The BIOS needs to reserve shadow GTT space for graphics. Some don't.
Detect this and disable IOMMU for graphics when it happens.
Based on a patch from David Woodhouse, modified to use symbolic values for
the relevant register.
Signed-off-by: Adam Jackson <ajax@xxxxxxxxxx>
---
drivers/pci/intel-iommu.c | 14 ++++++++++++--
1 files changed, 12 insertions(+), 2 deletions(-)
diff --git a/drivers/pci/intel-iommu.c b/drivers/pci/intel-iommu.c
index af19396..d67727e 100644
--- a/drivers/pci/intel-iommu.c
+++ b/drivers/pci/intel-iommu.c
@@ -3738,14 +3738,24 @@ static void __devinit quirk_iommu_rwbf(struct pci_dev *dev)
DECLARE_PCI_FIXUP_HEADER(PCI_VENDOR_ID_INTEL, 0x2a40, quirk_iommu_rwbf);
+#define GGC 0x52
+#define GGC_MEMORY_SIZE_MASK (0xf << 8)
+#define GGC_MEMORY_SIZE_NONE (0x0 << 8)
+#define GGC_MEMORY_SIZE_1M (0x1 << 8)
+#define GGC_MEMORY_SIZE_2M (0x3 << 8)
+#define GGC_MEMORY_VT_ENABLED (0x8 << 8)
+#define GGC_MEMORY_SIZE_2M_VT (0x9 << 8)
+#define GGC_MEMORY_SIZE_3M_VT (0xa << 8)
+#define GGC_MEMORY_SIZE_4M_VT (0xb << 8)
+
static void __devinit quirk_calpella_no_shadow_gtt(struct pci_dev *dev)
{
unsigned short ggc;
- if (pci_read_config_word(dev, 0x52, &ggc))
+ if (pci_read_config_word(dev, GGC, &ggc))
return;
- if (!(ggc & 0x800)) {
+ if (!(ggc & GGC_MEMORY_VT_ENABLED)) {
printk(KERN_INFO "DMAR: BIOS has allocated no shadow GTT; disabling IOMMU for graphics\n");
dmar_map_gfx = 0;
}
--
1.7.2.1
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