diff mbox series

[v6,2/4] iommu: Move global PASID allocation from SVA to core

Message ID 20230519203223.2777255-3-jacob.jun.pan@linux.intel.com (mailing list archive)
State Superseded
Headers show
Series Re-enable IDXD kernel workqueue under DMA API | expand

Commit Message

Jacob Pan May 19, 2023, 8:32 p.m. UTC 
Global PASID can be used beyond SVA. For example, drivers that use
Intel ENQCMD to submit work must use global PASIDs in that PASID
is stored in a per CPU MSR. When such device need to submit work
for in-kernel DMA with PASID, it must allocate PASIDs from the same
global number space to avoid conflict.

This patch moves global PASID allocation APIs from SVA to IOMMU APIs.
Reserved PASIDs, currently only RID_PASID, are excluded from the global
PASID allocation.

It is expected that device drivers will use the allocated PASIDs to
attach to appropriate IOMMU domains for use.

Signed-off-by: Jacob Pan <jacob.jun.pan@linux.intel.com>
---
v6: explicitly exclude reserved a range from SVA PASID allocation
    check mm PASID compatibility with device
v5: move PASID range check inside API so that device drivers only pass
    in struct device* (Kevin)
v4: move dummy functions outside ifdef CONFIG_IOMMU_SVA (Baolu)
---
 drivers/iommu/iommu-sva.c | 33 ++++++++++++++-------------------
 drivers/iommu/iommu.c     | 24 ++++++++++++++++++++++++
 include/linux/iommu.h     | 10 ++++++++++
 3 files changed, 48 insertions(+), 19 deletions(-)

Comments

Baolu Lu May 21, 2023, 6:21 a.m. UTC | #1 
On 5/20/23 4:32 AM, Jacob Pan wrote:
> Global PASID can be used beyond SVA. For example, drivers that use
> Intel ENQCMD to submit work must use global PASIDs in that PASID
> is stored in a per CPU MSR. When such device need to submit work
> for in-kernel DMA with PASID, it must allocate PASIDs from the same
> global number space to avoid conflict.
> 
> This patch moves global PASID allocation APIs from SVA to IOMMU APIs.
> Reserved PASIDs, currently only RID_PASID, are excluded from the global
> PASID allocation.
> 
> It is expected that device drivers will use the allocated PASIDs to
> attach to appropriate IOMMU domains for use.
> 
> Signed-off-by: Jacob Pan<jacob.jun.pan@linux.intel.com>
> ---
> v6: explicitly exclude reserved a range from SVA PASID allocation
>      check mm PASID compatibility with device
> v5: move PASID range check inside API so that device drivers only pass
>      in struct device* (Kevin)
> v4: move dummy functions outside ifdef CONFIG_IOMMU_SVA (Baolu)
> ---
>   drivers/iommu/iommu-sva.c | 33 ++++++++++++++-------------------
>   drivers/iommu/iommu.c     | 24 ++++++++++++++++++++++++
>   include/linux/iommu.h     | 10 ++++++++++
>   3 files changed, 48 insertions(+), 19 deletions(-)
> 
> diff --git a/drivers/iommu/iommu-sva.c b/drivers/iommu/iommu-sva.c
> index 9821bc44f5ac..7fe8e977d8eb 100644
> --- a/drivers/iommu/iommu-sva.c
> +++ b/drivers/iommu/iommu-sva.c
> @@ -10,33 +10,33 @@
>   #include "iommu-sva.h"
>   
>   static DEFINE_MUTEX(iommu_sva_lock);
> -static DEFINE_IDA(iommu_global_pasid_ida);
>   
>   /* Allocate a PASID for the mm within range (inclusive) */
> -static int iommu_sva_alloc_pasid(struct mm_struct *mm, ioasid_t min, ioasid_t max)
> +static int iommu_sva_alloc_pasid(struct mm_struct *mm, struct device *dev)
>   {
> +	ioasid_t pasid;
>   	int ret = 0;
>   
> -	if (min == IOMMU_PASID_INVALID ||
> -	    max == IOMMU_PASID_INVALID ||
> -	    min == 0 || max < min)
> -		return -EINVAL;
> -
>   	if (!arch_pgtable_dma_compat(mm))
>   		return -EBUSY;
>   
>   	mutex_lock(&iommu_sva_lock);
>   	/* Is a PASID already associated with this mm? */
>   	if (mm_valid_pasid(mm)) {
> -		if (mm->pasid < min || mm->pasid > max)
> -			ret = -EOVERFLOW;
> +		if (mm->pasid <= dev->iommu->max_pasids)
> +			goto out;
> +		dev_err(dev, "current mm PASID %d exceeds device range %d!",
> +			mm->pasid, dev->iommu->max_pasids);
> +		ret = -ERANGE;
>   		goto out;
>   	}

Nit: Above is just refactoring, so it's better to keep the code behavior
consistent. For example, no need to change the error# from -EOVERFLOW to
-ERANGE, and no need to leave a new kernel message.

Anyway, if you think these changes are helpful, it's better to have them
in separated patches.

In the end, perhaps we can simply have code like this:

	if (mm_valid_pasid(mm)) {
		if (mm->pasid > dev->iommu->max_pasids)
			ret = -EOVERFLOW;
		goto out;
	}

Others look good to me, with above addressed,

Reviewed-by: Lu Baolu <baolu.lu@linux.intel.com>

Best regards,
baolu
Jacob Pan May 22, 2023, 5:32 p.m. UTC | #2 
Hi Baolu,

On Sun, 21 May 2023 14:21:25 +0800, Baolu Lu <baolu.lu@linux.intel.com>
wrote:

> On 5/20/23 4:32 AM, Jacob Pan wrote:
> > Global PASID can be used beyond SVA. For example, drivers that use
> > Intel ENQCMD to submit work must use global PASIDs in that PASID
> > is stored in a per CPU MSR. When such device need to submit work
> > for in-kernel DMA with PASID, it must allocate PASIDs from the same
> > global number space to avoid conflict.
> > 
> > This patch moves global PASID allocation APIs from SVA to IOMMU APIs.
> > Reserved PASIDs, currently only RID_PASID, are excluded from the global
> > PASID allocation.
> > 
> > It is expected that device drivers will use the allocated PASIDs to
> > attach to appropriate IOMMU domains for use.
> > 
> > Signed-off-by: Jacob Pan<jacob.jun.pan@linux.intel.com>
> > ---
> > v6: explicitly exclude reserved a range from SVA PASID allocation
> >      check mm PASID compatibility with device
> > v5: move PASID range check inside API so that device drivers only pass
> >      in struct device* (Kevin)
> > v4: move dummy functions outside ifdef CONFIG_IOMMU_SVA (Baolu)
> > ---
> >   drivers/iommu/iommu-sva.c | 33 ++++++++++++++-------------------
> >   drivers/iommu/iommu.c     | 24 ++++++++++++++++++++++++
> >   include/linux/iommu.h     | 10 ++++++++++
> >   3 files changed, 48 insertions(+), 19 deletions(-)
> > 
> > diff --git a/drivers/iommu/iommu-sva.c b/drivers/iommu/iommu-sva.c
> > index 9821bc44f5ac..7fe8e977d8eb 100644
> > --- a/drivers/iommu/iommu-sva.c
> > +++ b/drivers/iommu/iommu-sva.c
> > @@ -10,33 +10,33 @@
> >   #include "iommu-sva.h"
> >   
> >   static DEFINE_MUTEX(iommu_sva_lock);
> > -static DEFINE_IDA(iommu_global_pasid_ida);
> >   
> >   /* Allocate a PASID for the mm within range (inclusive) */
> > -static int iommu_sva_alloc_pasid(struct mm_struct *mm, ioasid_t min,
> > ioasid_t max) +static int iommu_sva_alloc_pasid(struct mm_struct *mm,
> > struct device *dev) {
> > +	ioasid_t pasid;
> >   	int ret = 0;
> >   
> > -	if (min == IOMMU_PASID_INVALID ||
> > -	    max == IOMMU_PASID_INVALID ||
> > -	    min == 0 || max < min)
> > -		return -EINVAL;
> > -
> >   	if (!arch_pgtable_dma_compat(mm))
> >   		return -EBUSY;
> >   
> >   	mutex_lock(&iommu_sva_lock);
> >   	/* Is a PASID already associated with this mm? */
> >   	if (mm_valid_pasid(mm)) {
> > -		if (mm->pasid < min || mm->pasid > max)
> > -			ret = -EOVERFLOW;
> > +		if (mm->pasid <= dev->iommu->max_pasids)
> > +			goto out;
> > +		dev_err(dev, "current mm PASID %d exceeds device range
> > %d!",
> > +			mm->pasid, dev->iommu->max_pasids);
> > +		ret = -ERANGE;
> >   		goto out;
> >   	}  
> 
> Nit: Above is just refactoring, so it's better to keep the code behavior
> consistent. For example, no need to change the error# from -EOVERFLOW to
> -ERANGE, and no need to leave a new kernel message.
> 
> Anyway, if you think these changes are helpful, it's better to have them
> in separated patches.
> 
> In the end, perhaps we can simply have code like this:
> 
> 	if (mm_valid_pasid(mm)) {
> 		if (mm->pasid > dev->iommu->max_pasids)
> 			ret = -EOVERFLOW;
> 		goto out;
> 	}
> 
> Others look good to me, with above addressed,
> 
> Reviewed-by: Lu Baolu <baolu.lu@linux.intel.com>
> 
much better, will fix.

Thanks,

Jacob
Jason Gunthorpe May 29, 2023, 7:43 p.m. UTC | #3 
On Fri, May 19, 2023 at 01:32:21PM -0700, Jacob Pan wrote:
> Global PASID can be used beyond SVA. For example, drivers that use
> Intel ENQCMD to submit work must use global PASIDs in that PASID
> is stored in a per CPU MSR. When such device need to submit work
> for in-kernel DMA with PASID, it must allocate PASIDs from the same
> global number space to avoid conflict.
> 
> This patch moves global PASID allocation APIs from SVA to IOMMU APIs.
> Reserved PASIDs, currently only RID_PASID, are excluded from the global
> PASID allocation.
> 
> It is expected that device drivers will use the allocated PASIDs to
> attach to appropriate IOMMU domains for use.
> 
> Signed-off-by: Jacob Pan <jacob.jun.pan@linux.intel.com>
> ---
> v6: explicitly exclude reserved a range from SVA PASID allocation
>     check mm PASID compatibility with device
> v5: move PASID range check inside API so that device drivers only pass
>     in struct device* (Kevin)
> v4: move dummy functions outside ifdef CONFIG_IOMMU_SVA (Baolu)
> ---
>  drivers/iommu/iommu-sva.c | 33 ++++++++++++++-------------------
>  drivers/iommu/iommu.c     | 24 ++++++++++++++++++++++++
>  include/linux/iommu.h     | 10 ++++++++++
>  3 files changed, 48 insertions(+), 19 deletions(-)

Reviewed-by: Jason Gunthorpe <jgg@nvidia.com>
diff mbox series

Patch

diff --git a/drivers/iommu/iommu-sva.c b/drivers/iommu/iommu-sva.c
index 9821bc44f5ac..7fe8e977d8eb 100644
--- a/drivers/iommu/iommu-sva.c
+++ b/drivers/iommu/iommu-sva.c
@@ -10,33 +10,33 @@ 
 #include "iommu-sva.h"
 
 static DEFINE_MUTEX(iommu_sva_lock);
-static DEFINE_IDA(iommu_global_pasid_ida);
 
 /* Allocate a PASID for the mm within range (inclusive) */
-static int iommu_sva_alloc_pasid(struct mm_struct *mm, ioasid_t min, ioasid_t max)
+static int iommu_sva_alloc_pasid(struct mm_struct *mm, struct device *dev)
 {
+	ioasid_t pasid;
 	int ret = 0;
 
-	if (min == IOMMU_PASID_INVALID ||
-	    max == IOMMU_PASID_INVALID ||
-	    min == 0 || max < min)
-		return -EINVAL;
-
 	if (!arch_pgtable_dma_compat(mm))
 		return -EBUSY;
 
 	mutex_lock(&iommu_sva_lock);
 	/* Is a PASID already associated with this mm? */
 	if (mm_valid_pasid(mm)) {
-		if (mm->pasid < min || mm->pasid > max)
-			ret = -EOVERFLOW;
+		if (mm->pasid <= dev->iommu->max_pasids)
+			goto out;
+		dev_err(dev, "current mm PASID %d exceeds device range %d!",
+			mm->pasid, dev->iommu->max_pasids);
+		ret = -ERANGE;
 		goto out;
 	}
 
-	ret = ida_alloc_range(&iommu_global_pasid_ida, min, max, GFP_KERNEL);
-	if (ret < min)
+	pasid = iommu_alloc_global_pasid_dev(dev);
+	if (pasid == IOMMU_PASID_INVALID) {
+		ret = -ENOSPC;
 		goto out;
-	mm->pasid = ret;
+	}
+	mm->pasid = pasid;
 	ret = 0;
 out:
 	mutex_unlock(&iommu_sva_lock);
@@ -63,15 +63,10 @@  struct iommu_sva *iommu_sva_bind_device(struct device *dev, struct mm_struct *mm
 {
 	struct iommu_domain *domain;
 	struct iommu_sva *handle;
-	ioasid_t max_pasids;
 	int ret;
 
-	max_pasids = dev->iommu->max_pasids;
-	if (!max_pasids)
-		return ERR_PTR(-EOPNOTSUPP);
-
 	/* Allocate mm->pasid if necessary. */
-	ret = iommu_sva_alloc_pasid(mm, 1, max_pasids - 1);
+	ret = iommu_sva_alloc_pasid(mm, dev);
 	if (ret)
 		return ERR_PTR(ret);
 
@@ -216,5 +211,5 @@  void mm_pasid_drop(struct mm_struct *mm)
 	if (likely(!mm_valid_pasid(mm)))
 		return;
 
-	ida_free(&iommu_global_pasid_ida, mm->pasid);
+	iommu_free_global_pasid(mm->pasid);
 }
diff --git a/drivers/iommu/iommu.c b/drivers/iommu/iommu.c
index f1dcfa3f1a1b..786cb0f3acdf 100644
--- a/drivers/iommu/iommu.c
+++ b/drivers/iommu/iommu.c
@@ -39,6 +39,7 @@ 
 
 static struct kset *iommu_group_kset;
 static DEFINE_IDA(iommu_group_ida);
+static DEFINE_IDA(iommu_global_pasid_ida);
 
 static unsigned int iommu_def_domain_type __read_mostly;
 static bool iommu_dma_strict __read_mostly = IS_ENABLED(CONFIG_IOMMU_DEFAULT_DMA_STRICT);
@@ -3393,3 +3394,26 @@  struct iommu_domain *iommu_sva_domain_alloc(struct device *dev,
 
 	return domain;
 }
+
+ioasid_t iommu_alloc_global_pasid_dev(struct device *dev)
+{
+	int ret;
+	ioasid_t max;
+
+	max = dev->iommu->max_pasids;
+	ret = ida_alloc_range(&iommu_global_pasid_ida, IOMMU_FIRST_GLOBAL_PASID, max, GFP_KERNEL);
+	if (ret < 0)
+		return IOMMU_PASID_INVALID;
+
+	return ret;
+}
+EXPORT_SYMBOL_GPL(iommu_alloc_global_pasid_dev);
+
+void iommu_free_global_pasid(ioasid_t pasid)
+{
+	if (WARN_ON(pasid == IOMMU_PASID_INVALID))
+		return;
+
+	ida_free(&iommu_global_pasid_ida, pasid);
+}
+EXPORT_SYMBOL_GPL(iommu_free_global_pasid);
diff --git a/include/linux/iommu.h b/include/linux/iommu.h
index d8327f2b6fcc..fb4061c97d49 100644
--- a/include/linux/iommu.h
+++ b/include/linux/iommu.h
@@ -191,6 +191,7 @@  enum iommu_dev_features {
 };
 
 #define IOMMU_DEF_RID_PASID	(0U) /* Reserved for DMA w/o PASID */
+#define IOMMU_FIRST_GLOBAL_PASID	(1U) /*starting range for allocation */
 #define IOMMU_PASID_INVALID	(-1U)
 typedef unsigned int ioasid_t;
 
@@ -722,6 +723,8 @@  void iommu_detach_device_pasid(struct iommu_domain *domain,
 struct iommu_domain *
 iommu_get_domain_for_dev_pasid(struct device *dev, ioasid_t pasid,
 			       unsigned int type);
+ioasid_t iommu_alloc_global_pasid_dev(struct device *dev);
+void iommu_free_global_pasid(ioasid_t pasid);
 #else /* CONFIG_IOMMU_API */
 
 struct iommu_ops {};
@@ -1083,6 +1086,13 @@  iommu_get_domain_for_dev_pasid(struct device *dev, ioasid_t pasid,
 {
 	return NULL;
 }
+
+static inline ioasid_t iommu_alloc_global_pasid_dev(struct device *dev)
+{
+	return IOMMU_PASID_INVALID;
+}
+
+static inline void iommu_free_global_pasid(ioasid_t pasid) {}
 #endif /* CONFIG_IOMMU_API */
 
 /**