RE: [PATCH v1 03/17] intel_iommu: Add a placeholder variable for scalable modern mode

[Duan, Zhenzhong]

>-----Original Message-----
>From: CLEMENT MATHIEU--DRIF <clement.mathieu--drif@eviden.com>
>Subject: Re: [PATCH v1 03/17] intel_iommu: Add a placeholder variable for
>scalable modern mode
>
>
>
>On 18/07/2024 10:16, 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.
>>
>>
>> Add an new element scalable_mode in IntelIOMMUState to mark scalable
>> modern mode, this element will be exposed as an intel_iommu property
>> finally.
>>
>> For now, it's only a placehholder and used for cap/ecap initialization,
>> compatibility check and block host device passthrough until nesting
>> is supported.
>>
>> Signed-off-by: Yi Liu <yi.l.liu@intel.com>
>> Signed-off-by: Zhenzhong Duan <zhenzhong.duan@intel.com>
>> ---
>>   hw/i386/intel_iommu_internal.h |  2 ++
>>   include/hw/i386/intel_iommu.h  |  1 +
>>   hw/i386/intel_iommu.c          | 34 +++++++++++++++++++++++-----------
>>   3 files changed, 26 insertions(+), 11 deletions(-)
>>
>> diff --git a/hw/i386/intel_iommu_internal.h
>b/hw/i386/intel_iommu_internal.h
>> index c0ca7b372f..4e0331caba 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/include/hw/i386/intel_iommu.h
>b/include/hw/i386/intel_iommu.h
>> index 1eb05c29fc..788ed42477 100644
>> --- a/include/hw/i386/intel_iommu.h
>> +++ b/include/hw/i386/intel_iommu.h
>> @@ -262,6 +262,7 @@ struct IntelIOMMUState {
>>
>>       bool caching_mode;              /* RO - is cap CM enabled? */
>>       bool scalable_mode;             /* RO - is Scalable Mode supported? */
>> +    bool scalable_modern;           /* RO - is modern SM supported? */
>>       bool snoop_control;             /* RO - is SNP filed supported? */
>>
>>       dma_addr_t root;                /* Current root table pointer */
>> diff --git a/hw/i386/intel_iommu.c b/hw/i386/intel_iommu.c
>> index 1cff8b00ae..40cbd4a0f4 100644
>> --- a/hw/i386/intel_iommu.c
>> +++ b/hw/i386/intel_iommu.c
>> @@ -755,16 +755,20 @@ static inline bool
>vtd_is_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)
>>   {
>What about using the cap/ecap registers to know if the translation types
>are supported or not.
>Otherwise, we could add a comment to explain why we expect
>s->scalable_modern to give us enough information.

What about below:

/*
 *VTD_ECAP_FLTS in ecap is set if s->scalable_modern is true, or else 
VTD_ECAP_SLTS can be set or not depending on s->scalable_mode.
 *So it's simpler to check s->scalable_modern directly for a PASID entry type 
instead ecap bits.
 */

Thanks
Zhenzhong

>> +    X86IOMMUState *x86_iommu = X86_IOMMU_DEVICE(s);
>> +
>>       switch (VTD_PE_GET_TYPE(pe)) {
>> +    case VTD_SM_PASID_ENTRY_FLT:
>> +        return s->scalable_modern;
>>       case VTD_SM_PASID_ENTRY_SLT:
>> -        return true;
>> +        return !s->scalable_modern;
>> +    case VTD_SM_PASID_ENTRY_NESTED:
>> +        /* Not support NESTED page table type yet */
>> +        return false;
>>       case VTD_SM_PASID_ENTRY_PT:
>>           return x86_iommu->pt_supported;
>> -    case VTD_SM_PASID_ENTRY_FLT:
>> -    case VTD_SM_PASID_ENTRY_NESTED:
>>       default:
>>           /* Unknown type */
>>           return false;
>> @@ -813,7 +817,6 @@ 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;
>> @@ -827,7 +830,7 @@ 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;
>>       }
>>
>> @@ -3861,7 +3864,13 @@ static bool vtd_check_hiod(IntelIOMMUState
>*s, HostIOMMUDevice *hiod,
>>           return false;
>>       }
>>
>> -    return true;
>> +    if (!s->scalable_modern) {
>> +        /* All checks requested by VTD non-modern mode pass */
>> +        return true;
>> +    }
>> +
>> +    error_setg(errp, "host device is unsupported in scalable modern mode
>yet");
>> +    return false;
>>   }
>>
>>   static bool vtd_dev_set_iommu_device(PCIBus *bus, void *opaque, int
>devfn,
>> @@ -4084,7 +4093,10 @@ 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;
>>       }
>>
>> @@ -4251,9 +4263,9 @@ static bool vtd_decide_config(IntelIOMMUState
>*s, Error **errp)
>>           }
>>       }
>>
>> -    /* Currently only address widths supported are 39 and 48 bits */
>>       if ((s->aw_bits != VTD_HOST_AW_39BIT) &&
>> -        (s->aw_bits != VTD_HOST_AW_48BIT)) {
>> +        (s->aw_bits != VTD_HOST_AW_48BIT) &&
>> +        !s->scalable_modern) {
>>           error_setg(errp, "Supported values for aw-bits are: %d, %d",
>>                      VTD_HOST_AW_39BIT, VTD_HOST_AW_48BIT);
>>           return false;
>> --
>> 2.34.1
>>