From: Andy Lutomirski luto@kernel.org
This patch has been added to the 4.1 stable tree. If you have any objections, please let us know.
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[ Upstream commit 660da7c9228f685b2ebe664f9fd69aaddcc420b5 ]
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... Signed-off-by: Ingo Molnar mingo@kernel.org Signed-off-by: Sasha Levin alexander.levin@microsoft.com --- arch/x86/include/asm/tlbflush.h | 8 ++++++++ arch/x86/kernel/cpu/common.c | 22 ++++++++++++++++++++++ arch/x86/xen/enlighten.c | 6 ++++++ 3 files changed, 36 insertions(+)
diff --git a/arch/x86/include/asm/tlbflush.h b/arch/x86/include/asm/tlbflush.h index d9ee4674c235..0b0718d48cb9 100644 --- a/arch/x86/include/asm/tlbflush.h +++ b/arch/x86/include/asm/tlbflush.h @@ -184,6 +184,14 @@ 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) diff --git a/arch/x86/kernel/cpu/common.c b/arch/x86/kernel/cpu/common.c index 843be1de5ddb..f5647d238337 100644 --- a/arch/x86/kernel/cpu/common.c +++ b/arch/x86/kernel/cpu/common.c @@ -339,6 +339,25 @@ 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); + } + } +} + /* * Some CPU features depend on higher CPUID levels, which may not always * be available due to CPUID level capping or broken virtualization @@ -968,6 +987,9 @@ 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." diff --git a/arch/x86/xen/enlighten.c b/arch/x86/xen/enlighten.c index 1ecae556d4ed..809730c09e2b 100644 --- a/arch/x86/xen/enlighten.c +++ b/arch/x86/xen/enlighten.c @@ -432,6 +432,12 @@ static void __init xen_init_cpuid_mask(void) ~((1 << X86_FEATURE_MTRR) | /* disable MTRR */ (1 << X86_FEATURE_ACC)); /* thermal monitoring */
+ /* + * Xen PV would need some work to support PCID: CR3 handling as well + * as xen_flush_tlb_others() would need updating. + */ + cpuid_leaf1_ecx_mask &= ~(1 << (X86_FEATURE_PCID % 32)); /* disable PCID */ + if (!xen_initial_domain()) cpuid_leaf1_edx_mask &= ~((1 << X86_FEATURE_ACPI)); /* disable ACPI */