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Tsirkin" , Miguel Ojeda , Robin Murphy , rust-for-linux@vger.kernel.org, Sagi Grimberg , Stefano Stabellini , Steven Rostedt , virtualization@lists.linux.dev, Will Deacon , xen-devel@lists.xenproject.org Subject: [PATCH v4 15/16] block-dma: properly take MMIO path Date: Tue, 19 Aug 2025 20:36:59 +0300 Message-ID: <642dbeb7aa94257eaea71ec63c06e3f939270023.1755624249.git.leon@kernel.org> X-Mailer: git-send-email 2.50.1 In-Reply-To: References: X-Mailing-List: linuxppc-dev@lists.ozlabs.org List-Id: List-Help: List-Owner: List-Post: List-Archive: , List-Subscribe: , , List-Unsubscribe: Precedence: list MIME-Version: 1.0 Content-Transfer-Encoding: 8bit From: Leon Romanovsky Make sure that CPU is not synced and IOMMU is configured to take MMIO path by providing newly introduced DMA_ATTR_MMIO attribute. Signed-off-by: Leon Romanovsky --- block/blk-mq-dma.c | 13 +++++++++++-- include/linux/blk-mq-dma.h | 6 +++++- include/linux/blk_types.h | 2 ++ 3 files changed, 18 insertions(+), 3 deletions(-) diff --git a/block/blk-mq-dma.c b/block/blk-mq-dma.c index 37e2142be4f7..d415088ed9fd 100644 --- a/block/blk-mq-dma.c +++ b/block/blk-mq-dma.c @@ -87,8 +87,13 @@ static bool blk_dma_map_bus(struct blk_dma_iter *iter, struct phys_vec *vec) static bool blk_dma_map_direct(struct request *req, struct device *dma_dev, struct blk_dma_iter *iter, struct phys_vec *vec) { + unsigned int attrs = 0; + + if (req->cmd_flags & REQ_MMIO) + attrs = DMA_ATTR_MMIO; + iter->addr = dma_map_phys(dma_dev, vec->paddr, vec->len, - rq_dma_dir(req), 0); + rq_dma_dir(req), attrs); if (dma_mapping_error(dma_dev, iter->addr)) { iter->status = BLK_STS_RESOURCE; return false; @@ -103,14 +108,17 @@ static bool blk_rq_dma_map_iova(struct request *req, struct device *dma_dev, { enum dma_data_direction dir = rq_dma_dir(req); unsigned int mapped = 0; + unsigned int attrs = 0; int error; iter->addr = state->addr; iter->len = dma_iova_size(state); + if (req->cmd_flags & REQ_MMIO) + attrs = DMA_ATTR_MMIO; do { error = dma_iova_link(dma_dev, state, vec->paddr, mapped, - vec->len, dir, 0); + vec->len, dir, attrs); if (error) break; mapped += vec->len; @@ -176,6 +184,7 @@ bool blk_rq_dma_map_iter_start(struct request *req, struct device *dma_dev, * same as non-P2P transfers below and during unmap. */ req->cmd_flags &= ~REQ_P2PDMA; + req->cmd_flags |= REQ_MMIO; break; default: iter->status = BLK_STS_INVAL; diff --git a/include/linux/blk-mq-dma.h b/include/linux/blk-mq-dma.h index c26a01aeae00..6c55f5e58511 100644 --- a/include/linux/blk-mq-dma.h +++ b/include/linux/blk-mq-dma.h @@ -48,12 +48,16 @@ static inline bool blk_rq_dma_map_coalesce(struct dma_iova_state *state) static inline bool blk_rq_dma_unmap(struct request *req, struct device *dma_dev, struct dma_iova_state *state, size_t mapped_len) { + unsigned int attrs = 0; + if (req->cmd_flags & REQ_P2PDMA) return true; if (dma_use_iova(state)) { + if (req->cmd_flags & REQ_MMIO) + attrs = DMA_ATTR_MMIO; dma_iova_destroy(dma_dev, state, mapped_len, rq_dma_dir(req), - 0); + attrs); return true; } diff --git a/include/linux/blk_types.h b/include/linux/blk_types.h index 09b99d52fd36..283058bcb5b1 100644 --- a/include/linux/blk_types.h +++ b/include/linux/blk_types.h @@ -387,6 +387,7 @@ enum req_flag_bits { __REQ_FS_PRIVATE, /* for file system (submitter) use */ __REQ_ATOMIC, /* for atomic write operations */ __REQ_P2PDMA, /* contains P2P DMA pages */ + __REQ_MMIO, /* contains MMIO memory */ /* * Command specific flags, keep last: */ @@ -420,6 +421,7 @@ enum req_flag_bits { #define REQ_FS_PRIVATE (__force blk_opf_t)(1ULL << __REQ_FS_PRIVATE) #define REQ_ATOMIC (__force blk_opf_t)(1ULL << __REQ_ATOMIC) #define REQ_P2PDMA (__force blk_opf_t)(1ULL << __REQ_P2PDMA) +#define REQ_MMIO (__force blk_opf_t)(1ULL << __REQ_MMIO) #define REQ_NOUNMAP (__force blk_opf_t)(1ULL << __REQ_NOUNMAP) -- 2.50.1