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 <luto@xxxxxxxxxx>
---
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
--
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