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authorJoerg Roedel <joerg.roedel@amd.com>2010-04-07 12:57:35 +0200
committerJoerg Roedel <joerg.roedel@amd.com>2010-04-07 14:36:30 +0200
commit4b83873d3da0704987cb116833818ed96214ee29 (patch)
tree49ae6049ff73abdb9c11c1c46ef40b634f3deb62 /arch/x86/kernel/aperture_64.c
parent39a37ce1cc5eef420604fa68b776ff5dab400340 (diff)
x86/gart: Disable GART explicitly before initialization
If we boot into a crash-kernel the gart might still be enabled and its caches might be dirty. This can result in undefined behavior later. Fix it by explicitly disabling the gart hardware before initialization and flushing the caches after enablement. Signed-off-by: Joerg Roedel <joerg.roedel@amd.com>
Diffstat (limited to 'arch/x86/kernel/aperture_64.c')
-rw-r--r--arch/x86/kernel/aperture_64.c15
1 files changed, 14 insertions, 1 deletions
diff --git a/arch/x86/kernel/aperture_64.c b/arch/x86/kernel/aperture_64.c
index 3704997e8b2..b5d8b0bcf23 100644
--- a/arch/x86/kernel/aperture_64.c
+++ b/arch/x86/kernel/aperture_64.c
@@ -393,6 +393,7 @@ void __init gart_iommu_hole_init(void)
for (i = 0; i < ARRAY_SIZE(bus_dev_ranges); i++) {
int bus;
int dev_base, dev_limit;
+ u32 ctl;
bus = bus_dev_ranges[i].bus;
dev_base = bus_dev_ranges[i].dev_base;
@@ -406,7 +407,19 @@ void __init gart_iommu_hole_init(void)
gart_iommu_aperture = 1;
x86_init.iommu.iommu_init = gart_iommu_init;
- aper_order = (read_pci_config(bus, slot, 3, AMD64_GARTAPERTURECTL) >> 1) & 7;
+ ctl = read_pci_config(bus, slot, 3,
+ AMD64_GARTAPERTURECTL);
+
+ /*
+ * Before we do anything else disable the GART. It may
+ * still be enabled if we boot into a crash-kernel here.
+ * Reconfiguring the GART while it is enabled could have
+ * unknown side-effects.
+ */
+ ctl &= ~GARTEN;
+ write_pci_config(bus, slot, 3, AMD64_GARTAPERTURECTL, ctl);
+
+ aper_order = (ctl >> 1) & 7;
aper_size = (32 * 1024 * 1024) << aper_order;
aper_base = read_pci_config(bus, slot, 3, AMD64_GARTAPERTUREBASE) & 0x7fff;
aper_base <<= 25;