From mboxrd@z Thu Jan 1 00:00:00 1970 Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.remote-ip=209.85.216.44 ARC-Seal: i=1; d=subspace.kernel.org; s=arc20261015; a=rsa-sha256; cv=none; t=1794520027; b=M1n6ZGQd+QQ9a5lDhZThUhI14M509rDmvMXHWDv5P716ZgSi4d74Zn2Axpv1Jy3mWtO3 2DTVn8cYxMCFouPcvwfk4zKzwaQ4P3b0FdHtH4DhwtVgvjdUFNb/6Vp/P0qIDRvc4CjWm YG3Je8zndy2GMmbvrhMQ1sDeYE5Si0+6NQ6TOe6R+O9MBcNuLKsxXNVgHN2UeBoivJk7T iHnMh5vYPs9u2R5bvQneYSMIjddpGF59wlzFZbojN+2wCpqyQP+cPG77rKojoW3inU3Fg oi0nhxRY/xSehwzmFY/eNVLjknDb0F/PtBWi7QN7jVmcd0ZhoGqdA8ujsD2xD8BCANw== ARC-Message-Signature: i=1; d=subspace.kernel.org; s=arc20261015; a=rsa-sha256; c=relaxed/relaxed; t=1794520027; h=DMARC-Filter:Received:DKIM-Signature:X-Google-DKIM-Signature: X-Forwarded-Encrypted:X-Gm-Message-State:X-Gm-Gg:X-Received:Received: Mime-Version:Content-Transfer-Encoding:Content-Type:Date:Message-Id: Cc:Subject:From:To:X-Mailer:References:In-Reply-To; bh=MRvrBEIopDqvuVb/vZ72s+DUNbn5hAJVvZTwAj02wNI=; b=KjoObWxQB81aWlhL1HUARcF8T1l85+kmIKk0NzNs+vIsMQw+/sCuW8HDKtdMhR+h/7ue PIjqO7Ikez8KsG8VgwdJUcMwa3ozM0zQ7qAb5wS0fWyqpN/t9PEwsT1D+eN05S8Bev+cg XCTUjUTjPRRVCQyRJ2c/DmZa59t+KhWzySUDZfYx4uVpZ/vVEGIyQB7UYCByNCntsgM6V 4kOOZFWTozHIrrF4963N9heuQNTcnhlKtM0hbiDF478+hUIGYcKjbWboI9VTAI8JyrLez ahnYy0k0Q3SPvfYPD9cbXhr9c127DwKbp9wk4q0uBb0C9F7GsK9wCRZQjOJL5UTwOmg== ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dmarc=pass header.from=google.com; spf=pass smtp.mailfrom=google.com; dkim=pass header.d=google.com header.i=@google.com header.a=rsa-sha256 header.s=20260707 header.b=IqQicUBc; arc=none smtp.remote-ip=209.85.216.44 Received: from mail-pj1-f44.google.com (mail-pj1-f44.google.com [209.85.216.44]) (using TLSv1.3 with cipher TLS_AES_128_GCM_SHA256 (128/128 bits) key-exchange X25519 server-signature ECDSA (prime256v1) server-digest SHA256) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id D4D33606A32E for ; Thu, 12 Nov 2026 21:47:06 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.4.2 smtp.subspace.kernel.org D4D33606A32E 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=google.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=google.com header.i=@google.com header.a=rsa-sha256 header.s=20260707 header.b=IqQicUBc Received: by mail-pj1-f44.google.com with SMTP id 98e67ed59e1d1-3b0e0e65adbso115406a91.3 for ; Thu, 12 Nov 2026 13:47:06 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20260707; t=1794520026; x=1795124826; darn=vger.kernel.org; h=in-reply-to:references:to:from:subject:cc:message-id:date :content-type:content-transfer-encoding:mime-version:from:to:cc :subject:date:message-id:reply-to:content-type; bh=MRvrBEIopDqvuVb/vZ72s+DUNbn5hAJVvZTwAj02wNI=; b=IqQicUBcHFfASsPeC/FaWkK7/Crm2L2UYyn8/PxIFh5d3NQfwGTsj1ea0yYEQ647ZV /ccaegp04k9hdkyY2Ail6N4rBeUM3LACMz8nX+7douczOTVskMzZJ6rF5iaIrVQm2heW JeAJJRZGwbkWIX4oCdCOf9PAKsBXWkvG0Qf/0hEZ5qTZmjRSXZseI6akOjoL+PPSYmfs n/o355gYSqEM305OphinxwQkhxOcncDRdESkE1XHs1UYEEh7UGYPCzuqJ/L28TVUC0U6 aJlfLAOYc0LEA5khjKc7nJefwozvr0lPgi0RdEjsCmQOzXego5h4dYanuiOcrof8EvZv aU7A== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20260707; t=1794520026; x=1795124826; h=in-reply-to:references:to:from:subject:cc:message-id:date :content-type:content-transfer-encoding:mime-version:x-gm-gg :x-gm-message-state:from:to:cc:subject:date:message-id:reply-to :content-type; bh=MRvrBEIopDqvuVb/vZ72s+DUNbn5hAJVvZTwAj02wNI=; b=rNLsEJHuX+1heEOuG8hZc3vLU1lHkxwl8GUgSRCAMMRBhdnXDmdAsTFxfnkqvBotiQ WZgcwp2vOSncpzXJ3ivloX2yV7Q1kpEB4iC9nZXkBsktB20zVplsjfoQ1yFlfn5u/TSD 5F24MDTDXhrLx5UatB9mnxMNhKzucsKvBbODw5z9jtLIFDuGpcDeJ75aJu6pr03kppvS 0103ZYm7n9GVsqGQE5IkFDO2qdnsgR/ALOjysxoAYVFUYVsdhA3O+RnKdauQK+FpS6WX 6XbvH5kTP9v647gpnjjgllcNrEFSFPglD0fGUefuDI8Xt3/ohye8LgY0MKuSnO01Mlqm EPZA== X-Forwarded-Encrypted: i=1; AL+hErE/DsmYpO3bTXBmB8v9dZXXNMoT/gLT2tHNbIC0uYnq/G+m/ansomq5j/OInIs4LcqnM/fyOHj9pB4=@vger.kernel.org X-Gm-Message-State: APuU4Z+J/L5Ehou3HdaFz7WNWeTqlR4fEFMhJwliud5umWxh5W7+hFhi WYTbU07iu/zWhq1IwdxABLp8AIrGOIp4whxrv1UNwD6YGZMp5l0rlrAlbO6CJRcN8A== X-Gm-Gg: AYBFou042irFYRgFgtXKwuKqhkYA9Ocvogw24qxI19pq9PlaUt+/DnDSMx/auvClRRc hdA+IHAGK6PcbqHImEOjmCedjWhZACEjjlXmk+TexPppy/wSmpldlN6BnN6OrpM3Zd+glxYWFic yNPRMPEUEqWrsyQPOVHnccuAuqf6aUrqoYSHdsU+ffieGGbUwj1OZ5iywf231QEL904kpzPZIkW Z90y5vGvoviqLvEgLPaShnPteRbaCU0XwDrtpn5GtLRlxu9ZP1EOmlxaDxtF/zpuEGBiDwHCXJ8 huEp9lpwDr5xzxfr0i3G0WBKCyyhqwY1BHRZAuFIKPMJLBBY/IGwdg+lJs3InlxM56YWuUzcAun x3bKjlWtogGUkRr8Sy7oYxHB1GWFuX5Z30gybWj8b5gL3dOLykf9562/T5q73CJoXQ0OCIIZ8Y+ Dhyx3B5TXD9tNN37Zj8WDjkn55vi7uGBRy3TlCfo8lGp3DJdS5GrLi9pF+hCgEe9jmhlk4wqCSM goxCn9sZnvehpw4TiEUi/MrUVFk2ceGPmj4tcTX0H+TWxrkRqS6Hpjeq9w4WhdftKA41TZNibmp gfQ2dRdpmMLHh3hgTpkGIG3Ql3AX8tkGAQTwNVQsFC+46yh+mT1fI2PdiLXSxfpyCpmvtCqlNVk VAlDtIxHyew== X-Received: by 2002:a17:90b:30e:b0:3b0:97b8:d6bc with SMTP id 98e67ed59e1d1-3b1b0a0e889mr278699a91.16.1794520025137; Thu, 12 Nov 2026 13:47:05 -0800 (PST) Received: from localhost (33.79.127.34.bc.googleusercontent.com. [34.127.79.33]) by smtp.gmail.com with ESMTPSA id 98e67ed59e1d1-3b197d257a0sm6493095a91.11.2026.11.12.13.47.03 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Thu, 12 Nov 2026 13:47:04 -0800 (PST) X-Mailing-List: linux-pci@vger.kernel.org List-Id: List-Post: List-Help: List-Subscribe: List-Unsubscribe: List-Owner: Precedence: list Mime-Version: 1.0 Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset=UTF-8 Date: Thu, 12 Nov 2026 13:47:03 -0800 Message-Id: Cc: , , , , , , , , "Alex Williamson" , "Bjorn Helgaas" , =?utf-8?q?Christian_K=C3=B6nig?= , "Jason Gunthorpe" , "Josh Hilke" , "Kevin Tian" , "Leon Romanovsky" , "Logan Gunthorpe" , "Matt Evans" , "Matt Evans" , "Mina Almasry" , "Samiullah Khawaja" , "Shuah Khan" , "Sumit Semwal" , "Vipin Sharma" Subject: Re: [RFC PATCH 0/7] vfio: selftests: Add peer-to-peer DMA selftest From: "David Matlack" To: "Alex Mastro" , "David Matlack" X-Mailer: aerc 0.21.0 References: <20261111192411.4133780-1-dmatlack@google.com> In-Reply-To: On Thu Nov 12, 2026 at 12:35 PM PST, Alex Mastro wrote: > Hey David, > > On Wed, Nov 11, 2026 at 07:24:04PM +0000, David Matlack wrote: > =20 >> Is requiring userspace to re-issue IOMMU_IOAS_MAP_FILE the expected >> uAPI behavior? VFIO_DEVICE_RESET (and runtime PM transitions) on the >> target device also bracket the reset with >> vfio_pci_dma_buf_move(vdev, true) and vfio_pci_dma_buf_move(vdev, >> false), tearing down any active IOMMU_IOAS_MAP_FILE mapping of that >> device's BAR even though PCI_COMMAND_MEMORY remains enabled when >> VFIO_DEVICE_RESET returns. > > There was some discussion about this in the thread below. My understandin= g of > Jason's point is that the current behavior, and differences between what > revoking and move-capable importers see in regards to vfio-exported dma-b= uf is > somewhat incidental and not necessarily desirable. Thanks, I will read through that thread. It seemed like a surprising uAPI. > > https://lore.kernel.org/all/arMBqyI4XNfD+q1W@devgpu015.cco6.facebook.com/ > >> - Physical target devices and P2P topology checks: mem_bar_descs[] >> currently only matches QEMU's pci-testdev, and >> vfio_pci_has_p2p_path() does not yet check PCI topology or ACS to >> verify that P2P traffic can flow between two physical endpoints. >>=20 >> Suggestions on physical target BARs to add to mem_bar_descs[] and on >> checking P2P reachability from userspace are welcome. > > FWIW, you can also exercise the "P2P" path with just a single device if y= ou > IOMMU map a device's BAR into it's own IOAS, and have the device DMA itse= lf. For > eventually validating aspects of Live Update, maybe you don't necessarily= care > if an actual peer device is being DMA'd? The way I designed the P2P selftest support requires 2 things: (A) initiator: A device that has a VFIO selftests driver. (B) target: A device that can provide a memory BAR (vfio_pci_find_mem_bar(= )). So far I haven't found a single device that can do both. But you are right that theoretically a single device could satisfy both requirements. I can relax vfio_pci_has_p2p_path() to allow initiator =3D=3D target.