RE: [PATCH V10 08/11] iommu/vt-d: Add svm/sva invalidate function

[Tian, Kevin]

> From: Jacob Pan <jacob.jun.pan@xxxxxxxxxxxxxxx>
> Sent: Saturday, March 21, 2020 7:28 AM
> 
> When Shared Virtual Address (SVA) is enabled for a guest OS via
> vIOMMU, we need to provide invalidation support at IOMMU API and driver
> level. This patch adds Intel VT-d specific function to implement
> iommu passdown invalidate API for shared virtual address.
> 
> The use case is for supporting caching structure invalidation
> of assigned SVM capable devices. Emulated IOMMU exposes queue

emulated IOMMU -> vIOMMU, since virito-iommu could use the
interface as well.

> invalidation capability and passes down all descriptors from the guest
> to the physical IOMMU.
> 
> The assumption is that guest to host device ID mapping should be
> resolved prior to calling IOMMU driver. Based on the device handle,
> host IOMMU driver can replace certain fields before submit to the
> invalidation queue.
> 
> ---
> v7 review fixed in v10
> ---
> 
> Signed-off-by: Jacob Pan <jacob.jun.pan@xxxxxxxxxxxxxxx>
> Signed-off-by: Ashok Raj <ashok.raj@xxxxxxxxx>
> Signed-off-by: Liu, Yi L <yi.l.liu@xxxxxxxxx>
> ---
>  drivers/iommu/intel-iommu.c | 182
> ++++++++++++++++++++++++++++++++++++++++++++
>  1 file changed, 182 insertions(+)
> 
> diff --git a/drivers/iommu/intel-iommu.c b/drivers/iommu/intel-iommu.c
> index b1477cd423dd..a76afb0fd51a 100644
> --- a/drivers/iommu/intel-iommu.c
> +++ b/drivers/iommu/intel-iommu.c
> @@ -5619,6 +5619,187 @@ static void
> intel_iommu_aux_detach_device(struct iommu_domain *domain,
>  	aux_domain_remove_dev(to_dmar_domain(domain), dev);
>  }
> 
> +/*
> + * 2D array for converting and sanitizing IOMMU generic TLB granularity to
> + * VT-d granularity. Invalidation is typically included in the unmap operation
> + * as a result of DMA or VFIO unmap. However, for assigned devices guest
> + * owns the first level page tables. Invalidations of translation caches in the
> + * guest are trapped and passed down to the host.
> + *
> + * vIOMMU in the guest will only expose first level page tables, therefore
> + * we do not include IOTLB granularity for request without PASID (second
> level).

I would revise above as "We do not support IOTLB granularity for request 
without PASID (second level), therefore any vIOMMU implementation that
exposes the SVA capability to the guest should only expose the first level
page tables, implying all invalidation requests from the guest will include
a valid PASID"

> + *
> + * For example, to find the VT-d granularity encoding for IOTLB
> + * type and page selective granularity within PASID:
> + * X: indexed by iommu cache type
> + * Y: indexed by enum iommu_inv_granularity
> + * [IOMMU_CACHE_INV_TYPE_IOTLB][IOMMU_INV_GRANU_ADDR]
> + *
> + * Granu_map array indicates validity of the table. 1: valid, 0: invalid
> + *
> + */
> +const static int
> inv_type_granu_map[IOMMU_CACHE_INV_TYPE_NR][IOMMU_INV_GRANU_
> NR] = {
> +	/*
> +	 * PASID based IOTLB invalidation: PASID selective (per PASID),
> +	 * page selective (address granularity)
> +	 */
> +	{0, 1, 1},
> +	/* PASID based dev TLBs, only support all PASIDs or single PASID */
> +	{1, 1, 0},

Is this combination correct? when single PASID is being specified, it is 
essentially a page-selective invalidation since you need provide Address
and Size. 

> +	/* PASID cache */

PASID cache is fully managed by the host. Guest PASID cache invalidation
is interpreted by vIOMMU for bind and unbind operations. I don't think
we should accept any PASID cache invalidation from userspace or guest.

> +	{1, 1, 0}
> +};
> +
> +const static int
> inv_type_granu_table[IOMMU_CACHE_INV_TYPE_NR][IOMMU_INV_GRANU
> _NR] = {
> +	/* PASID based IOTLB */
> +	{0, QI_GRAN_NONG_PASID, QI_GRAN_PSI_PASID},
> +	/* PASID based dev TLBs */
> +	{QI_DEV_IOTLB_GRAN_ALL, QI_DEV_IOTLB_GRAN_PASID_SEL, 0},
> +	/* PASID cache */
> +	{QI_PC_ALL_PASIDS, QI_PC_PASID_SEL, 0},
> +};
> +
> +static inline int to_vtd_granularity(int type, int granu, int *vtd_granu)
> +{
> +	if (type >= IOMMU_CACHE_INV_TYPE_NR || granu >=
> IOMMU_INV_GRANU_NR ||
> +		!inv_type_granu_map[type][granu])
> +		return -EINVAL;
> +
> +	*vtd_granu = inv_type_granu_table[type][granu];
> +

btw do we really need both map and table here? Can't we just
use one table with unsupported granularity marked as a special
value?

> +	return 0;
> +}
> +
> +static inline u64 to_vtd_size(u64 granu_size, u64 nr_granules)
> +{
> +	u64 nr_pages = (granu_size * nr_granules) >> VTD_PAGE_SHIFT;
> +
> +	/* VT-d size is encoded as 2^size of 4K pages, 0 for 4k, 9 for 2MB, etc.
> +	 * IOMMU cache invalidate API passes granu_size in bytes, and
> number of
> +	 * granu size in contiguous memory.
> +	 */
> +	return order_base_2(nr_pages);
> +}
> +
> +#ifdef CONFIG_INTEL_IOMMU_SVM
> +static int intel_iommu_sva_invalidate(struct iommu_domain *domain,
> +		struct device *dev, struct iommu_cache_invalidate_info
> *inv_info)
> +{
> +	struct dmar_domain *dmar_domain = to_dmar_domain(domain);
> +	struct device_domain_info *info;
> +	struct intel_iommu *iommu;
> +	unsigned long flags;
> +	int cache_type;
> +	u8 bus, devfn;
> +	u16 did, sid;
> +	int ret = 0;
> +	u64 size = 0;
> +
> +	if (!inv_info || !dmar_domain ||
> +		inv_info->version !=
> IOMMU_CACHE_INVALIDATE_INFO_VERSION_1)
> +		return -EINVAL;
> +
> +	if (!dev || !dev_is_pci(dev))
> +		return -ENODEV;
> +
> +	iommu = device_to_iommu(dev, &bus, &devfn);
> +	if (!iommu)
> +		return -ENODEV;
> +
> +	spin_lock_irqsave(&device_domain_lock, flags);
> +	spin_lock(&iommu->lock);
> +	info = iommu_support_dev_iotlb(dmar_domain, iommu, bus, devfn);
> +	if (!info) {
> +		ret = -EINVAL;
> +		goto out_unlock;

-ENOTSUPP?

> +	}
> +	did = dmar_domain->iommu_did[iommu->seq_id];
> +	sid = PCI_DEVID(bus, devfn);
> +
> +	/* Size is only valid in non-PASID selective invalidation */
> +	if (inv_info->granularity != IOMMU_INV_GRANU_PASID)
> +		size = to_vtd_size(inv_info->addr_info.granule_size,
> +				   inv_info->addr_info.nb_granules);
> +
> +	for_each_set_bit(cache_type, (unsigned long *)&inv_info->cache,
> IOMMU_CACHE_INV_TYPE_NR) {
> +		int granu = 0;
> +		u64 pasid = 0;
> +
> +		ret = to_vtd_granularity(cache_type, inv_info->granularity,
> &granu);
> +		if (ret) {
> +			pr_err("Invalid cache type and granu
> combination %d/%d\n", cache_type,
> +				inv_info->granularity);
> +			break;
> +		}
> +
> +		/* PASID is stored in different locations based on granularity
> */
> +		if (inv_info->granularity == IOMMU_INV_GRANU_PASID &&
> +			inv_info->pasid_info.flags &
> IOMMU_INV_PASID_FLAGS_PASID)
> +			pasid = inv_info->pasid_info.pasid;
> +		else if (inv_info->granularity == IOMMU_INV_GRANU_ADDR
> &&
> +			inv_info->addr_info.flags &
> IOMMU_INV_ADDR_FLAGS_PASID)
> +			pasid = inv_info->addr_info.pasid;
> +		else {
> +			pr_err("Cannot find PASID for given cache type and
> granularity\n");
> +			break;
> +		}
> +
> +		switch (BIT(cache_type)) {
> +		case IOMMU_CACHE_INV_TYPE_IOTLB:
> +			if ((inv_info->granularity !=
> IOMMU_INV_GRANU_PASID) &&

granularity == IOMMU_INV_GRANU_ADDR? otherwise it's unclear
why IOMMU_INV_GRANU_DOMAIN also needs size check.

> +				size && (inv_info->addr_info.addr &
> ((BIT(VTD_PAGE_SHIFT + size)) - 1))) {
> +				pr_err("Address out of range, 0x%llx, size
> order %llu\n",
> +					inv_info->addr_info.addr, size);
> +				ret = -ERANGE;
> +				goto out_unlock;
> +			}
> +
> +			qi_flush_piotlb(iommu, did,
> +					pasid,
> +					mm_to_dma_pfn(inv_info-
> >addr_info.addr),
> +					(granu == QI_GRAN_NONG_PASID) ? -
> 1 : 1 << size,
> +					inv_info->addr_info.flags &
> IOMMU_INV_ADDR_FLAGS_LEAF);
> +
> +			/*
> +			 * Always flush device IOTLB if ATS is enabled since
> guest
> +			 * vIOMMU exposes CM = 1, no device IOTLB flush
> will be passed
> +			 * down.
> +			 */

Does VT-d spec mention that no device IOTLB flush is required when CM=1?

> +			if (info->ats_enabled) {
> +				qi_flush_dev_iotlb_pasid(iommu, sid, info-
> >pfsid,
> +						pasid, info->ats_qdep,
> +						inv_info->addr_info.addr,
> size,
> +						granu);
> +			}
> +			break;
> +		case IOMMU_CACHE_INV_TYPE_DEV_IOTLB:
> +			if (info->ats_enabled) {
> +				qi_flush_dev_iotlb_pasid(iommu, sid, info-
> >pfsid,
> +						inv_info->addr_info.pasid,
> info->ats_qdep,
> +						inv_info->addr_info.addr,
> size,
> +						granu);

I'm confused here. There are two granularities allowed for devtlb, but here
you only handle one of them?

> +			} else
> +				pr_warn("Passdown device IOTLB flush w/o
> ATS!\n");
> +
> +			break;
> +		case IOMMU_CACHE_INV_TYPE_PASID:
> +			qi_flush_pasid_cache(iommu, did, granu, inv_info-
> >pasid_info.pasid);
> +

as earlier comment, we shouldn't allow userspace or guest to invalidate
PASID cache

> +			break;
> +		default:
> +			dev_err(dev, "Unsupported IOMMU invalidation
> type %d\n",
> +				cache_type);
> +			ret = -EINVAL;
> +		}
> +	}
> +out_unlock:
> +	spin_unlock(&iommu->lock);
> +	spin_unlock_irqrestore(&device_domain_lock, flags);
> +
> +	return ret;
> +}
> +#endif
> +
>  static int intel_iommu_map(struct iommu_domain *domain,
>  			   unsigned long iova, phys_addr_t hpa,
>  			   size_t size, int iommu_prot, gfp_t gfp)
> @@ -6204,6 +6385,7 @@ const struct iommu_ops intel_iommu_ops = {
>  	.is_attach_deferred	= intel_iommu_is_attach_deferred,
>  	.pgsize_bitmap		= INTEL_IOMMU_PGSIZES,
>  #ifdef CONFIG_INTEL_IOMMU_SVM
> +	.cache_invalidate	= intel_iommu_sva_invalidate,
>  	.sva_bind_gpasid	= intel_svm_bind_gpasid,
>  	.sva_unbind_gpasid	= intel_svm_unbind_gpasid,
>  #endif
> --
> 2.7.4