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a="64989297" X-IronPort-AV: E=Sophos;i="6.18,300,1751266800"; d="scan'208";a="64989297" X-CSE-ConnectionGUID: 12amySd8Rj+HlKBGuFRQBQ== X-CSE-MsgGUID: M9l4AD8BQ/uEIGNhY+fsUA== X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="6.18,300,1751266800"; d="scan'208";a="178865063" 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, yi.l.liu@intel.com, clement.mathieu--drif@eviden.com, Zhenzhong Duan Subject: [PATCH v2 2/3] intel_iommu: Simplify caching mode check with VFIO device Date: Sun, 28 Sep 2025 23:42:05 -0400 Message-ID: <20250929034206.439266-3-zhenzhong.duan@intel.com> X-Mailer: git-send-email 2.47.1 In-Reply-To: <20250929034206.439266-1-zhenzhong.duan@intel.com> References: <20250929034206.439266-1-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; envelope-from=qemu-devel-bounces+importer=patchew.org@nongnu.org; helo=lists.gnu.org; Received-SPF: pass client-ip=198.175.65.15; envelope-from=zhenzhong.duan@intel.com; helo=mgamail.intel.com X-Spam_score_int: -48 X-Spam_score: -4.9 X-Spam_bar: ---- X-Spam_report: (-4.9 / 5.0 requ) BAYES_00=-1.9, DKIMWL_WL_HIGH=-0.539, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, DKIM_VALID_EF=-0.1, RCVD_IN_DNSWL_MED=-2.3, RCVD_IN_VALIDITY_CERTIFIED_BLOCKED=0.001, RCVD_IN_VALIDITY_RPBL_BLOCKED=0.001, SPF_HELO_NONE=0.001, T_SPF_TEMPERROR=0.01 autolearn=ham autolearn_force=no X-Spam_action: no action X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: qemu-devel-bounces+importer=patchew.org@nongnu.org Sender: qemu-devel-bounces+importer=patchew.org@nongnu.org X-ZohoMail-DKIM: pass (identity @intel.com) X-ZM-MESSAGEID: 1759117496636116600 Content-Type: text/plain; charset="utf-8" In early days, we have different tricks to ensure caching-mode=3Don with VF= IO device: 28cf553afe ("intel_iommu: Sanity check vfio-pci config on machine init done= ") c6cbc29d36 ("pc/q35: Disallow vfio-pci hotplug without VT-d caching mode") There is also a patch of same purpose but for VDPA device: b8d78277c0 ("intel-iommu: fail MAP notifier without caching mode") Because without caching mode, MAP notifier won't work correctly since guest won't send IOTLB update event when it establishes new mappings in the I/O p= age tables. Now with host IOMMU device interface between VFIO and vIOMMU, we can simpli= fy first two commits above with a small check in set_iommu_device(). This also works for future IOMMUFD backed VDPA implementation which may also need cac= hing mode on. But for legacy VDPA we still need commit b8d78277c0 as it doesn't use host IOMMU device interface. For coldplug VFIO device: qemu-system-x86_64: -device vfio-pci,host=3D0000:3b:00.0,id=3Dhostdev3,bu= s=3Droot0,iommufd=3Diommufd0: vfio 0000:3b:00.0: Failed to set vIOMMU: Devi= ce assignment is not allowed without enabling caching-mode=3Don for Intel I= OMMU. For hotplug VFIO device: if "iommu=3Doff" is configured in guest, Error: vfio 0000:3b:00.0: Failed to set vIOMMU: Device assignment is no= t allowed without enabling caching-mode=3Don for Intel IOMMU. else Error: vfio 0000:3b:00.0: memory listener initialization failed: Region= vtd-00.0-dmar: device 01.00.0 requires caching mode: Operation not support= ed The specialty for hotplug is due to the check in commit b8d78277c0 happen b= efore the check in set_iommu_device. Signed-off-by: Zhenzhong Duan --- hw/i386/intel_iommu.c | 40 ++++++---------------------------------- hw/i386/pc.c | 20 -------------------- 2 files changed, 6 insertions(+), 54 deletions(-) diff --git a/hw/i386/intel_iommu.c b/hw/i386/intel_iommu.c index f04300022e..c634121514 100644 --- a/hw/i386/intel_iommu.c +++ b/hw/i386/intel_iommu.c @@ -85,13 +85,6 @@ struct vtd_iotlb_key { static void vtd_address_space_refresh_all(IntelIOMMUState *s); static void vtd_address_space_unmap(VTDAddressSpace *as, IOMMUNotifier *n); =20 -static void vtd_panic_require_caching_mode(void) -{ - error_report("We need to set caching-mode=3Don for intel-iommu to enab= le " - "device assignment with IOMMU protection."); - exit(1); -} - static void vtd_define_quad(IntelIOMMUState *s, hwaddr addr, uint64_t val, uint64_t wmask, uint64_t w1cmask) { @@ -4378,6 +4371,12 @@ static bool vtd_dev_set_iommu_device(PCIBus *bus, vo= id *opaque, int devfn, =20 assert(hiod); =20 + if (!s->caching_mode) { + error_setg(errp, "Device assignment is not allowed without enablin= g " + "caching-mode=3Don for Intel IOMMU."); + return false; + } + vtd_iommu_lock(s); =20 if (g_hash_table_lookup(s->vtd_host_iommu_dev, &key)) { @@ -4910,32 +4909,6 @@ static bool vtd_decide_config(IntelIOMMUState *s, Er= ror **errp) return true; } =20 -static int vtd_machine_done_notify_one(Object *child, void *unused) -{ - IntelIOMMUState *iommu =3D INTEL_IOMMU_DEVICE(x86_iommu_get_default()); - - /* - * We hard-coded here because vfio-pci is the only special case - * here. Let's be more elegant in the future when we can, but so - * far there seems to be no better way. - */ - if (object_dynamic_cast(child, "vfio-pci") && !iommu->caching_mode) { - vtd_panic_require_caching_mode(); - } - - return 0; -} - -static void vtd_machine_done_hook(Notifier *notifier, void *unused) -{ - object_child_foreach_recursive(object_get_root(), - vtd_machine_done_notify_one, NULL); -} - -static Notifier vtd_machine_done_notify =3D { - .notify =3D vtd_machine_done_hook, -}; - static void vtd_realize(DeviceState *dev, Error **errp) { MachineState *ms =3D MACHINE(qdev_get_machine()); @@ -4990,7 +4963,6 @@ static void vtd_realize(DeviceState *dev, Error **err= p) pci_setup_iommu(bus, &vtd_iommu_ops, dev); /* Pseudo address space under root PCI bus. */ x86ms->ioapic_as =3D vtd_host_dma_iommu(bus, s, Q35_PSEUDO_DEVFN_IOAPI= C); - qemu_add_machine_init_done_notifier(&vtd_machine_done_notify); } =20 static void vtd_class_init(ObjectClass *klass, const void *data) diff --git a/hw/i386/pc.c b/hw/i386/pc.c index bc048a6d13..01cd9a67db 100644 --- a/hw/i386/pc.c +++ b/hw/i386/pc.c @@ -1720,25 +1720,6 @@ static void pc_machine_wakeup(MachineState *machine) cpu_synchronize_all_post_reset(); } =20 -static bool pc_hotplug_allowed(MachineState *ms, DeviceState *dev, Error *= *errp) -{ - X86IOMMUState *iommu =3D x86_iommu_get_default(); - IntelIOMMUState *intel_iommu; - - if (iommu && - object_dynamic_cast((Object *)iommu, TYPE_INTEL_IOMMU_DEVICE) && - object_dynamic_cast((Object *)dev, "vfio-pci")) { - intel_iommu =3D INTEL_IOMMU_DEVICE(iommu); - if (!intel_iommu->caching_mode) { - error_setg(errp, "Device assignment is not allowed without " - "enabling caching-mode=3Don for Intel IOMMU."); - return false; - } - } - - return true; -} - static void pc_machine_class_init(ObjectClass *oc, const void *data) { MachineClass *mc =3D MACHINE_CLASS(oc); @@ -1758,7 +1739,6 @@ static void pc_machine_class_init(ObjectClass *oc, co= nst void *data) x86mc->apic_xrupt_override =3D true; assert(!mc->get_hotplug_handler); mc->get_hotplug_handler =3D pc_get_hotplug_handler; - mc->hotplug_allowed =3D pc_hotplug_allowed; mc->auto_enable_numa_with_memhp =3D true; mc->auto_enable_numa_with_memdev =3D true; mc->has_hotpluggable_cpus =3D true; --=20 2.47.1