release/4.8.23/PCI-Don-t-update-VF-BARs-while-VF-memory-space-is-en.patch

From edbc201bd2bd85e1b4e8ab217e60bc0b5c7da0e9 Mon Sep 17 00:00:00 2001
From: Bjorn Helgaas <bhelgaas@google.com>
Date: Mon, 28 Nov 2016 16:43:06 -0600
Subject: [PATCH] PCI: Don't update VF BARs while VF memory space is enabled

commit 546ba9f8f22f71b0202b6ba8967be5cc6dae4e21 upstream.

If we update a VF BAR while it's enabled, there are two potential problems:

  1) Any driver that's using the VF has a cached BAR value that is stale
     after the update, and

  2) We can't update 64-bit BARs atomically, so the intermediate state
     (new lower dword with old upper dword) may conflict with another
     device, and an access by a driver unrelated to the VF may cause a bus
     error.

Warn about attempts to update VF BARs while they are enabled.  This is a
programming error, so use dev_WARN() to get a backtrace.

Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>
Reviewed-by: Gavin Shan <gwshan@linux.vnet.ibm.com>
Signed-off-by: Paul Gortmaker <paul.gortmaker@windriver.com>

diff --git a/drivers/pci/iov.c b/drivers/pci/iov.c
index f591b8fb029b..cd924b9b874d 100644
--- a/drivers/pci/iov.c
+++ b/drivers/pci/iov.c
@@ -563,6 +563,7 @@ void pci_iov_update_resource(struct pci_dev *dev, int resno)
 	struct resource *res = dev->resource + resno;
 	int vf_bar = resno - PCI_IOV_RESOURCES;
 	struct pci_bus_region region;
+	u16 cmd;
 	u32 new;
 	int reg;
 
@@ -574,6 +575,13 @@ void pci_iov_update_resource(struct pci_dev *dev, int resno)
 	if (!iov)
 		return;
 
+	pci_read_config_word(dev, iov->pos + PCI_SRIOV_CTRL, &cmd);
+	if ((cmd & PCI_SRIOV_CTRL_VFE) && (cmd & PCI_SRIOV_CTRL_MSE)) {
+		dev_WARN(&dev->dev, "can't update enabled VF BAR%d %pR\n",
+			 vf_bar, res);
+		return;
+	}
+
 	/*
 	 * Ignore unimplemented BARs, unused resource slots for 64-bit
 	 * BARs, and non-movable resources, e.g., those described via
-- 
2.12.0