Re: [PATCH v7 06/10] iommu/sva: Refactoring iommu_sva_bind/unbind_device()

[Baolu Lu <baolu.lu@linux.intel.com>]

On 2022/5/20 19:28, Jean-Philippe Brucker wrote:
> On Fri, May 20, 2022 at 02:38:12PM +0800, Baolu Lu wrote:
>> On 2022/5/20 00:39, Jean-Philippe Brucker wrote:
>>>> +struct iommu_sva *iommu_sva_bind_device(struct device *dev, struct mm_struct *mm)
>>>> +{
>>>> +	struct iommu_sva_domain *sva_domain;
>>>> +	struct iommu_domain *domain;
>>>> +	ioasid_t max_pasid = 0;
>>>> +	int ret = -EINVAL;
>>>> +
>>>> +	/* Allocate mm->pasid if necessary. */
>>>> +	if (!dev->iommu->iommu_dev->pasids)
>>>> +		return ERR_PTR(-EOPNOTSUPP);
>>>> +
>>>> +	if (dev_is_pci(dev)) {
>>>> +		max_pasid = pci_max_pasids(to_pci_dev(dev));
>>>> +		if (max_pasid < 0)
>>>> +			return ERR_PTR(max_pasid);
>>>> +	} else {
>>>> +		ret = device_property_read_u32(dev, "pasid-num-bits",
>>>> +					       &max_pasid);
>>>> +		if (ret)
>>>> +			return ERR_PTR(ret);
>>>> +		max_pasid = (1UL << max_pasid);
>>>> +	}
>>> The IOMMU driver needs this PASID width information earlier, when creating
>>> the PASID table (in .probe_device(), .attach_dev()). Since we're moving it
>>> to the IOMMU core to avoid code duplication, it should be done earlier and
>>> stored in dev->iommu
>> Yes, really. How about below changes?
>>
>>  From f1382579e8a15ca49acdf758d38fd36451ea174d Mon Sep 17 00:00:00 2001
>> From: Lu Baolu<baolu.lu@linux.intel.com>
>> Date: Mon, 28 Feb 2022 15:01:35 +0800
>> Subject: [PATCH 1/1] iommu: Add pasids field in struct dev_iommu
>>
>> Use this field to save the number of PASIDs that a device is able to
>> consume. It is a generic attribute of a device and lifting it into the
>> per-device dev_iommu struct could help to avoid the boilerplate code
>> in various IOMMU drivers.
>>
>> Signed-off-by: Lu Baolu<baolu.lu@linux.intel.com>
>> ---
>>   drivers/iommu/iommu.c | 15 +++++++++++++++
>>   include/linux/iommu.h |  2 ++
>>   2 files changed, 17 insertions(+)
>>
>> diff --git a/drivers/iommu/iommu.c b/drivers/iommu/iommu.c
>> index e49c5a5b8cc1..6b731171d42f 100644
>> --- a/drivers/iommu/iommu.c
>> +++ b/drivers/iommu/iommu.c
>> @@ -20,6 +20,7 @@
>>   #include <linux/idr.h>
>>   #include <linux/err.h>
>>   #include <linux/pci.h>
>> +#include <linux/pci-ats.h>
>>   #include <linux/bitops.h>
>>   #include <linux/property.h>
>>   #include <linux/fsl/mc.h>
>> @@ -194,6 +195,8 @@ EXPORT_SYMBOL_GPL(iommu_device_unregister);
>>   static struct dev_iommu *dev_iommu_get(struct device *dev)
>>   {
>>   	struct dev_iommu *param = dev->iommu;
>> +	u32 max_pasids = 0;
>> +	int ret;
>>
>>   	if (param)
>>   		return param;
>> @@ -202,6 +205,18 @@ static struct dev_iommu *dev_iommu_get(struct device
>> *dev)
>>   	if (!param)
>>   		return NULL;
>>
>> +	if (dev_is_pci(dev)) {
>> +		ret = pci_max_pasids(to_pci_dev(dev));
>> +		if (ret > 0)
>> +			max_pasids = ret;
>> +	} else {
>> +		ret = device_property_read_u32(dev, "pasid-num-bits",
>> +					       &max_pasids);
>> +		if (!ret)
>> +			max_pasids = (1UL << max_pasids);
>> +	}
>> +	param->pasids = max_pasids;
>> +
> we could also do a min() with the IOMMU PASID size here
> 
>>   	mutex_init(&param->lock);
>>   	dev->iommu = param;
>>   	return param;
>> diff --git a/include/linux/iommu.h b/include/linux/iommu.h
>> index 45f274b2640d..d4296136ba75 100644
>> --- a/include/linux/iommu.h
>> +++ b/include/linux/iommu.h
>> @@ -371,6 +371,7 @@ struct iommu_fault_param {
>>    * @fwspec:	 IOMMU fwspec data
>>    * @iommu_dev:	 IOMMU device this device is linked to
>>    * @priv:	 IOMMU Driver private data
>> + * @pasids:	 number of supported PASIDs
> 'max_pasids' to stay consistent?

Both done. How about below changes?

 From 008c73b9c0ad51a4a70a18d60361a76c28a63342 Mon Sep 17 00:00:00 2001
From: Lu Baolu <baolu.lu@linux.intel.com>
Date: Mon, 28 Feb 2022 15:01:35 +0800
Subject: [PATCH 1/1] iommu: Add max_pasids field in struct dev_iommu

Use this field to save the number of PASIDs that a device is able to
consume. It is a generic attribute of a device and lifting it into the
per-device dev_iommu struct could help to avoid the boilerplate code
in various IOMMU drivers.

Signed-off-by: Lu Baolu <baolu.lu@linux.intel.com>
---
  drivers/iommu/iommu.c | 26 ++++++++++++++++++++++++++
  include/linux/iommu.h |  2 ++
  2 files changed, 28 insertions(+)

diff --git a/drivers/iommu/iommu.c b/drivers/iommu/iommu.c
index 847ad47a2dfd..365d0f2b7f55 100644
--- a/drivers/iommu/iommu.c
+++ b/drivers/iommu/iommu.c
@@ -20,6 +20,7 @@
  #include <linux/idr.h>
  #include <linux/err.h>
  #include <linux/pci.h>
+#include <linux/pci-ats.h>
  #include <linux/bitops.h>
  #include <linux/property.h>
  #include <linux/fsl/mc.h>
@@ -218,6 +219,30 @@ static void dev_iommu_free(struct device *dev)
  	kfree(param);
  }

+static u32 dev_iommu_get_max_pasids(struct device *dev)
+{
+	u32 max_pasids = dev->iommu->iommu_dev->max_pasids;
+	u32 num_bits;
+	int ret;
+
+	if (!max_pasids)
+		return 0;
+
+	if (dev_is_pci(dev)) {
+		ret = pci_max_pasids(to_pci_dev(dev));
+		if (ret < 0)
+			return 0;
+
+		return min_t(u32, max_pasids, ret);
+	}
+
+	ret = device_property_read_u32(dev, "pasid-num-bits", &num_bits);
+	if (ret)
+		return 0;
+
+	return min_t(u32, max_pasids, 1UL << num_bits);
+}
+
  static int __iommu_probe_device(struct device *dev, struct list_head 
*group_list)
  {
  	const struct iommu_ops *ops = dev->bus->iommu_ops;
@@ -242,6 +267,7 @@ static int __iommu_probe_device(struct device *dev, 
struct list_head *group_list
  		goto out_module_put;
  	}

+	iommu_dev->max_pasids = dev_iommu_get_max_pasids(dev);
  	dev->iommu->iommu_dev = iommu_dev;

  	group = iommu_group_get_for_dev(dev);
diff --git a/include/linux/iommu.h b/include/linux/iommu.h
index 03fbb1b71536..d50afb2c9a09 100644
--- a/include/linux/iommu.h
+++ b/include/linux/iommu.h
@@ -364,6 +364,7 @@ struct iommu_fault_param {
   * @fwspec:	 IOMMU fwspec data
   * @iommu_dev:	 IOMMU device this device is linked to
   * @priv:	 IOMMU Driver private data
+ * @max_pasids:  number of PASIDs device can consume
   *
   * TODO: migrate other per device data pointers under iommu_dev_data, e.g.
   *	struct iommu_group	*iommu_group;
@@ -375,6 +376,7 @@ struct dev_iommu {
  	struct iommu_fwspec		*fwspec;
  	struct iommu_device		*iommu_dev;
  	void				*priv;
+	u32				max_pasids;
  };

  int iommu_device_register(struct iommu_device *iommu,

Best regards,
baolu