Re: [Qemu-devel] [Qemu-arm] [PATCH v7 13/20] hw/arm/smmuv3: Implement IOMMU memory region replay callback

[Linu Cherian <linuc.decode@gmail.com>]

Hi Eric,

On Fri Sep 01, 2017 at 07:21:16PM +0200, Eric Auger wrote:
> memory_region_iommu_replay() is used for VFIO integration.
> 
> However its default implementation is not adapted to SMMUv3
> IOMMU memory region. Indeed the input address range is too
> huge and its execution is too slow as it calls the translate()
> callback on each granule.
> 
> Let's implement the replay callback which hierarchically walk
> over the page table structure and notify only the segments
> that are populated with valid entries.
> 
> Signed-off-by: Eric Auger <eric.auger@redhat.com>
> ---
>  hw/arm/smmuv3.c     | 36 ++++++++++++++++++++++++++++++++++++
>  hw/arm/trace-events |  1 +
>  2 files changed, 37 insertions(+)
> 
> diff --git a/hw/arm/smmuv3.c b/hw/arm/smmuv3.c
> index 8e7d10d..c43bd93 100644
> --- a/hw/arm/smmuv3.c
> +++ b/hw/arm/smmuv3.c
> @@ -657,6 +657,41 @@ static int smmuv3_notify_entry(IOMMUTLBEntry *entry, void *private)
>      return 0;
>  }
>  
> +/* Unmap the whole notifier's range */
> +static void smmuv3_unmap_notifier_range(IOMMUNotifier *n)
> +{
> +    IOMMUTLBEntry entry;
> +    hwaddr size = n->end - n->start + 1;
> +
> +    entry.target_as = &address_space_memory;
> +    entry.iova = n->start & ~(size - 1);
> +    entry.perm = IOMMU_NONE;
> +    entry.addr_mask = size - 1;
> +
> +    memory_region_notify_one(n, &entry);
> +}
> +
> +static void smmuv3_replay(IOMMUMemoryRegion *mr, IOMMUNotifier *n)
> +{
> +    SMMUTransCfg cfg = {};
> +    int ret;
> +
> +    trace_smmuv3_replay(mr->parent_obj.name, n, n->start, n->end);
> +    smmuv3_unmap_notifier_range(n);
> +
> +    ret = smmuv3_decode_config(mr, &cfg);
> +    if (ret) {
> +        error_report("%s error decoding the configuration for iommu mr=%s",
> +                     __func__, mr->parent_obj.name);
> +    }
> 

On an invalid config being found, shouldnt we return rather than proceeding with
page table walk. For example on an invalid Stream table entry.

+
> +    if (cfg.disabled || cfg.bypassed) {
> +        return;
> +    }
> +    /* walk the page tables and replay valid entries */
> +    smmu_page_walk(&cfg, 0, (1ULL << (64 - cfg.tsz)) - 1, false,
> +                   smmuv3_notify_entry, n);
> +}
>  static void smmuv3_notify_iova_range(IOMMUMemoryRegion *mr, IOMMUNotifier *n,
>                                       uint64_t iova, size_t size)
>  {
> @@ -1095,6 +1130,7 @@ static void smmuv3_iommu_memory_region_class_init(ObjectClass *klass,
>  
>      imrc->translate = smmuv3_translate;
>      imrc->notify_flag_changed = smmuv3_notify_flag_changed;
> +    imrc->replay = smmuv3_replay;
>  }
>  
>  static const TypeInfo smmuv3_type_info = {
> diff --git a/hw/arm/trace-events b/hw/arm/trace-events
> index 4ac264d..15f84d6 100644
> --- a/hw/arm/trace-events
> +++ b/hw/arm/trace-events
> @@ -46,5 +46,6 @@ smmuv3_cfg_stage(int s, uint32_t oas, uint32_t tsz, uint64_t ttbr, bool aa64, ui
>  smmuv3_notify_flag_add(const char *iommu) "ADD SMMUNotifier node for iommu mr=%s"
>  smmuv3_notify_flag_del(const char *iommu) "DEL SMMUNotifier node for iommu mr=%s"
>  smmuv3_replay_mr(const char *name) "iommu mr=%s"
> +smmuv3_replay(const char *name, void *n, hwaddr start, hwaddr end) "iommu mr=%s notifier=%p [0x%"PRIx64",0x%"PRIx64"]"
>  smmuv3_notify_entry(hwaddr iova, hwaddr pa, hwaddr mask, int perm) "iova=0x%"PRIx64" pa=0x%" PRIx64" mask=0x%"PRIx64" perm=%d"
>  smmuv3_notify_iova_range(const char *name, uint64_t iova, size_t size, void *n) "iommu mr=%s iova=0x%"PRIx64" size=0x%lx n=%p"
> -- 
> 2.5.5
> 
> 

-- 
Linu cherian