Re: [PATCH v9 02/10] iommu/arm-smmu-v3: Use device properties for pasid-num-bits

Jonathan Cameron
2021-01-19T11:50:18Z

On Fri, 8 Jan 2021 15:52:10 +0100
Jean-Philippe Brucker <jean-philippe@linaro.org> wrote:

> The pasid-num-bits property shouldn't need a dedicated fwspec field,
> it's a job for device properties. Add properties for IORT, and access
> the number of PASID bits using device_property_read_u32().
>
> Suggested-by: Robin Murphy <robin.murphy@arm.com>
> Signed-off-by: Jean-Philippe Brucker <jean-philippe@linaro.org>

Nice

Acked-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>

Looks like we are fine not checking for missing properties because
ssid_bits == 0 corresponds to pasid off anyway.

> ---
> include/linux/iommu.h | 2 --
> drivers/acpi/arm64/iort.c | 13 +++++++------
> drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.c | 3 ++-
> drivers/iommu/of_iommu.c | 5 -----
> 4 files changed, 9 insertions(+), 14 deletions(-)
>
> diff --git a/include/linux/iommu.h b/include/linux/iommu.h
> index 26bcde5e7746..583c734b2e87 100644
> --- a/include/linux/iommu.h
> +++ b/include/linux/iommu.h
> @@ -570,7 +570,6 @@ struct iommu_group *fsl_mc_device_group(struct device *dev);
> * struct iommu_fwspec - per-device IOMMU instance data
> * @ops: ops for this device's IOMMU
> * @iommu_fwnode: firmware handle for this device's IOMMU
> - * @num_pasid_bits: number of PASID bits supported by this device
> * @num_ids: number of associated device IDs
> * @ids: IDs which this device may present to the IOMMU
> */
> @@ -578,7 +577,6 @@ struct iommu_fwspec {
> const struct iommu_ops *ops;
> struct fwnode_handle *iommu_fwnode;
> u32 flags;
> - u32 num_pasid_bits;
> unsigned int num_ids;
> u32 ids[];
> };
> diff --git a/drivers/acpi/arm64/iort.c b/drivers/acpi/arm64/iort.c
> index d4eac6d7e9fb..c9a8bbb74b09 100644
> --- a/drivers/acpi/arm64/iort.c
> +++ b/drivers/acpi/arm64/iort.c
> @@ -968,15 +968,16 @@ static int iort_pci_iommu_init(struct pci_dev *pdev, u16 alias, void *data)
> static void iort_named_component_init(struct device *dev,
> struct acpi_iort_node *node)
> {
> + struct property_entry props[2] = {};
> struct acpi_iort_named_component *nc;
> - struct iommu_fwspec *fwspec = dev_iommu_fwspec_get(dev);
> -
> - if (!fwspec)
> - return;
>
> nc = (struct acpi_iort_named_component *)node->node_data;
> - fwspec->num_pasid_bits = FIELD_GET(ACPI_IORT_NC_PASID_BITS,
> - nc->node_flags);
> + props[0] = PROPERTY_ENTRY_U32("pasid-num-bits",
> + FIELD_GET(ACPI_IORT_NC_PASID_BITS,
> + nc->node_flags));
> +
> + if (device_add_properties(dev, props))
> + dev_warn(dev, "Could not add device properties\n");
> }
>
> static int iort_nc_iommu_map(struct device *dev, struct acpi_iort_node *node)
> 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 8ca7415d785d..6a53b4edf054 100644
> --- a/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.c
> +++ b/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.c
> @@ -2366,7 +2366,8 @@ static struct iommu_device *arm_smmu_probe_device(struct device *dev)
> }
> }
>
> - master->ssid_bits = min(smmu->ssid_bits, fwspec->num_pasid_bits);
> + device_property_read_u32(dev, "pasid-num-bits", &master->ssid_bits);
> + master->ssid_bits = min(smmu->ssid_bits, master->ssid_bits);
>
> /*
> * Note that PASID must be enabled before, and disabled after ATS:
> diff --git a/drivers/iommu/of_iommu.c b/drivers/iommu/of_iommu.c
> index e505b9130a1c..a9d2df001149 100644
> --- a/drivers/iommu/of_iommu.c
> +++ b/drivers/iommu/of_iommu.c
> @@ -210,11 +210,6 @@ const struct iommu_ops *of_iommu_configure(struct device *dev,
> of_pci_iommu_init, &info);
> } else {
> err = of_iommu_configure_device(master_np, dev, id);
> -
> - fwspec = dev_iommu_fwspec_get(dev);
> - if (!err && fwspec)
> - of_property_read_u32(master_np, "pasid-num-bits",
> - &fwspec->num_pasid_bits);
> }
>
> /*