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

[CLEMENT MATHIEU--DRIF <clement.mathieu--drif@eviden.com>]

On 19/07/2024 04:47, Duan, Zhenzhong 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.
>
>
>> -----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.
>   */
Fine ;)
>
> 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
>>>