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a="62504858" X-IronPort-AV: E=Sophos;i="6.19,252,1754982000"; d="scan'208";a="62504858" X-CSE-ConnectionGUID: BhVqrqEdQKSkspzwT1BHoA== X-CSE-MsgGUID: YcGJoHkGTj+M1Z/r0iCTOA== X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="6.19,252,1754982000"; d="scan'208";a="183985915" From: Zhenzhong Duan To: qemu-devel@nongnu.org Cc: alex.williamson@redhat.com, clg@redhat.com, eric.auger@redhat.com, mst@redhat.com, jasowang@redhat.com, peterx@redhat.com, ddutile@redhat.com, jgg@nvidia.com, nicolinc@nvidia.com, skolothumtho@nvidia.com, joao.m.martins@oracle.com, clement.mathieu--drif@eviden.com, kevin.tian@intel.com, yi.l.liu@intel.com, chao.p.peng@intel.com, Zhenzhong Duan Subject: [PATCH v7 09/23] intel_iommu: Stick to system MR for IOMMUFD backed host device when x-flts=on Date: Fri, 24 Oct 2025 04:43:33 -0400 Message-ID: <20251024084349.102322-10-zhenzhong.duan@intel.com> X-Mailer: git-send-email 2.47.1 In-Reply-To: <20251024084349.102322-1-zhenzhong.duan@intel.com> References: <20251024084349.102322-1-zhenzhong.duan@intel.com> MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable Received-SPF: pass (zohomail.com: domain of gnu.org designates 209.51.188.17 as permitted sender) client-ip=209.51.188.17; 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charset="utf-8" When guest enables scalable mode and setup first stage page table, we don't want to use IOMMU MR but rather continue using the system MR for IOMMUFD backed host device. Then default HWPT in VFIO contains GPA->HPA mappings which could be reused as nesting parent HWPT to construct nested HWPT in vIOMMU. Suggested-by: Yi Liu Signed-off-by: Zhenzhong Duan Reviewed-by: Eric Auger Reviewed-by: Yi Liu --- hw/i386/intel_iommu.c | 36 ++++++++++++++++++++++++++++++++++-- 1 file changed, 34 insertions(+), 2 deletions(-) diff --git a/hw/i386/intel_iommu.c b/hw/i386/intel_iommu.c index 4c83578c54..ce4c54165e 100644 --- a/hw/i386/intel_iommu.c +++ b/hw/i386/intel_iommu.c @@ -41,6 +41,7 @@ #include "migration/misc.h" #include "migration/vmstate.h" #include "trace.h" +#include "system/iommufd.h" =20 /* context entry operations */ #define PASID_0 0 @@ -1713,6 +1714,24 @@ static bool vtd_dev_pt_enabled(IntelIOMMUState *s, V= TDContextEntry *ce, =20 } =20 +static VTDHostIOMMUDevice *vtd_find_hiod_iommufd(VTDAddressSpace *as) +{ + IntelIOMMUState *s =3D as->iommu_state; + struct vtd_as_key key =3D { + .bus =3D as->bus, + .devfn =3D as->devfn, + }; + VTDHostIOMMUDevice *vtd_hiod =3D g_hash_table_lookup(s->vtd_host_iommu= _dev, + &key); + + if (vtd_hiod && vtd_hiod->hiod && + object_dynamic_cast(OBJECT(vtd_hiod->hiod), + TYPE_HOST_IOMMU_DEVICE_IOMMUFD)) { + return vtd_hiod; + } + return NULL; +} + static bool vtd_as_pt_enabled(VTDAddressSpace *as) { IntelIOMMUState *s; @@ -1738,12 +1757,25 @@ static bool vtd_as_pt_enabled(VTDAddressSpace *as) /* Return whether the device is using IOMMU translation. */ static bool vtd_switch_address_space(VTDAddressSpace *as) { + IntelIOMMUState *s; bool use_iommu, pt; =20 assert(as); =20 - use_iommu =3D as->iommu_state->dmar_enabled && !vtd_as_pt_enabled(as); - pt =3D as->iommu_state->dmar_enabled && vtd_as_pt_enabled(as); + s =3D as->iommu_state; + use_iommu =3D s->dmar_enabled && !vtd_as_pt_enabled(as); + pt =3D s->dmar_enabled && vtd_as_pt_enabled(as); + + /* + * When guest enables scalable mode and sets up first stage page table, + * we stick to system MR for IOMMUFD backed host device. Then its + * default hwpt contains GPA->HPA mappings which is used directly if + * PGTT=3DPT and used as nesting parent if PGTT=3DFST. Otherwise fall = back + * to original processing. + */ + if (s->root_scalable && s->fsts && vtd_find_hiod_iommufd(as)) { + use_iommu =3D false; + } =20 trace_vtd_switch_address_space(pci_bus_num(as->bus), VTD_PCI_SLOT(as->devfn), --=20 2.47.1