A basic device-specific linear memory mapping was introduced back in
commit ("dma: Take into account dma_pfn_offset") as a single-valued offset
preserved in the device.dma_pfn_offset field, which was initialized for
instance by means of the "dma-ranges" DT property. Afterwards the
functionality was extended to support more than one device-specific region
defined in the device.dma_range_map list of maps. But all of these
improvements concerned a single pointer, page or sg DMA-mapping methods,
while the system resource mapping function turned to miss the
corresponding modification. Thus the dma_direct_map_resource() method now
just casts the CPU physical address to the device DMA address with no
dma-ranges-based mapping taking into account, which is obviously wrong.
Let's fix it by using the phys_to_dma_direct() method to get the
device-specific bus address from the passed memory resource for the case
of the directly mapped DMA.

Fixes: 25f1e1887088 ("dma: Take into account dma_pfn_offset")
Signed-off-by: Serge Semin <Sergey.Semin@baikalelectronics.ru>

---

After a long discussion with Christoph and Robin regarding this patch
here:
https://lore.kernel.org/lkml/20220324014836.19149-4-Sergey.Semin@baikalelectronics.ru
and here
https://lore.kernel.org/linux-pci/20220503225104.12108-2-Sergey.Semin@baikalelectronics.ru/
It was decided to consult with wider maintainers audience whether it's ok
to accept the change as is or a more sophisticated solution needs to be
found for the non-linear direct MMIO mapping.

Cc: Christoph Hellwig <hch@lst.de>
Cc: Robin Murphy <robin.murphy@arm.com>
Cc: Manivannan Sadhasivam <manivannan.sadhasivam@linaro.org>

file: arch/arm/mach-orion5x/board-dt.c
Cc: Andrew Lunn <andrew@lunn.ch>
Cc: Sebastian Hesselbarth <sebastian.hesselbarth@gmail.com>
Cc: Gregory Clement <gregory.clement@bootlin.com>
Cc: linux-arm-kernel@lists.infradead.org

file: drivers/crypto/marvell/cesa/cesa.c
Cc: Srujana Challa <schalla@marvell.com>
Cc: Arnaud Ebalard <arno@natisbad.org>
Cc: Boris Brezillon <bbrezillon@kernel.org>
Cc: linux-crypto@vger.kernel.org

file: drivers/dma/{fsl-edma-common.c,pl330.c,sh/rcar-dmac.c}
Cc: Vinod Koul <vkoul@kernel.org>
Cc: dmaengine@vger.kernel.org

file: arch/arm/boot/dts/{vfxxx.dtsi,ls1021a.dtsi,imx7ulp.dtsi,fsl-ls1043a.dtsi}
Cc: Shawn Guo <shawnguo@kernel.org>
Cc: Sascha Hauer <s.hauer@pengutronix.de>
Cc: Li Yang <leoyang.li@nxp.com>
Cc: linux-arm-kernel@lists.infradead.org

file: arch/arm/boot/dts/r8a77*.dtsi, arch/arm64/boot/dts/renesas/r8a77*.dtsi
Cc: Geert Uytterhoeven <geert+renesas@glider.be>
Cc: Magnus Damm <magnus.damm@gmail.com>
Cc: linux-renesas-soc@vger.kernel.org

file: drivers/gpu/drm/amd/amdgpu/amdgpu_vram_mgr.c
Cc: Alex Deucher <alexander.deucher@amd.com>
Cc: "Christian König" <christian.koenig@amd.com>
Cc: "Pan, Xinhui" <Xinhui.Pan@amd.com>

file: drivers/gpu/drm/virtio/virtgpu_vram.c
Cc: David Airlie <airlied@linux.ie>
Cc: Gerd Hoffmann <kraxel@redhat.com>

file: drivers/media/common/videobuf2/videobuf2-dma-contig.c
Cc: Tomasz Figa <tfiga@chromium.org>
Cc: Marek Szyprowski <m.szyprowski@samsung.com>

file: drivers/misc/habanalabs/common/memory.c
Cc: Oded Gabbay <ogabbay@kernel.org>
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

file: drivers/mtd/nand/raw/qcom_nandc.c
Cc: Manivannan Sadhasivam <mani@kernel.org>

file: arch/arm64/boot/dts/qcom/{ipq8074.dtsi,ipq6018.dtsi,qcom-sdx55.dtsi,qcom-ipq4019.dtsi,qcom-ipq8064.dtsi}
Cc: Andy Gross <agross@kernel.org>
Cc: Bjorn Andersson <bjorn.andersson@linaro.org>
Cc: linux-arm-msm@vger.kernel.org

file: drivers/net/ethernet/marvell/octeontx2/af/rvu.c
Cc: Sunil Goutham <sgoutham@marvell.com>
Cc: Linu Cherian <lcherian@marvell.com>
Cc: Geetha sowjanya <gakula@marvell.com>

file: drivers/ntb/ntb_transport.c
Cc: Jon Mason <jdmason@kudzu.us>
Cc: Dave Jiang <dave.jiang@intel.com>
Cc: ntb@lists.linux.dev
---
 kernel/dma/direct.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/kernel/dma/direct.c b/kernel/dma/direct.c
index 9743c6ccce1a..bc06db74dfdb 100644
--- a/kernel/dma/direct.c
+++ b/kernel/dma/direct.c
@@ -497,7 +497,7 @@ int dma_direct_map_sg(struct device *dev, struct scatterlist *sgl, int nents,
 dma_addr_t dma_direct_map_resource(struct device *dev, phys_addr_t paddr,
 		size_t size, enum dma_data_direction dir, unsigned long attrs)
 {
-	dma_addr_t dma_addr = paddr;
+	dma_addr_t dma_addr = phys_to_dma_direct(dev, paddr);
 
 	if (unlikely(!dma_capable(dev, dma_addr, size, false))) {
 		dev_err_once(dev,
-- 
2.35.1

Folks,

On Fri, Jun 10, 2022 at 11:08:02AM +0300, Serge Semin wrote:
> A basic device-specific linear memory mapping was introduced back in
> commit ("dma: Take into account dma_pfn_offset") as a single-valued offset
> preserved in the device.dma_pfn_offset field, which was initialized for
> instance by means of the "dma-ranges" DT property. Afterwards the
> functionality was extended to support more than one device-specific region
> defined in the device.dma_range_map list of maps. But all of these
> improvements concerned a single pointer, page or sg DMA-mapping methods,
> while the system resource mapping function turned to miss the
> corresponding modification. Thus the dma_direct_map_resource() method now
> just casts the CPU physical address to the device DMA address with no
> dma-ranges-based mapping taking into account, which is obviously wrong.
> Let's fix it by using the phys_to_dma_direct() method to get the
> device-specific bus address from the passed memory resource for the case
> of the directly mapped DMA.

So any comment on the suggest modification? Any notes against or for?

-Sergey

> 
> Fixes: 25f1e1887088 ("dma: Take into account dma_pfn_offset")
> Signed-off-by: Serge Semin <Sergey.Semin@baikalelectronics.ru>
> 
> ---
> 
> After a long discussion with Christoph and Robin regarding this patch
> here:
> https://lore.kernel.org/lkml/20220324014836.19149-4-Sergey.Semin@baikalelectronics.ru
> and here
> https://lore.kernel.org/linux-pci/20220503225104.12108-2-Sergey.Semin@baikalelectronics.ru/
> It was decided to consult with wider maintainers audience whether it's ok
> to accept the change as is or a more sophisticated solution needs to be
> found for the non-linear direct MMIO mapping.
> 
> Cc: Christoph Hellwig <hch@lst.de>
> Cc: Robin Murphy <robin.murphy@arm.com>
> Cc: Manivannan Sadhasivam <manivannan.sadhasivam@linaro.org>
> 
> file: arch/arm/mach-orion5x/board-dt.c
> Cc: Andrew Lunn <andrew@lunn.ch>
> Cc: Sebastian Hesselbarth <sebastian.hesselbarth@gmail.com>
> Cc: Gregory Clement <gregory.clement@bootlin.com>
> Cc: linux-arm-kernel@lists.infradead.org
> 
> file: drivers/crypto/marvell/cesa/cesa.c
> Cc: Srujana Challa <schalla@marvell.com>
> Cc: Arnaud Ebalard <arno@natisbad.org>
> Cc: Boris Brezillon <bbrezillon@kernel.org>
> Cc: linux-crypto@vger.kernel.org
> 
> file: drivers/dma/{fsl-edma-common.c,pl330.c,sh/rcar-dmac.c}
> Cc: Vinod Koul <vkoul@kernel.org>
> Cc: dmaengine@vger.kernel.org
> 
> file: arch/arm/boot/dts/{vfxxx.dtsi,ls1021a.dtsi,imx7ulp.dtsi,fsl-ls1043a.dtsi}
> Cc: Shawn Guo <shawnguo@kernel.org>
> Cc: Sascha Hauer <s.hauer@pengutronix.de>
> Cc: Li Yang <leoyang.li@nxp.com>
> Cc: linux-arm-kernel@lists.infradead.org
> 
> file: arch/arm/boot/dts/r8a77*.dtsi, arch/arm64/boot/dts/renesas/r8a77*.dtsi
> Cc: Geert Uytterhoeven <geert+renesas@glider.be>
> Cc: Magnus Damm <magnus.damm@gmail.com>
> Cc: linux-renesas-soc@vger.kernel.org
> 
> file: drivers/gpu/drm/amd/amdgpu/amdgpu_vram_mgr.c
> Cc: Alex Deucher <alexander.deucher@amd.com>
> Cc: "Christian König" <christian.koenig@amd.com>
> Cc: "Pan, Xinhui" <Xinhui.Pan@amd.com>
> 
> file: drivers/gpu/drm/virtio/virtgpu_vram.c
> Cc: David Airlie <airlied@linux.ie>
> Cc: Gerd Hoffmann <kraxel@redhat.com>
> 
> file: drivers/media/common/videobuf2/videobuf2-dma-contig.c
> Cc: Tomasz Figa <tfiga@chromium.org>
> Cc: Marek Szyprowski <m.szyprowski@samsung.com>
> 
> file: drivers/misc/habanalabs/common/memory.c
> Cc: Oded Gabbay <ogabbay@kernel.org>
> Cc: Arnd Bergmann <arnd@arndb.de>
> Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
> 
> file: drivers/mtd/nand/raw/qcom_nandc.c
> Cc: Manivannan Sadhasivam <mani@kernel.org>
> 
> file: arch/arm64/boot/dts/qcom/{ipq8074.dtsi,ipq6018.dtsi,qcom-sdx55.dtsi,qcom-ipq4019.dtsi,qcom-ipq8064.dtsi}
> Cc: Andy Gross <agross@kernel.org>
> Cc: Bjorn Andersson <bjorn.andersson@linaro.org>
> Cc: linux-arm-msm@vger.kernel.org
> 
> file: drivers/net/ethernet/marvell/octeontx2/af/rvu.c
> Cc: Sunil Goutham <sgoutham@marvell.com>
> Cc: Linu Cherian <lcherian@marvell.com>
> Cc: Geetha sowjanya <gakula@marvell.com>
> 
> file: drivers/ntb/ntb_transport.c
> Cc: Jon Mason <jdmason@kudzu.us>
> Cc: Dave Jiang <dave.jiang@intel.com>
> Cc: ntb@lists.linux.dev
> ---
>  kernel/dma/direct.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/kernel/dma/direct.c b/kernel/dma/direct.c
> index 9743c6ccce1a..bc06db74dfdb 100644
> --- a/kernel/dma/direct.c
> +++ b/kernel/dma/direct.c
> @@ -497,7 +497,7 @@ int dma_direct_map_sg(struct device *dev, struct scatterlist *sgl, int nents,
>  dma_addr_t dma_direct_map_resource(struct device *dev, phys_addr_t paddr,
>  		size_t size, enum dma_data_direction dir, unsigned long attrs)
>  {
> -	dma_addr_t dma_addr = paddr;
> +	dma_addr_t dma_addr = phys_to_dma_direct(dev, paddr);
>  
>  	if (unlikely(!dma_capable(dev, dma_addr, size, false))) {
>  		dev_err_once(dev,
> -- 
> 2.35.1
> 

I'd really like to hear something from the driver maintainers.  The
cod change itself looks fine, we just need to make sure it does not
break any driver assumptions.

And I think at least for the PCIe P2P and NTB cases I fear it might
break them.  The proper logic for those is in the p2p helpers, but
it seems like not everyone is using them.