Re: [PATCH v2 11/19] iommu/vt-d: Replace Intel specific PASID allocator with IOASID

[Jacob Pan <jacob.jun.pan-VuQAYsv1563Yd54FQh9/CA@public.gmane.org>]

On Thu, 25 Apr 2019 12:04:01 +0200
Auger Eric <eric.auger-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org> wrote:

> Hi Jacob,
> 
> On 4/24/19 1:31 AM, Jacob Pan wrote:
> > Make use of generic IOASID code to manage PASID allocation,
> > free, and lookup.
> > 
> > Signed-off-by: Jacob Pan <jacob.jun.pan-VuQAYsv1563Yd54FQh9/CA@public.gmane.org>
> > ---
> >  drivers/iommu/Kconfig       |  1 +
> >  drivers/iommu/intel-iommu.c |  9 ++++-----
> >  drivers/iommu/intel-pasid.c | 36
> > ------------------------------------ drivers/iommu/intel-svm.c   |
> > 41 ++++++++++++++++++++++++----------------- 4 files changed, 29
> > insertions(+), 58 deletions(-)
> > 
> > diff --git a/drivers/iommu/Kconfig b/drivers/iommu/Kconfig
> > index 6f07f3b..7f92009 100644
> > --- a/drivers/iommu/Kconfig
> > +++ b/drivers/iommu/Kconfig
> > @@ -204,6 +204,7 @@ config INTEL_IOMMU_SVM
> >  	bool "Support for Shared Virtual Memory with Intel IOMMU"
> >  	depends on INTEL_IOMMU && X86
> >  	select PCI_PASID
> > +	select IOASID
> >  	select MMU_NOTIFIER
> >  	help
> >  	  Shared Virtual Memory (SVM) provides a facility for
> > devices diff --git a/drivers/iommu/intel-iommu.c
> > b/drivers/iommu/intel-iommu.c index ec6f22d..785330a 100644
> > --- a/drivers/iommu/intel-iommu.c
> > +++ b/drivers/iommu/intel-iommu.c
> > @@ -5153,7 +5153,7 @@ static void auxiliary_unlink_device(struct
> > dmar_domain *domain, domain->auxd_refcnt--;
> >  
> >  	if (!domain->auxd_refcnt && domain->default_pasid > 0)
> > -		intel_pasid_free_id(domain->default_pasid);
> > +		ioasid_free(domain->default_pasid);
> >  }
> >  
> >  static int aux_domain_add_dev(struct dmar_domain *domain,
> > @@ -5171,9 +5171,8 @@ static int aux_domain_add_dev(struct
> > dmar_domain *domain, if (domain->default_pasid <= 0) {
> >  		int pasid;
> >  
> > -		pasid = intel_pasid_alloc_id(domain, PASID_MIN,
> > -
> > pci_max_pasids(to_pci_dev(dev)),
> > -					     GFP_KERNEL);
> > +		pasid = ioasid_alloc(NULL, PASID_MIN,
> > pci_max_pasids(to_pci_dev(dev)) - 1,
> > +				domain);
> >  		if (pasid <= 0) {  
> ioasid_t is a uint and returns INVALID_IOASID on error. Wouldn't it be
> simpler to make ioasid_alloc return an int?
Well, I think we still want the full uint range - 1(INVALID_IOASID).
Intel uses 20bit but I think SMMUs use 32 bits for streamID? I
should just check 
	if (pasid == INVALID_IOASID) {

> >  			pr_err("Can't allocate default pasid\n");
> >  			return -ENODEV;
> > @@ -5210,7 +5209,7 @@ static int aux_domain_add_dev(struct
> > dmar_domain *domain, spin_unlock(&iommu->lock);
> >  	spin_unlock_irqrestore(&device_domain_lock, flags);
> >  	if (!domain->auxd_refcnt && domain->default_pasid > 0)
> > -		intel_pasid_free_id(domain->default_pasid);
> > +		ioasid_free(domain->default_pasid);
> >  
> >  	return ret;
> >  }
> > diff --git a/drivers/iommu/intel-pasid.c
> > b/drivers/iommu/intel-pasid.c index 5b1d3be..d339e8f 100644
> > --- a/drivers/iommu/intel-pasid.c
> > +++ b/drivers/iommu/intel-pasid.c
> > @@ -26,42 +26,6 @@
> >   */
> >  static DEFINE_SPINLOCK(pasid_lock);
> >  u32 intel_pasid_max_id = PASID_MAX;
> > -static DEFINE_IDR(pasid_idr);
> > -
> > -int intel_pasid_alloc_id(void *ptr, int start, int end, gfp_t gfp)
> > -{
> > -	int ret, min, max;
> > -
> > -	min = max_t(int, start, PASID_MIN);
> > -	max = min_t(int, end, intel_pasid_max_id);
> > -
> > -	WARN_ON(in_interrupt());
> > -	idr_preload(gfp);
> > -	spin_lock(&pasid_lock);
> > -	ret = idr_alloc(&pasid_idr, ptr, min, max, GFP_ATOMIC);
> > -	spin_unlock(&pasid_lock);
> > -	idr_preload_end();
> > -
> > -	return ret;
> > -}
> > -
> > -void intel_pasid_free_id(int pasid)
> > -{
> > -	spin_lock(&pasid_lock);
> > -	idr_remove(&pasid_idr, pasid);
> > -	spin_unlock(&pasid_lock);
> > -}
> > -
> > -void *intel_pasid_lookup_id(int pasid)
> > -{
> > -	void *p;
> > -
> > -	spin_lock(&pasid_lock);
> > -	p = idr_find(&pasid_idr, pasid);
> > -	spin_unlock(&pasid_lock);
> > -
> > -	return p;
> > -}
> >  
> >  int vcmd_alloc_pasid(struct intel_iommu *iommu, unsigned int
> > *pasid) {
> > diff --git a/drivers/iommu/intel-svm.c b/drivers/iommu/intel-svm.c
> > index 8f87304..8fff212 100644
> > --- a/drivers/iommu/intel-svm.c
> > +++ b/drivers/iommu/intel-svm.c
> > @@ -25,6 +25,7 @@
> >  #include <linux/dmar.h>
> >  #include <linux/interrupt.h>
> >  #include <linux/mm_types.h>
> > +#include <linux/ioasid.h>
> >  #include <asm/page.h>
> >  
> >  #include "intel-pasid.h"
> > @@ -211,7 +212,9 @@ 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_flush_svm_range_dev(svm, sdev, 0, -1,
> > 0, !svm->mm)> +		/* for emulated iommu, PASID cache
> > invalidation implies IOTLB/DTLB */
> > +		if (!cap_caching_mode(svm->iommu->cap))
> > +			intel_flush_svm_range_dev(svm, sdev, 0,
> > -1, 0, !svm->mm);  
> This change is not documented in the commit message. Isn't it a
> separate fix?
right, should be separate.

> >  	}
> >  	rcu_read_unlock();
> >  
> > @@ -332,16 +335,15 @@ int intel_svm_bind_mm(struct device *dev, int
> > *pasid, int flags, struct svm_dev_ if (pasid_max >
> > intel_pasid_max_id) pasid_max = intel_pasid_max_id;
> >  
> > -		/* Do not use PASID 0 in caching mode (virtualised
> > IOMMU) */
> > -		ret = intel_pasid_alloc_id(svm,
> > -					   !!cap_caching_mode(iommu->cap),
> > -					   pasid_max - 1,
> > GFP_KERNEL);
> > -		if (ret < 0) {
> > +		/* Do not use PASID 0, reserved for RID to PASID */
> > +		svm->pasid = ioasid_alloc(NULL, PASID_MIN,
> > +					pasid_max - 1, svm);  
> the fact the max is not decremented compared to intel_pasid_alloc_id
> looks suspicious to me (exclusive to inclusive move). I guess it is a
> fix in which case this may be documented in the commit msg?
Yes, it should be in separate patch.

VT-d will always support device with full 20bit PASID range only, we
should fail svm_bind if device pasid_max < 20. It has to be
included in this series otherwise we could have assigned a device with <
20 PASID and our virtual command can only handle full 20bit.

> > +		if (svm->pasid == INVALID_IOASID) {
> >  			kfree(svm);
> >  			kfree(sdev);
> > +			ret = ENOSPC;  
> -ENOSPC
> >  			goto out;
> >  		}
> > -		svm->pasid = ret;
> >  		svm->notifier.ops = &intel_mmuops;
> >  		svm->mm = mm;
> >  		svm->flags = flags;
> > @@ -351,7 +353,7 @@ int intel_svm_bind_mm(struct device *dev, int
> > *pasid, int flags, struct svm_dev_ if (mm) {
> >  			ret =
> > mmu_notifier_register(&svm->notifier, mm); if (ret) {
> > -				intel_pasid_free_id(svm->pasid);
> > +				ioasid_free(svm->pasid);
> >  				kfree(svm);
> >  				kfree(sdev);
> >  				goto out;
> > @@ -367,7 +369,7 @@ int intel_svm_bind_mm(struct device *dev, int
> > *pasid, int flags, struct svm_dev_ if (ret) {
> >  			if (mm)
> >  				mmu_notifier_unregister(&svm->notifier,
> > mm);
> > -			intel_pasid_free_id(svm->pasid);
> > +			ioasid_free(svm->pasid);  
> the ioasid_free returned value never is tested. Is it useful?
> >  			kfree(svm);
> >  			kfree(sdev);
> >  			goto out;
> > @@ -400,7 +402,12 @@ int intel_svm_unbind_mm(struct device *dev,
> > int pasid) if (!iommu)
> >  		goto out;
> >  
> > -	svm = intel_pasid_lookup_id(pasid);
> > +	svm = ioasid_find(NULL, pasid, NULL);
> > +	if (IS_ERR(svm)) {
> > +		ret = PTR_ERR(svm);
> > +		goto out;
> > +	}
> > +
> >  	if (!svm)
> >  		goto out;
> >  
> > @@ -422,7 +429,7 @@ int intel_svm_unbind_mm(struct device *dev, int
> > pasid) kfree_rcu(sdev, rcu);
> >  
> >  				if (list_empty(&svm->devs)) {
> > -
> > intel_pasid_free_id(svm->pasid);
> > +					ioasid_free(svm->pasid);
> >  					if (svm->mm)
> >  						mmu_notifier_unregister(&svm->notifier,
> > svm->mm); 
> > @@ -457,10 +464,11 @@ int intel_svm_is_pasid_valid(struct device
> > *dev, int pasid) if (!iommu)
> >  		goto out;
> >  
> > -	svm = intel_pasid_lookup_id(pasid);
> > -	if (!svm)
> > +	svm = ioasid_find(NULL, pasid, NULL);
> > +	if (IS_ERR(svm)) {
> > +		ret = PTR_ERR(svm);
> >  		goto out;
> > -
> > +	}
> >  	/* init_mm is used in this case */
> >  	if (!svm->mm)
> >  		ret = 1;
> > @@ -567,13 +575,12 @@ static irqreturn_t prq_event_thread(int irq,
> > void *d) 
> >  		if (!svm || svm->pasid != req->pasid) {
> >  			rcu_read_lock();
> > -			svm = intel_pasid_lookup_id(req->pasid);
> > +			svm = ioasid_find(NULL, req->pasid, NULL);
> >  			/* It *can't* go away, because the driver
> > is not permitted
> >  			 * to unbind the mm while any page faults
> > are outstanding.
> >  			 * So we only need RCU to protect the
> > internal idr code. */ rcu_read_unlock();
> > -
> > -			if (!svm) {
> > +			if (IS_ERR(svm) || !svm) {
> >  				pr_err("%s: Page request for
> > invalid PASID %d: %08llx %08llx\n", iommu->name, req->pasid,
> > ((unsigned long long *)req)[0], ((unsigned long long *)req)[1]);
> >   
> 
> Thanks
> 
> Eric

[Jacob Pan]