 htop Signed-off-by: Fan Ni --- hw/cxl/cxl-host.c | 7 +++++-- 1 file changed, 5 insertions(+), 2 deletions(-) diff --git a/hw/cxl/cxl-host.c b/hw/cxl/cxl-host.c index 1adf61231a..5ca0d6fd8f 100644 --- a/hw/cxl/cxl-host.c +++ b/hw/cxl/cxl-host.c @@ -107,8 +107,11 @@ static bool cxl_hdm_find_target(uint32_t *cache_mem, hwaddr addr, uint32_t target_idx; ctrl = cache_mem[R_CXL_HDM_DECODER0_CTRL]; - if (!FIELD_EX32(ctrl, CXL_HDM_DECODER0_CTRL, COMMITTED)) { - return false; + + /* skip the check for passthrough decoder */ + if (FIELD_EX32(ctrl, CXL_HDM_DECODER0_CTRL, COMMIT) + && !FIELD_EX32(ctrl, CXL_HDM_DECODER0_CTRL, COMMITTED)) { + return false; } ig_enc = FIELD_EX32(ctrl, CXL_HDM_DECODER0_CTRL, IG);