Subject: Re: [PATCH v3 6/7] firmware: arm_ffa: Setup in-kernel users of FFA partitions

From: Jens Wiklander <[email-masked]>
Date: Mon, 7 Dec 2020 13:30:18 +0100

Hi Sudeep,

Some comments below.

On Fri, Dec 04, 2020 at 12:11:36PM +0000, Sudeep Holla wrote:
> Parse the FFA nodes from the device-tree and register all the partitions
> whose services will be used in the kernel.
> 
> In order to also enable in-kernel users of FFA interface, let us add
> simple set of operations for such devices.
> 
> The in-kernel users are registered without the character device interface.
> 
> Signed-off-by: Sudeep Holla <[email-masked]>
> ---
>  drivers/firmware/arm_ffa/common.h |   2 +
>  drivers/firmware/arm_ffa/driver.c | 186 ++++++++++++++++++++++++++++++
>  include/linux/arm_ffa.h           |  36 +++++-
>  3 files changed, 223 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/firmware/arm_ffa/common.h b/drivers/firmware/arm_ffa/common.h
> index d019348bf67d..eb1371c2b2b8 100644
> --- a/drivers/firmware/arm_ffa/common.h
> +++ b/drivers/firmware/arm_ffa/common.h
> @@ -6,6 +6,7 @@
>  #ifndef _FFA_COMMON_H
>  #define _FFA_COMMON_H
>  
> +#include <linux/arm_ffa.h>
>  #include <linux/arm-smccc.h>
>  #include <linux/err.h>
>  
> @@ -17,6 +18,7 @@ typedef ffa_res_t
>  
>  int __init arm_ffa_bus_init(void);
>  void __exit arm_ffa_bus_exit(void);
> +bool ffa_device_is_valid(struct ffa_device *ffa_dev);
>  
>  #ifdef CONFIG_ARM_FFA_SMCCC
>  int __init ffa_transport_init(ffa_fn **invoke_ffa_fn);
> diff --git a/drivers/firmware/arm_ffa/driver.c b/drivers/firmware/arm_ffa/driver.c
> index 257b331d781c..3e4ba841dbf8 100644
> --- a/drivers/firmware/arm_ffa/driver.c
> +++ b/drivers/firmware/arm_ffa/driver.c
> @@ -24,9 +24,13 @@
>  
>  #include <linux/arm_ffa.h>
>  #include <linux/bitfield.h>
> +#include <linux/device.h>
>  #include <linux/io.h>
> +#include <linux/kernel.h>
>  #include <linux/module.h>
> +#include <linux/of.h>
>  #include <linux/slab.h>
> +#include <linux/uuid.h>
>  
>  #include "common.h"
>  
> @@ -179,6 +183,20 @@ static int ffa_version_check(u32 *version)
>  	return 0;
>  }
>  
> +static int ffa_rx_release(void)
> +{
> +	ffa_res_t ret;
> +
> +	ret = invoke_ffa_fn(FFA_RX_RELEASE, 0, 0, 0, 0, 0, 0, 0);
> +
> +	if (ret.a0 == FFA_ERROR)
> +		return ffa_to_linux_errno((int)ret.a2);
> +
> +	/* check for ret.a0 == FFA_RX_RELEASE ? */
> +
> +	return 0;
> +}
> +
>  static int ffa_rxtx_map(phys_addr_t tx_buf, phys_addr_t rx_buf, u32 pg_cnt)
>  {
>  	ffa_res_t ret;
> @@ -203,6 +221,50 @@ static int ffa_rxtx_unmap(u16 vm_id)
>  	return 0;
>  }
>  
> +static int __ffa_partition_info_get(u32 uuid0, u32 uuid1, u32 uuid2, u32 uuid3,
> +				    struct ffa_partition_info **buffer)
> +{
> +	int count;
> +	ffa_res_t partition_info;
> +
> +	mutex_lock(&drv_info->rx_lock);
> +	partition_info = invoke_ffa_fn(FFA_PARTITION_INFO_GET, uuid0, uuid1,
> +				       uuid2, uuid3, 0, 0, 0);
> +
> +	if (partition_info.a0 == FFA_ERROR)
> +		return ffa_to_linux_errno((int)partition_info.a2);
> +
> +	count = partition_info.a2;
> +
> +	if (buffer)
> +		memcpy(*buffer, drv_info->rx_buffer, sizeof(*buffer) * count);
> +
> +	ffa_rx_release();
> +
> +	mutex_unlock(&drv_info->rx_lock);
> +
> +	return count;
> +}
> +
> +static int ffa_partition_probe(const char *uuid_str,
> +			       struct ffa_partition_info *buffer)
> +{
> +	int count;
> +	uuid_t uuid;
> +	u32 uuid0_4[4] = { 0 };
> +
> +	if (uuid_parse(uuid_str, &uuid)) {
> +		pr_err("invalid uuid (%s)\n", uuid_str);
> +		return -ENODEV;
> +	}
> +
> +	export_uuid((u8 *)uuid0_4, &uuid);
> +	count = __ffa_partition_info_get(uuid0_4[0], uuid0_4[1], uuid0_4[2],
> +					 uuid0_4[3], &buffer);
> +
> +	return count;
> +}
> +
>  #define VM_ID_MASK	GENMASK(15, 0)
>  static int ffa_id_get(u16 *vm_id)
>  {
> @@ -218,9 +280,125 @@ static int ffa_id_get(u16 *vm_id)
>  	return 0;
>  }
>  
> +static int ffa_msg_send_direct_req(u16 src_id, u16 dst_id,
> +				   struct ffa_send_direct_data *data)
> +{
> +	u32 src_dst_ids = PACK_TARGET_INFO(src_id, dst_id);
> +	ffa_res_t ret;
> +
> +	ret = invoke_ffa_fn(FFA_FN_NATIVE(MSG_SEND_DIRECT_REQ), src_dst_ids, 0,
> +			    data->data0, data->data1, data->data2,
> +			    data->data3, data->data4);
> +
> +	while (ret.a0 == FFA_INTERRUPT)
> +		ret = invoke_ffa_fn(FFA_RUN, ret.a1, 0, 0, 0, 0, 0, 0);
> +	if (ret.a0 == FFA_ERROR)
> +		return ffa_to_linux_errno((int)ret.a2);
> +
> +	if (ret.a0 == FFA_FN_NATIVE(MSG_SEND_DIRECT_RESP)) {
> +		data->data0 = ret.a3;
> +		data->data1 = ret.a4;
> +		data->data2 = ret.a5;
> +		data->data3 = ret.a6;
> +		data->data4 = ret.a7;
> +	}
> +
> +	return 0;
> +}
> +
> +static u32 ffa_api_version_get(void)
> +{
> +	return drv_info->version;
> +}
> +
> +static u16 ffa_partition_id_get(struct ffa_device *dev)
> +{
> +	return dev->vm_id;
> +}
> +
> +static int ffa_partition_info_get(const char *uuid_str,
> +				  struct ffa_partition_info *buffer)
> +{
> +	if (ffa_partition_probe(uuid_str, buffer) == 1)
> +		return 0;
> +
> +	return -ENOENT;
> +}
> +
> +static int ffa_sync_send_receive(struct ffa_device *dev, u16 ep,
> +				 struct ffa_send_direct_data *data)
> +{
> +	return ffa_msg_send_direct_req(dev->vm_id, ep, data);
> +}
> +
> +static const struct ffa_dev_ops ffa_ops = {
> +	.api_version_get = ffa_api_version_get,
> +	.partition_id_get = ffa_partition_id_get,
> +	.partition_info_get = ffa_partition_info_get,
> +	.sync_send_receive = ffa_sync_send_receive,
> +};
> +
> +const struct ffa_dev_ops *ffa_dev_ops_get(struct ffa_device *dev)
> +{
> +	if (ffa_device_is_valid(dev))
> +		return &ffa_ops;
> +
> +	return NULL;
> +}
> +EXPORT_SYMBOL_GPL(ffa_dev_ops_get);
> +
> +int ffa_setup_partitions(struct device_node *np)
> +{
> +	int ret;
> +	struct device_node *child;
> +	struct ffa_device *ffa_dev;
> +	struct ffa_partition_info pbuf;
> +	const char *p_uuid, *pfx = "Ignoring FFA partition";
> +	uuid_t uuid = UUID_INIT(0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0);
> +
> +	for_each_child_of_node(np, child) {

The spec says:
– If the Nil UUID is specified at the Non-secure virtual FF-A instance,
  the Hypervisor must provide information for partitions resident in both
  security states.

Doesn't that make this redundant?

> +		if (!of_device_is_compatible(child, "arm,ffa-1.0-partition")) {
> +			of_node_put(child);
> +			continue;
> +		}
> +
> +		if (of_property_read_string(child, "uuid", &p_uuid)) {
> +			pr_err("%s: failed to parse \"uuid\" property\n", pfx);
> +			of_node_put(child);
> +			continue;
> +		}
> +
> +		of_node_put(child);
> +
> +		if (uuid_parse(p_uuid, &uuid)) {
> +			pr_err("%s: invalid \"uuid\" property (%s)\n",
> +			       pfx, p_uuid);
> +			continue;
> +		}
> +
> +		ret = ffa_partition_probe(p_uuid, &pbuf);
> +		if (ret != 1) {

If ret is > 1 we're in deep trouble as we have a buffer overrun on the
stack.

Cheers,
Jens

> +			pr_err("%s: %s partition info probe failed\n",
> +			       pfx, p_uuid);
> +			return -EINVAL;
> +		}
> +
> +		ffa_dev = ffa_device_register(p_uuid, pbuf.id);
> +		if (!ffa_dev) {
> +			pr_err("%s: failed to register %s\n", pfx, p_uuid);
> +			continue;
> +		}
> +
> +		ffa_dev_set_drvdata(ffa_dev, drv_info);
> +	}
> +
> +	return 0;
> +}
> +
>  static int __init ffa_init(void)
>  {
>  	int ret;
> +	struct device_node *np;
>  
>  	ret = arm_ffa_bus_init();
>  	if (ret)
> @@ -267,6 +445,14 @@ static int __init ffa_init(void)
>  	mutex_init(&drv_info->rx_lock);
>  	mutex_init(&drv_info->tx_lock);
>  
> +	/* Set up all the partitions */
> +	np = of_find_compatible_node(NULL, NULL, "arm,ffa-1.0");
> +	if (!np)
> +		return 0;
> +
> +	ffa_setup_partitions(np);
> +	of_node_put(np);
> +
>  	return 0;
>  free_pages:
>  	if (drv_info->tx_buffer)
> diff --git a/include/linux/arm_ffa.h b/include/linux/arm_ffa.h
> index 3defddfb40fc..8604c48289ce 100644
> --- a/include/linux/arm_ffa.h
> +++ b/include/linux/arm_ffa.h
> @@ -6,7 +6,6 @@
>  #ifndef _LINUX_ARM_FFA_H
>  #define _LINUX_ARM_FFA_H
>  
> -#include <linux/cdev.h>
>  #include <linux/device.h>
>  #include <linux/module.h>
>  #include <linux/types.h>
> @@ -47,6 +46,7 @@ void ffa_device_unregister(struct ffa_device *ffa_dev);
>  int ffa_driver_register(struct ffa_driver *driver, struct module *owner,
>  			const char *mod_name);
>  void ffa_driver_unregister(struct ffa_driver *driver);
> +const struct ffa_dev_ops *ffa_dev_ops_get(struct ffa_device *dev);
>  
>  #else
>  static inline
> @@ -66,6 +66,10 @@ ffa_driver_register(struct ffa_driver *driver, struct module *owner,
>  
>  static inline void ffa_driver_unregister(struct ffa_driver *driver) {}
>  
> +const struct ffa_dev_ops *ffa_dev_ops_get(struct ffa_device *dev)
> +{
> +	return NULL;
> +}
>  #endif /* CONFIG_ARM_FFA_TRANSPORT */
>  
>  #define ffa_register(driver) \
> @@ -84,4 +88,34 @@ static inline void ffa_driver_unregister(struct ffa_driver *driver) {}
>  #define module_ffa_driver(__ffa_driver)	\
>  	module_driver(__ffa_driver, ffa_register, ffa_unregister)
>  
> +/* FFA transport related */
> +struct ffa_partition_info {
> +	u16 id;
> +	u16 exec_ctxt;
> +/* partition supports receipt of direct requests */
> +#define FFA_PARTITION_DIRECT_RECV	BIT(0)
> +/* partition can send direct requests. */
> +#define FFA_PARTITION_DIRECT_SEND	BIT(1)
> +/* partition can send and receive indirect messages. */
> +#define FFA_PARTITION_INDIRECT_MSG	BIT(2)
> +	u32 properties;
> +};
> +
> +struct ffa_send_direct_data {
> +	unsigned long data0;
> +	unsigned long data1;
> +	unsigned long data2;
> +	unsigned long data3;
> +	unsigned long data4;
> +};
> +
> +struct ffa_dev_ops {
> +	u32 (*api_version_get)(void);
> +	u16 (*partition_id_get)(struct ffa_device *dev);
> +	int (*partition_info_get)(const char *uuid_str,
> +				  struct ffa_partition_info *buffer);
> +	int (*sync_send_receive)(struct ffa_device *dev, u16 ep,
> +				 struct ffa_send_direct_data *data);
> +};
> +
>  #endif /* _LINUX_ARM_FFA_H */
> -- 
> 2.25.1
> 

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