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Context switches and TLB flushes can change individual bits of CR4. CR4 reads take several cycles, so store a shadow copy of CR4 in a per-cpu variable. To avoid wasting a cache line, I added the CR4 shadow to cpu_tlbstate, which is already touched in switch_mm. The heaviest users of the cr4 shadow will be switch_mm and __switch_to_xtra, and __switch_to_xtra is called shortly after switch_mm during context switch, so the cacheline is likely to be hot. Signed-off-by: Andy Lutomirski <luto@amacapital.net> Reviewed-by: Thomas Gleixner <tglx@linutronix.de> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Cc: Kees Cook <keescook@chromium.org> Cc: Andrea Arcangeli <aarcange@redhat.com> Cc: Vince Weaver <vince@deater.net> Cc: "hillf.zj" <hillf.zj@alibaba-inc.com> Cc: Valdis Kletnieks <Valdis.Kletnieks@vt.edu> Cc: Paul Mackerras <paulus@samba.org> Cc: Arnaldo Carvalho de Melo <acme@kernel.org> Cc: Linus Torvalds <torvalds@linux-foundation.org> Link: http://lkml.kernel.org/r/3a54dd3353fffbf84804398e00dfdc5b7c1afd7d.1414190806.git.luto@amacapital.net Signed-off-by: Ingo Molnar <mingo@kernel.org> |
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.. | ||
assigned-dev.c | ||
assigned-dev.h | ||
cpuid.c | ||
cpuid.h | ||
emulate.c | ||
i8254.c | ||
i8254.h | ||
i8259.c | ||
ioapic.c | ||
ioapic.h | ||
iommu.c | ||
irq_comm.c | ||
irq.c | ||
irq.h | ||
Kconfig | ||
kvm_cache_regs.h | ||
lapic.c | ||
lapic.h | ||
Makefile | ||
mmu_audit.c | ||
mmu.c | ||
mmu.h | ||
mmutrace.h | ||
paging_tmpl.h | ||
pmu.c | ||
svm.c | ||
trace.h | ||
tss.h | ||
vmx.c | ||
x86.c | ||
x86.h |