Re: [PATCH v2 07/22] intel_iommu: add set/unset_iommu_context callback

[Auger Eric]

Yi,

On 3/30/20 6:24 AM, Liu Yi L wrote:
> This patch adds set/unset_iommu_context() impelementation in Intel
This patch implements the set/unset_iommu_context() ops for Intel vIOMMU.
> vIOMMU. For Intel platform, pass-through modules (e.g. VFIO) could
> set HostIOMMUContext to Intel vIOMMU emulator.
> 
> Cc: Kevin Tian <address@hidden>
> Cc: Jacob Pan <address@hidden>
> Cc: Peter Xu <address@hidden>
> Cc: Yi Sun <address@hidden>
> Cc: Paolo Bonzini <address@hidden>
> Cc: Richard Henderson <address@hidden>
> Cc: Eduardo Habkost <address@hidden>
> Signed-off-by: Liu Yi L <address@hidden>
> ---
>  hw/i386/intel_iommu.c         | 71 
> ++++++++++++++++++++++++++++++++++++++++---
>  include/hw/i386/intel_iommu.h | 21 ++++++++++---
>  2 files changed, 83 insertions(+), 9 deletions(-)
> 
> diff --git a/hw/i386/intel_iommu.c b/hw/i386/intel_iommu.c
> index 4b22910..fd349c6 100644
> --- a/hw/i386/intel_iommu.c
> +++ b/hw/i386/intel_iommu.c
> @@ -3354,23 +3354,33 @@ static const MemoryRegionOps vtd_mem_ir_ops = {
>      },
>  };
>  
> -VTDAddressSpace *vtd_find_add_as(IntelIOMMUState *s, PCIBus *bus, int devfn)
> +/**
> + * Fetch a VTDBus instance for given PCIBus. If no existing instance,
> + * allocate one.
> + */
> +static VTDBus *vtd_find_add_bus(IntelIOMMUState *s, PCIBus *bus)
>  {
>      uintptr_t key = (uintptr_t)bus;
>      VTDBus *vtd_bus = g_hash_table_lookup(s->vtd_as_by_busptr, &key);
> -    VTDAddressSpace *vtd_dev_as;
> -    char name[128];
>  
>      if (!vtd_bus) {
>          uintptr_t *new_key = g_malloc(sizeof(*new_key));
>          *new_key = (uintptr_t)bus;
>          /* No corresponding free() */
> -        vtd_bus = g_malloc0(sizeof(VTDBus) + sizeof(VTDAddressSpace *) * \
> -                            PCI_DEVFN_MAX);
> +        vtd_bus = g_malloc0(sizeof(VTDBus));
>          vtd_bus->bus = bus;
>          g_hash_table_insert(s->vtd_as_by_busptr, new_key, vtd_bus);
>      }
> +    return vtd_bus;
> +}
>  
> +VTDAddressSpace *vtd_find_add_as(IntelIOMMUState *s, PCIBus *bus, int devfn)
> +{
> +    VTDBus *vtd_bus;
> +    VTDAddressSpace *vtd_dev_as;
> +    char name[128];
> +
> +    vtd_bus = vtd_find_add_bus(s, bus);
>      vtd_dev_as = vtd_bus->dev_as[devfn];
>  
>      if (!vtd_dev_as) {
> @@ -3436,6 +3446,55 @@ VTDAddressSpace *vtd_find_add_as(IntelIOMMUState *s, 
> PCIBus *bus, int devfn)
>      return vtd_dev_as;
>  }
>  
> +static int vtd_dev_set_iommu_context(PCIBus *bus, void *opaque,
> +                                     int devfn,
> +                                     HostIOMMUContext *iommu_ctx)
> +{
> +    IntelIOMMUState *s = opaque;
> +    VTDBus *vtd_bus;
> +    VTDHostIOMMUContext *vtd_dev_icx;
> +
> +    assert(0 <= devfn && devfn < PCI_DEVFN_MAX);
> +
> +    vtd_bus = vtd_find_add_bus(s, bus);
> +
> +    vtd_iommu_lock(s);
> +
> +    vtd_dev_icx = vtd_bus->dev_icx[devfn];
> +
> +    assert(!vtd_dev_icx);
> +
> +    vtd_bus->dev_icx[devfn] = vtd_dev_icx =
> +                    g_malloc0(sizeof(VTDHostIOMMUContext));
> +    vtd_dev_icx->vtd_bus = vtd_bus;
> +    vtd_dev_icx->devfn = (uint8_t)devfn;
> +    vtd_dev_icx->iommu_state = s;
> +    vtd_dev_icx->iommu_ctx = iommu_ctx;
> +
> +    vtd_iommu_unlock(s);
> +
> +    return 0;
> +}
> +
> +static void vtd_dev_unset_iommu_context(PCIBus *bus, void *opaque, int devfn)
> +{
> +    IntelIOMMUState *s = opaque;
> +    VTDBus *vtd_bus;
> +    VTDHostIOMMUContext *vtd_dev_icx;
> +
> +    assert(0 <= devfn && devfn < PCI_DEVFN_MAX);
> +
> +    vtd_bus = vtd_find_add_bus(s, bus);
> +
> +    vtd_iommu_lock(s);
> +
> +    vtd_dev_icx = vtd_bus->dev_icx[devfn];
> +    g_free(vtd_dev_icx);
> +    vtd_bus->dev_icx[devfn] = NULL;
> +
> +    vtd_iommu_unlock(s);
> +}
> +
>  static uint64_t get_naturally_aligned_size(uint64_t start,
>                                             uint64_t size, int gaw)
>  {
> @@ -3731,6 +3790,8 @@ static AddressSpace *vtd_host_dma_iommu(PCIBus *bus, 
> void *opaque, int devfn)
>  
>  static PCIIOMMUOps vtd_iommu_ops = {
>      .get_address_space = vtd_host_dma_iommu,
> +    .set_iommu_context = vtd_dev_set_iommu_context,
> +    .unset_iommu_context = vtd_dev_unset_iommu_context,
>  };
>  
>  static bool vtd_decide_config(IntelIOMMUState *s, Error **errp)
> diff --git a/include/hw/i386/intel_iommu.h b/include/hw/i386/intel_iommu.h
> index 3870052..b5fefb9 100644
> --- a/include/hw/i386/intel_iommu.h
> +++ b/include/hw/i386/intel_iommu.h
> @@ -64,6 +64,7 @@ typedef union VTD_IR_TableEntry VTD_IR_TableEntry;
>  typedef union VTD_IR_MSIAddress VTD_IR_MSIAddress;
>  typedef struct VTDPASIDDirEntry VTDPASIDDirEntry;
>  typedef struct VTDPASIDEntry VTDPASIDEntry;
> +typedef struct VTDHostIOMMUContext VTDHostIOMMUContext;
>  
>  /* Context-Entry */
>  struct VTDContextEntry {
> @@ -112,10 +113,20 @@ struct VTDAddressSpace {
>      IOVATree *iova_tree;          /* Traces mapped IOVA ranges */
>  };
>  
> +struct VTDHostIOMMUContext {


> +    VTDBus *vtd_bus;
> +    uint8_t devfn;
> +    HostIOMMUContext *iommu_ctx;
I don't get why we don't have standard QOM inheritance instead of this
handle?
VTDHostContext parent_obj;

like IOMMUMemoryRegion <- MemoryRegion <- Object
> +    IntelIOMMUState *iommu_state;
> +};
> +
>  struct VTDBus {
> -    PCIBus* bus;             /* A reference to the bus to provide 
> translation for */
> +    /* A reference to the bus to provide translation for */
> +    PCIBus *bus;
>      /* A table of VTDAddressSpace objects indexed by devfn */
> -    VTDAddressSpace *dev_as[];
> +    VTDAddressSpace *dev_as[PCI_DEVFN_MAX];
> +    /* A table of VTDHostIOMMUContext objects indexed by devfn */
> +    VTDHostIOMMUContext *dev_icx[PCI_DEVFN_MAX];
At this point of the review, it is unclear to me why the context is
associated to a device. Up to now you have not explained it should. If
so why isn't it part of VTDAddressSpace?

Thanks

Eric
>  };
>  
>  struct VTDIOTLBEntry {
> @@ -269,8 +280,10 @@ struct IntelIOMMUState {
>      bool dma_drain;                 /* Whether DMA r/w draining enabled */
>  
>      /*
> -     * Protects IOMMU states in general.  Currently it protects the
> -     * per-IOMMU IOTLB cache, and context entry cache in VTDAddressSpace.
> +     * iommu_lock protects below:
> +     * - per-IOMMU IOTLB caches
> +     * - context entry cache in VTDAddressSpace
> +     * - HostIOMMUContext pointer cached in vIOMMU
>       */
>      QemuMutex iommu_lock;
>  };
>