From 3dbe97efe8bf450b183d6dee2305cbc032e6b8a4 Mon Sep 17 00:00:00 2001
From: Myron Stowe <myron.stowe@redhat.com>
Date: Mon, 13 Aug 2018 12:19:39 -0600
Subject: [PATCH] PCI: Skip MPS logic for Virtual Functions (VFs)
Git-commit: 3dbe97efe8bf450b183d6dee2305cbc032e6b8a4
Patch-mainline: v4.19-rc1
References: bsc#1051510
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: 27d868b5e6cf ("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>
Acked-by: Takashi Iwai <tiwai@suse.de>
---
drivers/pci/probe.c | 4 ++++
1 file changed, 4 insertions(+)
diff --git a/drivers/pci/probe.c b/drivers/pci/probe.c
index 71412db3cbeb..c2533ed45fff 100644
--- a/drivers/pci/probe.c
+++ b/drivers/pci/probe.c
@@ -1730,6 +1730,10 @@ 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);
--
2.18.0