From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from bombadil.infradead.org (bombadil.infradead.org [198.137.202.133]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 27AB84204E for ; Tue, 23 Sep 2025 13:36:33 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=198.137.202.133 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1758634596; cv=none; b=kUEujavi7q9yHUAFhU+CJE7tOwR6i6Vpxuu1g8cyrv3xnp7TRZko7QgSFNAp25lMR+ZmF+ef0ggZC9tJau3+WgEL5jBbYUd7pumV7mN4YQDPRYJtfobPwItFhbNRbqoeHDPfUajCoj5tF2FqKoZsXCL9A2SriIccrn3Bsqzxgwc= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1758634596; c=relaxed/simple; bh=dvkBTMzAkRPtHEpwyjfjXXHumnpLiEFSH2/WjNbkDGI=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=L7rXj2lRb+VGElESUa/eomTcgad8y5XG9ujSWjP2jeunIaSr7/DSbd7FMUWKwJlVl+furLehb58Z+KaLTH8KFzbnNhvoUM3eXb0XDr9lfbPokxA0aI7flRtVmc+yBwxwA2LcrWKGq1r/Bd8pKU+YQh5novK2WtlYjdvXS6+M/M4= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=none (p=none dis=none) header.from=infradead.org; spf=none smtp.mailfrom=bombadil.srs.infradead.org; dkim=pass (2048-bit key) header.d=infradead.org header.i=@infradead.org header.b=3H1ZCxjj; arc=none smtp.client-ip=198.137.202.133 Authentication-Results: smtp.subspace.kernel.org; dmarc=none (p=none dis=none) header.from=infradead.org Authentication-Results: smtp.subspace.kernel.org; spf=none smtp.mailfrom=bombadil.srs.infradead.org Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=infradead.org header.i=@infradead.org header.b="3H1ZCxjj" DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=infradead.org; s=bombadil.20210309; h=In-Reply-To:Content-Transfer-Encoding :Content-Type:MIME-Version:References:Message-ID:Subject:Cc:To:From:Date: Sender:Reply-To:Content-ID:Content-Description; bh=qit3OXxpZh2ogtg5RstC5cs1VSqpbAxG4rhPfkTl5lc=; b=3H1ZCxjjBOdKNRVAfEFtmda4XE r6k9RE3NhaDKZGRQYCcecwPguTadehXBN5HoI5W5ztvjEoy3NIfXmJJf1EGXze48EbdYnG5Htn2Jy yQhGjPozo/FBt0U86G1DZtZb3EnjQY+iS/kbB0WsmkJley70/cjDqE+aHbU2r4rm35g3lOOzya38m oDyYAgnCSj0ih+4mTdDcFE539cgrvFnAYK7OrsUCnAmtBTapEfwY/u5MbLht+UItnDDD2hOiIKFp9 VhS/dpdN3r39gCtXzTwseCjAv6IfMu+0rEZNC6BcFfGqyyl/1K/y/rj2f7LhAV6DwYAyuFw/fXYdQ LZYwwGCA==; Received: from hch by bombadil.infradead.org with local (Exim 4.98.2 #2 (Red Hat Linux)) id 1v13C1-0000000DX9j-3ykz; Tue, 23 Sep 2025 13:36:29 +0000 Date: Tue, 23 Sep 2025 06:36:29 -0700 From: Christoph Hellwig To: Christian =?iso-8859-1?Q?K=F6nig?= Cc: Jason Gunthorpe , Matthew Brost , "Kasireddy, Vivek" , Simona Vetter , "dri-devel@lists.freedesktop.org" , "intel-xe@lists.freedesktop.org" , Bjorn Helgaas , Logan Gunthorpe , "linux-pci@vger.kernel.org" , Thomas =?iso-8859-1?Q?Hellstr=F6m?= Subject: Re: [PATCH v4 1/5] PCI/P2PDMA: Don't enforce ACS check for device functions of Intel GPUs Message-ID: References: <20250919122931.GR1391379@nvidia.com> <045c6892-9b15-4f31-aa6a-1f45528500f1@amd.com> <20250922122018.GU1391379@nvidia.com> <80d2d0d1-db44-4f0a-8481-c81058d47196@amd.com> <20250923121528.GH1391379@nvidia.com> <522d3d83-78b5-4682-bb02-d2ae2468d30a@amd.com> Precedence: bulk X-Mailing-List: linux-pci@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=iso-8859-1 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: <522d3d83-78b5-4682-bb02-d2ae2468d30a@amd.com> X-SRS-Rewrite: SMTP reverse-path rewritten from by bombadil.infradead.org. See http://www.infradead.org/rpr.html On Tue, Sep 23, 2025 at 02:45:10PM +0200, Christian König wrote: > On 23.09.25 14:15, Jason Gunthorpe wrote: > > On Tue, Sep 23, 2025 at 09:52:04AM +0200, Christian König wrote: > >> For example the ISP driver part of amdgpu provides the V4L2 > >> interface and when we interchange a DMA-buf with it we recognize that > >> it is actually the same device we work with. > > > > One of the issues here is the mis-use of dma_map_resource() to create > > dma_addr_t for PCI devices. This was never correct. > > That is not a mis-use at all but rather exactly what dma_map_resource() was created for. It isn't. dma_map_resource was not created for PCIe P2P, and does not work for the general case of PCIe P2P including offsets and switches. Using it always was a big, and the drm driver maitaintainers were constanty reminded of that and chose to ignore it with passion.