Re: [PATCH v4 4/8] iommu/vt-d: Attach/detach domains in auxiliary mode

[Lu Baolu]

Hi,

On 11/23/18 6:49 PM, Auger Eric wrote:
> Hi Lu,
>
> On 11/5/18 8:34 AM, Lu Baolu wrote:
> > When multiple domains per device has been enabled by the
> > device driver, the device will tag the default PASID for
> > the domain to all DMA traffics out of the subset of this
> > device; and the IOMMU should translate the DMA requests
> > in PASID granularity.
> >
> > This extends the intel_iommu_attach/detach_device() ops
> > to support managing PASID granular translation structures
> > when the device driver has enabled multiple domains per
> > device.
> >
> > Cc: Ashok Raj <ashok.raj@xxxxxxxxx>
> > Cc: Jacob Pan <jacob.jun.pan@xxxxxxxxxxxxxxx>
> > Cc: Kevin Tian <kevin.tian@xxxxxxxxx>
> > Signed-off-by: Sanjay Kumar <sanjay.k.kumar@xxxxxxxxx>
> > Signed-off-by: Lu Baolu <baolu.lu@xxxxxxxxxxxxxxx>
> > Signed-off-by: Liu Yi L <yi.l.liu@xxxxxxxxx>
> > ---
> >   drivers/iommu/intel-iommu.c | 192 +++++++++++++++++++++++++++++++-----
> >   include/linux/intel-iommu.h |  10 ++
> >   2 files changed, 180 insertions(+), 22 deletions(-)
> >
> > diff --git a/drivers/iommu/intel-iommu.c b/drivers/iommu/intel-iommu.c
> > index 2c86ac71c774..a61b25ad0d3b 100644
> > --- a/drivers/iommu/intel-iommu.c
> > +++ b/drivers/iommu/intel-iommu.c
> > @@ -2477,6 +2477,7 @@ static struct dmar_domain *dmar_insert_one_dev_info(struct intel_iommu *iommu,
> >   	info->iommu = iommu;
> >   	info->pasid_table = NULL;
> >   	info->auxd_enabled = 0;
> > +	INIT_LIST_HEAD(&info->auxiliary_domains);
> >   
> >   	if (dev && dev_is_pci(dev)) {
> >   		struct pci_dev *pdev = to_pci_dev(info->dev);
> > @@ -5010,35 +5011,134 @@ static void intel_iommu_domain_free(struct iommu_domain *domain)
> >   	domain_exit(to_dmar_domain(domain));
> >   }
> >   
> > -static int intel_iommu_attach_device(struct iommu_domain *domain,
> > -				     struct device *dev)
> > +/*
> > + * Check whether a @domain will be attached to the @dev in the
> > + * auxiliary mode.
> > + */
> > +static inline bool
> > +is_device_attach_aux_domain(struct device *dev, struct iommu_domain *domain)
> >   {
> > -	struct dmar_domain *dmar_domain = to_dmar_domain(domain);
> > -	struct intel_iommu *iommu;
> > -	int addr_width;
> > -	u8 bus, devfn;
> > +	struct device_domain_info *info = dev->archdata.iommu;
> >   
> > -	if (device_is_rmrr_locked(dev)) {
> > -		dev_warn(dev, "Device is ineligible for IOMMU domain attach due to platform RMRR requirement.  Contact your platform vendor.\n");
> > -		return -EPERM;
> > -	}
> > +	return info && info->auxd_enabled &&
> > +			domain->type == IOMMU_DOMAIN_UNMANAGED;
> > +}
> >   
> > -	/* normally dev is not mapped */
> > -	if (unlikely(domain_context_mapped(dev))) {
> > -		struct dmar_domain *old_domain;
> > +static void auxiliary_link_device(struct dmar_domain *domain,
> > +				  struct device *dev)
> > +{
> > +	struct device_domain_info *info = dev->archdata.iommu;
> >   
> > -		old_domain = find_domain(dev);
> > -		if (old_domain) {
> > -			rcu_read_lock();
> > -			dmar_remove_one_dev_info(old_domain, dev);
> > -			rcu_read_unlock();
> > +	assert_spin_locked(&device_domain_lock);
> > +	if (WARN_ON(!info))
> > +		return;
> >   
> > -			if (!domain_type_is_vm_or_si(old_domain) &&
> > -			     list_empty(&old_domain->devices))
> > -				domain_exit(old_domain);
> > +	domain->auxd_refcnt++;
> > +	list_add(&domain->auxd, &info->auxiliary_domains);
> > +}
> > +
> > +static void auxiliary_unlink_device(struct dmar_domain *domain,
> > +				    struct device *dev)
> > +{
> > +	struct device_domain_info *info = dev->archdata.iommu;
> > +
> > +	assert_spin_locked(&device_domain_lock);
> > +	if (WARN_ON(!info))
> > +		return;
> > +
> > +	list_del(&domain->auxd);
> > +	domain->auxd_refcnt--;
> > +
> > +	if (!domain->auxd_refcnt && domain->default_pasid > 0)
> > +		intel_pasid_free_id(domain->default_pasid);
> > +}
> > +
> > +static int domain_add_dev_auxd(struct dmar_domain *domain,
> > +			       struct device *dev)
> > +{
> > +	int ret;
> > +	u8 bus, devfn;
> > +	unsigned long flags;
> > +	struct intel_iommu *iommu;
> > +
> > +	iommu = device_to_iommu(dev, &bus, &devfn);
> > +	if (!iommu)
> > +		return -ENODEV;
> > +
> > +	spin_lock_irqsave(&device_domain_lock, flags);
> > +	if (domain->default_pasid <= 0) {
> > +		domain->default_pasid = intel_pasid_alloc_id(domain, PASID_MIN,
> > +				pci_max_pasids(to_pci_dev(dev)), GFP_ATOMIC);
> > +		if (domain->default_pasid < 0) {
> > +			pr_err("Can't allocate default pasid\n");
> > +			ret = -ENODEV;
> > +			goto pasid_failed;
> >   		}
> >   	}
> >   
> > +	spin_lock(&iommu->lock);
> You may comment your nested lock policy somewhere.

Yes. I will add below comments.

/*
 * iommu->lock must be held to attach domain to iommu and setup the
 * pasid entry for second level translation.
 */

> > +	ret = domain_attach_iommu(domain, iommu);
> > +	if (ret)
> > +		goto attach_failed;
> > +
> > +	/* Setup the PASID entry for mediated devices: */
> > +	ret = intel_pasid_setup_second_level(iommu, domain, dev,
> > +					     domain->default_pasid);
> > +	if (ret)
> > +		goto table_failed;
> > +	spin_unlock(&iommu->lock);
> > +
> > +	auxiliary_link_device(domain, dev);
> > +
> > +	spin_unlock_irqrestore(&device_domain_lock, flags);
> > +
> > +	return 0;
> > +
> > +table_failed:
> > +	domain_detach_iommu(domain, iommu);
> > +attach_failed:
> > +	spin_unlock(&iommu->lock);
> > +	if (!domain->auxd_refcnt && domain->default_pasid > 0)
> > +		intel_pasid_free_id(domain->default_pasid);
> > +pasid_failed:
> > +	spin_unlock_irqrestore(&device_domain_lock, flags);
> > +
> > +	return ret;
> > +}
> > +
> > +static void domain_remove_dev_aux(struct dmar_domain *domain,
> > +				  struct device *dev)
> > +{
> > +	struct device_domain_info *info;
> > +	struct intel_iommu *iommu;
> > +	unsigned long flags;
> > +
> > +	if (!is_device_attach_aux_domain(dev, &domain->domain))
> > +		return;
> > +
> > +	spin_lock_irqsave(&device_domain_lock, flags);
> > +	info = dev->archdata.iommu;
> > +	iommu = info->iommu;
> > +
> > +	intel_pasid_tear_down_entry(iommu, dev, domain->default_pasid);
> > +
> > +	auxiliary_unlink_device(domain, dev);
> > +
> > +	spin_lock(&iommu->lock);
> > +	domain_detach_iommu(domain, iommu);
> > +	spin_unlock(&iommu->lock);
> > +
> > +	spin_unlock_irqrestore(&device_domain_lock, flags);
> > +}
> > +
> > +static int __intel_iommu_attach_device(struct iommu_domain *domain,
> > +				       struct device *dev)
> > +{
> Maybe introducing __intel_iommu_attach_device in a patch prior to that
> one would help the review.

Yes. Will use a separated patch to introduce this helper.

> > +	struct dmar_domain *dmar_domain = to_dmar_domain(domain);
> > +	struct intel_iommu *iommu;
> > +	int addr_width;
> > +	u8 bus, devfn;
> > +
> >   	iommu = device_to_iommu(dev, &bus, &devfn);
> >   	if (!iommu)
> >   		return -ENODEV;
> > @@ -5071,7 +5171,47 @@ static int intel_iommu_attach_device(struct iommu_domain *domain,
> >   		dmar_domain->agaw--;
> >   	}
> >   
> > -	return domain_add_dev_info(dmar_domain, dev);
> > +	if (is_device_attach_aux_domain(dev, domain))
> > +		return domain_add_dev_auxd(dmar_domain, dev);
> why not putting this directly  into intel_iommu_attach_device_aux()?
> > +	else
> > +		return domain_add_dev_info(dmar_domain, dev);
> and this into intel_iommu_attach_device() as
> __intel_iommu_attach_device() is the common part now?

Good suggestion.

> > +}
> > +
> > +static int intel_iommu_attach_device(struct iommu_domain *domain,
> > +				     struct device *dev)
> > +{
> > +	if (device_is_rmrr_locked(dev)) {
> > +		dev_warn(dev, "Device is ineligible for IOMMU domain attach due to platform RMRR requirement.  Contact your platform vendor.\n");
> > +		return -EPERM;
> > +	}
> shouldn't we test this in the common part (ie. in
> __intel_iommu_attach_device). Don't RMRR also impact aux domains ?

RMRR is only for Request ID based DMA translation. Aux domain uses
pasid-granular translation, hence should not be impacted by RMRR.

Furthermore, as far as I know, RMRR only used for legacy devices and
should never be used with modern devices.

> > +
> > +	if (is_device_attach_aux_domain(dev, domain))
> > +		return -EPERM;
> > +
> > +	/* normally dev is not mapped */
> > +	if (unlikely(domain_context_mapped(dev))) {
> > +		struct dmar_domain *old_domain;
> > +
> > +		old_domain = find_domain(dev);
> > +		if (old_domain) {
> > +			rcu_read_lock();
> > +			dmar_remove_one_dev_info(old_domain, dev);
> > +			rcu_read_unlock();
> > +
> > +			if (!domain_type_is_vm_or_si(old_domain) &&
> > +			    list_empty(&old_domain->devices))
> > +				domain_exit(old_domain);
> > +		}
> > +	}
> > +
> > +	return __intel_iommu_attach_device(domain, dev);
> > +}
> > +
> > +static int intel_iommu_attach_device_aux(struct iommu_domain *domain,
> > +					 struct device *dev)
> > +{
> > +	return is_device_attach_aux_domain(dev, domain) ?
> > +			__intel_iommu_attach_device(domain, dev) : -EPERM;
> >   }
> >   
> >   static void intel_iommu_detach_device(struct iommu_domain *domain,
> > @@ -5080,6 +5220,12 @@ static void intel_iommu_detach_device(struct iommu_domain *domain,
> >   	dmar_remove_one_dev_info(to_dmar_domain(domain), dev);
> >   }
> >   
> > +static void intel_iommu_detach_device_aux(struct iommu_domain *domain,
> > +					  struct device *dev)
> > +{
> > +	domain_remove_dev_aux(to_dmar_domain(domain), dev);
> > +}
> > +
> >   static int intel_iommu_map(struct iommu_domain *domain,
> >   			   unsigned long iova, phys_addr_t hpa,
> >   			   size_t size, int iommu_prot)
> > @@ -5436,6 +5582,8 @@ const struct iommu_ops intel_iommu_ops = {
> >   	.domain_free		= intel_iommu_domain_free,
> >   	.attach_dev		= intel_iommu_attach_device,
> >   	.detach_dev		= intel_iommu_detach_device,
> > +	.attach_dev_aux		= intel_iommu_attach_device_aux,
> > +	.detach_dev_aux		= intel_iommu_detach_device_aux,
> >   	.map			= intel_iommu_map,
> >   	.unmap			= intel_iommu_unmap,
> >   	.iova_to_phys		= intel_iommu_iova_to_phys,
> > diff --git a/include/linux/intel-iommu.h b/include/linux/intel-iommu.h
> > index 6b198e13e75e..678c7fb05e74 100644
> > --- a/include/linux/intel-iommu.h
> > +++ b/include/linux/intel-iommu.h
> > @@ -473,9 +473,11 @@ struct dmar_domain {
> >   					/* Domain ids per IOMMU. Use u16 since
> >   					 * domain ids are 16 bit wide according
> >   					 * to VT-d spec, section 9.3 */
> > +	unsigned int	auxd_refcnt;	/* Refcount of auxiliary attaching */
> >   
> >   	bool has_iotlb_device;
> >   	struct list_head devices;	/* all devices' list */
> > +	struct list_head auxd;		/* link to device's auxiliary list */
> >   	struct iova_domain iovad;	/* iova's that belong to this domain */
> >   
> >   	struct dma_pte	*pgd;		/* virtual address */
> > @@ -494,6 +496,11 @@ struct dmar_domain {
> >   					   2 == 1GiB, 3 == 512GiB, 4 == 1TiB */
> >   	u64		max_addr;	/* maximum mapped address */
> >   
> > +	int		default_pasid;	/*
> > +					 * The default pasid used for non-SVM
> > +					 * traffic on mediated devices.
> > +					 */
> > +
> >   	struct iommu_domain domain;	/* generic domain data structure for
> >   					   iommu core */
> >   };
> > @@ -543,6 +550,9 @@ struct device_domain_info {
> >   	struct list_head link;	/* link to domain siblings */
> >   	struct list_head global; /* link to global list */
> >   	struct list_head table;	/* link to pasid table */
> > +	struct list_head auxiliary_domains; /* auxiliary domains
> > +					     * attached to this device
> > +					     */
> >   	u8 bus;			/* PCI bus number */
> >   	u8 devfn;		/* PCI devfn number */
> >   	u16 pfsid;		/* SRIOV physical function source ID */
> Thanks
>
> Eric

Best regards,
Lu Baolu