linux-kernel - [PATCH 5.5 106/189] s390/pci: Fix unexpected write combine on resource

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Message-Id: <20200310123650.411911992@linuxfoundation.org>
Date:   Tue, 10 Mar 2020 13:39:03 +0100
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     linux-kernel@...r.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        stable@...r.kernel.org, Niklas Schnelle <schnelle@...ux.ibm.com>,
        Pierre Morel <pmorel@...ux.ibm.com>,
        Vasily Gorbik <gor@...ux.ibm.com>
Subject: [PATCH 5.5 106/189] s390/pci: Fix unexpected write combine on resource

From: Niklas Schnelle <schnelle@...ux.ibm.com>

commit df057c914a9c219ac8b8ed22caf7da2f80c1fe26 upstream.

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@...r.kernel.org
Fixes: 71ba41c9b1d9 ("s390/pci: provide support for MIO instructions")
Signed-off-by: Niklas Schnelle <schnelle@...ux.ibm.com>
Reviewed-by: Pierre Morel <pmorel@...ux.ibm.com>
Signed-off-by: Vasily Gorbik <gor@...ux.ibm.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>

---
 arch/s390/pci/pci.c |    4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

--- a/arch/s390/pci/pci.c
+++ b/arch/s390/pci/pci.c
@@ -424,7 +424,7 @@ static void zpci_map_resources(struct pc
 
 		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;
 		else
 			pdev->resource[i].start = (resource_size_t __force)
 				pci_iomap_range_fh(pdev, i, 0, 0);
@@ -531,7 +531,7 @@ static int zpci_setup_bus_resources(stru
 			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;
 		else
 			addr = ZPCI_ADDR(entry);
 		size = 1UL << zdev->bars[i].size;