[PATCH v1 03/15] intel_iommu: Check for compatibility with IOMMUFD backed device when x-flts=on

[Zhenzhong Duan]

When vIOMMU is configured x-flts=on in scalable mode, stage-1 page table
is passed to host to construct nested page table. We need to check
compatibility of some critical IOMMU capabilities between vIOMMU and
host IOMMU to ensure guest stage-1 page table could be used by host.

For instance, vIOMMU supports stage-1 1GB huge page mapping, but host
does not, then this IOMMUFD backed device should be failed.

Signed-off-by: Yi Liu <yi.l....@intel.com>
Signed-off-by: Zhenzhong Duan <zhenzhong.d...@intel.com>
---
 hw/i386/intel_iommu_internal.h |  1 +
 hw/i386/intel_iommu.c          | 28 ++++++++++++++++++++++++++++
 2 files changed, 29 insertions(+)

diff --git a/hw/i386/intel_iommu_internal.h b/hw/i386/intel_iommu_internal.h
index e8b211e8b0..2cda744786 100644
--- a/hw/i386/intel_iommu_internal.h
+++ b/hw/i386/intel_iommu_internal.h
@@ -191,6 +191,7 @@
 #define VTD_ECAP_PT                 (1ULL << 6)
 #define VTD_ECAP_SC                 (1ULL << 7)
 #define VTD_ECAP_MHMV               (15ULL << 20)
+#define VTD_ECAP_NEST               (1ULL << 26)
 #define VTD_ECAP_SRS                (1ULL << 31)
 #define VTD_ECAP_PASID              (1ULL << 40)
 #define VTD_ECAP_SMTS               (1ULL << 43)
diff --git a/hw/i386/intel_iommu.c b/hw/i386/intel_iommu.c
index a2f3250724..c42ef83ddc 100644
--- a/hw/i386/intel_iommu.c
+++ b/hw/i386/intel_iommu.c
@@ -39,6 +39,7 @@
 #include "kvm/kvm_i386.h"
 #include "migration/vmstate.h"
 #include "trace.h"
+#include "system/iommufd.h"
 
 /* context entry operations */
 #define VTD_CE_GET_RID2PASID(ce) \
@@ -4361,6 +4362,33 @@ static bool vtd_check_hiod(IntelIOMMUState *s, 
HostIOMMUDevice *hiod,
         return true;
     }
 
+#ifdef CONFIG_IOMMUFD
+    struct HostIOMMUDeviceCaps *caps = &hiod->caps;
+    struct iommu_hw_info_vtd *vtd = &caps->vendor_caps.vtd;
+
+    /* Remaining checks are all stage-1 translation specific */
+    if (!object_dynamic_cast(OBJECT(hiod), TYPE_HOST_IOMMU_DEVICE_IOMMUFD)) {
+        error_setg(errp, "Need IOMMUFD backend when x-flts=on");
+        return false;
+    }
+
+    if (caps->type != IOMMU_HW_INFO_TYPE_INTEL_VTD) {
+        error_setg(errp, "Incompatible host platform IOMMU type %d",
+                   caps->type);
+        return false;
+    }
+
+    if (!(vtd->ecap_reg & VTD_ECAP_NEST)) {
+        error_setg(errp, "Host IOMMU doesn't support nested translation");
+        return false;
+    }
+
+    if (s->fs1gp && !(vtd->cap_reg & VTD_CAP_FS1GP)) {
+        error_setg(errp, "Stage-1 1GB huge page is unsupported by host IOMMU");
+        return false;
+    }
+#endif
+
     error_setg(errp, "host device is uncompatible with stage-1 translation");
     return false;
 }
-- 
2.34.1