提交 3dbe97ef 编写于 作者: M Myron Stowe 提交者: Bjorn Helgaas

PCI: Skip MPS logic for Virtual Functions (VFs)

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: 27d868b5 ("PCI: Set MPS to match upstream bridge")
Signed-off-by: NMyron Stowe <myron.stowe@redhat.com>
Signed-off-by: NBjorn 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>
上级 2d1ce5ec
...@@ -1730,6 +1730,10 @@ static void pci_configure_mps(struct pci_dev *dev) ...@@ -1730,6 +1730,10 @@ static void pci_configure_mps(struct pci_dev *dev)
if (!pci_is_pcie(dev) || !bridge || !pci_is_pcie(bridge)) if (!pci_is_pcie(dev) || !bridge || !pci_is_pcie(bridge))
return; return;
/* MPS and MRRS fields are of type 'RsvdP' for VFs, short-circuit out */
if (dev->is_virtfn)
return;
mps = pcie_get_mps(dev); mps = pcie_get_mps(dev);
p_mps = pcie_get_mps(bridge); p_mps = pcie_get_mps(bridge);
......
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