Re: [PATCH v4 01/15] hw/pci: Add a pci_setup_iommu_ops() helper

[Eric Auger <eauger@redhat.com>]

Hi Joao,

On 6/22/23 23:48, Joao Martins wrote:
> From: Yi Liu <yi.l.liu@intel.com>
> 
> Add a pci_setup_iommu_ops() that uses a newly added structure
> (PCIIOMMUOps) instead of using PCIIOMMUFunc. The old pci_setup_iommu()
> that uses PCIIOMMUFunc is still kept for other IOMMUs to get an
> an address space for a PCI device in vendor specific way.
double 'an'
> 
> In preparation to expand to supplying vIOMMU attributes, add a
> alternate helper pci_setup_iommu_ops() to setup the PCI device IOMMU.
> For now the PCIIOMMUOps just defines the address_space, but it will
> be extended to have another callback.
> 
> Signed-off-by: Yi Liu <yi.l.liu@intel.com>
> [joao: Massage commit message and subject, and make it a complementary
> rather than changing every single consumer of pci_setup_iommu()]
> Signed-off-by: Joao Martins <joao.m.martins@oracle.com>
> ---
> v1: https://lore.kernel.org/all/20210302203827.437645-5-yi.l.liu@intel.com/
> ---
>  include/hw/pci/pci.h     |  7 +++++++
>  include/hw/pci/pci_bus.h |  1 +
>  hw/pci/pci.c             | 26 +++++++++++++++++++++++---
>  3 files changed, 31 insertions(+), 3 deletions(-)
> 
> diff --git a/include/hw/pci/pci.h b/include/hw/pci/pci.h
> index e6d0574a2999..f59aef5a329a 100644
> --- a/include/hw/pci/pci.h
> +++ b/include/hw/pci/pci.h
> @@ -368,6 +368,13 @@ typedef AddressSpace *(*PCIIOMMUFunc)(PCIBus *, void *, int);
>  AddressSpace *pci_device_iommu_address_space(PCIDevice *dev);
>  void pci_setup_iommu(PCIBus *bus, PCIIOMMUFunc fn, void *opaque);
>  
> +typedef struct PCIIOMMUOps PCIIOMMUOps;
> +struct PCIIOMMUOps {
> +    AddressSpace * (*get_address_space)(PCIBus *bus,
> +                                void *opaque, int32_t devfn);
> +};
> +void pci_setup_iommu_ops(PCIBus *bus, const PCIIOMMUOps *iommu_ops, void *opaque);
> +
>  pcibus_t pci_bar_address(PCIDevice *d,
>                           int reg, uint8_t type, pcibus_t size);
>  
> diff --git a/include/hw/pci/pci_bus.h b/include/hw/pci/pci_bus.h
> index 56531759578f..fb770b236d69 100644
> --- a/include/hw/pci/pci_bus.h
> +++ b/include/hw/pci/pci_bus.h
> @@ -35,6 +35,7 @@ struct PCIBus {
>      enum PCIBusFlags flags;
>      PCIIOMMUFunc iommu_fn;
>      void *iommu_opaque;
> +    const PCIIOMMUOps *iommu_ops;
>      uint8_t devfn_min;
>      uint32_t slot_reserved_mask;
>      pci_set_irq_fn set_irq;
> diff --git a/hw/pci/pci.c b/hw/pci/pci.c
> index bf38905b7dc0..4e32c09e81d6 100644
> --- a/hw/pci/pci.c
> +++ b/hw/pci/pci.c
> @@ -2639,7 +2639,15 @@ AddressSpace *pci_device_iommu_address_space(PCIDevice *dev)
>      PCIBus *iommu_bus = bus;
>      uint8_t devfn = dev->devfn;
>  
> -    while (iommu_bus && !iommu_bus->iommu_fn && iommu_bus->parent_dev) {
> +    /*
> +     * get_address_space() callback is mandatory when iommu uses
> +     * pci_setup_iommu_ops(), so needs to ensure its presence in
> +     * the iommu_bus search.
the fact that it is mandatory should also be documented along with the
PCIIOMMUOps struct definition and enforced at  pci_setup_iommu_ops()
removing the need for checking iommu_bus->iommu_ops->get_address_space
> +     */
> +    while (iommu_bus &&
> +           !(iommu_bus->iommu_fn ||
> +            (iommu_bus->iommu_ops && iommu_bus->iommu_ops->get_address_space)) &&
> +           iommu_bus->parent_dev) {
>          PCIBus *parent_bus = pci_get_bus(iommu_bus->parent_dev);
>  
>          /*
> @@ -2678,8 +2686,14 @@ AddressSpace *pci_device_iommu_address_space(PCIDevice *dev)
>  
>          iommu_bus = parent_bus;
>      }
> -    if (!pci_bus_bypass_iommu(bus) && iommu_bus && iommu_bus->iommu_fn) {
> -        return iommu_bus->iommu_fn(bus, iommu_bus->iommu_opaque, devfn);
> +    if (!pci_bus_bypass_iommu(bus) && iommu_bus) {
> +        if (iommu_bus->iommu_fn) {
> +           return iommu_bus->iommu_fn(bus, iommu_bus->iommu_opaque, devfn);
> +        } else if (iommu_bus->iommu_ops &&
> +                   iommu_bus->iommu_ops->get_address_space) {
> +           return iommu_bus->iommu_ops->get_address_space(bus,
> +                                           iommu_bus->iommu_opaque, devfn);
> +        }
>      }
>      return &address_space_memory;
>  }
> @@ -2690,6 +2704,12 @@ void pci_setup_iommu(PCIBus *bus, PCIIOMMUFunc fn, void *opaque)
>      bus->iommu_opaque = opaque;
>  }
>  
> +void pci_setup_iommu_ops(PCIBus *bus, const PCIIOMMUOps *ops, void *opaque)
> +{
> +    bus->iommu_ops = ops;
> +    bus->iommu_opaque = opaque;
maybe assert if both iommu_fn and iommu_ops are set to make sure the
conversion is not done partially? If I understand it correctly either of
those 2 ops should be set and not both.
> +}
> +
>  static void pci_dev_get_w64(PCIBus *b, PCIDevice *dev, void *opaque)
>  {
>      Range *range = opaque;

Thanks

Eric