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SubjectRe: [PATCH v6 05/22] iommu: Introduce cache_invalidate API
On Thu, 21 Mar 2019 15:32:45 +0100
Auger Eric <eric.auger@redhat.com> wrote:

> Hi jean, Jacob,
>
> On 3/21/19 3:13 PM, Jean-Philippe Brucker wrote:
> > On 21/03/2019 13:54, Auger Eric wrote:
> >> Hi Jacob, Jean-Philippe,
> >>
> >> On 3/20/19 5:50 PM, Jean-Philippe Brucker wrote:
> >>> On 20/03/2019 16:37, Jacob Pan wrote:
> >>> [...]
> >>>>> +struct iommu_inv_addr_info {
> >>>>> +#define IOMMU_INV_ADDR_FLAGS_PASID (1 << 0)
> >>>>> +#define IOMMU_INV_ADDR_FLAGS_ARCHID (1 << 1)
> >>>>> +#define IOMMU_INV_ADDR_FLAGS_LEAF (1 << 2)
> >>>>> + __u32 flags;
> >>>>> + __u32 archid;
> >>>>> + __u64 pasid;
> >>>>> + __u64 addr;
> >>>>> + __u64 granule_size;
> >>>>> + __u64 nb_granules;
> >>>>> +};
> >>>>> +
> >>>>> +/**
> >>>>> + * First level/stage invalidation information
> >>>>> + * @cache: bitfield that allows to select which caches to
> >>>>> invalidate
> >>>>> + * @granularity: defines the lowest granularity used for the
> >>>>> invalidation:
> >>>>> + * domain > pasid > addr
> >>>>> + *
> >>>>> + * Not all the combinations of cache/granularity make sense:
> >>>>> + *
> >>>>> + * type | DEV_IOTLB | IOTLB |
> >>>>> PASID |
> >>>>> + * granularity | | |
> >>>>> cache |
> >>>>> + *
> >>>>> -------------+---------------+---------------+---------------+
> >>>>> + * DOMAIN | N/A | Y |
> >>>>> Y |
> >>>>> + * PASID | Y | Y |
> >>>>> Y |
> >>>>> + * ADDR | Y | Y |
> >>>>> N/A |
> >>>>> + */
> >>>>> +struct iommu_cache_invalidate_info {
> >>>>> +#define IOMMU_CACHE_INVALIDATE_INFO_VERSION_1 1
> >>>>> + __u32 version;
> >>>>> +/* IOMMU paging structure cache */
> >>>>> +#define IOMMU_CACHE_INV_TYPE_IOTLB (1 << 0) /* IOMMU
> >>>>> IOTLB */ +#define IOMMU_CACHE_INV_TYPE_DEV_IOTLB (1 <<
> >>>>> 1) /* Device IOTLB */ +#define
> >>>>> IOMMU_CACHE_INV_TYPE_PASID (1 << 2) /* PASID cache */
> >>>> Just a clarification, this used to be an enum. You do intend to
> >>>> issue a single invalidation request on multiple cache types?
> >>>> Perhaps for virtio-IOMMU? I only see a single cache type in your
> >>>> patch #14. For VT-d we plan to issue one cache type at a time
> >>>> for now. So this format works for us.
> >>>
> >>> Yes for virtio-iommu I'd like as little overhead as possible,
> >>> which means a single invalidation message to hit both IOTLB and
> >>> ATC at once, and the ability to specify multiple pages with
> >>> @nb_granules.
> >> The original request/explanation from Jean-Philippe can be found
> >> here: https://lkml.org/lkml/2019/1/28/1497
> >>
> >>>
> >>>> However, if multiple cache types are issued in a single
> >>>> invalidation. They must share a single granularity, not all
> >>>> combinations are valid. e.g. dev IOTLB does not support domain
> >>>> granularity. Just a reminder, not an issue. Driver could filter
> >>>> out invalid combinations.
> >> Sure I will add a comment about this restriction.
> >>>
> >>> Agreed. Even the core could filter out invalid combinations based
> >>> on the table above: IOTLB and domain granularity are N/A.
> >> I don't get this sentence. What about vtd IOTLB domain-selective
> >> invalidation:
> >
> > My mistake: I meant dev-IOTLB and domain granularity are N/A
>
> Ah OK, no worries.
>
> How do we proceed further with those user APIs? Besides the comment to
> be added above and previous suggestion from Jean ("Invalidations by
> @granularity use field ...), have we reached a consensus now on:
>
> - attach/detach_pasid_table
> - cache_invalidate
> - fault data and fault report API?
>
These APIs are sufficient for today's VT-d use and leave enough space
for extension. E.g. new fault reasons.

I have cherry picked the above APIs from your patchset to enable VT-d
nested translation. Going forward, I will reuse these until they get
merged.

> If not, please let me know.
>
> Thanks
>
> Eric
>
>
> >
> > Thanks,
> > Jean
> >
> >> "
> >> • IOTLB entries caching mappings associated with the specified
> >> domain-id are invalidated.
> >> • Paging-structure-cache entries caching mappings associated with
> >> the specified domain-id are invalidated.
> >> "
> >>
> >> Thanks
> >>
> >> Eric
> >>
> >>>
> >>> Thanks,
> >>> Jean
> >>>
> >>>>
> >>>>> + __u8 cache;
> >>>>> + __u8 granularity;
> >>>>> + __u8 padding[2];
> >>>>> + union {
> >>>>> + __u64 pasid;
> >>>>> + struct iommu_inv_addr_info addr_info;
> >>>>> + };
> >>>>> +};
> >>>>> +
> >>>>> +
> >>>>> #endif /* _UAPI_IOMMU_H */
> >>>>
> >>>> [Jacob Pan]
> >>>> _______________________________________________
> >>>> iommu mailing list
> >>>> iommu@lists.linux-foundation.org
> >>>> https://lists.linuxfoundation.org/mailman/listinfo/iommu
> >>>>
> >>>
> >> _______________________________________________
> >> iommu mailing list
> >> iommu@lists.linux-foundation.org
> >> https://lists.linuxfoundation.org/mailman/listinfo/iommu
> >>
> >

[Jacob Pan]

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