[PATCH v3 2/2] PCI: Disable VF's memory space on updating IOV BAR in pci_update_resource()

[Gavin Shan]

pci_update_resource() might be called to update (shift) IOV BARs
in PPC PowerNV specific pcibios_sriov_enable() when enabling PF's
SRIOV capability. At that point, the PF have been functional if
the SRIOV is enabled through sysfs entry "sriov_numvfs". The PF's
memory decoding (0x2 in PCI_COMMAND) shouldn't be disabled when
updating its IOV BARs with pci_update_resource(). Otherwise, we
receives EEH error caused by MMIO access to PF's memory BARs during
the window when PF's memory decoding is disabled.

   sriov_numvfs_store
   pdev->driver->sriov_configure
   mlx5_core_sriov_configure
   pci_enable_sriov
   sriov_enable
   pcibios_sriov_enable
   pnv_pci_sriov_enable
   pnv_pci_vf_resource_shift
   pci_update_resource

This disables VF's memory space instead of PF's memory decoding
when 64-bits IOV BARs are updated in pci_update_resource().

Reported-by: Carol Soto <cls...@us.ibm.com>
Suggested-by: Bjorn Helgaas <bhelg...@google.com>
Signed-off-by: Gavin Shan <gws...@linux.vnet.ibm.com>
Tested-by: Carol Soto <cls...@us.ibm.com>
---
 drivers/pci/setup-res.c | 28 ++++++++++++++++++++--------
 1 file changed, 20 insertions(+), 8 deletions(-)

diff --git a/drivers/pci/setup-res.c b/drivers/pci/setup-res.c
index 66c4d8f..1456896 100644
--- a/drivers/pci/setup-res.c
+++ b/drivers/pci/setup-res.c
@@ -29,10 +29,10 @@
 void pci_update_resource(struct pci_dev *dev, int resno)
 {
        struct pci_bus_region region;
-       bool disable;
-       u16 cmd;
+       bool disable = false;
+       u16 cmd, bit;
        u32 new, check, mask;
-       int reg;
+       int reg, cmd_reg;
        enum pci_bar_type type;
        struct resource *res = dev->resource + resno;
 
@@ -81,11 +81,23 @@ void pci_update_resource(struct pci_dev *dev, int resno)
         * disable decoding so that a half-updated BAR won't conflict
         * with another device.
         */
-       disable = (res->flags & IORESOURCE_MEM_64) && !dev->mmio_always_on;
+       if (res->flags & IORESOURCE_MEM_64) {
+               if (resno <= PCI_ROM_RESOURCE) {
+                       disable = !dev->mmio_always_on;
+                       cmd_reg = PCI_COMMAND;
+                       bit = PCI_COMMAND_MEMORY;
+               } else {
+#ifdef CONFIG_PCI_IOV
+                       disable = true;
+                       cmd_reg = dev->sriov->pos + PCI_SRIOV_CTRL;
+                       bit = PCI_SRIOV_CTRL_MSE;
+#endif
+               }
+       }
+
        if (disable) {
-               pci_read_config_word(dev, PCI_COMMAND, &cmd);
-               pci_write_config_word(dev, PCI_COMMAND,
-                                     cmd & ~PCI_COMMAND_MEMORY);
+               pci_read_config_word(dev, cmd_reg, &cmd);
+               pci_write_config_word(dev, cmd_reg, cmd & ~bit);
        }
 
        pci_write_config_dword(dev, reg, new);
@@ -107,7 +119,7 @@ void pci_update_resource(struct pci_dev *dev, int resno)
        }
 
        if (disable)
-               pci_write_config_word(dev, PCI_COMMAND, cmd);
+               pci_write_config_word(dev, cmd_reg, cmd);
 }
 
 int pci_claim_resource(struct pci_dev *dev, int resource)
-- 
2.1.0