Re: [PATCH v1 09/11] hw/pci: Introduce pci_device_set/unset_iommu_device()

[Michael S. Tsirkin]

On Wed, Feb 28, 2024 at 11:58:58AM +0800, Zhenzhong Duan wrote:
> From: Yi Liu <yi.l.liu@intel.com>
> 
> This adds pci_device_set/unset_iommu_device() to set/unset
> HostIOMMUDevice for a given PCIe device. Caller of set
> should fail if set operation fails.
> 
> Extract out pci_device_get_iommu_bus_devfn() to facilitate
> implementation of pci_device_set/unset_iommu_device().
> 
> Signed-off-by: Yi Liu <yi.l.liu@intel.com>
> Signed-off-by: Yi Sun <yi.y.sun@linux.intel.com>
> Signed-off-by: Nicolin Chen <nicolinc@nvidia.com>
> Signed-off-by: Zhenzhong Duan <zhenzhong.duan@intel.com>
> ---
>  include/hw/pci/pci.h | 38 ++++++++++++++++++++++++++-
>  hw/pci/pci.c         | 62 +++++++++++++++++++++++++++++++++++++++++---
>  2 files changed, 96 insertions(+), 4 deletions(-)
> 
> diff --git a/include/hw/pci/pci.h b/include/hw/pci/pci.h
> index fa6313aabc..8fe6f746d7 100644
> --- a/include/hw/pci/pci.h
> +++ b/include/hw/pci/pci.h
> @@ -3,6 +3,7 @@
>  
>  #include "exec/memory.h"
>  #include "sysemu/dma.h"
> +#include "sysemu/host_iommu_device.h"
>  
>  /* PCI includes legacy ISA access.  */
>  #include "hw/isa/isa.h"
> @@ -384,10 +385,45 @@ typedef struct PCIIOMMUOps {
>       *
>       * @devfn: device and function number
>       */
> -   AddressSpace * (*get_address_space)(PCIBus *bus, void *opaque, int devfn);
> +    AddressSpace * (*get_address_space)(PCIBus *bus, void *opaque, int 
> devfn);
> +    /**
> +     * @set_iommu_device: attach a HostIOMMUDevice to a vIOMMU
> +     *
> +     * Optional callback, if not implemented in vIOMMU, then vIOMMU can't
> +     * retrieve host information from the associated HostIOMMUDevice.
> +     *
> +     * Return true if HostIOMMUDevice is attached, or else return false
> +     * with errp set.
> +     *
> +     * @bus: the #PCIBus of the PCI device.
> +     *
> +     * @opaque: the data passed to pci_setup_iommu().
> +     *
> +     * @devfn: device and function number of the PCI device.
> +     *
> +     * @dev: the data structure representing host IOMMU device.
> +     *
> +     */
> +    int (*set_iommu_device)(PCIBus *bus, void *opaque, int devfn,
> +                            HostIOMMUDevice *dev, Error **errp);
> +    /**
> +     * @unset_iommu_device: detach a HostIOMMUDevice from a vIOMMU
> +     *
> +     * Optional callback.
> +     *
> +     * @bus: the #PCIBus of the PCI device.
> +     *
> +     * @opaque: the data passed to pci_setup_iommu().
> +     *
> +     * @devfn: device and function number of the PCI device.
> +     */
> +    void (*unset_iommu_device)(PCIBus *bus, void *opaque, int devfn);
>  } PCIIOMMUOps;


So I expected someone to implement these new callbacks but I see
no implementation in this patchset.

Is this just infrastructure that will be used later?
A bit hard to judge without a user ...



>  AddressSpace *pci_device_iommu_address_space(PCIDevice *dev);
> +int pci_device_set_iommu_device(PCIDevice *dev, HostIOMMUDevice *base_dev,
> +                                Error **errp);
> +void pci_device_unset_iommu_device(PCIDevice *dev);
>  
>  /**
>   * pci_setup_iommu: Initialize specific IOMMU handlers for a PCIBus
> diff --git a/hw/pci/pci.c b/hw/pci/pci.c
> index 76080af580..8078307963 100644
> --- a/hw/pci/pci.c
> +++ b/hw/pci/pci.c
> @@ -2672,11 +2672,14 @@ static void pci_device_class_base_init(ObjectClass 
> *klass, void *data)
>      }
>  }
>  
> -AddressSpace *pci_device_iommu_address_space(PCIDevice *dev)
> +static void pci_device_get_iommu_bus_devfn(PCIDevice *dev,
> +                                           PCIBus **aliased_bus,
> +                                           PCIBus **piommu_bus,
> +                                           int *aliased_devfn)
>  {
>      PCIBus *bus = pci_get_bus(dev);
>      PCIBus *iommu_bus = bus;
> -    uint8_t devfn = dev->devfn;
> +    int devfn = dev->devfn;
>  
>      while (iommu_bus && !iommu_bus->iommu_ops && iommu_bus->parent_dev) {
>          PCIBus *parent_bus = pci_get_bus(iommu_bus->parent_dev);
> @@ -2717,13 +2720,66 @@ AddressSpace 
> *pci_device_iommu_address_space(PCIDevice *dev)
>  
>          iommu_bus = parent_bus;
>      }
> -    if (!pci_bus_bypass_iommu(bus) && iommu_bus->iommu_ops) {
> +
> +    assert(0 <= devfn && devfn < PCI_DEVFN_MAX);
> +    assert(iommu_bus);
> +
> +    if (pci_bus_bypass_iommu(bus) || !iommu_bus->iommu_ops) {
> +        iommu_bus = NULL;
> +    }
> +
> +    *piommu_bus = iommu_bus;
> +
> +    if (aliased_bus) {
> +        *aliased_bus = bus;
> +    }
> +
> +    if (aliased_devfn) {
> +        *aliased_devfn = devfn;
> +    }
> +}
> +
> +AddressSpace *pci_device_iommu_address_space(PCIDevice *dev)
> +{
> +    PCIBus *bus;
> +    PCIBus *iommu_bus;
> +    int devfn;
> +
> +    pci_device_get_iommu_bus_devfn(dev, &bus, &iommu_bus, &devfn);
> +    if (iommu_bus) {
>          return iommu_bus->iommu_ops->get_address_space(bus,
>                                   iommu_bus->iommu_opaque, devfn);
>      }
>      return &address_space_memory;
>  }
>  
> +int pci_device_set_iommu_device(PCIDevice *dev, HostIOMMUDevice *base_dev,
> +                                Error **errp)
> +{
> +    PCIBus *iommu_bus;
> +
> +    pci_device_get_iommu_bus_devfn(dev, NULL, &iommu_bus, NULL);
> +    if (iommu_bus && iommu_bus->iommu_ops->set_iommu_device) {
> +        return iommu_bus->iommu_ops->set_iommu_device(pci_get_bus(dev),
> +                                                      
> iommu_bus->iommu_opaque,
> +                                                      dev->devfn, base_dev,
> +                                                      errp);
> +    }
> +    return 0;
> +}
> +
> +void pci_device_unset_iommu_device(PCIDevice *dev)
> +{
> +    PCIBus *iommu_bus;
> +
> +    pci_device_get_iommu_bus_devfn(dev, NULL, &iommu_bus, NULL);
> +    if (iommu_bus && iommu_bus->iommu_ops->unset_iommu_device) {
> +        return iommu_bus->iommu_ops->unset_iommu_device(pci_get_bus(dev),
> +                                                        
> iommu_bus->iommu_opaque,
> +                                                        dev->devfn);
> +    }
> +}
> +
>  void pci_setup_iommu(PCIBus *bus, const PCIIOMMUOps *ops, void *opaque)
>  {
>      /*
> -- 
> 2.34.1