From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mail-wr1-f46.google.com (mail-wr1-f46.google.com [209.85.221.46]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 440BA37FF70 for ; Mon, 9 Feb 2026 15:38:14 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=209.85.221.46 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1770651494; cv=none; b=FFTJwT7hPGCmtWJlhwsRymxpi71a5SWTgjbXjcxKKMYO8EQyvohMkO3C44jvGrlcS8pHgvJl0WGF0tKgSZJHTMRjl52XgzVLaOhQhNMUj+y+dmjbLTWeQSRt6vB+pL0Ap+lvbHZ2j0J/CASWQyBSM6r/9rDUkcAROeAge63vaa4= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1770651494; c=relaxed/simple; bh=ntpJZbbpBAGBfrW0cjUkMTCbCe6n90bP2ZCU7ZGm4GQ=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=iMTcLQFk3rCLHuXuNMLlF3Q6HMwYZcP82lReYy6b85CavhO1Jj7rLSAVEQZt1y7dRPMozB6sJxX2olojqRHfmDQR3/NHgshrwW5/SnPIXeeKrsoLSx/WWfD/kI3jeMrg+ZDt57h3Fk8ynFH7DyhDwPLctZMgWii709vTkRfaSAk= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=none (p=none dis=none) header.from=resnulli.us; spf=none smtp.mailfrom=resnulli.us; dkim=pass (2048-bit key) header.d=resnulli-us.20230601.gappssmtp.com header.i=@resnulli-us.20230601.gappssmtp.com header.b=nKkuBN2i; arc=none smtp.client-ip=209.85.221.46 Authentication-Results: smtp.subspace.kernel.org; dmarc=none (p=none dis=none) header.from=resnulli.us Authentication-Results: smtp.subspace.kernel.org; spf=none smtp.mailfrom=resnulli.us Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=resnulli-us.20230601.gappssmtp.com header.i=@resnulli-us.20230601.gappssmtp.com header.b="nKkuBN2i" Received: by mail-wr1-f46.google.com with SMTP id ffacd0b85a97d-4359a302794so1976775f8f.1 for ; Mon, 09 Feb 2026 07:38:14 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=resnulli-us.20230601.gappssmtp.com; s=20230601; t=1770651493; x=1771256293; darn=vger.kernel.org; h=content-transfer-encoding:mime-version:references:in-reply-to :message-id:date:subject:cc:to:from:from:to:cc:subject:date :message-id:reply-to; bh=10eo7Xx3UsXznodXP/t6JgtysFzGllvuxfjnxVYXEzw=; b=nKkuBN2iTUOR3NFsSwXZayT/YuZ89208RN4C4ikwE4JLWD+c8YwEvVlvQzkdsUhbML ioCU6i/BOMSAZbIBzB3Yg1bXrPIat0e/1EH7RdTkuewF3bSHrXR0cKk8nrMDhNUM7tvz m83Jxcz+heGRicwa3eLkTOqfR8wy7bG6TqvqIKfAp0LQ5ojcOWPkzCzajs0hHT6RPxAr f41mtFOv6yVbbDQRRgyX79XnZEt6Yig3Ajk7QKI8MDjx7Xo3BlwXYfDEClCDF/B5BtCZ gz56kLbcG28HNvMjPfgaoY1kleahNwLtWWvQoFZLF6Dbtk7kjsmAZonc/R8+q4uoNbYc x/IA== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1770651493; x=1771256293; h=content-transfer-encoding:mime-version:references:in-reply-to :message-id:date:subject:cc:to:from:x-gm-gg:x-gm-message-state:from :to:cc:subject:date:message-id:reply-to; bh=10eo7Xx3UsXznodXP/t6JgtysFzGllvuxfjnxVYXEzw=; b=v/LfSeC3l9ZOXCugUuYK9IfJobCoGgF8oZODnUEoSS3Wud4Jx3TWRmY1CZLW9x5o51 m1IKSutLz+6B75UH3xaKh13Qhu3J3+4kWrhgRQJByLqmLM0yzKYGO7XOJcOanRhq6bka uJ1Cn8lzNKoZCfJIrujHSP2p2q7h5cvS6lJ+QUMGCM+ydu9ttaFormEjp403WXi86wK6 IYgrZzOo2filf7g/bl5I/HUEmBol+aDfJRQVIzv09qlNNhZKlpsJkH/cpo3n3QQb4TPe /HUoSGhhlZ207L4ghAbNh7jVMT2hG4qcDqQh6HKYtVpwHLQxHBAyrDiTEZxxarhSSNSP Xfqg== X-Forwarded-Encrypted: i=1; AJvYcCWBVR9/QH2Zg0sewTsmT+xpyHzdfUEJ+In0/LciRVQJE+0/sDK+1X7b1D3KQxjZCoVOMxcovwfq+IqIgQ==@vger.kernel.org X-Gm-Message-State: AOJu0YxF/V6ItxjZaOuRg1xZKRns1HYDgzKNRILA0D/ECzmokKAHnFy5 /8HyC5R/W5u/4ISKLkdtVEUSb5cSIewrcfz8TxqrqJqP1QCa7R6m79J/LK2QFNFU+Ls= X-Gm-Gg: AZuq6aJb8XfAypUhQLISWn/8eZgigXX3mcR+FfuQFolQWOBx3ovrUAFfgK9/DxOZ82E SQinXiosDZMzggbQ3Gl3RJbngURS053WlB/8/K63AbBeci9/wP1VPHhnpx2aXFgPOc7xdvTx0px dUcYV8czp/d89PPOHp+dKRGLmN3xszBUuvA7lTeWenR9dw+YhCSX09rvJB0NHOF94Qi9m5gV3lg ZU/gCwvEgDKgZZMlVQQmZ494owC96CT3DntriF5GzrtrQvszr02PYSEQxZDPswJIpUzVyvvmitm /jZG0LGhf5OU72XPXsi2xnx260HWgYC5K66bKaBzhYvL/r69Y/MgzJKxBy5DDJ70u0F3xDa1V2y EwINSYltVPOqP8gt/51ljJs6EqcVi+oYlhM/xSJaukMEABB7MGCcEepnqXG5hwwFUuvlkGNqSol +Qhw== X-Received: by 2002:a05:6000:4211:b0:435:b755:c67e with SMTP id ffacd0b85a97d-4362938a453mr16934813f8f.49.1770651492550; Mon, 09 Feb 2026 07:38:12 -0800 (PST) Received: from localhost ([85.163.81.98]) by smtp.gmail.com with ESMTPSA id ffacd0b85a97d-436296bd4a1sm27481147f8f.17.2026.02.09.07.38.11 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Mon, 09 Feb 2026 07:38:12 -0800 (PST) From: Jiri Pirko To: dri-devel@lists.freedesktop.org, linaro-mm-sig@lists.linaro.org, iommu@lists.linux.dev, linux-media@vger.kernel.org Cc: 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, jgg@ziepe.ca, leon@kernel.org, sean.anderson@linux.dev, ptesarik@suse.com, catalin.marinas@arm.com, aneesh.kumar@kernel.org, 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: [PATCH 2/5] dma-mapping: introduce DMA_ATTR_CC_DECRYPTED for pre-decrypted memory Date: Mon, 9 Feb 2026 16:38:06 +0100 Message-ID: <20260209153809.250835-3-jiri@resnulli.us> X-Mailer: git-send-email 2.51.1 In-Reply-To: <20260209153809.250835-1-jiri@resnulli.us> References: <20260209153809.250835-1-jiri@resnulli.us> Precedence: bulk X-Mailing-List: linux-media@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit From: Jiri Pirko This is only relevant inside confidential computing (CoCo) virtual machines, not on the hypervisor side. Current CoCo designs don't place a vIOMMU in front of untrusted devices. Instead, the DMA API forces all untrusted device DMA through swiotlb bounce buffers (is_swiotlb_force_bounce()) which copies data into decrypted memory on behalf of the device. When a caller has already arranged for the memory to be decrypted via set_memory_decrypted(), the DMA API needs to know so it can map directly using the unencrypted physical address rather than bounce buffering. Following the pattern of DMA_ATTR_MMIO, add DMA_ATTR_CC_DECRYPTED for this purpose. Like the MMIO case, only the caller knows what kind of memory it has and must inform the DMA API for it to work correctly. Signed-off-by: Jiri Pirko --- include/linux/dma-mapping.h | 7 +++++++ include/trace/events/dma.h | 3 ++- kernel/dma/direct.h | 14 +++++++++++--- 3 files changed, 20 insertions(+), 4 deletions(-) diff --git a/include/linux/dma-mapping.h b/include/linux/dma-mapping.h index aa36a0d1d9df..052235feb853 100644 --- a/include/linux/dma-mapping.h +++ b/include/linux/dma-mapping.h @@ -78,6 +78,13 @@ */ #define DMA_ATTR_MMIO (1UL << 10) +/* + * DMA_ATTR_CC_DECRYPTED: Indicates memory that has been explicitly decrypted + * (shared) for confidential computing guests. The caller must have + * called set_memory_decrypted(). A struct page is required. + */ +#define DMA_ATTR_CC_DECRYPTED (1UL << 11) + /* * A dma_addr_t can hold any valid DMA or bus address for the platform. It can * be given to a device to use as a DMA source or target. It is specific to a diff --git a/include/trace/events/dma.h b/include/trace/events/dma.h index b3fef140ae15..b3c2cee8841a 100644 --- a/include/trace/events/dma.h +++ b/include/trace/events/dma.h @@ -32,7 +32,8 @@ TRACE_DEFINE_ENUM(DMA_NONE); { DMA_ATTR_ALLOC_SINGLE_PAGES, "ALLOC_SINGLE_PAGES" }, \ { DMA_ATTR_NO_WARN, "NO_WARN" }, \ { DMA_ATTR_PRIVILEGED, "PRIVILEGED" }, \ - { DMA_ATTR_MMIO, "MMIO" }) + { DMA_ATTR_MMIO, "MMIO" }, \ + { DMA_ATTR_CC_DECRYPTED, "CC_DECRYPTED" }) DECLARE_EVENT_CLASS(dma_map, TP_PROTO(struct device *dev, phys_addr_t phys_addr, dma_addr_t dma_addr, diff --git a/kernel/dma/direct.h b/kernel/dma/direct.h index 62f0d9d0ba02..ae5bc1919e1c 100644 --- a/kernel/dma/direct.h +++ b/kernel/dma/direct.h @@ -87,16 +87,24 @@ 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) - return DMA_MAPPING_ERROR; + if (!(attrs & DMA_ATTR_CC_DECRYPTED)) { + if (attrs & DMA_ATTR_MMIO) + return DMA_MAPPING_ERROR; - return swiotlb_map(dev, phys, size, dir, attrs); + return swiotlb_map(dev, phys, size, dir, attrs); + } + } else if (attrs & DMA_ATTR_CC_DECRYPTED) { + return DMA_MAPPING_ERROR; } if (attrs & DMA_ATTR_MMIO) { dma_addr = phys; if (unlikely(!dma_capable(dev, dma_addr, size, false))) goto err_overflow; + } else if (attrs & DMA_ATTR_CC_DECRYPTED) { + dma_addr = phys_to_dma_unencrypted(dev, phys); + if (unlikely(!dma_capable(dev, dma_addr, size, false))) + goto err_overflow; } else { dma_addr = phys_to_dma(dev, phys); if (unlikely(!dma_capable(dev, dma_addr, size, true)) || -- 2.51.1