From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from gabe.freedesktop.org (gabe.freedesktop.org [131.252.210.177]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id 94E5BCD5BAC for ; Thu, 21 May 2026 15:35:53 +0000 (UTC) Received: from gabe.freedesktop.org (localhost [127.0.0.1]) by gabe.freedesktop.org (Postfix) with ESMTP id 0157F10E2D8; Thu, 21 May 2026 15:35:53 +0000 (UTC) Authentication-Results: gabe.freedesktop.org; dkim=pass (2048-bit key; unprotected) header.d=kernel.org header.i=@kernel.org header.b="bEhNVt1G"; dkim-atps=neutral Received: from tor.source.kernel.org (tor.source.kernel.org [172.105.4.254]) by gabe.freedesktop.org (Postfix) with ESMTPS id 1105D10E2D8 for ; Thu, 21 May 2026 15:35:52 +0000 (UTC) Received: from smtp.kernel.org (quasi.space.kernel.org [100.103.45.18]) by tor.source.kernel.org (Postfix) with ESMTP id 4BBA8601F3; Thu, 21 May 2026 15:35:51 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 8EBDC1F00A3B; Thu, 21 May 2026 15:35:43 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1779377751; bh=5PUD/3vmVzMg81CR18Fk250apIi9RXyWW+eG5eaM6s8=; h=From:To:Cc:Subject:In-Reply-To:References:Date; b=bEhNVt1GsNTReAabbrbOrGd7094+P/Sa5116B7JLNnREdhOzMGX2Gz8rO+jhs2hjr zSsrlqBKOoM5flIzMvqZnYd7J9cRg2EDO74CdatpbE2YJ1B0uNV1ztRl6S0G+N0vsU yB1er4WO6TtsqsXhRMk1/TlGmKa+L1/FsD2GOdqw+oQm9GLeFT3Bj3KKSnDOBHF4B/ U+yyOFENz4I54n62JgPRSNPUjWlQ+ltOi5Wo2jvwQbED3vUWkLuR6lXfvEDJvLC4tN p2nKWsvyoT705a20eObfWQInTblFf6CCtvyGPA+dGyxm9WCeiQxTawQdn76dB9GHg8 A/2+Gwm/0LbAQ== X-Mailer: emacs 30.2 (via feedmail 11-beta-1 I) From: Aneesh Kumar K.V To: Jason Gunthorpe Cc: Jiri Pirko , dri-devel@lists.freedesktop.org, linaro-mm-sig@lists.linaro.org, iommu@lists.linux.dev, linux-media@vger.kernel.org, sumit.semwal@linaro.org, benjamin.gaignard@collabora.com, Brian.Starkey@arm.com, jstultz@google.com, tjmercier@google.com, christian.koenig@amd.com, m.szyprowski@samsung.com, robin.murphy@arm.com, leon@kernel.org, sean.anderson@linux.dev, ptesarik@suse.com, catalin.marinas@arm.com, suzuki.poulose@arm.com, steven.price@arm.com, thomas.lendacky@amd.com, john.allen@amd.com, ashish.kalra@amd.com, suravee.suthikulpanit@amd.com, linux-coco@lists.linux.dev Subject: Re: [PATCH v5 1/2] dma-mapping: introduce DMA_ATTR_CC_SHARED for shared memory In-Reply-To: <20260426130531.GF804026@ziepe.ca> References: <20260325192352.437608-1-jiri@resnulli.us> <20260325192352.437608-2-jiri@resnulli.us> <4qdizkkoeke3cvkcf35upa7p7ick6s654eqlrizmi7ozkw5eze@tnpk2e34xgwl> <20260421121004.GA3611611@ziepe.ca> <20260424225514.GE804026@ziepe.ca> <20260426130531.GF804026@ziepe.ca> Date: Thu, 21 May 2026 21:05:39 +0530 Message-ID: MIME-Version: 1.0 Content-Type: text/plain X-BeenThere: dri-devel@lists.freedesktop.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Direct Rendering Infrastructure - Development List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: dri-devel-bounces@lists.freedesktop.org Sender: "dri-devel" Jason Gunthorpe writes: >> > static inline dma_addr_t dma_direct_map_phys(struct device *dev, >> > phys_addr_t phys, size_t size, enum dma_data_direction dir, >> > unsigned long attrs, bool flush) >> > { >> > dma_addr_t dma_addr; >> > >> > if (is_swiotlb_force_bounce(dev)) { >> > if (attrs & (DMA_ATTR_MMIO | DMA_ATTR_REQUIRE_COHERENT)) >> > return DMA_MAPPING_ERROR; >> > >> > return swiotlb_map(dev, phys, size, dir, attrs); >> > } >> > >> > if (attrs & DMA_ATTR_MMIO) { >> > dma_addr = phys; >> > if (unlikely(!dma_capable(dev, dma_addr, size, false, attrs))) >> > goto err_overflow; >> > goto dma_mapped; >> >> I suspect P2P is probably broken on CC because this doesn't make >> sense.. > > Actually, I suppose it is fully broken because it will jump to swiotlb > and then should fail. > >> This should flow into the >> phys_to_dma_unencrypted/phys_to_dma_encrypted block as well AFAICT, it >> shouldn't just assign phys. Assigning phys to dma on a CC system is >> always wrong, right? >> >> It is is more like >> >> /* To be updated, callers should specify MMIO | CC_SHARED instead of >> * implying it. */ >> if (attrs & DMA_ATTR_MMIO) >> attrs |= DMA_ATTR_CC_SHARED; > > So no need for this if, we can go directly to marking the MMIO callers > with DMA_ATTR_CC_SHARED once this is fixed for mmio: > >> if (attrs & DMA_ATTR_CC_SHARED) { >> dma_addr = phys_to_dma_unencrypted(dev, phys); >> } else { >> dma_addr = phys_to_dma_encrypted(dev, phys); >> } > > Jasn I am wondering whether this is better static inline dma_addr_t dma_direct_map_phys(struct device *dev, phys_addr_t phys, size_t size, enum dma_data_direction dir, unsigned long attrs, bool flush) { dma_addr_t dma_addr; /* * For a device requiring unencrypted DMA, MMIO memory is treated * as shared. */ if (force_dma_unencrypted(dev) && (attrs & DMA_ATTR_MMIO)) attrs |= DMA_ATTR_CC_SHARED; ..... if (attrs & DMA_ATTR_CC_SHARED) dma_addr = phys_to_dma_unencrypted(dev, phys); else dma_addr = phys_to_dma_encrypted(dev, phys); if (attrs & DMA_ATTR_MMIO) { if (unlikely(!dma_capable(dev, dma_addr, size, false, attrs))) goto err_overflow; goto dma_mapped; } .... -aneesh