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

[CLEMENT MATHIEU--DRIF]

On 03/07/2024 14:14, Yi Liu wrote:
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> 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?
We need more parameters than what the existing translation function has.
This one is designed to get translations for a range instead of just a 
single address.
The main purpose is to expose an API that has the same parameters as a 
PCIe translation request message
and to give all the information the IOMMU needs to process the request.
>
>>   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