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cpufreq: intel_pstate: Always read hwp_cap_cached with READ_ONCE() 

Because intel_pstate_get_hwp_max() which updates hwp_cap_cached
may run in parallel with the readers of it, annotate all of the
read accesses to it with READ_ONCE().

Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Tested-by: Chen Yu <yu.c.chen@intel.com>
This commit is contained in:
Rafael J. Wysocki 2021-01-07 19:42:15 +01:00
parent 7c53f6b671
commit 9dd04ec6bc
1 changed files with 7 additions and 6 deletions
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13
drivers/cpufreq/intel_pstate.c
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@ -914,7 +914,7 @@ static void intel_pstate_hwp_offline(struct cpudata *cpu)
} }
value &= ~GENMASK_ULL(31, 0); value &= ~GENMASK_ULL(31, 0);
min_perf = HWP_LOWEST_PERF(cpu->hwp_cap_cached); min_perf = HWP_LOWEST_PERF(READ_ONCE(cpu->hwp_cap_cached));
/* Set hwp_max = hwp_min */ /* Set hwp_max = hwp_min */
value |= HWP_MAX_PERF(min_perf); value |= HWP_MAX_PERF(min_perf);
@ -1750,6 +1750,7 @@ static int hwp_boost_hold_time_ns = 3 * NSEC_PER_MSEC;
static inline void intel_pstate_hwp_boost_up(struct cpudata *cpu) static inline void intel_pstate_hwp_boost_up(struct cpudata *cpu)
{ {
u64 hwp_req = READ_ONCE(cpu->hwp_req_cached); u64 hwp_req = READ_ONCE(cpu->hwp_req_cached);
u64 hwp_cap = READ_ONCE(cpu->hwp_cap_cached);
u32 max_limit = (hwp_req & 0xff00) >> 8; u32 max_limit = (hwp_req & 0xff00) >> 8;
u32 min_limit = (hwp_req & 0xff); u32 min_limit = (hwp_req & 0xff);
u32 boost_level1; u32 boost_level1;
@ -1776,14 +1777,14 @@ static inline void intel_pstate_hwp_boost_up(struct cpudata *cpu)
cpu->hwp_boost_min = min_limit; cpu->hwp_boost_min = min_limit;
/* level at half way mark between min and guranteed */ /* level at half way mark between min and guranteed */
boost_level1 = (HWP_GUARANTEED_PERF(cpu->hwp_cap_cached) + min_limit) >> 1; boost_level1 = (HWP_GUARANTEED_PERF(hwp_cap) + min_limit) >> 1;
if (cpu->hwp_boost_min < boost_level1) if (cpu->hwp_boost_min < boost_level1)
cpu->hwp_boost_min = boost_level1; cpu->hwp_boost_min = boost_level1;
else if (cpu->hwp_boost_min < HWP_GUARANTEED_PERF(cpu->hwp_cap_cached)) else if (cpu->hwp_boost_min < HWP_GUARANTEED_PERF(hwp_cap))
cpu->hwp_boost_min = HWP_GUARANTEED_PERF(cpu->hwp_cap_cached); cpu->hwp_boost_min = HWP_GUARANTEED_PERF(hwp_cap);
else if (cpu->hwp_boost_min == HWP_GUARANTEED_PERF(cpu->hwp_cap_cached) && else if (cpu->hwp_boost_min == HWP_GUARANTEED_PERF(hwp_cap) &&
max_limit != HWP_GUARANTEED_PERF(cpu->hwp_cap_cached)) max_limit != HWP_GUARANTEED_PERF(hwp_cap))
cpu->hwp_boost_min = max_limit; cpu->hwp_boost_min = max_limit;
else else
return; return;