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PCI: Skip MPS logic for Virtual Functions (VFs) 

commit 3dbe97efe8 upstream.

PCIe r4.0, sec 9.3.5.4, "Device Control Register", shows both
Max_Payload_Size (MPS) and Max_Read_request_Size (MRRS) to be 'RsvdP' for
VFs.  Just prior to the table it states:

  "PF and VF functionality is defined in Section 7.5.3.4 except where
   noted in Table 9-16.  For VF fields marked 'RsvdP', the PF setting
   applies to the VF."

All of which implies that with respect to Max_Payload_Size Supported
(MPSS), MPS, and MRRS values, we should not be paying any attention to the
VF's fields, but rather only to the PF's.  Only looking at the PF's fields
also logically makes sense as it's the sole physical interface to the PCIe
bus.

Link: https://bugzilla.kernel.org/show_bug.cgi?id=200527
Fixes: 27d868b5e6 ("PCI: Set MPS to match upstream bridge")
Signed-off-by: Myron Stowe <myron.stowe@redhat.com>
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>
Cc: stable@vger.kernel.org # 4.3+
Cc: Keith Busch <keith.busch@intel.com>
Cc: Sinan Kaya <okaya@kernel.org>
Cc: Dongdong Liu <liudongdong3@huawei.com>
Cc: Jon Mason <jdmason@kudzu.us>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
pull/10/head
Myron Stowe 2018-08-13 12:19:39 -06:00 committed by Greg Kroah-Hartman
parent cf9c2bc5ee
commit 8af37982c3
1 changed files with 4 additions and 0 deletions
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4
drivers/pci/probe.c
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@ -1560,6 +1560,10 @@ static void pci_configure_mps(struct pci_dev *dev)
if (!pci_is_pcie(dev) || !bridge || !pci_is_pcie(bridge))
return;
/* MPS and MRRS fields are of type 'RsvdP' for VFs, short-circuit out */
if (dev->is_virtfn)
return;
mps = pcie_get_mps(dev);
p_mps = pcie_get_mps(bridge);