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[142.162.112.119]) by smtp.gmail.com with ESMTPSA id d75a77b69052e-50939ec5017sm30688511cf.8.2026.03.12.05.20.59 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Thu, 12 Mar 2026 05:20:59 -0700 (PDT) Received: from jgg by wakko with local (Exim 4.97) (envelope-from ) id 1w0f2A-00000006et5-427z; Thu, 12 Mar 2026 09:20:58 -0300 Date: Thu, 12 Mar 2026 09:20:58 -0300 From: Jason Gunthorpe To: Leon Romanovsky Cc: Marek Szyprowski , Robin Murphy , "Michael S. Tsirkin" , Petr Tesarik , Jonathan Corbet , Shuah Khan , Jason Wang , Xuan Zhuo , Eugenio =?utf-8?B?UMOpcmV6?= , Steven Rostedt , Masami Hiramatsu , Mathieu Desnoyers , Joerg Roedel , Will Deacon , Andrew Morton , iommu@lists.linux.dev, linux-kernel@vger.kernel.org, linux-doc@vger.kernel.org, virtualization@lists.linux.dev, linux-rdma@vger.kernel.org, linux-trace-kernel@vger.kernel.org, linux-mm@kvack.org Subject: Re: [PATCH v2 5/8] dma-direct: prevent SWIOTLB path when DMA_ATTR_REQUIRE_COHERENT is set Message-ID: <20260312122058.GE1469476@ziepe.ca> References: <20260311-dma-debug-overlap-v2-0-e00bc2ca346d@nvidia.com> <20260311-dma-debug-overlap-v2-5-e00bc2ca346d@nvidia.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20260311-dma-debug-overlap-v2-5-e00bc2ca346d@nvidia.com> X-Rspamd-Queue-Id: 7583520008 X-Stat-Signature: 7wo8a9jsqu9dzx7fyxo3fapfz9go1ezj X-Rspam-User: X-Rspamd-Server: rspam05 X-HE-Tag: 1773318061-732300 X-HE-Meta: U2FsdGVkX19ASZP7eZLYt5GisaljOU+VrEGdEVjVxOUzMPiY1AyTAHX36C7LKmjhOYi+jV9MYlCLwvyng6D3vIFT9EZ6zffeFAd2nU9oD4Kz9aoLtrz3LOeP01D2dXTSOGfZkTX8yAQtDwEM7hP6YCil+gXC1A0qM5S4zPIJhThqZAQqu7zz/USpwIjgYGTujWacUEXaWmovnoZ41a+IC+6l+iz4hmh/J1qhBtKYvboLorK7AOwCB9tB1JDBD5cdOCSL5KT23/MbscpbKuWLyf3/KAxYBRzJd69pA4P7XvTlhId8fiFkt3DXMBnzS+IXYxx/AysHO9LnRq1R0Q67p5D4+pv8/4wQevc6ioztdduihiChk4v6ZI27i4cDiUe/xNYXknUwaMqqWbACaPyOm7m1SKteGSg2kdZap35ceHj5bwZgemnNw1IvpEXH3g0Yb9GdRaGscqOk8Su4+0+R2eEv4tLjXaQjrwLjKGLyRJOn4bBCAfltAtpjCpUbI+skNmUZ9D+8RfuNUr67j58TPGZM/tbsZn3KbhnmsB1ASIMDq2QwGBfUgkW/uisB6CRCPdGUzlPLX/qHso1gA/0DC4bIcvZdTUib5lZSgtNp1nGBicnDfABFz8qsmBZ76C+4xmz8dMkZk8dEGeFKecGyZr7tTtzuXfvE2Xw8rraIOFRQLcES7jpxXVFxbOpBrnJLoSFTTU3s5YN8p88Gun7QmUFjmHWjlt0hmYTbtaLNjOHG36l9bRBN1o3qKRK27BiT7tOw6NrpVoUSopw7Q2ktpbGO7vYdXOutXhetM7zMQjGlx4dsaRW7msxUfh6yoyelH+8/S1zNJ1EuVGgyxh45xaN1nJQ0xTwcc/EwpOrFLD5Dw37F5hWQ5/x+alvpHwNJJPm7IT+FzE+0BDGW1MtGEblYXohSxEpuqbNrUEsMFuyyo2j8YQyXW+dn7vnjRAk3xBHYs9X0U0+uM8gkj7+ N4336paN 3OythK3wGWvJIJWFASYTSAMJY4GgBZAgGqqnkdg00ReO/3oiyaAry9Cvl52HQ1sLP7kwegOKlAKm+Jq8a3IIPKGTtkD0owPy/JrD7Y5Ew92nmDi9sC8/pgPi0L3MmD83TyrxAV2vLyjnMsFTSUkxwQNp2Ecv+YVy55D8mWLT8xzZRf2yqa1bSReQ9G/6xSxo63BjXlGVPCwC6LdaUtJSzycubaPZcDpJi9UWxxi6Ft+xNOvdB/q2FmIO53leyCxlG/X7ZPfJdyKlUmoByhFU+GVKiY0V49eGrhCYoYjqqIy7HM+N1zDsxOrh8dysFiKbXwo1guANmykVEaOD20rV+kigUnjlRMY+L9lGp0AfuMU0bw4s= Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On Wed, Mar 11, 2026 at 09:08:48PM +0200, Leon Romanovsky wrote: > From: Leon Romanovsky > > DMA_ATTR_REQUIRE_COHERENT indicates that SWIOTLB must not be used. > Ensure the SWIOTLB path is declined whenever the DMA direct path is > selected. > > Signed-off-by: Leon Romanovsky > --- > kernel/dma/direct.h | 7 ++++--- > 1 file changed, 4 insertions(+), 3 deletions(-) > > diff --git a/kernel/dma/direct.h b/kernel/dma/direct.h > index e89f175e9c2d0..6184ff303f080 100644 > --- a/kernel/dma/direct.h > +++ b/kernel/dma/direct.h > @@ -84,7 +84,7 @@ static inline dma_addr_t dma_direct_map_phys(struct device *dev, > dma_addr_t dma_addr; > > if (is_swiotlb_force_bounce(dev)) { > - if (attrs & DMA_ATTR_MMIO) > + if (attrs & (DMA_ATTR_MMIO | DMA_ATTR_REQUIRE_COHERENT)) > return DMA_MAPPING_ERROR; > > return swiotlb_map(dev, phys, size, dir, attrs); Oh here it is, still maybe it is better to put it in swiotlb_map() ? Jason