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

[Jason Wang]

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.

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
> >