Re: [kvm-unit-tests PATCH] powerpc: Rework the rtas_token() function

[Laurent Vivier <lvivier@redhat.com>]

On 31/05/2017 13:15, Thomas Huth wrote:
> RTAS tokens can have any value, also 0xffffffff is theoretically
> allowed (which is currently used for the RTAS_UNKNOWN_SERVICE error
> code). Thus we should not mix error codes and tokens in the return
> value here and return the token value via a pointer parameter
> instead.
> 
> This patch also adds a check to rtas_token() to test whether the device
> tree is available at all. This fixes a possible endless loop that
> happens without device tree, spamming the console with "rtas_node:
> /rtas: FDT_ERR_BADMAGIC" messages: Somewhere the code calls abort()
> due to the missing device tree, and abort() calls exit() which in
> turn tries to shut down the VM with rtas_power_off(). rtas_power_off()
> needs the device tree again to look up the right RTAS token, where we
> then end up in the next iteration.
> 
> Signed-off-by: Thomas Huth <thuth@redhat.com>
> ---
>  lib/powerpc/asm/rtas.h |  2 +-
>  lib/powerpc/rtas.c     | 30 ++++++++++++++++++++++--------
>  lib/powerpc/smp.c      | 11 ++++++-----
>  powerpc/rtas.c         | 24 +++++++++++++-----------
>  4 files changed, 42 insertions(+), 25 deletions(-)
> 
> diff --git a/lib/powerpc/asm/rtas.h b/lib/powerpc/asm/rtas.h
> index 9012a1e..6fb407a 100644
> --- a/lib/powerpc/asm/rtas.h
> +++ b/lib/powerpc/asm/rtas.h
> @@ -21,7 +21,7 @@ struct rtas_args {
>  };
>  
>  extern void rtas_init(void);
> -extern int rtas_token(const char *service);
> +extern int rtas_token(const char *service, uint32_t *token);
>  extern int rtas_call(int token, int nargs, int nret, int *outputs, ...);
>  
>  extern void rtas_power_off(void);
> diff --git a/lib/powerpc/rtas.c b/lib/powerpc/rtas.c
> index 3407e25..2e7e0da 100644
> --- a/lib/powerpc/rtas.c
> +++ b/lib/powerpc/rtas.c
> @@ -69,17 +69,22 @@ void rtas_init(void)
>  	}
>  }
>  
> -int rtas_token(const char *service)
> +int rtas_token(const char *service, uint32_t *token)
>  {
>  	const struct fdt_property *prop;
> -	u32 *token;
> +	u32 *data;
> +
> +	if (!dt_available())
> +		return RTAS_UNKNOWN_SERVICE;
>  
>  	prop = fdt_get_property(dt_fdt(), rtas_node(), service, NULL);
> -	if (prop) {
> -		token = (u32 *)prop->data;
> -		return fdt32_to_cpu(*token);
> -	}
> -	return RTAS_UNKNOWN_SERVICE;
> +	if (!prop)
> +		return RTAS_UNKNOWN_SERVICE;
> +
> +	data = (u32 *)prop->data;
> +	*token = fdt32_to_cpu(*data);
> +
> +	return 0;
>  }
>  
>  int rtas_call(int token, int nargs, int nret, int *outputs, ...)
> @@ -116,6 +121,15 @@ int rtas_call(int token, int nargs, int nret, int *outputs, ...)
>  
>  void rtas_power_off(void)
>  {
> -	int ret = rtas_call(rtas_token("power-off"), 2, 1, NULL, -1, -1);
> +	uint32_t token;
> +	int ret;
> +
> +	ret = rtas_token("power-off", &token);
> +	if (ret) {
> +		puts("RTAS power-off not available\n");
> +		return;
> +	}
> +
> +	ret = rtas_call(token, 2, 1, NULL, -1, -1);
>  	printf("RTAS power-off returned %d\n", ret);
>  }
> diff --git a/lib/powerpc/smp.c b/lib/powerpc/smp.c
> index e18894b..afe4361 100644
> --- a/lib/powerpc/smp.c
> +++ b/lib/powerpc/smp.c
> @@ -27,12 +27,13 @@ struct secondary_entry_data {
>   */
>  int start_thread(int cpu_id, secondary_entry_fn entry, uint32_t r3)
>  {
> -	int query_token, start_token, outputs[1], ret;
> +	uint32_t query_token, start_token;
> +	int outputs[1], ret;
>  
> -	query_token = rtas_token("query-cpu-stopped-state");
> -	start_token = rtas_token("start-cpu");
> -	assert(query_token != RTAS_UNKNOWN_SERVICE &&
> -		start_token != RTAS_UNKNOWN_SERVICE);
> +	ret = rtas_token("query-cpu-stopped-state", &query_token);
> +	assert(ret == 0);
> +	ret = rtas_token("start-cpu", &start_token);
> +	assert(ret == 0);
>  
>  	ret = rtas_call(query_token, 1, 2, outputs, cpu_id);
>  	if (ret) {
> diff --git a/powerpc/rtas.c b/powerpc/rtas.c
> index 1b1e9c7..5d43f33 100644
> --- a/powerpc/rtas.c
> +++ b/powerpc/rtas.c
> @@ -39,14 +39,14 @@ static unsigned long mktime(int year, int month, int day,
>  
>  static void check_get_time_of_day(unsigned long start)
>  {
> -	int token;
> +	uint32_t token;
>  	int ret;
>  	int now[8];
>  	unsigned long t1, t2, count;
>  
> -	token = rtas_token("get-time-of-day");
> -	report("token available", token != RTAS_UNKNOWN_SERVICE);
> -	if (token == RTAS_UNKNOWN_SERVICE)
> +	ret = rtas_token("get-time-of-day", &token);
> +	report("token available", ret == 0);
> +	if (ret)
>  		return;
>  
>  	ret = rtas_call(token, 0, 8, now);
> @@ -74,23 +74,25 @@ static void check_get_time_of_day(unsigned long start)
>  
>  static void check_set_time_of_day(void)
>  {
> -	int token;
> +	uint32_t stod_token, gtod_token;
>  	int ret;
>  	int date[8];
>  	unsigned long t1, t2, count;
>  
> -	token = rtas_token("set-time-of-day");
> -	report("token available", token != RTAS_UNKNOWN_SERVICE);
> -	if (token == RTAS_UNKNOWN_SERVICE)
> +	ret = rtas_token("set-time-of-day", &stod_token);
> +	report("token available", ret == 0);
> +	if (ret)
>  		return;
>  
>  	/* 23:59:59 28/2/2000 */
>  
> -	ret = rtas_call(token, 7, 1, NULL, 2000, 2, 28, 23, 59, 59);
> +	ret = rtas_call(stod_token, 7, 1, NULL, 2000, 2, 28, 23, 59, 59);
>  	report("execution", ret == 0);
>  
>  	/* check it has worked */
> -	ret = rtas_call(rtas_token("get-time-of-day"), 0, 8, date);
> +	ret = rtas_token("get-time-of-day", &gtod_token);
> +	assert(ret == 0);
> +	ret = rtas_call(gtod_token, 0, 8, date);
>  	report("re-read", ret == 0);
>  	t1 = mktime(2000, 2, 28, 23, 59, 59);
>  	t2 = mktime(date[0], date[1], date[2],
> @@ -100,7 +102,7 @@ static void check_set_time_of_day(void)
>  	/* check it is running */
>  	count = 0;
>  	do {
> -		ret = rtas_call(rtas_token("get-time-of-day"), 0, 8, date);
> +		ret = rtas_call(gtod_token, 0, 8, date);
>  		t2 = mktime(date[0], date[1], date[2],
>  			    date[3], date[4], date[5]);
>  		count++;
> 
Reviewed-by: Laurent Vivier <lvivier@redhat.com>