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>

diff --git a/arch/x86/kernel/aperture_64.c b/arch/x86/kernel/aperture_64.c
index 3704997e8b2573bda630720f4c47bd4a7ec3b8c5..b5d8b0bcf23588a413d5766d160e24ac6c811441 100644 (file)
--- 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;

diff --git a/arch/x86/kernel/pci-gart_64.c b/arch/x86/kernel/pci-gart_64.c
index f3af115a573a5adbb053eae3a6c6921acf8b41fd..0ae24d9b44b340851764b05cd24d17c6cf205c97 100644 (file)
--- a/arch/x86/kernel/pci-gart_64.c
+++ b/arch/x86/kernel/pci-gart_64.c
@@ -564,6 +564,9 @@ 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();
 }
 
 /*