From: Zhenzhong Duan Date: Tue, 6 Jan 2026 06:12:47 +0000 (-0500) Subject: hw/pci: Introduce pci_device_get_viommu_flags() X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=844302bd5961d8e7a35b601495b9af8f3d26a4c8;p=thirdparty%2Fqemu.git hw/pci: Introduce pci_device_get_viommu_flags() Introduce a new PCIIOMMUOps optional callback, get_viommu_flags() which allows to retrieve flags exposed by a vIOMMU. The first planned vIOMMU device flag is VIOMMU_FLAG_WANT_NESTING_PARENT that advertises the support of HW nested stage translation scheme and wants other sub-system like VFIO's cooperation to create nesting parent HWPT. pci_device_get_viommu_flags() is a wrapper that can be called on a PCI device potentially protected by a vIOMMU. get_viommu_flags() is designed to return 64bit bitmap of purely vIOMMU flags which are only determined by user's configuration, no host capabilities involved. Reasons are: 1. host may has heterogeneous IOMMUs, each with different capabilities 2. this is migration friendly, return value is consistent between source and target. Note that this op will be invoked at the attach_device() stage, at which point host IOMMU capabilities are not yet forwarded to the vIOMMU through the set_iommu_device() callback that will be after the attach_device(). See below sequence: vfio_device_attach(): iommufd_cdev_attach(): pci_device_get_viommu_flags() for HW nesting cap create a nesting parent HWPT attach device to the HWPT vfio_device_hiod_create_and_realize() creating hiod ... pci_device_set_iommu_device(hiod) Suggested-by: Yi Liu Signed-off-by: Zhenzhong Duan Reviewed-by: Nicolin Chen Reviewed-by: Eric Auger Reviewed-by: Yi Liu Reviewed-by: Cédric Le Goater Reviewed-by: Michael S. Tsirkin Link: https://lore.kernel.org/qemu-devel/20260106061304.314546-6-zhenzhong.duan@intel.com [ clg: include/hw/core/iommu.h: Changed Copyright date 2025 -> 2026 ] Signed-off-by: Cédric Le Goater --- diff --git a/MAINTAINERS b/MAINTAINERS index d16e620e01..620b184aa5 100644 --- a/MAINTAINERS +++ b/MAINTAINERS @@ -2368,6 +2368,7 @@ F: include/system/iommufd.h F: backends/host_iommu_device.c F: include/system/host_iommu_device.h F: include/qemu/chardev_open.h +F: include/hw/core/iommu.h F: util/chardev_open.c F: docs/devel/vfio-iommufd.rst diff --git a/hw/pci/pci.c b/hw/pci/pci.c index 0d4cf906f0..a136e772a3 100644 --- a/hw/pci/pci.c +++ b/hw/pci/pci.c @@ -3021,6 +3021,17 @@ void pci_device_unset_iommu_device(PCIDevice *dev) } } +uint64_t pci_device_get_viommu_flags(PCIDevice *dev) +{ + PCIBus *iommu_bus; + + pci_device_get_iommu_bus_devfn(dev, &iommu_bus, NULL, NULL); + if (iommu_bus && iommu_bus->iommu_ops->get_viommu_flags) { + return iommu_bus->iommu_ops->get_viommu_flags(iommu_bus->iommu_opaque); + } + return 0; +} + int pci_pri_request_page(PCIDevice *dev, uint32_t pasid, bool priv_req, bool exec_req, hwaddr addr, bool lpig, uint16_t prgi, bool is_read, bool is_write) diff --git a/include/hw/core/iommu.h b/include/hw/core/iommu.h new file mode 100644 index 0000000000..fcbbcd1015 --- /dev/null +++ b/include/hw/core/iommu.h @@ -0,0 +1,25 @@ +/* + * General vIOMMU flags + * + * Copyright (C) 2026 Intel Corporation. + * + * SPDX-License-Identifier: GPL-2.0-or-later + */ + +#ifndef HW_IOMMU_H +#define HW_IOMMU_H + +#include "qemu/bitops.h" + +/* + * Theoretical vIOMMU flags. Only determined by the vIOMMU device properties and + * independent on the actual host IOMMU capabilities they may depend on. Each + * flag can be an expectation or request to other sub-system or just a pure + * vIOMMU capability. vIOMMU can choose which flags to expose. + */ +enum viommu_flags { + /* vIOMMU needs nesting parent HWPT to create nested HWPT */ + VIOMMU_FLAG_WANT_NESTING_PARENT = BIT_ULL(0), +}; + +#endif /* HW_IOMMU_H */ diff --git a/include/hw/pci/pci.h b/include/hw/pci/pci.h index b22d350ba2..868817cc05 100644 --- a/include/hw/pci/pci.h +++ b/include/hw/pci/pci.h @@ -462,6 +462,18 @@ typedef struct PCIIOMMUOps { * @devfn: device and function number of the PCI device. */ void (*unset_iommu_device)(PCIBus *bus, void *opaque, int devfn); + /** + * @get_viommu_flags: get vIOMMU flags + * + * Optional callback, if not implemented, then vIOMMU doesn't support + * exposing flags to other sub-system, e.g., VFIO. + * + * @opaque: the data passed to pci_setup_iommu(). + * + * Returns: bitmap with each bit representing a vIOMMU flag defined in + * enum viommu_flags. + */ + uint64_t (*get_viommu_flags)(void *opaque); /** * @get_iotlb_info: get properties required to initialize a device IOTLB. * @@ -644,6 +656,16 @@ bool pci_device_set_iommu_device(PCIDevice *dev, HostIOMMUDevice *hiod, Error **errp); void pci_device_unset_iommu_device(PCIDevice *dev); +/** + * pci_device_get_viommu_flags: get vIOMMU flags. + * + * Returns: bitmap with each bit representing a vIOMMU flag defined in + * enum viommu_flags. Or 0 if vIOMMU doesn't report any. + * + * @dev: PCI device pointer. + */ +uint64_t pci_device_get_viommu_flags(PCIDevice *dev); + /** * pci_iommu_get_iotlb_info: get properties required to initialize a * device IOTLB.