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From: Logan Gunthorpe <logang@deltatee.com>
To: Bjorn Helgaas <helgaas@kernel.org>,
	"Kasireddy, Vivek" <vivek.kasireddy@intel.com>
Cc: "dri-devel@lists.freedesktop.org"
	<dri-devel@lists.freedesktop.org>,
	"intel-xe@lists.freedesktop.org" <intel-xe@lists.freedesktop.org>,
	Bjorn Helgaas <bhelgaas@google.com>,
	"linux-pci@vger.kernel.org" <linux-pci@vger.kernel.org>
Subject: Re: [PATCH v2 1/5] PCI/P2PDMA: Don't enforce ACS check for functions of same device
Date: Wed, 30 Oct 2024 15:20:02 -0600	[thread overview]
Message-ID: <7e146e2f-5d7c-4f28-b801-360795b4cae7@deltatee.com> (raw)
In-Reply-To: <20241030184641.GA1210322@bhelgaas>



On 2024-10-30 12:46, Bjorn Helgaas wrote:
> On Fri, Oct 25, 2024 at 06:57:37AM +0000, Kasireddy, Vivek wrote:
> In the PCIe world, I don't think a TLP can "loop back" to another
> function on the same device.

I'm not sure if the spec says anything that specifically denies this.
But it seems to me that it would be possible for a multifunction device
to handle a transfer to a neighbouring function internally and not
actually involve the PCIe fabric. This seems like something we'd want to
support if and when such a device were to be created.

Logan

  reply	other threads:[~2024-10-30 21:20 UTC|newest]

Thread overview: 24+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2024-10-21  5:21 [PATCH v2 0/5] drm/xe/sriov: Don't migrate dmabuf BO to System RAM while running in VM Vivek Kasireddy
2024-10-21  5:21 ` [PATCH v2 1/5] PCI/P2PDMA: Don't enforce ACS check for functions of same device Vivek Kasireddy
2024-10-22 15:16   ` Bjorn Helgaas
2024-10-22 21:15     ` Logan Gunthorpe
2024-10-24  5:50       ` Kasireddy, Vivek
2024-10-24 16:21         ` Logan Gunthorpe
2024-10-24 18:01           ` Bjorn Helgaas
2024-10-24  5:58     ` Kasireddy, Vivek
2024-10-24 17:59       ` Bjorn Helgaas
2024-10-25  6:57         ` Kasireddy, Vivek
2024-10-30 18:46           ` Bjorn Helgaas
2024-10-30 21:20             ` Logan Gunthorpe [this message]
2024-10-30 22:07               ` Bjorn Helgaas
2024-10-31  6:59                 ` Kasireddy, Vivek
2024-10-21  5:21 ` [PATCH v2 2/5] drm/xe/dmabuf: Don't migrate BO to System RAM while running in VF mode Vivek Kasireddy
2024-10-21  5:21 ` [PATCH v2 3/5] drm/xe/pf: Add a helper function to get a VF's backing object in LMEM Vivek Kasireddy
2024-10-21  5:21 ` [PATCH v2 4/5] drm/xe/bo: Create new dma_addr array for dmabuf BOs associated with VFs Vivek Kasireddy
2024-10-22 10:12   ` kernel test robot
2024-10-22 10:54   ` kernel test robot
2024-10-21  5:21 ` [PATCH v2 5/5] drm/xe/pt: Add an additional check for dmabuf BOs while updating PTEs Vivek Kasireddy
2024-10-22 12:58   ` kernel test robot
2024-10-21  5:52 ` ✓ CI.Patch_applied: success for drm/xe/sriov: Don't migrate dmabuf BO to System RAM while running in VM (rev2) Patchwork
2024-10-21  5:52 ` ✗ CI.checkpatch: warning " Patchwork
2024-10-21  5:52 ` ✗ CI.KUnit: failure " Patchwork

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