From nobody Wed Apr 1 10:59:32 2026 Received: from mail-wm1-f73.google.com (mail-wm1-f73.google.com [209.85.128.73]) (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 CA542327C18 for ; Mon, 30 Mar 2026 14:51:25 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=209.85.128.73 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1774882287; cv=none; b=OQwKFvTVmbvtkz99ypo80XzHrrC7dMR9gmByZUyXMRPdt/PbXGKguPCyGkYyJHl+yp0naPltolx80SGeoVRoWMQhWFzAruczM1u4GAz3JJRs5vDRkhY0r1mC+JcG8fZQSep4EWkqwidE/AsSjmrb5UXaRYwlEvsE6NuBgNbBENU= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1774882287; c=relaxed/simple; bh=FXMPltbZcZ5fueDOME6tu6lHCg7hLrz8WRDK2s/pB8o=; h=Date:In-Reply-To:Mime-Version:References:Message-ID:Subject:From: To:Cc:Content-Type; b=NvLsOH6DunMPnzvUzVZLF6XYBFO84GDejYZJz7NOZc8iGh6FEH1/UiQ5pR1hAUNCH8vGhpwaYn7HacSzRPciQxkkojl8oXZmTUc4xers75WDs+7ju9xRx/PQax8XJWog8u1Wnr3p9yOQdubfoKExv2W4WhCHDrlqcuA/w2kKc9Q= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dmarc=pass (p=reject dis=none) header.from=google.com; spf=pass smtp.mailfrom=flex--smostafa.bounces.google.com; dkim=pass (2048-bit key) header.d=google.com header.i=@google.com header.b=FI5MJTWP; arc=none smtp.client-ip=209.85.128.73 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=reject dis=none) header.from=google.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=flex--smostafa.bounces.google.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=google.com header.i=@google.com header.b="FI5MJTWP" Received: by mail-wm1-f73.google.com with SMTP id 5b1f17b1804b1-48542d5aa9eso41527305e9.0 for ; Mon, 30 Mar 2026 07:51:25 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20251104; t=1774882284; x=1775487084; darn=vger.kernel.org; h=cc:to:from:subject:message-id:references:mime-version:in-reply-to :date:from:to:cc:subject:date:message-id:reply-to; bh=J65BpbTDZfVi4pM0t9Ln1+SAYufEj40Do3q1lK1k0LY=; b=FI5MJTWPRFJ6yZws+SUsOTVYt27wYF5WWAHFMD9xyz2IiWV/Y4AIamUEVHw34vwB5o b7AdsMPr9nGC3JPbINtklHB+mpIbRDipUSU7qOexSZBhgzHOORtlHCaqWNsBxekLaE+j uLHyqQPacc1yUfArjB3Ky8OorYf5N46SuG1dMBJNyzDaGcO40/QKfMGuBUjNZywIKwVD u0lGVsgr3NNqtrdYg+I/Wp6ExidgsY4nWuXJmWqgsuIPRdmLo3aopwJtVrb0o1DSW/tZ Vb1K05vGmPrni5W4wm3oBWPnif2f4mzlKZ1oddw4v3dwok8Z/DXq/xsWtHKUPxIvi7KN AEzw== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20251104; t=1774882284; x=1775487084; h=cc:to:from:subject:message-id:references:mime-version:in-reply-to :date:x-gm-message-state:from:to:cc:subject:date:message-id:reply-to; bh=J65BpbTDZfVi4pM0t9Ln1+SAYufEj40Do3q1lK1k0LY=; b=Z5YqnUajkRJgW5muFkGZc5UPK13Df2+GaDbAdueWK/gJ/i0lIYCUFF4JH2c76Rp0YY SFA2g9VpQCuNkE8qjg6Ug5/0ASeAQ6Z1OB7a6NL/pNL/b2BONFBsssb4dzNheIpRg58Y UvK+7JJ6cxN+z1Ngbcylj1rfWTxhDWa4/dwE81YVNKtvD7ZPE9pavyUhtF3hAW/LwhGm DtBXr4lIkpIYhx3Ahn7+inu2Cg+LCmq32ioTxtr+j2bSsHhJojKTB3Ah/ZI8VtIVuwe7 yCxw7dvfxT/T2pMT2nRmUZTjurtA6aX6TJclUnMNzeBTFeqtxINEvxXnHy+zjXxub0z0 JikQ== X-Forwarded-Encrypted: i=1; AJvYcCVU82bIJrLTmfHRI851mgqxM35/bU1T25mj2LAuhwd7KZYyyevcoAAtIpKFhexNqybFwEv3BAn9OThtVvc=@vger.kernel.org X-Gm-Message-State: AOJu0Yy6YHR2CtXGua3idjSWWcXMEN/OiWAGEJUIUr3m4uBX+Y6/C34t DiV2DdUR7P5GSUOi+6aIFO+ywAIBnpaLuT5tX6Nl/uAJ5NR+pD+mqJ5O01H+vOI5fu7ESX3lKnC drzeXTLA23NkynQ== X-Received: from wmpd21.prod.google.com ([2002:a05:600c:4c15:b0:485:3890:399c]) (user=smostafa job=prod-delivery.src-stubby-dispatcher) by 2002:a05:600c:1d1e:b0:486:fe46:b647 with SMTP id 5b1f17b1804b1-48727f00d8fmr210293035e9.10.1774882283962; Mon, 30 Mar 2026 07:51:23 -0700 (PDT) Date: Mon, 30 Mar 2026 14:50:39 +0000 In-Reply-To: <20260330145043.1586623-1-smostafa@google.com> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: Mime-Version: 1.0 References: <20260330145043.1586623-1-smostafa@google.com> X-Mailer: git-send-email 2.53.0.1185.g05d4b7b318-goog Message-ID: <20260330145043.1586623-2-smostafa@google.com> Subject: [RFC PATCH v2 1/5] dma-mapping: Avoid double decrypting with DMA_RESTRICTED_POOL From: Mostafa Saleh To: iommu@lists.linux.dev, linux-kernel@vger.kernel.org Cc: robin.murphy@arm.com, m.szyprowski@samsung.com, will@kernel.org, maz@kernel.org, suzuki.poulose@arm.com, catalin.marinas@arm.com, jiri@resnulli.us, jgg@ziepe.ca, aneesh.kumar@kernel.org, Mostafa Saleh Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset="utf-8" In case a device have a restricted DMA pool, it will be decrypted by default. However, in the path of dma_direct_alloc() memory can be allocated from this pool using, __dma_direct_alloc_pages() =3D> dma_direct_alloc_swiotlb() After that from the same function, it will attempt to decrypt it using dma_set_decrypted() if force_dma_unencrypted(). Which results in the memory being decrypted twice. It's not clear how the does realm world/hypervisors deal with that, for example: - CCA: Clear a bit in the page table and call realm IPA_STATE_SET. - TDX: Issue a hypercall. - pKVM: Which doesn't implement force_dma_unencrypted() at the moment, uses a share hypercall. Change that to only encrypt/decrypt memory that are not allocated from the restricted dma pools. Fixes: f4111e39a52a ("swiotlb: Add restricted DMA alloc/free support") Signed-off-by: Mostafa Saleh --- kernel/dma/direct.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) diff --git a/kernel/dma/direct.c b/kernel/dma/direct.c index 8f43a930716d..27d804f0473f 100644 --- a/kernel/dma/direct.c +++ b/kernel/dma/direct.c @@ -79,7 +79,7 @@ bool dma_coherent_ok(struct device *dev, phys_addr_t phys= , size_t size) =20 static int dma_set_decrypted(struct device *dev, void *vaddr, size_t size) { - if (!force_dma_unencrypted(dev)) + if (!force_dma_unencrypted(dev) || is_swiotlb_for_alloc(dev)) return 0; return set_memory_decrypted((unsigned long)vaddr, PFN_UP(size)); } @@ -88,7 +88,7 @@ static int dma_set_encrypted(struct device *dev, void *va= ddr, size_t size) { int ret; =20 - if (!force_dma_unencrypted(dev)) + if (!force_dma_unencrypted(dev) || is_swiotlb_for_alloc(dev)) return 0; ret =3D set_memory_encrypted((unsigned long)vaddr, PFN_UP(size)); if (ret) --=20 2.53.0.1185.g05d4b7b318-goog