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x86/mm: Enable CR4.PCIDE on supported systems 

We can use PCID if the CPU has PCID and PGE and we're not on Xen.

By itself, this has no effect. A followup patch will start using PCID.

Signed-off-by: Andy Lutomirski <luto@kernel.org>
Reviewed-by: Nadav Amit <nadav.amit@gmail.com>
Reviewed-by: Boris Ostrovsky <boris.ostrovsky@oracle.com>
Reviewed-by: Thomas Gleixner <tglx@linutronix.de>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Arjan van de Ven <arjan@linux.intel.com>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Dave Hansen <dave.hansen@intel.com>
Cc: Juergen Gross <jgross@suse.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Mel Gorman <mgorman@suse.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Rik van Riel <riel@redhat.com>
Cc: linux-mm@kvack.org
Link: http://lkml.kernel.org/r/6327ecd907b32f79d5aa0d466f04503bbec5df88.1498751203.git.luto@kernel.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
This commit is contained in:
Andy Lutomirski 2017-06-29 08:53:21 -07:00 committed by Ingo Molnar
parent 0790c9aad8
commit 660da7c922
3 changed files with 36 additions and 0 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

8
arch/x86/include/asm/tlbflush.h
View File

@ -243,6 +243,14 @@ static inline void __flush_tlb_all(void)
__flush_tlb_global();
else
__flush_tlb();
/*
* Note: if we somehow had PCID but not PGE, then this wouldn't work --
* we'd end up flushing kernel translations for the current ASID but
* we might fail to flush kernel translations for other cached ASIDs.
*
* To avoid this issue, we force PCID off if PGE is off.
*/
}
static inline void __flush_tlb_one(unsigned long addr)

22
arch/x86/kernel/cpu/common.c
View File

@ -329,6 +329,25 @@ static __always_inline void setup_smap(struct cpuinfo_x86 *c)
}
}
static void setup_pcid(struct cpuinfo_x86 *c)
{
if (cpu_has(c, X86_FEATURE_PCID)) {
if (cpu_has(c, X86_FEATURE_PGE)) {
cr4_set_bits(X86_CR4_PCIDE);
} else {
/*
* flush_tlb_all(), as currently implemented, won't
* work if PCID is on but PGE is not. Since that
* combination doesn't exist on real hardware, there's
* no reason to try to fully support it, but it's
* polite to avoid corrupting data if we're on
* an improperly configured VM.
*/
clear_cpu_cap(c, X86_FEATURE_PCID);
}
}
}
/*
* Protection Keys are not available in 32-bit mode.
*/
@ -1143,6 +1162,9 @@ static void identify_cpu(struct cpuinfo_x86 *c)
setup_smep(c);
setup_smap(c);
/* Set up PCID */
setup_pcid(c);
/*
* The vendor-specific functions might have changed features.
* Now we do "generic changes."

6
arch/x86/xen/enlighten_pv.c
View File

@ -295,6 +295,12 @@ static void __init xen_init_capabilities(void)
setup_clear_cpu_cap(X86_FEATURE_ACC);
setup_clear_cpu_cap(X86_FEATURE_X2APIC);
/*
* Xen PV would need some work to support PCID: CR3 handling as well
* as xen_flush_tlb_others() would need updating.
*/
setup_clear_cpu_cap(X86_FEATURE_PCID);
if (!xen_initial_domain())
setup_clear_cpu_cap(X86_FEATURE_ACPI);