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([2a01:e0a:280:24f0:9db0:474c:ff43:9f5c]) by smtp.gmail.com with ESMTPSA id 5b1f17b1804b1-46e2a9b6e1bsm117222865e9.10.2025.09.26.00.21.26 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Fri, 26 Sep 2025 00:21:26 -0700 (PDT) Message-ID: Date: Fri, 26 Sep 2025 09:21:25 +0200 MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH 2/2] intel_iommu: Simplify caching mode check with VFIO device To: Zhenzhong Duan , qemu-devel@nongnu.org Cc: alex.williamson@redhat.com, eric.auger@redhat.com, mst@redhat.com, jasowang@redhat.com, peterx@redhat.com, yi.l.liu@intel.com, clement.mathieu--drif@eviden.com References: <20250919070638.983549-1-zhenzhong.duan@intel.com> <20250919070638.983549-3-zhenzhong.duan@intel.com> From: =?UTF-8?Q?C=C3=A9dric_Le_Goater?= Content-Language: en-US, fr Autocrypt: addr=clg@redhat.com; keydata= xsFNBFu8o3UBEADP+oJVJaWm5vzZa/iLgpBAuzxSmNYhURZH+guITvSySk30YWfLYGBWQgeo 8NzNXBY3cH7JX3/a0jzmhDc0U61qFxVgrPqs1PQOjp7yRSFuDAnjtRqNvWkvlnRWLFq4+U5t yzYe4SFMjFb6Oc0xkQmaK2flmiJNnnxPttYwKBPd98WfXMmjwAv7QfwW+OL3VlTPADgzkcqj 53bfZ4VblAQrq6Ctbtu7JuUGAxSIL3XqeQlAwwLTfFGrmpY7MroE7n9Rl+hy/kuIrb/TO8n0 ZxYXvvhT7OmRKvbYuc5Jze6o7op/bJHlufY+AquYQ4dPxjPPVUT/DLiUYJ3oVBWFYNbzfOrV RxEwNuRbycttMiZWxgflsQoHF06q/2l4ttS3zsV4TDZudMq0TbCH/uJFPFsbHUN91qwwaN/+ gy1j7o6aWMz+Ib3O9dK2M/j/O/Ube95mdCqN4N/uSnDlca3YDEWrV9jO1mUS/ndOkjxa34ia 70FjwiSQAsyIwqbRO3CGmiOJqDa9qNvd2TJgAaS2WCw/TlBALjVQ7AyoPEoBPj31K74Wc4GS Rm+FSch32ei61yFu6ACdZ12i5Edt+To+hkElzjt6db/UgRUeKfzlMB7PodK7o8NBD8outJGS tsL2GRX24QvvBuusJdMiLGpNz3uqyqwzC5w0Fd34E6G94806fwARAQABzSJDw6lkcmljIExl IEdvYXRlciA8Y2xnQHJlZGhhdC5jb20+wsGRBBMBCAA7FiEEoPZlSPBIlev+awtgUaNDx8/7 7KEFAmTLlVECGwMFCwkIBwICIgIGFQoJCAsCBBYCAwECHgcCF4AACgkQUaNDx8/77KG0eg// S0zIzTcxkrwJ/9XgdcvVTnXLVF9V4/tZPfB7sCp8rpDCEseU6O0TkOVFoGWM39sEMiQBSvyY lHrP7p7E/JYQNNLh441MfaX8RJ5Ul3btluLapm8oHp/vbHKV2IhLcpNCfAqaQKdfk8yazYhh EdxTBlzxPcu+78uE5fF4wusmtutK0JG0sAgq0mHFZX7qKG6LIbdLdaQalZ8CCFMKUhLptW71 xe+aNrn7hScBoOj2kTDRgf9CE7svmjGToJzUxgeh9mIkxAxTu7XU+8lmL28j2L5uNuDOq9vl hM30OT+pfHmyPLtLK8+GXfFDxjea5hZLF+2yolE/ATQFt9AmOmXC+YayrcO2ZvdnKExZS1o8 VUKpZgRnkwMUUReaF/mTauRQGLuS4lDcI4DrARPyLGNbvYlpmJWnGRWCDguQ/LBPpbG7djoy k3NlvoeA757c4DgCzggViqLm0Bae320qEc6z9o0X0ePqSU2f7vcuWN49Uhox5kM5L86DzjEQ RHXndoJkeL8LmHx8DM+kx4aZt0zVfCHwmKTkSTQoAQakLpLte7tWXIio9ZKhUGPv/eHxXEoS 0rOOAZ6np1U/xNR82QbF9qr9TrTVI3GtVe7Vxmff+qoSAxJiZQCo5kt0YlWwti2fFI4xvkOi V7lyhOA3+/3oRKpZYQ86Frlo61HU3r6d9wzOwU0EW7yjdQEQALyDNNMw/08/fsyWEWjfqVhW pOOrX2h+z4q0lOHkjxi/FRIRLfXeZjFfNQNLSoL8j1y2rQOs1j1g+NV3K5hrZYYcMs0xhmrZ KXAHjjDx7FW3sG3jcGjFW5Xk4olTrZwFsZVUcP8XZlArLmkAX3UyrrXEWPSBJCXxDIW1hzwp bV/nVbo/K9XBptT/wPd+RPiOTIIRptjypGY+S23HYBDND3mtfTz/uY0Jytaio9GETj+fFis6 TxFjjbZNUxKpwftu/4RimZ7qL+uM1rG1lLWc9SPtFxRQ8uLvLOUFB1AqHixBcx7LIXSKZEFU CSLB2AE4wXQkJbApye48qnZ09zc929df5gU6hjgqV9Gk1rIfHxvTsYltA1jWalySEScmr0iS YBZjw8Nbd7SxeomAxzBv2l1Fk8fPzR7M616dtb3Z3HLjyvwAwxtfGD7VnvINPbzyibbe9c6g LxYCr23c2Ry0UfFXh6UKD83d5ybqnXrEJ5n/t1+TLGCYGzF2erVYGkQrReJe8Mld3iGVldB7 JhuAU1+d88NS3aBpNF6TbGXqlXGF6Yua6n1cOY2Yb4lO/mDKgjXd3aviqlwVlodC8AwI0Sdu jWryzL5/AGEU2sIDQCHuv1QgzmKwhE58d475KdVX/3Vt5I9kTXpvEpfW18TjlFkdHGESM/Jx IqVsqvhAJkalABEBAAHCwV8EGAECAAkFAlu8o3UCGwwACgkQUaNDx8/77KEhwg//WqVopd5k 8hQb9VVdk6RQOCTfo6wHhEqgjbXQGlaxKHoXywEQBi8eULbeMQf5l4+tHJWBxswQ93IHBQjK yKyNr4FXseUI5O20XVNYDJZUrhA4yn0e/Af0IX25d94HXQ5sMTWr1qlSK6Zu79lbH3R57w9j hQm9emQEp785ui3A5U2Lqp6nWYWXz0eUZ0Tad2zC71Gg9VazU9MXyWn749s0nXbVLcLS0yop s302Gf3ZmtgfXTX/W+M25hiVRRKCH88yr6it+OMJBUndQVAA/fE9hYom6t/zqA248j0QAV/p LHH3hSirE1mv+7jpQnhMvatrwUpeXrOiEw1nHzWCqOJUZ4SY+HmGFW0YirWV2mYKoaGO2YBU wYF7O9TI3GEEgRMBIRT98fHa0NPwtlTktVISl73LpgVscdW8yg9Gc82oe8FzU1uHjU8b10lU XOMHpqDDEV9//r4ZhkKZ9C4O+YZcTFu+mvAY3GlqivBNkmYsHYSlFsbxc37E1HpTEaSWsGfA HQoPn9qrDJgsgcbBVc1gkUT6hnxShKPp4PlsZVMNjvPAnr5TEBgHkk54HQRhhwcYv1T2QumQ izDiU6iOrUzBThaMhZO3i927SG2DwWDVzZltKrCMD1aMPvb3NU8FOYRhNmIFR3fcalYr+9gD uVKe8BVz4atMOoktmt0GWTOC8P4= In-Reply-To: <20250919070638.983549-3-zhenzhong.duan@intel.com> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 8bit Received-SPF: pass client-ip=170.10.129.124; envelope-from=clg@redhat.com; helo=us-smtp-delivery-124.mimecast.com X-Spam_score_int: -24 X-Spam_score: -2.5 X-Spam_bar: -- X-Spam_report: (-2.5 / 5.0 requ) BAYES_00=-1.9, DKIMWL_WL_HIGH=-0.445, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, DKIM_VALID_EF=-0.1, RCVD_IN_DNSWL_NONE=-0.0001, RCVD_IN_MSPIKE_H4=0.001, RCVD_IN_MSPIKE_WL=0.001, RCVD_IN_VALIDITY_CERTIFIED_BLOCKED=0.001, RCVD_IN_VALIDITY_RPBL_BLOCKED=0.001, SPF_HELO_PASS=-0.001, SPF_PASS=-0.001 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+qemu-devel=archiver.kernel.org@nongnu.org Sender: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org On 9/19/25 09:06, Zhenzhong Duan wrote: > In early days, we have different tricks to ensure caching-mode=on with VFIO > 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") > 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 page > tables. > > Now with host IOMMU device interface between VFIO and vIOMMU, we can simplify > it with a small check in set_iommu_device(). This also works for future VDPA > implementation which may also need caching mode on. > > For coldplug VFIO device: > > qemu-system-x86_64: -device vfio-pci,host=0000:3b:00.0,id=hostdev3,bus=root0,iommufd=iommufd0: vfio 0000:3b:00.0: Failed to set vIOMMU: Device assignment is not allowed without enabling caching-mode=on for Intel IOMMU. > > For hotplug VFIO device: > > Error: vfio 0000:3b:00.0: Failed to set vIOMMU: Device assignment is not allowed without enabling caching-mode=on for Intel IOMMU. > > Signed-off-by: Zhenzhong Duan > --- > hw/i386/intel_iommu.c | 47 ++++++------------------------------------- > hw/i386/pc.c | 20 ------------------ > 2 files changed, 6 insertions(+), 61 deletions(-) This is a nice cleanup. Acked-by: Cédric Le Goater Thanks, C. > > diff --git a/hw/i386/intel_iommu.c b/hw/i386/intel_iommu.c > index f04300022e..5c67b42dde 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); > > -static void vtd_panic_require_caching_mode(void) > -{ > - error_report("We need to set caching-mode=on for intel-iommu to enable " > - "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) > { > @@ -3731,13 +3724,6 @@ static int vtd_iommu_notify_flag_changed(IOMMUMemoryRegion *iommu, > "Snoop Control with vhost or VFIO is not supported"); > return -ENOTSUP; > } > - if (!s->caching_mode && (new & IOMMU_NOTIFIER_MAP)) { > - error_setg_errno(errp, ENOTSUP, > - "device %02x.%02x.%x requires caching mode", > - pci_bus_num(vtd_as->bus), PCI_SLOT(vtd_as->devfn), > - PCI_FUNC(vtd_as->devfn)); > - return -ENOTSUP; > - } > if (!x86_iommu->dt_supported && (new & IOMMU_NOTIFIER_DEVIOTLB_UNMAP)) { > error_setg_errno(errp, ENOTSUP, > "device %02x.%02x.%x requires device IOTLB mode", > @@ -4378,6 +4364,12 @@ static bool vtd_dev_set_iommu_device(PCIBus *bus, void *opaque, int devfn, > > assert(hiod); > > + if (!s->caching_mode) { > + error_setg(errp, "Device assignment is not allowed without enabling " > + "caching-mode=on for Intel IOMMU."); > + return false; > + } > + > vtd_iommu_lock(s); > > if (g_hash_table_lookup(s->vtd_host_iommu_dev, &key)) { > @@ -4910,32 +4902,6 @@ static bool vtd_decide_config(IntelIOMMUState *s, Error **errp) > return true; > } > > -static int vtd_machine_done_notify_one(Object *child, void *unused) > -{ > - IntelIOMMUState *iommu = 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 = { > - .notify = vtd_machine_done_hook, > -}; > - > static void vtd_realize(DeviceState *dev, Error **errp) > { > MachineState *ms = MACHINE(qdev_get_machine()); > @@ -4990,7 +4956,6 @@ static void vtd_realize(DeviceState *dev, Error **errp) > pci_setup_iommu(bus, &vtd_iommu_ops, dev); > /* Pseudo address space under root PCI bus. */ > x86ms->ioapic_as = vtd_host_dma_iommu(bus, s, Q35_PSEUDO_DEVFN_IOAPIC); > - qemu_add_machine_init_done_notifier(&vtd_machine_done_notify); > } > > 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(); > } > > -static bool pc_hotplug_allowed(MachineState *ms, DeviceState *dev, Error **errp) > -{ > - X86IOMMUState *iommu = 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 = INTEL_IOMMU_DEVICE(iommu); > - if (!intel_iommu->caching_mode) { > - error_setg(errp, "Device assignment is not allowed without " > - "enabling caching-mode=on for Intel IOMMU."); > - return false; > - } > - } > - > - return true; > -} > - > static void pc_machine_class_init(ObjectClass *oc, const void *data) > { > MachineClass *mc = MACHINE_CLASS(oc); > @@ -1758,7 +1739,6 @@ static void pc_machine_class_init(ObjectClass *oc, const void *data) > x86mc->apic_xrupt_override = true; > assert(!mc->get_hotplug_handler); > mc->get_hotplug_handler = pc_get_hotplug_handler; > - mc->hotplug_allowed = pc_hotplug_allowed; > mc->auto_enable_numa_with_memhp = true; > mc->auto_enable_numa_with_memdev = true; > mc->has_hotpluggable_cpus = true;