From mboxrd@z Thu Jan 1 00:00:00 1970 Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.remote-ip=100.103.45.18 ARC-Seal: i=1; d=subspace.kernel.org; s=arc20261015; a=rsa-sha256; cv=none; t=1794250133; b=Xy2bXFkR6Nq7AV0rJLPrpKrCzIOLa/01KsvgSt15A+pkSYkY6jBMhxDJlth+VSWABOdo ExHXUk37ItCO4J7zqqdzV4lDTRyOK3oqiuDv/P2+AijNqS1D0paXx2wW9hRJCrmyp2NaG cS5lvin2uqiYis84DPaqKJINDcmkjSEtZ7VQjznGaVUqcpjYpJO+MgNv48KiPNG44Tu9x PjvzcsiIPrtEAxJaquqw9XQhipG0sqnej6/j1+ijRBvInl+mKOuFGfZFU0sr5HTPD8Kp7 LmMtyMuEa02SxD9m920y7SgKQ/0hljIZuCbrS9LvlaWNtvk5X939p+LEN50gYAGyCTQ== ARC-Message-Signature: i=1; d=subspace.kernel.org; s=arc20261015; a=rsa-sha256; c=relaxed/relaxed; t=1794250133; h=Received:DKIM-Signature:Message-ID:From:Subject:Reply-To:To:Cc: In-Reply-To:References:Content-Type:Content-Transfer-Encoding:Date; bh=iTJg2YCjC51OJ3EPD4rFVoz/yZJ6J2PaGNMU8OYKbts=; b=VVImGcGGNTZNO7gwQJsCnO3ZO/SigVHrIv8Orn5pQENYNISuxLM7FSp7vgTI8Q4TUdlk Wbz594kRkaadOaXl8TCa08OZ7WeeXbOMjCWztIYRqqKFDplDf0oRoTLT2ShrC9GYsBIqZ vd07MPGFSEOK737/br6u2G75Ppb4LTWHw4GrHZ/kKOdxvO8Hfi9eEyXdoVHjmm8z6AIi+ Ad649hovXkDHAs9weizHpahPijOs1rcKL/1q55FwRcMXemcLeDNrmJyt9QxzjtLzIXDoJ iMFuMJUdlDk8jMeZ/VvsTVMS0DhKYdtd6BcmIydsmjfO59VjA2urfMUE9VedTzAuo9g== ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dkim=pass header.d=kernel.org header.i=@kernel.org header.a=rsa-sha256 header.s=k20260515 header.b=StBcI0sj; arc=none smtp.remote-ip=100.103.45.18 Received: from smtp.kernel.org (quasi.space.kernel.org [100.103.45.18]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature ECDSA (prime256v1)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 29BD9606A326 for ; Mon, 9 Nov 2026 18:48:52 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.a=rsa-sha256 header.s=k20260515 header.b=StBcI0sj Received: by smtp.kernel.org (Postfix) with ESMTPSA id 7CC551F0089F; Mon, 9 Nov 2026 18:48:52 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1794250132; bh=iTJg2YCjC51OJ3EPD4rFVoz/yZJ6J2PaGNMU8OYKbts=; h=From:Subject:Reply-To:To:Cc:In-Reply-To:References:Date; b=StBcI0sjFy0YCJGDWYGBqkfcwbkAfHLpKFOlXqyLzoHsHhUnRuk6FHX82m0gP9s/+ Al1Gy1adbseV8hjKAWJ28kOmGjaM2jy119nF1Dcotk3kr7YCQi/FW/9ST06hEO7OHT RDsxJQV4k/Z1zphurrU/Og6ac8xTYMsCx3s3UFDq7/WcLd4PJ59eT4x5wEO1Mm6u4O zrzsdZQkvCzfmO78VASqX1efmDw6Lh/tXI6ja/pNPswIW986MG5MsKNPfWgBuNSYgi 9G9wHJXXCBZ3+hjAxc4lImkwWb8LaDtrHxuo2+IX6aUAZegYPGONtVAN81ZWU2IedZ l5LEfoxUyWdIg== Message-ID: From: sashiko-bot@kernel.org Subject: Re: [PATCH] virtio_pci: limit Oracle DSC2-200 virtio-net to 48-bit DMA Reply-To: sashiko-reviews@lists.linux.dev To: "Vlad Poenaru" Cc: virtualization@lists.linux.dev, "Michael S. Tsirkin" , "Eugenio Perez" In-Reply-To: <20261109184253.531677-1-vlad.wing@gmail.com> References: <20261109184253.531677-1-vlad.wing@gmail.com> Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: quoted-printable Date: Mon, 09 Nov 2026 18:48:52 +0000 X-Mailing-List: virtualization@lists.linux.dev List-Id: List-Post: List-Help: List-Subscribe: List-Unsubscribe: List-Owner: Precedence: list > The virtio-net function of the AMD Pensando DSC2-200 (Elba) DPU, as > shipped by Oracle (1af4:1041, subsystem 108e:1200), cannot DMA to > arbitrary 64-bit bus addresses, and Oracle advises limiting it to 48 > bits. virtio_pci gives it a 64-bit mask, so its virtqueues stop > completing requests once the IOMMU starts handing it IOVAs above 2^48. > The card is used in OCI bare-metal shapes such as BM.Standard.E6.288. >=20 > On those AMD EPYC 9005 hosts the AMD IOMMU supports a 6-level v1 page > table (EFR[HATS] =3D 2), so the aperture spans all 64 bits and the IOVA > allocator, which works down from min(mask, aperture), returns addresses > just below 2^64: >=20 > - With iommu.forcedac=3D1, the first control virtqueue command never > completes and virtio_net hangs in probe. >=20 > [ ... ] >=20 > Cc: stable@vger.kernel.org # 6.5+ > Co-developed-by: Kyle McMartin > Signed-off-by: Kyle McMartin > Signed-off-by: Vlad Poenaru Sashiko has reviewed this patch and found no issues. --=20 Sashiko AI review =C2=B7 https://sashiko.dev/#/patchset/20261109184253.5316= 77-1-vlad.wing@gmail.com?part=3D1