2022-03-21 15:47:06

by Lu Baolu

Subject: [PATCH RFC 01/11] iommu: Add pasid_bits field in struct dev_iommu

Use this field to save the pasid/ssid bits that a device is able to
support with its IOMMU hardware. It is a generic attribute of a device
and lifting it into the per-device dev_iommu struct makes it possible
to allocate a PASID for device without calls into the IOMMU drivers.
Any iommu driver which suports PASID related features should set this
field before features are enabled on the devices.

Signed-off-by: Lu Baolu <[email protected]>
---
include/linux/iommu.h | 1 +
drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.c | 1 +
drivers/iommu/intel/iommu.c | 5 ++++-
3 files changed, 6 insertions(+), 1 deletion(-)

diff --git a/include/linux/iommu.h b/include/linux/iommu.h
index 6ef2df258673..36f43af0af53 100644
--- a/include/linux/iommu.h
+++ b/include/linux/iommu.h
@@ -368,6 +368,7 @@ struct dev_iommu {
struct iommu_fwspec *fwspec;
struct iommu_device *iommu_dev;
void *priv;
+ unsigned int pasid_bits;
};

int iommu_device_register(struct iommu_device *iommu,
diff --git a/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.c b/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.c
index 627a3ed5ee8f..8e262210b5ad 100644
--- a/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.c
+++ b/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.c
@@ -2812,6 +2812,7 @@ static int arm_smmu_dev_enable_feature(struct device *dev,
master->iopf_enabled = true;
return 0;
case IOMMU_DEV_FEAT_SVA:
+ dev->iommu->pasid_bits = master->ssid_bits;
return arm_smmu_master_enable_sva(master);
default:
return -EINVAL;
diff --git a/drivers/iommu/intel/iommu.c b/drivers/iommu/intel/iommu.c
index 6f7485c44a4b..c1b91bce1530 100644
--- a/drivers/iommu/intel/iommu.c
+++ b/drivers/iommu/intel/iommu.c
@@ -4587,8 +4587,11 @@ static struct iommu_device *intel_iommu_probe_device(struct device *dev)
if (pasid_supported(iommu)) {
int features = pci_pasid_features(pdev);

- if (features >= 0)
+ if (features >= 0) {
info->pasid_supported = features | 1;
+ dev->iommu->pasid_bits =
+ fls(pci_max_pasids(pdev)) - 1;
+ }
}

if (info->ats_supported && ecap_prs(iommu->ecap) &&
--
2.25.1

2022-03-21 21:17:17

by Jean-Philippe Brucker

Subject: Re: [PATCH RFC 01/11] iommu: Add pasid_bits field in struct dev_iommu

Hi Baolu,

On Sun, Mar 20, 2022 at 02:40:20PM +0800, Lu Baolu wrote:
> diff --git a/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.c b/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.c
> index 627a3ed5ee8f..8e262210b5ad 100644
> --- a/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.c
> +++ b/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.c
> @@ -2812,6 +2812,7 @@ static int arm_smmu_dev_enable_feature(struct device *dev,
> master->iopf_enabled = true;
> return 0;
> case IOMMU_DEV_FEAT_SVA:
> + dev->iommu->pasid_bits = master->ssid_bits;

This would be better in arm_smmu_probe_device()

Thanks,
Jean

> return arm_smmu_master_enable_sva(master);
> default:
> return -EINVAL;

2022-03-22 01:11:42

by Lu Baolu

Subject: Re: [PATCH RFC 01/11] iommu: Add pasid_bits field in struct dev_iommu

On 2022/3/21 19:22, Jean-Philippe Brucker wrote:
> Hi Baolu,
>
> On Sun, Mar 20, 2022 at 02:40:20PM +0800, Lu Baolu wrote:
>> diff --git a/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.c b/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.c
>> index 627a3ed5ee8f..8e262210b5ad 100644
>> --- a/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.c
>> +++ b/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.c
>> @@ -2812,6 +2812,7 @@ static int arm_smmu_dev_enable_feature(struct device *dev,
>> master->iopf_enabled = true;
>> return 0;
>> case IOMMU_DEV_FEAT_SVA:
>> + dev->iommu->pasid_bits = master->ssid_bits;
> This would be better in arm_smmu_probe_device()

Sure.

Best regards,
baolu