[Xen-devel] [RFC PATCH 17/30] q35: Fix incorrect values for PCIEXBAR masks

[Alexey Gerasimenko <x1917x@xxxxxxxxx>]

There are two small issues in PCIEXBAR address mask handling:
- wrong bit positions for address mask bits (see PCIEXBAR description
  in Q35 datasheet)
- incorrect usage of 64ADR_MASK

Due to this, attempting to write a valid PCIEXBAR address may cause it to
shift to another address, causing memory layout corruption where emulated
MMIO regions may overlap real (passed through) MMIO ranges. Fix this
by providing correct values.

Signed-off-by: Alexey Gerasimenko <x1917x@xxxxxxxxx>
---
 hw/pci-host/q35.c         | 6 +++---
 include/hw/pci-host/q35.h | 4 ++--
 2 files changed, 5 insertions(+), 5 deletions(-)

diff --git a/hw/pci-host/q35.c b/hw/pci-host/q35.c
index 8c1603fce9..b9a49721e2 100644
--- a/hw/pci-host/q35.c
+++ b/hw/pci-host/q35.c
@@ -322,12 +322,12 @@ static void mch_update_pciexbar(MCHPCIState *mch)
         break;
     case MCH_HOST_BRIDGE_PCIEXBAR_LENGTH_128M:
         length = 128 * 1024 * 1024;
-        addr_mask |= MCH_HOST_BRIDGE_PCIEXBAR_128ADMSK |
-            MCH_HOST_BRIDGE_PCIEXBAR_64ADMSK;
+        addr_mask |= MCH_HOST_BRIDGE_PCIEXBAR_128ADMSK;
         break;
     case MCH_HOST_BRIDGE_PCIEXBAR_LENGTH_64M:
         length = 64 * 1024 * 1024;
-        addr_mask |= MCH_HOST_BRIDGE_PCIEXBAR_64ADMSK;
+        addr_mask |= MCH_HOST_BRIDGE_PCIEXBAR_64ADMSK |
+            MCH_HOST_BRIDGE_PCIEXBAR_128ADMSK;
         break;
     case MCH_HOST_BRIDGE_PCIEXBAR_LENGTH_RVD:
     default:
diff --git a/include/hw/pci-host/q35.h b/include/hw/pci-host/q35.h
index 8f4ddde393..ec8d77fa8b 100644
--- a/include/hw/pci-host/q35.h
+++ b/include/hw/pci-host/q35.h
@@ -103,8 +103,8 @@ typedef struct Q35PCIHost {
 #define MCH_HOST_BRIDGE_PCIEXBAR_DEFAULT       0xb0000000
 #define MCH_HOST_BRIDGE_PCIEXBAR_MAX           (0x10000000) /* 256M */
 #define MCH_HOST_BRIDGE_PCIEXBAR_ADMSK         Q35_MASK(64, 35, 28)
-#define MCH_HOST_BRIDGE_PCIEXBAR_128ADMSK      ((uint64_t)(1 << 26))
-#define MCH_HOST_BRIDGE_PCIEXBAR_64ADMSK       ((uint64_t)(1 << 25))
+#define MCH_HOST_BRIDGE_PCIEXBAR_128ADMSK      ((uint64_t)(1 << 27))
+#define MCH_HOST_BRIDGE_PCIEXBAR_64ADMSK       ((uint64_t)(1 << 26))
 #define MCH_HOST_BRIDGE_PCIEXBAR_LENGTH_MASK   ((uint64_t)(0x3 << 1))
 #define MCH_HOST_BRIDGE_PCIEXBAR_LENGTH_256M   ((uint64_t)(0x0 << 1))
 #define MCH_HOST_BRIDGE_PCIEXBAR_LENGTH_128M   ((uint64_t)(0x1 << 1))
-- 
2.11.0


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