Commit d85cf93d authored by Jeremy Fitzhardinge's avatar Jeremy Fitzhardinge Committed by Thomas Gleixner
Browse files

x86/paravirt: make arch_flush_lazy_mmu/cpu disable preemption 



Impact: avoid access to percpu vars in preempible context

They are intended to be used whenever there's the possibility
that there's some stale state which is going to be overwritten
with a queued update, or to force a state change when we may be
in lazy mode.  Either way, we could end up calling it with
preemption enabled, so wrap the functions in their own little
preempt-disable section so they can be safely called in any
context (though preemption should never be enabled if we're actually
in a lazy state).

(Move out of line to avoid #include dependencies.)
    
Signed-off-by: default avatarJeremy Fitzhardinge <jeremy.fitzhardinge@citrix.com>
Signed-off-by: default avatarThomas Gleixner <tglx@linutronix.de>
parent be03d9e8

arch/x86/include/asm/paravirt.h

+2 −15
Original line number Diff line number Diff line
@@ -1352,14 +1352,7 @@ static inline void arch_leave_lazy_cpu_mode(void) 
	PVOP_VCALL0(pv_cpu_ops.lazy_mode.leave);

}



static inline void arch_flush_lazy_cpu_mode(void)

{

	if (unlikely(paravirt_get_lazy_mode() == PARAVIRT_LAZY_CPU)) {

		arch_leave_lazy_cpu_mode();

		arch_enter_lazy_cpu_mode();

	}

}



void arch_flush_lazy_cpu_mode(void);



#define  __HAVE_ARCH_ENTER_LAZY_MMU_MODE

static inline void arch_enter_lazy_mmu_mode(void)
@@ -1372,13 +1365,7 @@ static inline void arch_leave_lazy_mmu_mode(void) 
	PVOP_VCALL0(pv_mmu_ops.lazy_mode.leave);

}



static inline void arch_flush_lazy_mmu_mode(void)

{

	if (unlikely(paravirt_get_lazy_mode() == PARAVIRT_LAZY_MMU)) {

		arch_leave_lazy_mmu_mode();

		arch_enter_lazy_mmu_mode();

	}

}

void arch_flush_lazy_mmu_mode(void);



static inline void __set_fixmap(unsigned /* enum fixed_addresses */ idx,

				unsigned long phys, pgprot_t flags)

arch/x86/kernel/paravirt.c

+24 −0
Original line number Diff line number Diff line
@@ -268,6 +268,30 @@ enum paravirt_lazy_mode paravirt_get_lazy_mode(void) 
	return __get_cpu_var(paravirt_lazy_mode);

}



void arch_flush_lazy_mmu_mode(void)

{

	preempt_disable();



	if (paravirt_get_lazy_mode() == PARAVIRT_LAZY_MMU) {

		arch_leave_lazy_mmu_mode();

		arch_enter_lazy_mmu_mode();

	}



	preempt_enable();

}



void arch_flush_lazy_cpu_mode(void)

{

	preempt_disable();



	if (paravirt_get_lazy_mode() == PARAVIRT_LAZY_CPU) {

		arch_leave_lazy_cpu_mode();

		arch_enter_lazy_cpu_mode();

	}



	preempt_enable();

}



struct pv_info pv_info = {

	.name = "bare hardware",

	.paravirt_enabled = 0,

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