[PATCH 1/1] x86/vtd: Mask DMAR faults for IGD devices

[Brendan Kerrigan <brendank310@xxxxxxxxx>]

From: Brendan Kerrigan <kerriganb@xxxxxxxxxxxx>

The Intel graphics device records DMAR faults regardless
of the Fault Process Disable bit being set. When this fault
occurs, enable the Interrupt Mask (IM) bit in the Fault
Event Control (FECTL) register to prevent the continued
recording of the fault.

Signed-off-by: Brendan Kerrigan <kerriganb@xxxxxxxxxxxx>
---
 xen/drivers/passthrough/vtd/iommu.c | 9 +++++++++
 1 file changed, 9 insertions(+)

diff --git a/xen/drivers/passthrough/vtd/iommu.c 
b/xen/drivers/passthrough/vtd/iommu.c
index 07d40b37fe..288399d816 100644
--- a/xen/drivers/passthrough/vtd/iommu.c
+++ b/xen/drivers/passthrough/vtd/iommu.c
@@ -41,6 +41,8 @@
 #include "vtd.h"
 #include "../ats.h"
 
+#define IS_IGD(seg, id) (0 == seg && 0 == PCI_BUS(id) && 2 == PCI_SLOT(id) && 
0 == PCI_FUNC(id))
+
 struct mapped_rmrr {
     struct list_head list;
     u64 base, end;
@@ -872,6 +874,13 @@ static int iommu_page_fault_do_one(struct vtd_iommu 
*iommu, int type,
     printk(XENLOG_G_WARNING VTDPREFIX "%s: reason %02x - %s\n",
            kind, fault_reason, reason);
 
+    if ( DMA_REMAP == fault_type && type && IS_IGD(seg, source_id) ) {
+        u32 fectl = dmar_readl(iommu->reg, DMAR_FECTL_REG);
+        fectl |= DMA_FECTL_IM;
+        dmar_writel(iommu->reg, DMAR_FECTL_REG, fectl);
+        printk(XENLOG_G_WARNING VTDPREFIX "Disabling DMAR faults for IGD\n");
+    }
+
     if ( iommu_verbose && fault_type == DMA_REMAP )
         print_vtd_entries(iommu, PCI_BUS(source_id), PCI_DEVFN2(source_id),
                           addr >> PAGE_SHIFT);
-- 
2.17.1