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Fri, 26 Dec 2025 14:54:12 -0800 (PST) Received: from barry-desktop.hub ([47.72.129.29]) by smtp.gmail.com with ESMTPSA id 98e67ed59e1d1-34e772ac1acsm9981428a91.9.2025.12.26.14.54.05 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Fri, 26 Dec 2025 14:54:11 -0800 (PST) From: Barry Song <21cnbao@gmail.com> To: catalin.marinas@arm.com, m.szyprowski@samsung.com, robin.murphy@arm.com, will@kernel.org, iommu@lists.linux.dev, linux-arm-kernel@lists.infradead.org Cc: linux-kernel@vger.kernel.org, xen-devel@lists.xenproject.org, Barry Song , Leon Romanovsky , Ada Couprie Diaz , Ard Biesheuvel , Marc Zyngier , Anshuman Khandual , Ryan Roberts , Suren Baghdasaryan , Joerg Roedel , Tangquan Zheng Subject: [PATCH RFC v2 7/8] dma-iommu: Support DMA sync batch mode for IOVA link and unlink Date: Sat, 27 Dec 2025 11:52:47 +1300 Message-ID: <20251226225254.46197-8-21cnbao@gmail.com> X-Mailer: git-send-email 2.48.1 In-Reply-To: <20251226225254.46197-1-21cnbao@gmail.com> References: <20251226225254.46197-1-21cnbao@gmail.com> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset="utf-8" From: Barry Song Apply batched DMA synchronization to __dma_iova_link() and iommu_dma_iova_unlink_range_slow(). For multiple sync_dma_for_device() and sync_dma_for_cpu() calls, we only need to wait once for the completion of all sync operations, rather than waiting for each one individually. I do not have the hardware to test this, so it is marked as RFC. I would greatly appreciate it if someone could test it. Suggested-by: Marek Szyprowski Cc: Leon Romanovsky Cc: Catalin Marinas Cc: Will Deacon Cc: Marek Szyprowski Cc: Ada Couprie Diaz Cc: Ard Biesheuvel Cc: Marc Zyngier Cc: Anshuman Khandual Cc: Ryan Roberts Cc: Suren Baghdasaryan Cc: Robin Murphy Cc: Joerg Roedel Cc: Tangquan Zheng Signed-off-by: Barry Song --- drivers/iommu/dma-iommu.c | 15 +++++++++------ 1 file changed, 9 insertions(+), 6 deletions(-) diff --git a/drivers/iommu/dma-iommu.c b/drivers/iommu/dma-iommu.c index 6827763a3877..ffa940bdbbaf 100644 --- a/drivers/iommu/dma-iommu.c +++ b/drivers/iommu/dma-iommu.c @@ -1849,10 +1849,8 @@ static int __dma_iova_link(struct device *dev, dma_a= ddr_t addr, bool coherent =3D dev_is_dma_coherent(dev); int prot =3D dma_info_to_prot(dir, coherent, attrs); =20 - if (!coherent && !(attrs & (DMA_ATTR_SKIP_CPU_SYNC | DMA_ATTR_MMIO))) { + if (!coherent && !(attrs & (DMA_ATTR_SKIP_CPU_SYNC | DMA_ATTR_MMIO))) arch_sync_dma_for_device(phys, size, dir); - arch_sync_dma_flush(); - } =20 return iommu_map_nosync(iommu_get_dma_domain(dev), addr, phys, size, prot, GFP_ATOMIC); @@ -1995,6 +1993,8 @@ int dma_iova_sync(struct device *dev, struct dma_iova= _state *state, dma_addr_t addr =3D state->addr + offset; size_t iova_start_pad =3D iova_offset(iovad, addr); =20 + if (!dev_is_dma_coherent(dev)) + arch_sync_dma_flush(); return iommu_sync_map(domain, addr - iova_start_pad, iova_align(iovad, size + iova_start_pad)); } @@ -2008,6 +2008,8 @@ static void iommu_dma_iova_unlink_range_slow(struct d= evice *dev, struct iommu_dma_cookie *cookie =3D domain->iova_cookie; struct iova_domain *iovad =3D &cookie->iovad; size_t iova_start_pad =3D iova_offset(iovad, addr); + bool need_sync_dma =3D !dev_is_dma_coherent(dev) && + !(attrs & (DMA_ATTR_SKIP_CPU_SYNC | DMA_ATTR_MMIO)); dma_addr_t end =3D addr + size; =20 do { @@ -2023,16 +2025,17 @@ static void iommu_dma_iova_unlink_range_slow(struct= device *dev, end - addr, iovad->granule - iova_start_pad); =20 if (!dev_is_dma_coherent(dev) && - !(attrs & (DMA_ATTR_SKIP_CPU_SYNC | DMA_ATTR_MMIO))) { + !(attrs & (DMA_ATTR_SKIP_CPU_SYNC | DMA_ATTR_MMIO))) arch_sync_dma_for_cpu(phys, len, dir); - arch_sync_dma_flush(); - } =20 swiotlb_tbl_unmap_single(dev, phys, len, dir, attrs); =20 addr +=3D len; iova_start_pad =3D 0; } while (addr < end); + + if (need_sync_dma) + arch_sync_dma_flush(); } =20 static void __iommu_dma_iova_unlink(struct device *dev, --=20 2.43.0