[F][PATCH 1/1] s390/pci: Fix unexpected write combine on resource

frank.heimes at canonical.com frank.heimes at canonical.com
Mon Mar 9 06:30:02 UTC 2020

From: Niklas Schnelle <schnelle at linux.ibm.com>

BugLink: https://bugs.launchpad.net/bugs/1866162

In the initial MIO support introduced in

commit 71ba41c9b1d9 ("s390/pci: provide support for MIO instructions")

zpci_map_resource() and zpci_setup_resources() default to using the
mio_wb address as the resource's start address. This means users of the
mapping, which includes most drivers, will get write combining on PCI
Stores. This may lead to problems when drivers expect write through
behavior when not using an explicit ioremap_wc().

Cc: stable at vger.kernel.org
Fixes: 71ba41c9b1d9 ("s390/pci: provide support for MIO instructions")
Signed-off-by: Niklas Schnelle <schnelle at linux.ibm.com>
Reviewed-by: Pierre Morel <pmorel at linux.ibm.com>
Signed-off-by: Vasily Gorbik <gor at linux.ibm.com>
(cherry picked from commit df057c914a9c219ac8b8ed22caf7da2f80c1fe26)
Signed-off-by: Frank Heimes <frank.heimes at canonical.com>
 arch/s390/pci/pci.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/arch/s390/pci/pci.c b/arch/s390/pci/pci.c
index 5b24fcc9c361..6105b1b6e49b 100644
--- a/arch/s390/pci/pci.c
+++ b/arch/s390/pci/pci.c
@@ -423,7 +423,7 @@ static void zpci_map_resources(struct pci_dev *pdev)
 		if (zpci_use_mio(zdev))
 			pdev->resource[i].start =
-				(resource_size_t __force) zdev->bars[i].mio_wb;
+				(resource_size_t __force) zdev->bars[i].mio_wt;
 			pdev->resource[i].start = (resource_size_t __force)
 				pci_iomap_range_fh(pdev, i, 0, 0);
@@ -530,7 +530,7 @@ static int zpci_setup_bus_resources(struct zpci_dev *zdev,
 			flags |= IORESOURCE_MEM_64;
 		if (zpci_use_mio(zdev))
-			addr = (unsigned long) zdev->bars[i].mio_wb;
+			addr = (unsigned long) zdev->bars[i].mio_wt;
 			addr = ZPCI_ADDR(entry);
 		size = 1UL << zdev->bars[i].size;

More information about the kernel-team mailing list