x86/gart: Disable GART explicitly before initialization

commit 4b83873d3da0704987cb116833818ed96214ee29 upstream.

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>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

diff --git a/arch/x86/kernel/aperture_64.c b/arch/x86/kernel/aperture_64.c
index 128111d8ffe0de7ffcdaf0891221ff37d0ae61f8..082089ec5594f365d3a41f272d7d86d1735c0b72 100644 (file)
--- a/arch/x86/kernel/aperture_64.c
+++ b/arch/x86/kernel/aperture_64.c
@@ -389,6 +389,7 @@ 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;
@@ -401,7 +402,19 @@ void __init gart_iommu_hole_init(void)
                        iommu_detected = 1;
                        gart_iommu_aperture = 1;
 
-                       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;

diff --git a/arch/x86/kernel/pci-gart_64.c b/arch/x86/kernel/pci-gart_64.c
index fcc0b5c022c10cbe545c7f781cf25bcdd805e7f8..c245b6a3de8e72265aca69f1ed58b6cf9b20d11c 100644 (file)
--- a/arch/x86/kernel/pci-gart_64.c
+++ b/arch/x86/kernel/pci-gart_64.c
@@ -553,6 +553,9 @@ static void enable_gart_translations(void)
 
                enable_gart_translation(dev, __pa(agp_gatt_table));
        }
+
+       /* Flush the GART-TLB to remove stale entries */
+       k8_flush_garts();
 }
 
 /*