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x86/mm/pat: Untangle pat_init()

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Split it into a BSP and AP version which makes the PAT
initialization path actually readable again.

Signed-off-by: Borislav Petkov <bp@suse.de>
Reviewed-by: Toshi Kani <toshi.kani@hp.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Andy Lutomirski <luto@amacapital.net>
Cc: Elliott@hp.com
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Luis R. Rodriguez <mcgrof@suse.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: arnd@arndb.de
Cc: hch@lst.de
Cc: hmh@hmh.eng.br
Cc: jgross@suse.com
Cc: konrad.wilk@oracle.com
Cc: linux-mm <linux-mm@kvack.org>
Cc: linux-nvdimm@lists.01.org
Cc: stefan.bader@canonical.com
Cc: yigal@plexistor.com
Link: http://lkml.kernel.org/r/1433436928-31903-2-git-send-email-bp@alien8.de
Signed-off-by: Ingo Molnar <mingo@kernel.org>
This commit is contained in:
Borislav Petkov 2015-06-04 18:55:09 +02:00 committed by Ingo Molnar
parent d6472302f2
commit 9dac629094
1 changed files with 40 additions and 29 deletions
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69
arch/x86/mm/pat.c
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@ -36,6 +36,8 @@
#undef pr_fmt
#define pr_fmt(fmt) "" fmt
static bool boot_cpu_done;
static int __read_mostly __pat_enabled = IS_ENABLED(CONFIG_X86_PAT);
static inline void pat_disable(const char *reason)
@ -194,31 +196,47 @@ void pat_init_cache_modes(void)
#define PAT(x, y) ((u64)PAT_ ## y << ((x)*8))
static void pat_bsp_init(u64 pat)
{
if (!cpu_has_pat) {
pat_disable("PAT not supported by CPU.");
return;
}
rdmsrl(MSR_IA32_CR_PAT, boot_pat_state);
if (!boot_pat_state) {
pat_disable("PAT MSR is 0, disabled.");
return;
}
wrmsrl(MSR_IA32_CR_PAT, pat);
pat_init_cache_modes();
}
static void pat_ap_init(u64 pat)
{
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("x86/PAT: PAT enabled, but not supported by secondary CPU\n");
}
wrmsrl(MSR_IA32_CR_PAT, pat);
}
void pat_init(void)
{
u64 pat;
bool boot_cpu = !boot_pat_state;
if (!pat_enabled())
return;
if (!cpu_has_pat) {
if (!boot_pat_state) {
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();
}
}
/* Set PWT to Write-Combining. All other bits stay the same */
/*
* Set PWT to Write-Combining. All other bits stay the same:
*
* PTE encoding used in Linux:
* PAT
* |PCD
@ -233,19 +251,12 @@ 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;
}
if (!boot_cpu_done) {
pat_bsp_init(pat);
boot_cpu_done = true;
} else {
pat_ap_init(pat);
}
wrmsrl(MSR_IA32_CR_PAT, pat);
if (boot_cpu)
pat_init_cache_modes();
}
#undef PAT