Re: [PATCH v11 07/10] iommu/vt-d: Add svm/sva invalidate function

[Auger Eric <eric.auger@redhat.com>]

Hi Jacob,
On 4/10/20 11:56 PM, Jacob Pan wrote:
> On Thu, 9 Apr 2020 10:50:34 +0200
> Auger Eric <eric.auger@redhat.com> wrote:
> 
>> Hi Jacob,
>>
>> On 4/3/20 8:42 PM, Jacob Pan wrote:
>>> 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
>>> 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.
>>>
>>> ---
>>> v11 - Removed 2D map array, use -EINVAL in granularity lookup array.
>>>       Fixed devTLB invalidation granularity mapping. Disregard G=1
>>> case and use address selective invalidation only.
>>>
>>> v7 review fixed in v10
>>> ---
>>>
>>> Signed-off-by: Jacob Pan <jacob.jun.pan@linux.intel.com>
>>> Signed-off-by: Ashok Raj <ashok.raj@intel.com>
>>> Signed-off-by: Liu, Yi L <yi.l.liu@intel.com>
>>> ---
>>>  drivers/iommu/intel-iommu.c | 158
>>> ++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 158
>>> insertions(+)
>>>
>>> diff --git a/drivers/iommu/intel-iommu.c
>>> b/drivers/iommu/intel-iommu.c index 94c7993dac6a..045c5c08d71d
>>> 100644 --- a/drivers/iommu/intel-iommu.c
>>> +++ b/drivers/iommu/intel-iommu.c
>>> @@ -5594,6 +5594,163 @@ 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 support IOTLB granularity for request without PASID
>>> (second level).
>>> + *
>>> + * 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]
>>> + */
>>> +
>>> +const static int
>>> inv_type_granu_table[IOMMU_CACHE_INV_TYPE_NR][IOMMU_INV_GRANU_NR] =
>>> {
>>> +	/*
>>> +	 * PASID based IOTLB invalidation: PASID selective (per
>>> PASID),
>>> +	 * page selective (address granularity)
>>> +	 */
>>> +	{-EINVAL, QI_GRAN_NONG_PASID, QI_GRAN_PSI_PASID},
>>> +	/* PASID based dev TLBs */
>>> +	{-EINVAL, -EINVAL, QI_DEV_IOTLB_GRAN_PASID_SEL},
>>> +	/* PASID cache */
>>> +	{-EINVAL, -EINVAL, -EINVAL}
>>> +};
>>> +
>>> +static inline int to_vtd_granularity(int type, int granu)
>>> +{
>>> +	return inv_type_granu_table[type][granu];
>>> +}
>>> +
>>> +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;  
>>
>> Check (domain->flags & DOMAIN_FLAG_NESTING_MODE)?
> Good point
> 
>>> +
>>> +	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;
>>> +	}
>>> +	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;
>>> +
>>> +		granu = to_vtd_granularity(cache_type,
>>> inv_info->granularity);
>>> +		if (granu == -EINVAL) {
>>> +			pr_err("Invalid cache type and granu
>>> combination %d/%d\n", cache_type,
>>> +				inv_info->granularity);  
>> rate unlimited traces here and after.
still to be fixed
>> ret = -EINVAL?
>> also related to the discussion we had on the VFIO series. What is the
>> error policy?
> Invalidation should not fail, there is no way to tell the guest. this
> can be a void function or VFIO can ignore it similar to what is done to
> iommu_unmap.
OK it was just for reminder
> 
> 
>>> +			break;
>>> +		}
>>> +
>>> +		/* PASID is stored in different locations based on
>>> granularity */  
>> not sure the above comment really is requested
> Just to explain the situation where PASID can be in pasid_info or
> addr_info.
> 
>>> +		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;
>>> +
>>> +		switch (BIT(cache_type)) {
>>> +		case IOMMU_CACHE_INV_TYPE_IOTLB:
>>> +			if ((inv_info->granularity ==
>>> IOMMU_INV_GRANU_ADDR) &&
>>> +				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),  
>> This does not sound correct to me:
>> inv_info->addr_info.addr and inv_info->addr_info.flags are not valid
>> in case of PASID-selective invalidation
> If granu is PASID-selective, this address is ignored. Since npages = -1.
Ah OK. Maybe add a comment since it is a bit strange to see irrelevant
fields to be called in PASID-selective case.

Thanks

Eric
> 
>>> +					(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. vIOMMU
>>> +			 * in the guest may assume IOTLB flush is
>>> inclusive,
>>> +			 * which is more efficient.
>>> +			 */
>>> +			if (info->ats_enabled)
>>> +				qi_flush_dev_iotlb_pasid(iommu,
>>> sid, info->pfsid,
>>> +						pasid,
>>> info->ats_qdep,
>>> +
>>> inv_info->addr_info.addr, size,  
>> same
>>> +						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,  
>> nit: use pasid directly
> will do.
> 
>>> +
>>> inv_info->addr_info.addr, size,
>>> +						granu);
>>> +			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);
>>> +			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)
>>> @@ -6179,6 +6336,7 @@ 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
>>>   
>> Thanks
>>
>> Eric
>>
> 
> [Jacob Pan]
>