RE: [PATCH v5 18/20] intel_iommu: Introduce a property x-flts for scalable modern mode

[Duan, Zhenzhong]

Hi Clement,

>-----Original Message-----
>From: CLEMENT MATHIEU--DRIF <clement.mathieu--drif@eviden.com>
>Subject: Re: [PATCH v5 18/20] intel_iommu: Introduce a property x-flts for
>scalable modern mode
>
>Hi zhenzhong,
>Just one comment but you can add Reviewed-by: Clément Mathieu--
>Drif<clement.mathieu--drif@eviden.com>
>
>
>On 11/11/2024 09:34, Zhenzhong Duan wrote:
>> Caution: External email. Do not open attachments or click links, unless this
>email comes from a known sender and you know the content is safe.
>>
>>
>> Intel VT-d 3.0 introduces scalable mode, and it has a bunch of capabilities
>> related to scalable mode translation, thus there are multiple combinations.
>>
>> This vIOMMU implementation wants to simplify it with a new property "x-flts".
>> When enabled in scalable mode, first stage translation also known as scalable
>> modern mode is supported. When enabled in legacy mode, throw out error.
>>
>> With scalable modern mode exposed to user, also accurate the pasid entry
>> check in vtd_pe_type_check().
>>
>> Suggested-by: Jason Wang <jasowang@redhat.com>
>> Signed-off-by: Yi Liu <yi.l.liu@intel.com>
>> Signed-off-by: Yi Sun <yi.y.sun@linux.intel.com>
>> Signed-off-by: Zhenzhong Duan <zhenzhong.duan@intel.com>
>> ---
>>   hw/i386/intel_iommu_internal.h |  2 ++
>>   hw/i386/intel_iommu.c          | 28 +++++++++++++++++++---------
>>   2 files changed, 21 insertions(+), 9 deletions(-)
>>
>> diff --git a/hw/i386/intel_iommu_internal.h b/hw/i386/intel_iommu_internal.h
>> index 2c977aa7da..e8b211e8b0 100644
>> --- a/hw/i386/intel_iommu_internal.h
>> +++ b/hw/i386/intel_iommu_internal.h
>> @@ -195,6 +195,7 @@
>>   #define VTD_ECAP_PASID              (1ULL << 40)
>>   #define VTD_ECAP_SMTS               (1ULL << 43)
>>   #define VTD_ECAP_SLTS               (1ULL << 46)
>> +#define VTD_ECAP_FLTS               (1ULL << 47)
>>
>>   /* CAP_REG */
>>   /* (offset >> 4) << 24 */
>> @@ -211,6 +212,7 @@
>>   #define VTD_CAP_SLLPS               ((1ULL << 34) | (1ULL << 35))
>>   #define VTD_CAP_DRAIN_WRITE         (1ULL << 54)
>>   #define VTD_CAP_DRAIN_READ          (1ULL << 55)
>> +#define VTD_CAP_FS1GP               (1ULL << 56)
>>   #define VTD_CAP_DRAIN               (VTD_CAP_DRAIN_READ |
>VTD_CAP_DRAIN_WRITE)
>>   #define VTD_CAP_CM                  (1ULL << 7)
>>   #define VTD_PASID_ID_SHIFT          20
>> diff --git a/hw/i386/intel_iommu.c b/hw/i386/intel_iommu.c
>> index b921793c3a..a7a81aebee 100644
>> --- a/hw/i386/intel_iommu.c
>> +++ b/hw/i386/intel_iommu.c
>> @@ -803,16 +803,18 @@ static inline bool
>vtd_is_fl_level_supported(IntelIOMMUState *s, uint32_t level)
>>   }
>>
>>   /* Return true if check passed, otherwise false */
>> -static inline bool vtd_pe_type_check(X86IOMMUState *x86_iommu,
>> -                                     VTDPASIDEntry *pe)
>> +static inline bool vtd_pe_type_check(IntelIOMMUState *s, VTDPASIDEntry *pe)
>>   {
>>       switch (VTD_PE_GET_TYPE(pe)) {
>> -    case VTD_SM_PASID_ENTRY_SLT:
>> -        return true;
>> -    case VTD_SM_PASID_ENTRY_PT:
>> -        return x86_iommu->pt_supported;
>>       case VTD_SM_PASID_ENTRY_FLT:
>> +        return !!(s->ecap & VTD_ECAP_FLTS);
>> +    case VTD_SM_PASID_ENTRY_SLT:
>> +        return !!(s->ecap & VTD_ECAP_SLTS);
>>       case VTD_SM_PASID_ENTRY_NESTED:
>> +        /* Not support NESTED page table type yet */
>> +        return false;
>> +    case VTD_SM_PASID_ENTRY_PT:
>> +        return !!(s->ecap & VTD_ECAP_PT);
>>       default:
>>           /* Unknown type */
>>           return false;
>> @@ -861,7 +863,6 @@ static int
>vtd_get_pe_in_pasid_leaf_table(IntelIOMMUState *s,
>>       uint8_t pgtt;
>>       uint32_t index;
>>       dma_addr_t entry_size;
>> -    X86IOMMUState *x86_iommu = X86_IOMMU_DEVICE(s);
>>
>>       index = VTD_PASID_TABLE_INDEX(pasid);
>>       entry_size = VTD_PASID_ENTRY_SIZE;
>> @@ -875,7 +876,7 @@ static int
>vtd_get_pe_in_pasid_leaf_table(IntelIOMMUState *s,
>>       }
>>
>>       /* Do translation type check */
>> -    if (!vtd_pe_type_check(x86_iommu, pe)) {
>> +    if (!vtd_pe_type_check(s, pe)) {
>>           return -VTD_FR_PASID_TABLE_ENTRY_INV;
>>       }
>>
>> @@ -3827,6 +3828,7 @@ static Property vtd_properties[] = {
>>                         VTD_HOST_ADDRESS_WIDTH),
>>       DEFINE_PROP_BOOL("caching-mode", IntelIOMMUState, caching_mode,
>FALSE),
>>       DEFINE_PROP_BOOL("x-scalable-mode", IntelIOMMUState, scalable_mode,
>FALSE),
>> +    DEFINE_PROP_BOOL("x-flts", IntelIOMMUState, scalable_modern, FALSE),
>>       DEFINE_PROP_BOOL("snoop-control", IntelIOMMUState, snoop_control,
>false),
>>       DEFINE_PROP_BOOL("x-pasid-mode", IntelIOMMUState, pasid, false),
>>       DEFINE_PROP_BOOL("dma-drain", IntelIOMMUState, dma_drain, true),
>> @@ -4558,7 +4560,10 @@ static void vtd_cap_init(IntelIOMMUState *s)
>>       }
>>
>>       /* TODO: read cap/ecap from host to decide which cap to be exposed. */
>> -    if (s->scalable_mode) {
>> +    if (s->scalable_modern) {
>> +        s->ecap |= VTD_ECAP_SMTS | VTD_ECAP_FLTS;
>> +        s->cap |= VTD_CAP_FS1GP;
>> +    } else if (s->scalable_mode) {
>>           s->ecap |= VTD_ECAP_SMTS | VTD_ECAP_SRS | VTD_ECAP_SLTS;
>>       }
>>
>> @@ -4737,6 +4742,11 @@ static bool vtd_decide_config(IntelIOMMUState *s,
>Error **errp)
>>           }
>>       }
>>
>> +    if (!s->scalable_mode && s->scalable_modern) {
>> +        error_setg(errp, "Legacy mode: not support x-flts=on");
>The error message should be "x-flts=on not supported in legacy mode" or
>even "x-flts is only available in scalable mode" as there is no FLT in
>legacy mode

OK, will do.
But I'm not quite clear of the difference between
"Legacy mode: not support x-flts=on" and "x-flts=on not supported in legacy 
mode".
Is it because the later looks more formal or the former has ambiguity?

Thanks
Zhenzhong