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Subject[tip: x86/mm] x86/mm/pat: Clean up PAT initialization flags
The following commit has been merged into the x86/mm branch of tip:

Commit-ID: d891b9219d2a73640d2f2a216ecb6fb29d832013
Gitweb: https://git.kernel.org/tip/d891b9219d2a73640d2f2a216ecb6fb29d832013
Author: Ingo Molnar <mingo@kernel.org>
AuthorDate: Tue, 19 Nov 2019 11:46:36 +01:00
Committer: Ingo Molnar <mingo@kernel.org>
CommitterDate: Tue, 10 Dec 2019 10:12:55 +01:00

x86/mm/pat: Clean up PAT initialization flags

Right now we have these variables that impact the PAT initialization sequence:

pat_disabled
boot_cpu_done
pat_initialized
init_cm_done

Some have a pat_ prefix, some not, and the naming is random,
which makes their purpose rather opaque.

Name them consistently and according to their role:

pat_disabled
pat_bp_initialized
pat_bp_enabled
pat_cm_initialized

Also rename pat_bsp_init() => pat_bp_init(), to use the canonical
abbreviation.

Also add a warning for double calls of init_cache_modes(), the call chains
leading to this are complex and I couldn't convince myself that we never
call this function twice - so utilize the flag for a debug check.

No change in functionality intended.

Signed-off-by: Ingo Molnar <mingo@kernel.org>
---
arch/x86/mm/pat.c | 26 ++++++++++++++------------
1 file changed, 14 insertions(+), 12 deletions(-)

diff --git a/arch/x86/mm/pat.c b/arch/x86/mm/pat.c
index 4a18049..f1677fa 100644
--- a/arch/x86/mm/pat.c
+++ b/arch/x86/mm/pat.c
@@ -61,10 +61,10 @@
#undef pr_fmt
#define pr_fmt(fmt) "" fmt

-static bool __read_mostly boot_cpu_done;
+static bool __read_mostly pat_bp_initialized;
static bool __read_mostly pat_disabled = !IS_ENABLED(CONFIG_X86_PAT);
-static bool __read_mostly pat_initialized;
-static bool __read_mostly init_cm_done;
+static bool __read_mostly pat_bp_enabled;
+static bool __read_mostly pat_cm_initialized;

/*
* PAT support is enabled by default, but can be disabled for
@@ -75,7 +75,7 @@ void pat_disable(const char *msg_reason)
if (pat_disabled)
return;

- if (boot_cpu_done) {
+ if (pat_bp_initialized) {
WARN_ONCE(1, "x86/PAT: PAT cannot be disabled after initialization\n");
return;
}
@@ -93,7 +93,7 @@ early_param("nopat", nopat);

bool pat_enabled(void)
{
- return pat_initialized;
+ return pat_bp_enabled;
}
EXPORT_SYMBOL_GPL(pat_enabled);

@@ -224,6 +224,8 @@ static void __init_cache_modes(u64 pat)
char pat_msg[33];
int i;

+ WARN_ON_ONCE(pat_cm_initialized);
+
pat_msg[32] = 0;
for (i = 7; i >= 0; i--) {
cache = pat_get_cache_mode((pat >> (i * 8)) & 7,
@@ -232,12 +234,12 @@ static void __init_cache_modes(u64 pat)
}
pr_info("x86/PAT: Configuration [0-7]: %s\n", pat_msg);

- init_cm_done = true;
+ pat_cm_initialized = true;
}

#define PAT(x, y) ((u64)PAT_ ## y << ((x)*8))

-static void pat_bsp_init(u64 pat)
+static void pat_bp_init(u64 pat)
{
u64 tmp_pat;

@@ -253,7 +255,7 @@ static void pat_bsp_init(u64 pat)
}

wrmsrl(MSR_IA32_CR_PAT, pat);
- pat_initialized = true;
+ pat_bp_enabled = true;

__init_cache_modes(pat);
}
@@ -275,7 +277,7 @@ void init_cache_modes(void)
{
u64 pat = 0;

- if (init_cm_done)
+ if (pat_cm_initialized)
return;

if (boot_cpu_has(X86_FEATURE_PAT)) {
@@ -395,9 +397,9 @@ void pat_init(void)
PAT(4, WB) | PAT(5, WP) | PAT(6, UC_MINUS) | PAT(7, WT);
}

- if (!boot_cpu_done) {
- pat_bsp_init(pat);
- boot_cpu_done = true;
+ if (!pat_bp_initialized) {
+ pat_bp_init(pat);
+ pat_bp_initialized = true;
} else {
pat_ap_init(pat);
}
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