[PATCH v6 10/22] intel_iommu: Check for compatibility with IOMMUFD backed device when x-flts=on

[Zhenzhong Duan <zhenzhong.duan@intel.com>]

When vIOMMU is configured x-flts=on in scalable mode, first stage page table
is passed to host to construct nested page table for passthrough devices.

We need to check compatibility of some critical IOMMU capabilities between
vIOMMU and host IOMMU to ensure guest first stage page table could be used by
host.

For instance, vIOMMU supports first stage 1GB large page mapping, but host does
not, then this IOMMUFD backed device should fail.

Even of the checks pass, for now we willingly reject the association because
all the bits are not there yet, it will be relaxed in the end of this series.

Reviewed-by: Yi Liu <yi.l.liu@intel.com>
Signed-off-by: Zhenzhong Duan <zhenzhong.duan@intel.com>
Reviewed-by: Eric Auger <eric.auger@redhat.com>
---
 hw/i386/intel_iommu.c | 25 ++++++++++++++++++++++++-
 1 file changed, 24 insertions(+), 1 deletion(-)

diff --git a/hw/i386/intel_iommu.c b/hw/i386/intel_iommu.c
index bd80de1670..bcfbc5dd46 100644
--- a/hw/i386/intel_iommu.c
+++ b/hw/i386/intel_iommu.c
@@ -4387,8 +4387,31 @@ 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 first stage 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 (s->fs1gp && !(vtd->cap_reg & VTD_CAP_FS1GP)) {
+        error_setg(errp,
+                   "First stage 1GB large page is unsupported by host IOMMU");
+        return false;
+    }
+#endif
+
     error_setg(errp,
-               "host device is uncompatible with first stage translation");
+               "host IOMMU is incompatible with guest first stage translation");
     return false;
 }
 
-- 
2.47.1