diff options
Diffstat (limited to 'src/include/cpu')
| -rw-r--r-- | src/include/cpu/x86/cache.h | 15 |
1 files changed, 14 insertions, 1 deletions
diff --git a/src/include/cpu/x86/cache.h b/src/include/cpu/x86/cache.h index 4143d972f5..d4d9160252 100644 --- a/src/include/cpu/x86/cache.h +++ b/src/include/cpu/x86/cache.h @@ -9,9 +9,11 @@ #define CR0_NoWriteThrough (CR0_NW) #define CPUID_FEATURE_CLFLUSH_BIT 19 +#define CPUID_FEATURE_SELF_SNOOP_BIT 27 #if !defined(__ASSEMBLER__) +#include <arch/cpuid.h> #include <stdbool.h> #include <stddef.h> @@ -51,6 +53,16 @@ static __always_inline void enable_cache(void) write_cr0(cr0); } +/* + * Cache flushing is the most time-consuming step when programming the MTRRs. + * However, if the processor supports cache self-snooping (ss), we can skip + * this step and save time. + */ +static __always_inline bool self_snooping_supported(void) +{ + return (cpuid_edx(1) >> CPUID_FEATURE_SELF_SNOOP_BIT) & 1; +} + static __always_inline void disable_cache(void) { /* Disable and write back the cache */ @@ -58,7 +70,8 @@ static __always_inline void disable_cache(void) cr0 = read_cr0(); cr0 |= CR0_CD; write_cr0(cr0); - wbinvd(); + if (!self_snooping_supported()) + wbinvd(); } #endif /* !__ASSEMBLER__ */ |