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[34.124.168.21]) by smtp.gmail.com with ESMTPSA id a92af1059eb24-13e72745b1bsm22459117c88.14.2026.07.30.12.37.20 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Thu, 30 Jul 2026 12:37:24 -0700 (PDT) Date: Thu, 30 Jul 2026 19:37:16 +0000 From: Pranjal Shrivastava To: Matt Evans Cc: Alex Williamson , Leon Romanovsky , Jason Gunthorpe , Alex Mastro , Christian =?iso-8859-1?Q?K=F6nig?= , Bjorn Helgaas , Logan Gunthorpe , Kevin Tian , Longfang Liu , Mahmoud Adam , David Matlack , =?iso-8859-1?Q?Bj=F6rn_T=F6pel?= , Sumit Semwal , Ankit Agrawal , Alistair Popple , Vivek Kasireddy , linux-kernel@vger.kernel.org, linux-media@vger.kernel.org, dri-devel@lists.freedesktop.org, linaro-mm-sig@lists.linaro.org, kvm@vger.kernel.org, linux-pci@vger.kernel.org Subject: Re: [PATCH v5 2/9] PCI/P2PDMA: Add CONFIG_PCI_P2PDMA_CORE Message-ID: References: <20260715174737.15287-1-matt@ozlabs.org> <20260715174737.15287-3-matt@ozlabs.org> 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=us-ascii Content-Disposition: inline In-Reply-To: <20260715174737.15287-3-matt@ozlabs.org> On Wed, Jul 15, 2026 at 06:47:25PM +0100, Matt Evans wrote: > The P2PDMA code currently provides two features under the same > CONFIG_PCI_P2PDMA option: > > 1. Locate providers via pcim_p2pdma_provider() > 2. Manage actual P2P DMA > > Some drivers (such as vfio-pci) depend on (1), without having a hard > dependency on (2). > > A future vfio-pci commit will rely on pcim_p2pdma_provider() always > being present. If that depended on CONFIG_PCI_P2PDMA, it would make > vfio-pci only available if CONFIG_ZONE_DEVICE is present (e.g. 64-bit > systems), even when P2P is not needed. > > To resolve this, introduce CONFIG_PCI_P2PDMA_CORE and refactor the > basic provider functionality into a new p2pdma_core.c file. This is > available even if the CONFIG_PCI_P2PDMA feature is disabled (or > unavailable due to !CONFIG_ZONE_DEVICE), satisfying (1). > > Then, when the original CONFIG_PCI_P2PDMA is set, drivers have access > to the additional P2P features of (2). This still depends on > CONFIG_ZONE_DEVICE. > > Signed-off-by: Matt Evans > Acked-by: Bjorn Helgaas > Reviewed-by: Logan Gunthorpe Reviewed-by: Pranjal Shrivastava Thanks, Praan