Re: [PATCH v3 1/3] arm,smmu: switch to using iommu_fwspec functions

[Rahul Singh <Rahul.Singh@arm.com>]

Hello Stefano,

> On 26 Jan 2021, at 10:58 pm, Stefano Stabellini <sstabellini@kernel.org> wrote:
> 
> From: Brian Woods <brian.woods@xilinx.com>
> 
> Modify the smmu driver so that it uses the iommu_fwspec helper
> functions.  This means both ARM IOMMU drivers will both use the
> iommu_fwspec helper functions, making enabling generic device tree
> bindings in the SMMU driver much cleaner.
> 
> Signed-off-by: Brian Woods <brian.woods@xilinx.com>
> Signed-off-by: Stefano Stabellini <stefano.stabellini@xilinx.com>

Reviewed-by: Rahul Singh <rahul.singh@arm.com>
Tested-by: Rahul Singh <rahul.singh@arm.com>

Regards,
Rahul
> ---
> Changes in v3:
> - add a comment in iommu_add_dt_device
> - don't allocate fwspec twice in arm_smmu_add_device
> - reuse existing fwspec pointer, don't add a second one
> - add comment about supporting fwspec at the top of the file
> ---
> xen/drivers/passthrough/arm/smmu.c    | 98 ++++++++++++++++-----------
> xen/drivers/passthrough/device_tree.c |  7 ++
> 2 files changed, 66 insertions(+), 39 deletions(-)
> 
> diff --git a/xen/drivers/passthrough/arm/smmu.c b/xen/drivers/passthrough/arm/smmu.c
> index 3e8aa37866..3898d1d737 100644
> --- a/xen/drivers/passthrough/arm/smmu.c
> +++ b/xen/drivers/passthrough/arm/smmu.c
> @@ -32,6 +32,9 @@
>  *	- 4k and 64k pages, with contiguous pte hints.
>  *	- Up to 48-bit addressing (dependent on VA_BITS)
>  *	- Context fault reporting
> + *
> + * Changes compared to Linux driver:
> + *	- support for fwspec
>  */
> 
> 
> @@ -49,6 +52,7 @@
> #include <asm/atomic.h>
> #include <asm/device.h>
> #include <asm/io.h>
> +#include <asm/iommu_fwspec.h>
> #include <asm/platform.h>
> 
> /* Xen: The below defines are redefined within the file. Undef it */
> @@ -302,9 +306,6 @@ static struct iommu_group *iommu_group_get(struct device *dev)
> 
> /***** Start of Linux SMMU code *****/
> 
> -/* Maximum number of stream IDs assigned to a single device */
> -#define MAX_MASTER_STREAMIDS		MAX_PHANDLE_ARGS
> -
> /* Maximum number of context banks per SMMU */
> #define ARM_SMMU_MAX_CBS		128
> 
> @@ -597,8 +598,6 @@ struct arm_smmu_smr {
> };
> 
> struct arm_smmu_master_cfg {
> -	int				num_streamids;
> -	u16				streamids[MAX_MASTER_STREAMIDS];
> 	struct arm_smmu_smr		*smrs;
> };
> 
> @@ -686,6 +685,14 @@ static struct arm_smmu_option_prop arm_smmu_options[] = {
> 	{ 0, NULL},
> };
> 
> +static inline struct iommu_fwspec *
> +arm_smmu_get_fwspec(struct arm_smmu_master_cfg *cfg)
> +{
> +	struct arm_smmu_master *master = container_of(cfg,
> +			                                      struct arm_smmu_master, cfg);
> +	return dev_iommu_fwspec_get(&master->of_node->dev);
> +}
> +
> static void parse_driver_options(struct arm_smmu_device *smmu)
> {
> 	int i = 0;
> @@ -779,8 +786,9 @@ static int register_smmu_master(struct arm_smmu_device *smmu,
> 				struct device *dev,
> 				struct of_phandle_args *masterspec)
> {
> -	int i;
> +	int i, ret = 0;
> 	struct arm_smmu_master *master;
> +	struct iommu_fwspec *fwspec;
> 
> 	master = find_smmu_master(smmu, masterspec->np);
> 	if (master) {
> @@ -790,34 +798,37 @@ static int register_smmu_master(struct arm_smmu_device *smmu,
> 		return -EBUSY;
> 	}
> 
> -	if (masterspec->args_count > MAX_MASTER_STREAMIDS) {
> -		dev_err(dev,
> -			"reached maximum number (%d) of stream IDs for master device %s\n",
> -			MAX_MASTER_STREAMIDS, masterspec->np->name);
> -		return -ENOSPC;
> -	}
> -
> 	master = devm_kzalloc(dev, sizeof(*master), GFP_KERNEL);
> 	if (!master)
> 		return -ENOMEM;
> +	master->of_node = masterspec->np;
> 
> -	master->of_node			= masterspec->np;
> -	master->cfg.num_streamids	= masterspec->args_count;
> +	ret = iommu_fwspec_init(&master->of_node->dev, smmu->dev);
> +	if (ret) {
> +		kfree(master);
> +		return ret;
> +	}
> +	fwspec = dev_iommu_fwspec_get(dev);
> +
> +	/* adding the ids here */
> +	ret = iommu_fwspec_add_ids(&masterspec->np->dev,
> +				   masterspec->args,
> +				   masterspec->args_count);
> +	if (ret)
> +		return ret;
> 
> 	/* Xen: Let Xen know that the device is protected by an SMMU */
> 	dt_device_set_protected(masterspec->np);
> 
> -	for (i = 0; i < master->cfg.num_streamids; ++i) {
> -		u16 streamid = masterspec->args[i];
> -
> -		if (!(smmu->features & ARM_SMMU_FEAT_STREAM_MATCH) &&
> -		     (streamid >= smmu->num_mapping_groups)) {
> -			dev_err(dev,
> -				"stream ID for master device %s greater than maximum allowed (%d)\n",
> -				masterspec->np->name, smmu->num_mapping_groups);
> -			return -ERANGE;
> +	if (!(smmu->features & ARM_SMMU_FEAT_STREAM_MATCH)) {
> +		for (i = 0; i < fwspec->num_ids; ++i) {
> +			if (masterspec->args[i] >= smmu->num_mapping_groups) {
> +				dev_err(dev,
> +					"stream ID for master device %s greater than maximum allowed (%d)\n",
> +					masterspec->np->name, smmu->num_mapping_groups);
> +				return -ERANGE;
> +			}
> 		}
> -		master->cfg.streamids[i] = streamid;
> 	}
> 	return insert_smmu_master(smmu, master);
> }
> @@ -1390,6 +1401,7 @@ static int arm_smmu_master_configure_smrs(struct arm_smmu_device *smmu,
> 	int i;
> 	struct arm_smmu_smr *smrs;
> 	void __iomem *gr0_base = ARM_SMMU_GR0(smmu);
> +	struct iommu_fwspec *fwspec = arm_smmu_get_fwspec(cfg);
> 
> 	if (!(smmu->features & ARM_SMMU_FEAT_STREAM_MATCH))
> 		return 0;
> @@ -1397,15 +1409,14 @@ static int arm_smmu_master_configure_smrs(struct arm_smmu_device *smmu,
> 	if (cfg->smrs)
> 		return -EEXIST;
> 
> -	smrs = kmalloc_array(cfg->num_streamids, sizeof(*smrs), GFP_KERNEL);
> +	smrs = kmalloc_array(fwspec->num_ids, sizeof(*smrs), GFP_KERNEL);
> 	if (!smrs) {
> -		dev_err(smmu->dev, "failed to allocate %d SMRs\n",
> -			cfg->num_streamids);
> +		dev_err(smmu->dev, "failed to allocate %d SMRs\n", fwspec->num_ids);
> 		return -ENOMEM;
> 	}
> 
> 	/* Allocate the SMRs on the SMMU */
> -	for (i = 0; i < cfg->num_streamids; ++i) {
> +	for (i = 0; i < fwspec->num_ids; ++i) {
> 		int idx = __arm_smmu_alloc_bitmap(smmu->smr_map, 0,
> 						  smmu->num_mapping_groups);
> 		if (IS_ERR_VALUE(idx)) {
> @@ -1416,12 +1427,12 @@ static int arm_smmu_master_configure_smrs(struct arm_smmu_device *smmu,
> 		smrs[i] = (struct arm_smmu_smr) {
> 			.idx	= idx,
> 			.mask	= 0, /* We don't currently share SMRs */
> -			.id	= cfg->streamids[i],
> +			.id	= fwspec->ids[i],
> 		};
> 	}
> 
> 	/* It worked! Now, poke the actual hardware */
> -	for (i = 0; i < cfg->num_streamids; ++i) {
> +	for (i = 0; i < fwspec->num_ids; ++i) {
> 		u32 reg = SMR_VALID | smrs[i].id << SMR_ID_SHIFT |
> 			  smrs[i].mask << SMR_MASK_SHIFT;
> 		writel_relaxed(reg, gr0_base + ARM_SMMU_GR0_SMR(smrs[i].idx));
> @@ -1443,12 +1454,13 @@ static void arm_smmu_master_free_smrs(struct arm_smmu_device *smmu,
> 	int i;
> 	void __iomem *gr0_base = ARM_SMMU_GR0(smmu);
> 	struct arm_smmu_smr *smrs = cfg->smrs;
> +	struct iommu_fwspec *fwspec = arm_smmu_get_fwspec(cfg);
> 
> 	if (!smrs)
> 		return;
> 
> 	/* Invalidate the SMRs before freeing back to the allocator */
> -	for (i = 0; i < cfg->num_streamids; ++i) {
> +	for (i = 0; i < fwspec->num_ids; ++i) {
> 		u8 idx = smrs[i].idx;
> 
> 		writel_relaxed(~SMR_VALID, gr0_base + ARM_SMMU_GR0_SMR(idx));
> @@ -1465,16 +1477,17 @@ static int arm_smmu_domain_add_master(struct arm_smmu_domain *smmu_domain,
> 	int i, ret;
> 	struct arm_smmu_device *smmu = smmu_domain->smmu;
> 	void __iomem *gr0_base = ARM_SMMU_GR0(smmu);
> +	struct iommu_fwspec *fwspec = arm_smmu_get_fwspec(cfg);
> 
> 	/* Devices in an IOMMU group may already be configured */
> 	ret = arm_smmu_master_configure_smrs(smmu, cfg);
> 	if (ret)
> 		return ret == -EEXIST ? 0 : ret;
> 
> -	for (i = 0; i < cfg->num_streamids; ++i) {
> +	for (i = 0; i < fwspec->num_ids; ++i) {
> 		u32 idx, s2cr;
> 
> -		idx = cfg->smrs ? cfg->smrs[i].idx : cfg->streamids[i];
> +		idx = cfg->smrs ? cfg->smrs[i].idx : fwspec->ids[i];
> 		s2cr = S2CR_TYPE_TRANS |
> 		       (smmu_domain->cfg.cbndx << S2CR_CBNDX_SHIFT);
> 		writel_relaxed(s2cr, gr0_base + ARM_SMMU_GR0_S2CR(idx));
> @@ -1489,6 +1502,7 @@ static void arm_smmu_domain_remove_master(struct arm_smmu_domain *smmu_domain,
> 	int i;
> 	struct arm_smmu_device *smmu = smmu_domain->smmu;
> 	void __iomem *gr0_base = ARM_SMMU_GR0(smmu);
> +	struct iommu_fwspec *fwspec = arm_smmu_get_fwspec(cfg);
> 
> 	/* An IOMMU group is torn down by the first device to be removed */
> 	if ((smmu->features & ARM_SMMU_FEAT_STREAM_MATCH) && !cfg->smrs)
> @@ -1499,8 +1513,8 @@ static void arm_smmu_domain_remove_master(struct arm_smmu_domain *smmu_domain,
> 	 * that it can be re-allocated immediately.
> 	 * Xen: Unlike Linux, any access to non-configured stream will fault.
> 	 */
> -	for (i = 0; i < cfg->num_streamids; ++i) {
> -		u32 idx = cfg->smrs ? cfg->smrs[i].idx : cfg->streamids[i];
> +	for (i = 0; i < fwspec->num_ids; ++i) {
> +		u32 idx = cfg->smrs ? cfg->smrs[i].idx : fwspec->ids[i];
> 
> 		writel_relaxed(S2CR_TYPE_FAULT,
> 			       gr0_base + ARM_SMMU_GR0_S2CR(idx));
> @@ -1903,9 +1917,9 @@ static int arm_smmu_add_device(struct device *dev)
> 	struct arm_smmu_device *smmu;
> 	struct arm_smmu_master_cfg *cfg;
> 	struct iommu_group *group;
> +	struct iommu_fwspec *fwspec;
> 	void (*releasefn)(void *) = NULL;
> 	int ret;
> -
> 	smmu = find_smmu_for_device(dev);
> 	if (!smmu)
> 		return -ENODEV;
> @@ -1925,13 +1939,19 @@ static int arm_smmu_add_device(struct device *dev)
> 			goto out_put_group;
> 		}
> 
> -		cfg->num_streamids = 1;
> +		ret = iommu_fwspec_init(dev, smmu->dev);
> +		if (ret) {
> +			kfree(cfg);
> +			goto out_put_group;
> +		}
> +		fwspec = dev_iommu_fwspec_get(dev);
> +
> 		/*
> 		 * Assume Stream ID == Requester ID for now.
> 		 * We need a way to describe the ID mappings in FDT.
> 		 */
> 		pci_for_each_dma_alias(pdev, __arm_smmu_get_pci_sid,
> -				       &cfg->streamids[0]);
> +				       &fwspec->ids[0]);
> 		releasefn = __arm_smmu_release_pci_iommudata;
> 	} else {
> 		struct arm_smmu_master *master;
> diff --git a/xen/drivers/passthrough/device_tree.c b/xen/drivers/passthrough/device_tree.c
> index 999b831d90..a51ae3c9c3 100644
> --- a/xen/drivers/passthrough/device_tree.c
> +++ b/xen/drivers/passthrough/device_tree.c
> @@ -140,6 +140,13 @@ int iommu_add_dt_device(struct dt_device_node *np)
>     if ( !ops )
>         return -EINVAL;
> 
> +	/*
> +	 * This is needed in case a device has both the iommus property and
> +	 * also apperars in the mmu-masters list.
> +	 */
> +    if ( dt_device_is_protected(np) )
> +        return 0;
> +
>     if ( dev_iommu_fwspec_get(dev) )
>         return -EEXIST;
> 
> -- 
> 2.17.1
> 
>