Re: [Qemu-devel] [PATCH qemu v17 06/12] memory: Add reporting of supported page sizes

[Alex Williamson]

On Wed,  1 Jun 2016 18:57:37 +1000
Alexey Kardashevskiy <address@hidden> wrote:

> Every IOMMU has some granularity which MemoryRegionIOMMUOps::translate
> uses when translating, however this information is not available outside
> the translate context for various checks.
> 
> This adds a get_page_sizes callback to MemoryRegionIOMMUOps and
> a wrapper for it so IOMMU users (such as VFIO) can know the actual
> page size(s) used by an IOMMU.
> 
> As IOMMU MR represents a guest IOMMU, this uses TARGET_PAGE_SIZE
> as fallback.
> 
> This removes vfio_container_granularity() and uses new helper in
> memory_region_iommu_replay() when replaying IOMMU mappings on added
> IOMMU memory region.
> 
> Signed-off-by: Alexey Kardashevskiy <address@hidden>
> Reviewed-by: David Gibson <address@hidden>
> ---
> Changes:
> v16:
> * used memory_region_iommu_get_page_sizes() instead of
> mr->iommu_ops->get_page_sizes() in memory_region_iommu_replay()
> 
> v15:
> * s/qemu_real_host_page_size/TARGET_PAGE_SIZE/ in 
> memory_region_iommu_get_page_sizes
> 
> v14:
> * removed vfio_container_granularity(), changed memory_region_iommu_replay()
> 
> v4:
> * s/1<<TARGET_PAGE_BITS/qemu_real_host_page_size/
> ---
>  hw/ppc/spapr_iommu.c  |  8 ++++++++
>  hw/vfio/common.c      |  6 ------
>  include/exec/memory.h | 18 ++++++++++++++----
>  memory.c              | 16 +++++++++++++---
>  4 files changed, 35 insertions(+), 13 deletions(-)
> 
> diff --git a/hw/ppc/spapr_iommu.c b/hw/ppc/spapr_iommu.c
> index a3cc572..90a45c0 100644
> --- a/hw/ppc/spapr_iommu.c
> +++ b/hw/ppc/spapr_iommu.c
> @@ -149,6 +149,13 @@ static void spapr_tce_table_pre_save(void *opaque)
>                                 tcet->bus_offset, tcet->page_shift);
>  }
>  
> +static uint64_t spapr_tce_get_page_sizes(MemoryRegion *iommu)
> +{
> +    sPAPRTCETable *tcet = container_of(iommu, sPAPRTCETable, iommu);
> +
> +    return 1ULL << tcet->page_shift;
> +}
> +
>  static int spapr_tce_table_post_load(void *opaque, int version_id)
>  {
>      sPAPRTCETable *tcet = SPAPR_TCE_TABLE(opaque);
> @@ -228,6 +235,7 @@ static const VMStateDescription vmstate_spapr_tce_table = 
> {
>  
>  static MemoryRegionIOMMUOps spapr_iommu_ops = {
>      .translate = spapr_tce_translate_iommu,
> +    .get_page_sizes = spapr_tce_get_page_sizes,
>  };
>  
>  static int spapr_tce_table_realize(DeviceState *dev)
> diff --git a/hw/vfio/common.c b/hw/vfio/common.c
> index e51ed3a..f1a12b0 100644
> --- a/hw/vfio/common.c
> +++ b/hw/vfio/common.c
> @@ -322,11 +322,6 @@ out:
>      rcu_read_unlock();
>  }
>  
> -static hwaddr vfio_container_granularity(VFIOContainer *container)
> -{
> -    return (hwaddr)1 << ctz64(container->iova_pgsizes);
> -}
> -
>  static void vfio_listener_region_add(MemoryListener *listener,
>                                       MemoryRegionSection *section)
>  {
> @@ -394,7 +389,6 @@ static void vfio_listener_region_add(MemoryListener 
> *listener,
>  
>          memory_region_register_iommu_notifier(giommu->iommu, &giommu->n);
>          memory_region_iommu_replay(giommu->iommu, &giommu->n,
> -                                   vfio_container_granularity(container),
>                                     false);

nit, fix the now unnecessary line wrap.  Otherwise,

Acked-by: Alex Williamson <address@hidden>

>  
>          return;
> diff --git a/include/exec/memory.h b/include/exec/memory.h
> index f649697..bd9625f 100644
> --- a/include/exec/memory.h
> +++ b/include/exec/memory.h
> @@ -149,6 +149,8 @@ typedef struct MemoryRegionIOMMUOps MemoryRegionIOMMUOps;
>  struct MemoryRegionIOMMUOps {
>      /* Return a TLB entry that contains a given address. */
>      IOMMUTLBEntry (*translate)(MemoryRegion *iommu, hwaddr addr, bool 
> is_write);
> +    /* Returns supported page sizes */
> +    uint64_t (*get_page_sizes)(MemoryRegion *iommu);
>  };
>  
>  typedef struct CoalescedMemoryRange CoalescedMemoryRange;
> @@ -571,6 +573,15 @@ static inline bool memory_region_is_iommu(MemoryRegion 
> *mr)
>  
>  
>  /**
> + * memory_region_iommu_get_page_sizes: get supported page sizes in an iommu
> + *
> + * Returns %bitmap of supported page sizes for an iommu.
> + *
> + * @mr: the memory region being queried
> + */
> +uint64_t memory_region_iommu_get_page_sizes(MemoryRegion *mr);
> +
> +/**
>   * memory_region_notify_iommu: notify a change in an IOMMU translation entry.
>   *
>   * @mr: the memory region that was changed
> @@ -594,16 +605,15 @@ void memory_region_register_iommu_notifier(MemoryRegion 
> *mr, Notifier *n);
>  
>  /**
>   * memory_region_iommu_replay: replay existing IOMMU translations to
> - * a notifier
> + * a notifier with the minimum page granularity returned by
> + * mr->iommu_ops->get_page_sizes().
>   *
>   * @mr: the memory region to observe
>   * @n: the notifier to which to replay iommu mappings
> - * @granularity: Minimum page granularity to replay notifications for
>   * @is_write: Whether to treat the replay as a translate "write"
>   *     through the iommu
>   */
> -void memory_region_iommu_replay(MemoryRegion *mr, Notifier *n,
> -                                hwaddr granularity, bool is_write);
> +void memory_region_iommu_replay(MemoryRegion *mr, Notifier *n, bool 
> is_write);
>  
>  /**
>   * memory_region_unregister_iommu_notifier: unregister a notifier for
> diff --git a/memory.c b/memory.c
> index 4e3cda8..761ae92 100644
> --- a/memory.c
> +++ b/memory.c
> @@ -1500,12 +1500,22 @@ void 
> memory_region_register_iommu_notifier(MemoryRegion *mr, Notifier *n)
>      notifier_list_add(&mr->iommu_notify, n);
>  }
>  
> -void memory_region_iommu_replay(MemoryRegion *mr, Notifier *n,
> -                                hwaddr granularity, bool is_write)
> +uint64_t memory_region_iommu_get_page_sizes(MemoryRegion *mr)
>  {
> -    hwaddr addr;
> +    assert(memory_region_is_iommu(mr));
> +    if (mr->iommu_ops && mr->iommu_ops->get_page_sizes) {
> +        return mr->iommu_ops->get_page_sizes(mr);
> +    }
> +    return TARGET_PAGE_SIZE;
> +}
> +
> +void memory_region_iommu_replay(MemoryRegion *mr, Notifier *n, bool is_write)
> +{
> +    hwaddr addr, granularity;
>      IOMMUTLBEntry iotlb;
>  
> +    granularity = (hwaddr)1 << ctz64(memory_region_iommu_get_page_sizes(mr));
> +
>      for (addr = 0; addr < memory_region_size(mr); addr += granularity) {
>          iotlb = mr->iommu_ops->translate(mr, addr, is_write);
>          if (iotlb.perm != IOMMU_NONE) {