Re: [PATCH ats_vtd v5 19/22] memory: add an API for ATS support

[Yi Liu <yi.l.liu@intel.com>]

On 2024/7/2 13:52, CLEMENT MATHIEU--DRIF wrote:
> From: Clément Mathieu--Drif <clement.mathieu--drif@eviden.com>
> 
> IOMMU have to implement iommu_ats_request_translation to support ATS.
> 
> Devices can use IOMMU_TLB_ENTRY_TRANSLATION_ERROR to check the tlb
> entries returned by a translation request.
> 
> Signed-off-by: Clément Mathieu--Drif <clement.mathieu--drif@eviden.com>
> ---
>   include/exec/memory.h | 26 ++++++++++++++++++++++++++
>   system/memory.c       | 20 ++++++++++++++++++++
>   2 files changed, 46 insertions(+)
> 
> diff --git a/include/exec/memory.h b/include/exec/memory.h
> index 003ee06610..48555c87c6 100644
> --- a/include/exec/memory.h
> +++ b/include/exec/memory.h
> @@ -148,6 +148,10 @@ struct IOMMUTLBEntry {
>       uint32_t         pasid;
>   };
>   
> +/* Check if an IOMMU TLB entry indicates a translation error */
> +#define IOMMU_TLB_ENTRY_TRANSLATION_ERROR(entry) ((((entry)->perm) & IOMMU_RW) \
> +                                                    == IOMMU_NONE)
> +
>   /*
>    * Bitmap for different IOMMUNotifier capabilities. Each notifier can
>    * register with one or multiple IOMMU Notifier capability bit(s).
> @@ -571,6 +575,20 @@ struct IOMMUMemoryRegionClass {
>        int (*iommu_set_iova_ranges)(IOMMUMemoryRegion *iommu,
>                                     GList *iova_ranges,
>                                     Error **errp);
> +
> +    /**
> +     * @iommu_ats_request_translation:
> +     * This method must be implemented if the IOMMU has ATS enabled
> +     *
> +     * @see pci_ats_request_translation_pasid
> +     */
> +    ssize_t (*iommu_ats_request_translation)(IOMMUMemoryRegion *iommu,
> +                                             bool priv_req, bool exec_req,
> +                                             hwaddr addr, size_t length,
> +                                             bool no_write,
> +                                             IOMMUTLBEntry *result,
> +                                             size_t result_length,
> +                                             uint32_t *err_count);
>   };
>   

I'm not quite understanding why the existing translate() does not work.
Could you elaborate?

>   typedef struct RamDiscardListener RamDiscardListener;
> @@ -1926,6 +1944,14 @@ void memory_region_iommu_replay(IOMMUMemoryRegion *iommu_mr, IOMMUNotifier *n);
>   void memory_region_unregister_iommu_notifier(MemoryRegion *mr,
>                                                IOMMUNotifier *n);
>   
> +ssize_t memory_region_iommu_ats_request_translation(IOMMUMemoryRegion *iommu_mr,
> +                                                bool priv_req, bool exec_req,
> +                                                hwaddr addr, size_t length,
> +                                                bool no_write,
> +                                                IOMMUTLBEntry *result,
> +                                                size_t result_length,
> +                                                uint32_t *err_count);
> +
>   /**
>    * memory_region_iommu_get_attr: return an IOMMU attr if get_attr() is
>    * defined on the IOMMU.
> diff --git a/system/memory.c b/system/memory.c
> index 74cd73ebc7..8268df7bf5 100644
> --- a/system/memory.c
> +++ b/system/memory.c
> @@ -2005,6 +2005,26 @@ void memory_region_unregister_iommu_notifier(MemoryRegion *mr,
>       memory_region_update_iommu_notify_flags(iommu_mr, NULL);
>   }
>   
> +ssize_t memory_region_iommu_ats_request_translation(IOMMUMemoryRegion *iommu_mr,
> +                                                    bool priv_req,
> +                                                    bool exec_req,
> +                                                    hwaddr addr, size_t length,
> +                                                    bool no_write,
> +                                                    IOMMUTLBEntry *result,
> +                                                    size_t result_length,
> +                                                    uint32_t *err_count)
> +{
> +    IOMMUMemoryRegionClass *imrc = memory_region_get_iommu_class_nocheck(iommu_mr);
> +
> +    if (!imrc->iommu_ats_request_translation) {
> +        return -ENODEV;
> +    }
> +
> +    return imrc->iommu_ats_request_translation(iommu_mr, priv_req, exec_req,
> +                                               addr, length, no_write, result,
> +                                               result_length, err_count);
> +}
> +
>   void memory_region_notify_iommu_one(IOMMUNotifier *notifier,
>                                       IOMMUTLBEvent *event)
>   {

-- 
Regards,
Yi Liu