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

[Auger Eric]

On 3/28/20 11:01 AM, Tian, Kevin wrote:
>> 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.
I tend to agree here.
> 
>> +	{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?
I asked the same question some time ago. If I remember correctly the
issue is while a granu can be supported in inv_type_granu_map, the
associated value in inv_type_granu_table can be 0. This typically
matches both values of G field (0 or 1) in the invalidation cmd. See
other comment below.
> 
>> +	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?
granu is the result of to_vtd_granularity() so it can take either of the
2 values.

Thanks

Eric
> 
>> +			} 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
>