Re: [Qemu-devel] [PATCH V3 04/10] exec: introduce address_space_get_iotlb_entry()

[Paolo Bonzini]

On 07/11/2016 08:09, Jason Wang wrote:
> This patch introduces a helper to query the iotlb entry for a
> possible iova. This will be used by later device IOTLB API to enable
> the capability for a dataplane (e.g vhost) to query the IOTLB.
> 
> Cc: Paolo Bonzini <address@hidden>
> Cc: Peter Crosthwaite <address@hidden>
> Cc: Richard Henderson <address@hidden>
> Signed-off-by: Jason Wang <address@hidden>
> ---
>  exec.c                | 33 +++++++++++++++++++++++++++++++++
>  include/exec/memory.h |  6 ++++++
>  2 files changed, 39 insertions(+)
> 
> diff --git a/exec.c b/exec.c
> index b1094c0..f108cf6 100644
> --- a/exec.c
> +++ b/exec.c
> @@ -449,6 +449,39 @@ address_space_translate_internal(AddressSpaceDispatch 
> *d, hwaddr addr, hwaddr *x
>  }
>  
>  /* Called from RCU critical section */
> +IOMMUTLBEntry address_space_get_iotlb_entry(AddressSpace *as, hwaddr addr,
> +                                            bool is_write)
> +{
> +    IOMMUTLBEntry iotlb = {0};
> +    MemoryRegionSection *section;
> +    MemoryRegion *mr;
> +
> +    for (;;) {
> +        AddressSpaceDispatch *d = atomic_rcu_read(&as->dispatch);
> +        section = address_space_lookup_region(d, addr, false);
> +        addr = addr - section->offset_within_address_space
> +               + section->offset_within_region;
> +        mr = section->mr;
> +
> +        if (!mr->iommu_ops) {
> +            break;
> +        }
> +
> +        iotlb = mr->iommu_ops->translate(mr, addr, is_write);
> +        if (!(iotlb.perm & (1 << is_write))) {
> +            iotlb.target_as = NULL;
> +            break;
> +        }
> +
> +        addr = ((iotlb.translated_addr & ~iotlb.addr_mask)
> +                | (addr & iotlb.addr_mask));
> +        as = iotlb.target_as;
> +    }
> +
> +    return iotlb;
> +}
> +
> +/* Called from RCU critical section */
>  MemoryRegion *address_space_translate(AddressSpace *as, hwaddr addr,
>                                        hwaddr *xlat, hwaddr *plen,
>                                        bool is_write)
> diff --git a/include/exec/memory.h b/include/exec/memory.h
> index 9728a2f..e605de3 100644
> --- a/include/exec/memory.h
> +++ b/include/exec/memory.h
> @@ -1404,6 +1404,12 @@ void address_space_stq_le(AddressSpace *as, hwaddr 
> addr, uint64_t val,
>  void address_space_stq_be(AddressSpace *as, hwaddr addr, uint64_t val,
>                              MemTxAttrs attrs, MemTxResult *result);
>  
> +/* address_space_get_iotlb_entry: translate an address into an IOTLB
> + * entry. Should be called from an RCU critical section.
> + */
> +IOMMUTLBEntry address_space_get_iotlb_entry(AddressSpace *as, hwaddr addr,
> +                                            bool is_write);
> +
>  /* address_space_translate: translate an address range into an address space
>   * into a MemoryRegion and an address range into that section.  Should be
>   * called from an RCU critical section, to avoid that the last reference
> 

Acked-by: Paolo Bonzini <address@hidden>