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Tue, 04 Jul 2023 01:06:48 -0700 (PDT) Received: from mnissler.ba.rivosinc.com ([66.220.2.162]) by smtp.gmail.com with ESMTPSA id u1-20020aa78381000000b00662c4ca18ebsm15113101pfm.128.2023.07.04.01.06.47 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Tue, 04 Jul 2023 01:06:48 -0700 (PDT) From: Mattias Nissler To: qemu-devel@nongnu.org Cc: Elena Ufimtseva , Jagannathan Raman , =?utf-8?q?Philippe_Mathieu-Daud?= =?utf-8?q?=C3=A9?= , Paolo Bonzini , Peter Xu , stefanha@redhat.com, David Hildenbrand , john.levon@nutanix.com, Mattias Nissler Subject: [PATCH 3/3] vfio-user: Message-based DMA support Date: Tue, 4 Jul 2023 01:06:27 -0700 Message-Id: <20230704080628.852525-4-mnissler@rivosinc.com> X-Mailer: git-send-email 2.34.1 In-Reply-To: <20230704080628.852525-1-mnissler@rivosinc.com> References: <20230704080628.852525-1-mnissler@rivosinc.com> MIME-Version: 1.0 Received-SPF: pass client-ip=2607:f8b0:4864:20::436; envelope-from=mnissler@rivosinc.com; helo=mail-pf1-x436.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 Wire up support for DMA for the case where the vfio-user client does not provide mmap()-able file descriptors, but DMA requests must be performed via the VFIO-user protocol. This installs an indirect memory region, which already works for pci_dma_{read,write}, and pci_dma_map works thanks to the existing DMA bounce buffering support. Note that while simple scenarios work with this patch, there's a known race condition in libvfio-user that will mess up the communication channel: https://github.com/nutanix/libvfio-user/issues/279 I intend to contribute a fix for this problem, see discussion on the github issue for more details. Signed-off-by: Mattias Nissler --- hw/remote/vfio-user-obj.c | 62 ++++++++++++++++++++++++++++++++++----- 1 file changed, 55 insertions(+), 7 deletions(-) diff --git a/hw/remote/vfio-user-obj.c b/hw/remote/vfio-user-obj.c index 8b10c32a3c..9799580c77 100644 --- a/hw/remote/vfio-user-obj.c +++ b/hw/remote/vfio-user-obj.c @@ -300,6 +300,53 @@ static ssize_t vfu_object_cfg_access(vfu_ctx_t *vfu_ctx, char * const buf, return count; } +static MemTxResult vfu_dma_read(void *opaque, hwaddr addr, uint64_t *val, + unsigned size, MemTxAttrs attrs) +{ + MemoryRegion *region = opaque; + VfuObject *o = VFU_OBJECT(region->owner); + + dma_sg_t *sg = alloca(dma_sg_size()); + vfu_dma_addr_t vfu_addr = (vfu_dma_addr_t)(region->addr + addr); + if (vfu_addr_to_sgl(o->vfu_ctx, vfu_addr, size, sg, 1, PROT_READ) < 0 || + vfu_sgl_read(o->vfu_ctx, sg, 1, val) != 0) { + return MEMTX_ERROR; + } + + return MEMTX_OK; +} + +static MemTxResult vfu_dma_write(void *opaque, hwaddr addr, uint64_t val, + unsigned size, MemTxAttrs attrs) +{ + MemoryRegion *region = opaque; + VfuObject *o = VFU_OBJECT(region->owner); + + dma_sg_t *sg = alloca(dma_sg_size()); + vfu_dma_addr_t vfu_addr = (vfu_dma_addr_t)(region->addr + addr); + if (vfu_addr_to_sgl(o->vfu_ctx, vfu_addr, size, sg, 1, PROT_WRITE) < 0 || + vfu_sgl_write(o->vfu_ctx, sg, 1, &val) != 0) { + return MEMTX_ERROR; + } + + return MEMTX_OK; +} + +static const MemoryRegionOps vfu_dma_ops = { + .read_with_attrs = vfu_dma_read, + .write_with_attrs = vfu_dma_write, + .endianness = DEVICE_NATIVE_ENDIAN, + .valid = { + .min_access_size = 1, + .max_access_size = 8, + .unaligned = true, + }, + .impl = { + .min_access_size = 1, + .max_access_size = 8, + }, +}; + static void dma_register(vfu_ctx_t *vfu_ctx, vfu_dma_info_t *info) { VfuObject *o = vfu_get_private(vfu_ctx); @@ -308,17 +355,18 @@ static void dma_register(vfu_ctx_t *vfu_ctx, vfu_dma_info_t *info) g_autofree char *name = NULL; struct iovec *iov = &info->iova; - if (!info->vaddr) { - return; - } - name = g_strdup_printf("mem-%s-%"PRIx64"", o->device, - (uint64_t)info->vaddr); + (uint64_t)iov->iov_base); subregion = g_new0(MemoryRegion, 1); - memory_region_init_ram_ptr(subregion, NULL, name, - iov->iov_len, info->vaddr); + if (info->vaddr) { + memory_region_init_ram_ptr(subregion, OBJECT(o), name, + iov->iov_len, info->vaddr); + } else { + memory_region_init_io(subregion, OBJECT(o), &vfu_dma_ops, subregion, + name, iov->iov_len); + } dma_as = pci_device_iommu_address_space(o->pci_dev);