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>
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@ -243,6 +243,14 @@ static inline void __flush_tlb_all(void)
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__flush_tlb_global();
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else
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__flush_tlb();
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/*
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* Note: if we somehow had PCID but not PGE, then this wouldn't work --
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* we'd end up flushing kernel translations for the current ASID but
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* we might fail to flush kernel translations for other cached ASIDs.
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*
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* To avoid this issue, we force PCID off if PGE is off.
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*/
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}
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static inline void __flush_tlb_one(unsigned long addr)
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@ -329,6 +329,25 @@ static __always_inline void setup_smap(struct cpuinfo_x86 *c)
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}
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}
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static void setup_pcid(struct cpuinfo_x86 *c)
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{
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if (cpu_has(c, X86_FEATURE_PCID)) {
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if (cpu_has(c, X86_FEATURE_PGE)) {
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cr4_set_bits(X86_CR4_PCIDE);
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} else {
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/*
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* flush_tlb_all(), as currently implemented, won't
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* work if PCID is on but PGE is not. Since that
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* combination doesn't exist on real hardware, there's
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* no reason to try to fully support it, but it's
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* polite to avoid corrupting data if we're on
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* an improperly configured VM.
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*/
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clear_cpu_cap(c, X86_FEATURE_PCID);
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}
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}
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}
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/*
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* Protection Keys are not available in 32-bit mode.
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*/
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@ -1143,6 +1162,9 @@ static void identify_cpu(struct cpuinfo_x86 *c)
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setup_smep(c);
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setup_smap(c);
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/* Set up PCID */
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setup_pcid(c);
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/*
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* The vendor-specific functions might have changed features.
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* Now we do "generic changes."
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@ -295,6 +295,12 @@ static void __init xen_init_capabilities(void)
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setup_clear_cpu_cap(X86_FEATURE_ACC);
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setup_clear_cpu_cap(X86_FEATURE_X2APIC);
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/*
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* Xen PV would need some work to support PCID: CR3 handling as well
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* as xen_flush_tlb_others() would need updating.
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*/
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setup_clear_cpu_cap(X86_FEATURE_PCID);
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if (!xen_initial_domain())
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setup_clear_cpu_cap(X86_FEATURE_ACPI);
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