[Xen-devel] [PATCH 1/2] x86/iommu: avoid mapping the interrupt address range for hwdom

[Roger Pau Monne <roger.pau@xxxxxxxxxx>]

Current code only prevent mapping the lapic page into the guest
physical memory map. Expand the range to be 0xFEEx_xxxx as described
in the Intel VTd specification section 3.13 "Handling Requests to
Interrupt Address Range".

AMD also lists this address range in the AMD SR5690 Databook, section
2.4.4 "MSI Interrupt Handling and MSI to HT Interrupt Conversion".

Requested-by: Andrew Cooper <andrew.cooper3@xxxxxxxxxx>
Signed-off-by: Roger Pau Monné <roger.pau@xxxxxxxxxx>
---
Cc: Jan Beulich <jbeulich@xxxxxxxx>
Cc: Andrew Cooper <andrew.cooper3@xxxxxxxxxx>
---
 xen/drivers/passthrough/x86/iommu.c | 16 +++-------------
 1 file changed, 3 insertions(+), 13 deletions(-)

diff --git a/xen/drivers/passthrough/x86/iommu.c 
b/xen/drivers/passthrough/x86/iommu.c
index 0fa6dcc3fd..88a87cf7a4 100644
--- a/xen/drivers/passthrough/x86/iommu.c
+++ b/xen/drivers/passthrough/x86/iommu.c
@@ -226,19 +226,9 @@ static bool __hwdom_init hwdom_iommu_map(const struct 
domain *d,
             return false;
     }
 
-    /*
-     * Check that it doesn't overlap with the LAPIC
-     * TODO: if the guest relocates the MMIO area of the LAPIC Xen should make
-     * sure there's nothing in the new address that would prevent trapping.
-     */
-    if ( has_vlapic(d) )
-    {
-        const struct vcpu *v;
-
-        for_each_vcpu(d, v)
-            if ( pfn == PFN_DOWN(vlapic_base_address(vcpu_vlapic(v))) )
-                return false;
-    }
+    /* Check that it doesn't overlap with the Interrupt Address Range. */
+    if ( pfn >= 0xfee00 && pfn <= 0xfeeff )
+        return false;
     /* ... or the IO-APIC */
     for ( i = 0; has_vioapic(d) && i < d->arch.hvm.nr_vioapics; i++ )
         if ( pfn == PFN_DOWN(domain_vioapic(d, i)->base_address) )
-- 
2.20.1 (Apple Git-117)


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