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

[Jason Wang]

On Mon, Dec 9, 2024 at 2:15 PM CLEMENT MATHIEU--DRIF
<clement.mathieu--drif@eviden.com> wrote:
>
>
>
> On 09/12/2024 04:13, Jason Wang 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.
> >
> >
> > On Wed, Dec 4, 2024 at 2:14 PM CLEMENT MATHIEU--DRIF
> > <clement.mathieu--drif@eviden.com> wrote:
> >>
> >>
> >>
> >> On 04/12/2024 04:34, Jason Wang 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.
> >>>
> >>>
> >>> On Mon, Nov 11, 2024 at 4:39 PM Zhenzhong Duan <zhenzhong.duan@intel.com> 
> >>> wrote:
> >>>>
> >>>> 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");
> >>>
> >>> This seems to be wired, should we say "scalable mode is needed for
> >>> scalable modern mode"?
> >>
> >> Hi Jason,
> >>
> >> We agreed to use the following sentence: "x-flts is only available in
> >> scalable mode"
> >>
> >> Does it look goot to you?
> >
> > Better but if we add more features to the scalable modern, we need to
> > change the error message here.
>
> Hi Jason
>
> Maybe the weirdness comes from the fact that x-flts on the command line
> is mapped to scalable_modern in the code?

Yes, actually the code checks if scalable mode is enabled if scalable
modern is enabled. But this is inconsistent with the error message
(though x-flts was implied there probably).

Thanks


>
> Thanks
>  >cmd
>
> >
> > Thanks
> >
> >>
> >> Thanks
> >> cmd
> >>
> >>>
> >>>> +        return false;
> >>>> +    }
> >>>> +
> >>>>        if (!s->scalable_modern && s->aw_bits != VTD_HOST_AW_39BIT &&
> >>>>            s->aw_bits != VTD_HOST_AW_48BIT) {
> >>>>            error_setg(errp, "%s mode: supported values for aw-bits are: 
> >>>> %d, %d",
> >>>> --
> >>>> 2.34.1
> >>>>
> >>>
> >>> Thanks
> >>>
> >