[PULL,21/48] intel_iommu: Set default aw_bits to 48 starting from QEMU 9.2

Commit Message

Michael S. Tsirkin Jan. 15, 2025, 6:09 p.m. UTC

From: Zhenzhong Duan <[e-mail]>

According to VTD spec, stage-1 page table could support 4-level and
5-level paging.

However, 5-level paging translation emulation is unsupported yet.
That means the only supported value for aw_bits is 48. So default
aw_bits to 48 when stage-1 translation is turned on.

For legacy and scalable modes, 48 is the default choice for modern
OS when both 48 and 39 are supported. So it makes sense to set
default to 48 for these two modes too starting from QEMU 9.2.
Use pc_compat_9_1 to handle the compatibility for machines before
9.2.

Suggested-by: Jason Wang <[e-mail]>
Signed-off-by: Zhenzhong Duan <[e-mail]>
Reviewed-by: Clément Mathieu--Drif<[e-mail]>
Reviewed-by: Yi Liu <[e-mail]>
Acked-by: Jason Wang <[e-mail]>
Message-Id: <[e-mail]>
Reviewed-by: Michael S. Tsirkin <[e-mail]>
Signed-off-by: Michael S. Tsirkin <[e-mail]>
---
 include/hw/i386/intel_iommu.h | 2 +-
 hw/i386/pc.c                  | 1 +
 2 files changed, 2 insertions(+), 1 deletion(-)

Patch

diff --git a/include/hw/i386/intel_iommu.h b/include/hw/i386/intel_iommu.h
index a434c2489c..72428fefa4 100644
--- a/include/hw/i386/intel_iommu.h
+++ b/include/hw/i386/intel_iommu.h
@@ -45,7 +45,7 @@  OBJECT_DECLARE_SIMPLE_TYPE(IntelIOMMUState, INTEL_IOMMU_DEVICE)
 #define DMAR_REG_SIZE               0x230
 #define VTD_HOST_AW_39BIT           39
 #define VTD_HOST_AW_48BIT           48
-#define VTD_HOST_ADDRESS_WIDTH      VTD_HOST_AW_39BIT
+#define VTD_HOST_ADDRESS_WIDTH      VTD_HOST_AW_48BIT
 #define VTD_HAW_MASK(aw)            ((1ULL << (aw)) - 1)
 
 #define DMAR_REPORT_F_INTR          (1)
diff --git a/hw/i386/pc.c b/hw/i386/pc.c
index 9334b033f6..b46975c8a4 100644
--- a/hw/i386/pc.c
+++ b/hw/i386/pc.c
@@ -86,6 +86,7 @@  GlobalProperty pc_compat_9_1[] = {
     { "ICH9-LPC", "x-smi-swsmi-timer", "off" },
     { "ICH9-LPC", "x-smi-periodic-timer", "off" },
     { TYPE_INTEL_IOMMU_DEVICE, "stale-tm", "on" },
+    { TYPE_INTEL_IOMMU_DEVICE, "aw-bits", "39" },
 };
 const size_t pc_compat_9_1_len = G_N_ELEMENTS(pc_compat_9_1);