[v11,07/13] iommu/vt-d: Add SVA domain support

Commit Message

Baolu Lu Aug. 17, 2022, 1:20 a.m. UTC

Add support for SVA domain allocation and provide an SVA-specific
iommu_domain_ops. This implementation is based on the existing SVA
code. Possible cleanup and refactoring are left for incremental
changes later.

Signed-off-by: Lu Baolu <[e-mail]>
Reviewed-by: Kevin Tian <[e-mail]>
Reviewed-by: Jason Gunthorpe <[e-mail]>
Reviewed-by: Yi Liu <[e-mail]>
---
 drivers/iommu/intel/iommu.h |  5 ++++
 drivers/iommu/intel/iommu.c |  2 ++
 drivers/iommu/intel/svm.c   | 50 +++++++++++++++++++++++++++++++++++++
 3 files changed, 57 insertions(+)

Comments

Jason Gunthorpe Aug. 18, 2022, 1:36 p.m. UTC | #1

On Wed, Aug 17, 2022 at 09:20:18AM +0800, Lu Baolu wrote:

> +static int intel_svm_set_dev_pasid(struct iommu_domain *domain,
> +				   struct device *dev, ioasid_t pasid)
> +{
> +	struct device_domain_info *info = dev_iommu_priv_get(dev);
> +	struct intel_iommu *iommu = info->iommu;
> +	struct iommu_sva *sva;
> +	int ret = 0;
> +
> +	mutex_lock(&pasid_mutex);
> +	/*
> +	 * Detach the domain if a blocking domain is set. Check the
> +	 * right domain type once the IOMMU driver supports a real
> +	 * blocking domain.
> +	 */
> +	if (!domain || domain->type == IOMMU_DOMAIN_UNMANAGED) {
> +		intel_svm_unbind_mm(dev, pasid);

See, I think this is exactly the wrong way to use the ops

The blockin domain ops should have its own function that just
unconditionally calls intel_svm_unbind_mm()

> +	} else {
> +		struct mm_struct *mm = domain->mm;
> +
> +		sva = intel_svm_bind_mm(iommu, dev, mm);
> +		if (IS_ERR(sva))
> +			ret = PTR_ERR(sva);

And similarly the SVA domain should have its own op that does this SVM
call.

Muxing the ops with tests on the domain is an anti-pattern. In fact I
would say any time you see an op testing the domain->type it is very
suspicious.

Jason

Baolu Lu Aug. 23, 2022, 7:33 a.m. UTC | #2

On 2022/8/18 21:36, Jason Gunthorpe wrote:
> On Wed, Aug 17, 2022 at 09:20:18AM +0800, Lu Baolu wrote:
> 
>> +static int intel_svm_set_dev_pasid(struct iommu_domain *domain,
>> +				   struct device *dev, ioasid_t pasid)
>> +{
>> +	struct device_domain_info *info = dev_iommu_priv_get(dev);
>> +	struct intel_iommu *iommu = info->iommu;
>> +	struct iommu_sva *sva;
>> +	int ret = 0;
>> +
>> +	mutex_lock(&pasid_mutex);
>> +	/*
>> +	 * Detach the domain if a blocking domain is set. Check the
>> +	 * right domain type once the IOMMU driver supports a real
>> +	 * blocking domain.
>> +	 */
>> +	if (!domain || domain->type == IOMMU_DOMAIN_UNMANAGED) {
>> +		intel_svm_unbind_mm(dev, pasid);
> 
> See, I think this is exactly the wrong way to use the ops
> 
> The blockin domain ops should have its own function that just
> unconditionally calls intel_svm_unbind_mm()
> 
>> +	} else {
>> +		struct mm_struct *mm = domain->mm;
>> +
>> +		sva = intel_svm_bind_mm(iommu, dev, mm);
>> +		if (IS_ERR(sva))
>> +			ret = PTR_ERR(sva);
> 
> And similarly the SVA domain should have its own op that does this SVM
> call.
> 
> Muxing the ops with tests on the domain is an anti-pattern. In fact I
> would say any time you see an op testing the domain->type it is very
> suspicious.

Both agreed. Will fix them in the next version.

Best regards,
baolu

Patch

diff --git a/drivers/iommu/intel/iommu.h b/drivers/iommu/intel/iommu.h
index a9b8367c9361..4875c9974abd 100644
--- a/drivers/iommu/intel/iommu.h
+++ b/drivers/iommu/intel/iommu.h
@@ -747,6 +747,7 @@  void intel_svm_unbind(struct iommu_sva *handle);
 u32 intel_svm_get_pasid(struct iommu_sva *handle);
 int intel_svm_page_response(struct device *dev, struct iommu_fault_event *evt,
 			    struct iommu_page_response *msg);
+struct iommu_domain *intel_svm_domain_alloc(void);
 
 struct intel_svm_dev {
 	struct list_head list;
@@ -772,6 +773,10 @@  struct intel_svm {
 };
 #else
 static inline void intel_svm_check(struct intel_iommu *iommu) {}
+static inline struct iommu_domain *intel_svm_domain_alloc(void)
+{
+	return NULL;
+}
 #endif
 
 #ifdef CONFIG_INTEL_IOMMU_DEBUGFS
diff --git a/drivers/iommu/intel/iommu.c b/drivers/iommu/intel/iommu.c
index 7cca030a508e..27c9fd6139a8 100644
--- a/drivers/iommu/intel/iommu.c
+++ b/drivers/iommu/intel/iommu.c
@@ -4149,6 +4149,8 @@  static struct iommu_domain *intel_iommu_domain_alloc(unsigned type)
 		return domain;
 	case IOMMU_DOMAIN_IDENTITY:
 		return &si_domain->domain;
+	case IOMMU_DOMAIN_SVA:
+		return intel_svm_domain_alloc();
 	default:
 		return NULL;
 	}
diff --git a/drivers/iommu/intel/svm.c b/drivers/iommu/intel/svm.c
index 2420fa5c2360..16a4d413fce4 100644
--- a/drivers/iommu/intel/svm.c
+++ b/drivers/iommu/intel/svm.c
@@ -928,3 +928,53 @@  int intel_svm_page_response(struct device *dev,
 	mutex_unlock(&pasid_mutex);
 	return ret;
 }
+
+static int intel_svm_set_dev_pasid(struct iommu_domain *domain,
+				   struct device *dev, ioasid_t pasid)
+{
+	struct device_domain_info *info = dev_iommu_priv_get(dev);
+	struct intel_iommu *iommu = info->iommu;
+	struct iommu_sva *sva;
+	int ret = 0;
+
+	mutex_lock(&pasid_mutex);
+	/*
+	 * Detach the domain if a blocking domain is set. Check the
+	 * right domain type once the IOMMU driver supports a real
+	 * blocking domain.
+	 */
+	if (!domain || domain->type == IOMMU_DOMAIN_UNMANAGED) {
+		intel_svm_unbind_mm(dev, pasid);
+	} else {
+		struct mm_struct *mm = domain->mm;
+
+		sva = intel_svm_bind_mm(iommu, dev, mm);
+		if (IS_ERR(sva))
+			ret = PTR_ERR(sva);
+	}
+	mutex_unlock(&pasid_mutex);
+
+	return ret;
+}
+
+static void intel_svm_domain_free(struct iommu_domain *domain)
+{
+	kfree(to_dmar_domain(domain));
+}
+
+static const struct iommu_domain_ops intel_svm_domain_ops = {
+	.set_dev_pasid		= intel_svm_set_dev_pasid,
+	.free			= intel_svm_domain_free,
+};
+
+struct iommu_domain *intel_svm_domain_alloc(void)
+{
+	struct dmar_domain *domain;
+
+	domain = kzalloc(sizeof(*domain), GFP_KERNEL);
+	if (!domain)
+		return NULL;
+	domain->domain.ops = &intel_svm_domain_ops;
+
+	return &domain->domain;
+}