[Mesa-dev] [PATCH v2 4/5] i965: perf: add support for userspace configurations

[Lionel Landwerlin]

On 29/08/17 14:39, Emil Velikov wrote:
> Hi Lionel,
>
> On 29 August 2017 at 14:05, Lionel Landwerlin
> <lionel.g.landwerlin at intel.com> wrote:
>> This allows us to deploy new configurations without touching the
>> kernel.
>>
>> v2: Detect loadable configs without creating one (Chris)
>>
>> Signed-off-by: Lionel Landwerlin <lionel.g.landwerlin at intel.com>
>> ---
>>   src/mesa/drivers/dri/i965/brw_performance_query.c | 98 ++++++++++++++++++++++-
>>   1 file changed, 95 insertions(+), 3 deletions(-)
>>
>> diff --git a/src/mesa/drivers/dri/i965/brw_performance_query.c b/src/mesa/drivers/dri/i965/brw_performance_query.c
>> index 4b585c95b7d..6ec6b417e52 100644
>> --- a/src/mesa/drivers/dri/i965/brw_performance_query.c
>> +++ b/src/mesa/drivers/dri/i965/brw_performance_query.c
>> @@ -1717,11 +1717,11 @@ read_file_uint64(const char *file, uint64_t *val)
>>
>>       fd = open(file, 0);
>>       if (fd < 0)
>> -       return false;
>> +        return false;
>>       n = read(fd, buf, sizeof (buf) - 1);
>>       close(fd);
>>       if (n < 0)
>> -       return false;
>> +        return false;
>>
>>       buf[n] = '\0';
>>       *val = strtoull(buf, NULL, 0);
>> @@ -1807,6 +1807,95 @@ read_sysfs_drm_device_file_uint64(struct brw_context *brw,
>>      return read_file_uint64(buf, value);
>>   }
>>
>> +static bool
>> +kernel_has_dynamic_config_support(struct brw_context *brw,
>> +                                  const char *sysfs_dev_dir)
>> +{
>> +   __DRIscreen *screen = brw->screen->driScrnPriv;
>> +   struct hash_entry *entry;
>> +
>> +   hash_table_foreach(brw->perfquery.oa_metrics_table, entry) {
>> +      struct brw_perf_query_info *query = entry->data;
>> +      char config_path[256];
>> +      uint64_t config_id;
>> +
>> +      snprintf(config_path, sizeof(config_path),
>> +               "%s/metrics/%s/id", sysfs_dev_dir, query->guid);
>> +
>> +      /* Look for the test config, which we know we can't replace. */
>> +      if (read_file_uint64(config_path, &config_id) && config_id == 1) {
>> +         uint32_t mux_regs[] = { 0x9888 /* NOA_WRITE */, 0x0 };
> The array seems to have a sentinel, yet one provides explicit array
> size (of 1) further down.
> Having a look through i915_drm.h the expectation is not documented.

This is the number of pair of (register, value).

>
> Can I suggest adding a comment [in the kernel i915_drm.h], or dropping
> the sentinel - whichever seems applicable.

I guess I'll add a comment in the kernel.

>
>> +         struct drm_i915_perf_oa_config config;
>> +
> Unless I failed at math - the struct does not seem compat safe.
> That is sizeof(struct drm_i915_perf_oa_config) varies across 32/64bit builds.

Hmm... What's not compat safe in there? :

struct drm_i915_perf_oa_config {
         /** String formatted like "%08x-%04x-%04x-%04x-%012x" */
         char uuid[36];

         __u32 n_mux_regs;
         __u32 n_boolean_regs;
         __u32 n_flex_regs;

         __u64 mux_regs_ptr;
         __u64 boolean_regs_ptr;
         __u64 flex_regs_ptr;
};


>
> Some padding should fix it.
>
> HTH
> Emil
>