Sadly, hardware turbo mode buttons are few and far between in these degenerate times. Add a software control at /proc/sys/turbo_mode.
Unfortunately, Linux graphical environments have become very heavy-weight and are essentially unusable on non-Turbo systems. The VT console works very well, though. Due to KVM limitations, turbo mode is permanently on in a KVM guest. Signed-off-by: Andy Lutomirski <[email protected]> --- arch/x86/mm/pat.c | 63 +++++++++++++++++++++++++++++++++++++++++++++++++++++-- 1 file changed, 61 insertions(+), 2 deletions(-) diff --git a/arch/x86/mm/pat.c b/arch/x86/mm/pat.c index faec01e7a17d..f703d8b1ed20 100644 --- a/arch/x86/mm/pat.c +++ b/arch/x86/mm/pat.c @@ -69,6 +69,8 @@ static int __init pat_debug_setup(char *str) } __setup("debugpat", pat_debug_setup); +static int turbo_mode = 1; + #ifdef CONFIG_X86_PAT /* * X86 PAT uses page flags arch_1 and uncached together to keep track of @@ -176,6 +178,62 @@ static enum page_cache_mode pat_get_cache_mode(unsigned pat_val, char *msg) #undef CM +#define PAT(x, y) ((u64)PAT_ ## y << ((x)*8)) + +static void update_local_turbo_mode(void *dummy) +{ + unsigned long cr0 = read_cr0(); + + /* + * KVM doesn't properly handle CD. + * + * XXX: this may interact poorly with CPU hotplug. + */ + + if (turbo_mode) + write_cr0(cr0 & ~X86_CR0_CD); + else + write_cr0(cr0 | X86_CR0_CD); +} + +static void update_turbo_mode(void) +{ + on_each_cpu(update_local_turbo_mode, NULL, 1); + + if (!turbo_mode) + wbinvd(); +} + +static int turbo_mode_handler(struct ctl_table *table, int write, + void __user *buffer, size_t *lenp, + loff_t *ppos) +{ + int error; + + error = proc_dointvec_minmax(table, write, buffer, lenp, ppos); + if (error) + return error; + + if (write) + update_turbo_mode(); + + return 0; +} + +static int zero, one = 1; +static struct ctl_table turbo_mode_table[] = { + { + .procname = "turbo_mode", + .data = &turbo_mode, + .maxlen = sizeof(int), + .mode = 0644, + .proc_handler = turbo_mode_handler, + .extra1 = &zero, + .extra2 = &one, + }, + {} +}; + /* * Update the cache mode to pgprot translation tables according to PAT * configuration. @@ -196,8 +254,6 @@ void pat_init_cache_modes(u64 pat) pr_info("x86/PAT: Configuration [0-7]: %s\n", pat_msg); } -#define PAT(x, y) ((u64)PAT_ ## y << ((x)*8)) - static void pat_bsp_init(u64 pat) { u64 tmp_pat; @@ -1096,6 +1152,9 @@ static int __init pat_memtype_list_init(void) debugfs_create_file("pat_memtype_list", S_IRUSR, arch_debugfs_dir, NULL, &memtype_fops); } + + register_sysctl_table(turbo_mode_table); + return 0; } -- 2.5.5
