[PATCH v2 2/2] PCI: Don't disable PF's memory decoding when enabling SRIOV

[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 doesn't change the PF's memory decoding in the path by introducing
additional parameter (@mmio_force_on) to pci_update_resource() in
the above path.

Reported-by: Carol Soto <clsoto at us.ibm.com>
Signed-off-by: Gavin Shan <gwshan at linux.vnet.ibm.com>
Tested-by: Carol Soto <clsoto at us.ibm.com>
---
 arch/powerpc/platforms/powernv/pci-ioda.c | 2 +-
 drivers/pci/iov.c                         | 2 +-
 drivers/pci/pci.c                         | 2 +-
 drivers/pci/setup-res.c                   | 9 +++++----
 include/linux/pci.h                       | 2 +-
 5 files changed, 9 insertions(+), 8 deletions(-)

diff --git a/arch/powerpc/platforms/powernv/pci-ioda.c b/arch/powerpc/platforms/powernv/pci-ioda.c
index 38a5c65..f4ccc5b 100644
--- a/arch/powerpc/platforms/powernv/pci-ioda.c
+++ b/arch/powerpc/platforms/powernv/pci-ioda.c
@@ -1006,7 +1006,7 @@ static int pnv_pci_vf_resource_shift(struct pci_dev *dev, int offset)
 		dev_info(&dev->dev, "VF BAR%d: %pR shifted to %pR (%sabling %d VFs shifted by %d)\n",
 			 i, &res2, res, (offset > 0) ? "En" : "Dis",
 			 num_vfs, offset);
-		pci_update_resource(dev, i + PCI_IOV_RESOURCES);
+		pci_update_resource(dev, i + PCI_IOV_RESOURCES, true);
 	}
 	return 0;
 }
diff --git a/drivers/pci/iov.c b/drivers/pci/iov.c
index f1343f0..db31966 100644
--- a/drivers/pci/iov.c
+++ b/drivers/pci/iov.c
@@ -511,7 +511,7 @@ static void sriov_restore_state(struct pci_dev *dev)
 		return;
 
 	for (i = PCI_IOV_RESOURCES; i <= PCI_IOV_RESOURCE_END; i++)
-		pci_update_resource(dev, i);
+		pci_update_resource(dev, i, false);
 
 	pci_write_config_dword(dev, iov->pos + PCI_SRIOV_SYS_PGSIZE, iov->pgsz);
 	pci_iov_set_numvfs(dev, iov->num_VFs);
diff --git a/drivers/pci/pci.c b/drivers/pci/pci.c
index aab9d51..87a33c0 100644
--- a/drivers/pci/pci.c
+++ b/drivers/pci/pci.c
@@ -545,7 +545,7 @@ static void pci_restore_bars(struct pci_dev *dev)
 		return;
 
 	for (i = 0; i < PCI_BRIDGE_RESOURCES; i++)
-		pci_update_resource(dev, i);
+		pci_update_resource(dev, i, false);
 }
 
 static const struct pci_platform_pm_ops *pci_platform_pm;
diff --git a/drivers/pci/setup-res.c b/drivers/pci/setup-res.c
index 66c4d8f..e8a50ff 100644
--- a/drivers/pci/setup-res.c
+++ b/drivers/pci/setup-res.c
@@ -26,7 +26,7 @@
 #include "pci.h"
 
 
-void pci_update_resource(struct pci_dev *dev, int resno)
+void pci_update_resource(struct pci_dev *dev, int resno, bool mmio_force_on)
 {
 	struct pci_bus_region region;
 	bool disable;
@@ -81,7 +81,8 @@ 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;
+	disable = (res->flags & IORESOURCE_MEM_64) &&
+		  !mmio_force_on && !dev->mmio_always_on;
 	if (disable) {
 		pci_read_config_word(dev, PCI_COMMAND, &cmd);
 		pci_write_config_word(dev, PCI_COMMAND,
@@ -310,7 +311,7 @@ int pci_assign_resource(struct pci_dev *dev, int resno)
 	res->flags &= ~IORESOURCE_STARTALIGN;
 	dev_info(&dev->dev, "BAR %d: assigned %pR\n", resno, res);
 	if (resno < PCI_BRIDGE_RESOURCES)
-		pci_update_resource(dev, resno);
+		pci_update_resource(dev, resno, false);
 
 	return 0;
 }
@@ -350,7 +351,7 @@ int pci_reassign_resource(struct pci_dev *dev, int resno, resource_size_t addsiz
 	dev_info(&dev->dev, "BAR %d: reassigned %pR (expanded by %#llx)\n",
 		 resno, res, (unsigned long long) addsize);
 	if (resno < PCI_BRIDGE_RESOURCES)
-		pci_update_resource(dev, resno);
+		pci_update_resource(dev, resno, false);
 
 	return 0;
 }
diff --git a/include/linux/pci.h b/include/linux/pci.h
index 0ab8359..99231d1 100644
--- a/include/linux/pci.h
+++ b/include/linux/pci.h
@@ -1039,7 +1039,7 @@ int pci_try_reset_bus(struct pci_bus *bus);
 void pci_reset_secondary_bus(struct pci_dev *dev);
 void pcibios_reset_secondary_bus(struct pci_dev *dev);
 void pci_reset_bridge_secondary_bus(struct pci_dev *dev);
-void pci_update_resource(struct pci_dev *dev, int resno);
+void pci_update_resource(struct pci_dev *dev, int resno, bool mmio_force_on);
 int __must_check pci_assign_resource(struct pci_dev *dev, int i);
 int __must_check pci_reassign_resource(struct pci_dev *dev, int i, resource_size_t add_size, resource_size_t align);
 int pci_select_bars(struct pci_dev *dev, unsigned long flags);
-- 
2.1.0