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Subject[PATCH v11 1/12] x86, mm, pat: Cleanup init flags in pat_init()
Date
From: Toshi Kani <toshi.kani@hp.com>

pat_init() uses two flags, 'boot_cpu' and 'boot_pat_state', for
tracking the boot CPU's initialization status. 'boot_pat_state'
is also overloaded to carry the boot PAT value.

This patch cleans this up by replacing them with a new single
flag, 'boot_cpu_done', to track the boot CPU's initialization
status. 'boot_pat_state' is only used to carry the boot PAT
value as a result.

Suggested-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Toshi Kani <toshi.kani@hp.com>
---
arch/x86/mm/pat.c | 40 +++++++++++++++++++---------------------
1 file changed, 19 insertions(+), 21 deletions(-)

diff --git a/arch/x86/mm/pat.c b/arch/x86/mm/pat.c
index a1c9654..e1ec6a7 100644
--- a/arch/x86/mm/pat.c
+++ b/arch/x86/mm/pat.c
@@ -197,24 +197,29 @@ void pat_init_cache_modes(void)
void pat_init(void)
{
u64 pat;
- bool boot_cpu = !boot_pat_state;
+ static bool boot_cpu_done;

if (!pat_enabled())
return;

- if (!cpu_has_pat) {
- if (!boot_pat_state) {
+ if (!boot_cpu_done) {
+ if (!cpu_has_pat) {
pat_disable("PAT not supported by CPU.");
return;
- } else {
- /*
- * If this happens we are on a secondary CPU, but
- * switched to PAT on the boot CPU. We have no way to
- * undo PAT.
- */
- pr_err("x86/PAT: PAT enabled, but not supported by secondary CPU\n");
- BUG();
}
+
+ rdmsrl(MSR_IA32_CR_PAT, boot_pat_state);
+ if (!boot_pat_state) {
+ pat_disable("PAT read returns always zero, disabled.");
+ return;
+ }
+ } else if (!cpu_has_pat) {
+ /*
+ * If this happens we are on a secondary CPU, but
+ * switched to PAT on the boot CPU. We have no way to
+ * undo PAT.
+ */
+ panic("PAT enabled, but not supported by secondary CPU\n");
}

/* Set PWT to Write-Combining. All other bits stay the same */
@@ -233,19 +238,12 @@ void pat_init(void)
pat = PAT(0, WB) | PAT(1, WC) | PAT(2, UC_MINUS) | PAT(3, UC) |
PAT(4, WB) | PAT(5, WC) | PAT(6, UC_MINUS) | PAT(7, UC);

- /* Boot CPU check */
- if (!boot_pat_state) {
- rdmsrl(MSR_IA32_CR_PAT, boot_pat_state);
- if (!boot_pat_state) {
- pat_disable("PAT read returns always zero, disabled.");
- return;
- }
- }
-
wrmsrl(MSR_IA32_CR_PAT, pat);

- if (boot_cpu)
+ if (!boot_cpu_done) {
pat_init_cache_modes();
+ boot_cpu_done = true;
+ }
}

#undef PAT

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