diff options
| author | Aaron Durbin <adurbin@chromium.org> | 2012-12-11 17:15:13 -0600 |
|---|---|---|
| committer | Ronald G. Minnich <rminnich@gmail.com> | 2013-03-14 05:10:32 +0100 |
| commit | dc278f8fd0318caf0c11330478dff8453bb1107d (patch) | |
| tree | a7806a62b78a1915cf9838f2a5a144c89c9d8faf /src/cpu/intel/haswell/haswell_init.c | |
| parent | c1989c494e2628618067d03d9e192ac25b4f42d1 (diff) | |
haswell: Properly Guard Engergy Policy by CPUID
The IA32_ENERGY_PERFORMANCE_BIAS MSR can only be read or written
to if the CPU supports it. The support is indicated by ECX[3] for
cpuid(6). Without this guard, some Haswell parts would GP# fault
in this routine.
No more GP# while running on haswell CRBs.
Change-Id: If41e1e133e5faebb3ed578cba60743ce7e1c196f
Signed-off-by: Aaron Durbin <adurbin@chromium.org>
Reviewed-on: http://review.coreboot.org/2639
Tested-by: build bot (Jenkins)
Reviewed-by: Martin Roth <martin.roth@se-eng.com>
Diffstat (limited to 'src/cpu/intel/haswell/haswell_init.c')
| -rw-r--r-- | src/cpu/intel/haswell/haswell_init.c | 6 |
1 files changed, 6 insertions, 0 deletions
diff --git a/src/cpu/intel/haswell/haswell_init.c b/src/cpu/intel/haswell/haswell_init.c index 01d151ee06..9984c55d95 100644 --- a/src/cpu/intel/haswell/haswell_init.c +++ b/src/cpu/intel/haswell/haswell_init.c @@ -404,6 +404,12 @@ static void set_max_ratio(void) static void set_energy_perf_bias(u8 policy) { msr_t msr; + int ecx; + + /* Determine if energy efficient policy is supported. */ + ecx = cpuid_ecx(0x6); + if (!(ecx & (1 << 3))) + return; /* Energy Policy is bits 3:0 */ msr = rdmsr(IA32_ENERGY_PERFORMANCE_BIAS); |