Re: [PATCH v4 3/5] iommu/vt-d: Disable non-recoverable fault processing before unbind

[Jacob Pan]

On Thu,  7 May 2020 08:55:32 +0800
Lu Baolu <baolu.lu@xxxxxxxxxxxxxxx> wrote:

> When a PASID is used for SVA by the device, it's possible that the
> PASID entry is cleared before the device flushes all ongoing DMA
> requests. The IOMMU should ignore the non-recoverable faults caused
> by these requests.
Perhaps be more specific, only untranslated requests causes UR.

> Intel VT-d provides such function through the FPD
> bit of the PASID entry. This sets FPD bit when PASID entry is cleared
> in the mm notifier and clear it when the pasid is unbound.
> 
> Signed-off-by: Lu Baolu <baolu.lu@xxxxxxxxxxxxxxx>
> ---
>  drivers/iommu/intel-iommu.c |  4 ++--
>  drivers/iommu/intel-pasid.c | 26 +++++++++++++++++++++-----
>  drivers/iommu/intel-pasid.h |  3 ++-
>  drivers/iommu/intel-svm.c   |  9 ++++++---
>  4 files changed, 31 insertions(+), 11 deletions(-)
> 
> diff --git a/drivers/iommu/intel-iommu.c b/drivers/iommu/intel-iommu.c
> index d1866c0905b1..7811422b5a68 100644
> --- a/drivers/iommu/intel-iommu.c
> +++ b/drivers/iommu/intel-iommu.c
> @@ -5352,7 +5352,7 @@ static void __dmar_remove_one_dev_info(struct
> device_domain_info *info) if (info->dev) {
>  		if (dev_is_pci(info->dev) && sm_supported(iommu))
>  			intel_pasid_tear_down_entry(iommu, info->dev,
> -					PASID_RID2PASID);
> +					PASID_RID2PASID, false);
>  
>  		iommu_disable_dev_iotlb(info);
>  		domain_context_clear(iommu, info->dev);
> @@ -5587,7 +5587,7 @@ static void aux_domain_remove_dev(struct
> dmar_domain *domain, auxiliary_unlink_device(domain, dev);
>  
>  	spin_lock(&iommu->lock);
> -	intel_pasid_tear_down_entry(iommu, dev,
> domain->default_pasid);
> +	intel_pasid_tear_down_entry(iommu, dev,
> domain->default_pasid, false); domain_detach_iommu(domain, iommu);
>  	spin_unlock(&iommu->lock);
>  
> diff --git a/drivers/iommu/intel-pasid.c b/drivers/iommu/intel-pasid.c
> index 7969e3dac2ad..11aef6c12972 100644
> --- a/drivers/iommu/intel-pasid.c
> +++ b/drivers/iommu/intel-pasid.c
> @@ -292,7 +292,20 @@ static inline void pasid_clear_entry(struct
> pasid_entry *pe) WRITE_ONCE(pe->val[7], 0);
>  }
>  
> -static void intel_pasid_clear_entry(struct device *dev, int pasid)
> +static inline void pasid_clear_entry_with_fpd(struct pasid_entry *pe)
> +{
> +	WRITE_ONCE(pe->val[0], PASID_PTE_FPD);
> +	WRITE_ONCE(pe->val[1], 0);
> +	WRITE_ONCE(pe->val[2], 0);
> +	WRITE_ONCE(pe->val[3], 0);
> +	WRITE_ONCE(pe->val[4], 0);
> +	WRITE_ONCE(pe->val[5], 0);
> +	WRITE_ONCE(pe->val[6], 0);
> +	WRITE_ONCE(pe->val[7], 0);
> +}
> +
> +static void
> +intel_pasid_clear_entry(struct device *dev, int pasid, bool
> pf_ignore) {
>  	struct pasid_entry *pe;
>  
> @@ -300,7 +313,10 @@ static void intel_pasid_clear_entry(struct
> device *dev, int pasid) if (WARN_ON(!pe))
>  		return;
>  
> -	pasid_clear_entry(pe);
> +	if (pf_ignore)
> +		pasid_clear_entry_with_fpd(pe);
> +	else
> +		pasid_clear_entry(pe);
>  }
>  
>  static inline void pasid_set_bits(u64 *ptr, u64 mask, u64 bits)
> @@ -533,8 +549,8 @@ devtlb_invalidation_with_pasid(struct intel_iommu
> *iommu, qi_flush_dev_iotlb(iommu, sid, pfsid, qdep, 0, 64 -
> VTD_PAGE_SHIFT); }
>  
> -void intel_pasid_tear_down_entry(struct intel_iommu *iommu,
> -				 struct device *dev, int pasid)
> +void intel_pasid_tear_down_entry(struct intel_iommu *iommu, struct
> device *dev,
> +				 int pasid, bool pf_ignore)
>  {
>  	struct pasid_entry *pte;
>  	u16 did;
> @@ -544,7 +560,7 @@ void intel_pasid_tear_down_entry(struct
> intel_iommu *iommu, return;
>  
>  	did = pasid_get_domain_id(pte);
> -	intel_pasid_clear_entry(dev, pasid);
> +	intel_pasid_clear_entry(dev, pasid, pf_ignore);
>  
>  	if (!ecap_coherent(iommu->ecap))
>  		clflush_cache_range(pte, sizeof(*pte));
> diff --git a/drivers/iommu/intel-pasid.h b/drivers/iommu/intel-pasid.h
> index a41b09b3ffde..e6dd95ffe381 100644
> --- a/drivers/iommu/intel-pasid.h
> +++ b/drivers/iommu/intel-pasid.h
> @@ -15,6 +15,7 @@
>  #define PASID_MAX			0x100000
>  #define PASID_PTE_MASK			0x3F
>  #define PASID_PTE_PRESENT		1
> +#define PASID_PTE_FPD			2
>  #define PDE_PFN_MASK			PAGE_MASK
>  #define PASID_PDE_SHIFT			6
>  #define MAX_NR_PASID_BITS		20
> @@ -120,7 +121,7 @@ int intel_pasid_setup_nested(struct intel_iommu
> *iommu, struct iommu_gpasid_bind_data_vtd *pasid_data,
>  			     struct dmar_domain *domain, int
> addr_width); void intel_pasid_tear_down_entry(struct intel_iommu
> *iommu,
> -				 struct device *dev, int pasid);
> +				 struct device *dev, int pasid, bool
> pf_ignore); int vcmd_alloc_pasid(struct intel_iommu *iommu, unsigned
> int *pasid); void vcmd_free_pasid(struct intel_iommu *iommu, unsigned
> int pasid); #endif /* __INTEL_PASID_H */
> diff --git a/drivers/iommu/intel-svm.c b/drivers/iommu/intel-svm.c
> index 83dc4319f661..9561ba59a170 100644
> --- a/drivers/iommu/intel-svm.c
> +++ b/drivers/iommu/intel-svm.c
> @@ -207,7 +207,8 @@ static void intel_mm_release(struct mmu_notifier
> *mn, struct mm_struct *mm) */
>  	rcu_read_lock();
>  	list_for_each_entry_rcu(sdev, &svm->devs, list) {
> -		intel_pasid_tear_down_entry(svm->iommu, sdev->dev,
> svm->pasid);
> +		intel_pasid_tear_down_entry(svm->iommu, sdev->dev,
> +					    svm->pasid, true);
>  		intel_flush_svm_range_dev(svm, sdev, 0, -1, 0);
>  	}
>  	rcu_read_unlock();
> @@ -400,7 +401,8 @@ int intel_svm_unbind_gpasid(struct device *dev,
> int pasid) sdev->users--;
>  		if (!sdev->users) {
>  			list_del_rcu(&sdev->list);
> -			intel_pasid_tear_down_entry(iommu, dev,
> svm->pasid);
> +			intel_pasid_tear_down_entry(iommu, dev,
> +						    svm->pasid,
> false); intel_flush_svm_range_dev(svm, sdev, 0, -1, 0);
>  			/* TODO: Drain in flight PRQ for the PASID
> since it
>  			 * may get reused soon, we don't want to
> @@ -643,7 +645,8 @@ int intel_svm_unbind_mm(struct device *dev, int
> pasid)
>  			 * to use. We have a *shared* PASID table,
> because it's
>  			 * large and has to be physically
> contiguous. So it's
>  			 * hard to be as defensive as we might like.
> */
> -			intel_pasid_tear_down_entry(iommu, dev,
> svm->pasid);
> +			intel_pasid_tear_down_entry(iommu, dev,
> +						    svm->pasid,
> false); intel_flush_svm_range_dev(svm, sdev, 0, -1, 0);
>  			kfree_rcu(sdev, rcu);
>  
Reviewed-by: Jacob Pan <jacob.jun.pan@xxxxxxxxxxxxxxx>