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Commit 2829b449 authored by Jeremy Fitzhardinge's avatar Jeremy Fitzhardinge
Browse files

x86/paravirt: allow preemption with lazy mmu mode 



Impact: remove obsolete checks, simplification

Lift restrictions on preemption with lazy mmu mode, as it is now allowed.

Signed-off-by: default avatarJeremy Fitzhardinge <jeremy.fitzhardinge@citrix.com>
Acked-by: default avatarPeter Zijlstra <a.p.zijlstra@chello.nl>
parent 224101ed

arch/x86/kernel/paravirt.c

+4 −3
Original line number Diff line number Diff line
@@ -247,7 +247,6 @@ static DEFINE_PER_CPU(enum paravirt_lazy_mode, paravirt_lazy_mode) = PARAVIRT_LA 
static inline void enter_lazy(enum paravirt_lazy_mode mode)

{

	BUG_ON(__get_cpu_var(paravirt_lazy_mode) != PARAVIRT_LAZY_NONE);

	BUG_ON(preemptible());



	__get_cpu_var(paravirt_lazy_mode) = mode;

}
@@ -255,7 +254,6 @@ static inline void enter_lazy(enum paravirt_lazy_mode mode) 
static void leave_lazy(enum paravirt_lazy_mode mode)

{

	BUG_ON(__get_cpu_var(paravirt_lazy_mode) != mode);

	BUG_ON(preemptible());



	__get_cpu_var(paravirt_lazy_mode) = PARAVIRT_LAZY_NONE;

}
@@ -272,6 +270,8 @@ void paravirt_leave_lazy_mmu(void) 


void paravirt_start_context_switch(struct task_struct *prev)

{

	BUG_ON(preemptible());



	if (percpu_read(paravirt_lazy_mode) == PARAVIRT_LAZY_MMU) {

		arch_leave_lazy_mmu_mode();

		set_ti_thread_flag(task_thread_info(prev), TIF_LAZY_MMU_UPDATES);
@@ -281,6 +281,8 @@ void paravirt_start_context_switch(struct task_struct *prev) 


void paravirt_end_context_switch(struct task_struct *next)

{

	BUG_ON(preemptible());



	leave_lazy(PARAVIRT_LAZY_CPU);



	if (test_and_clear_ti_thread_flag(task_thread_info(next), TIF_LAZY_MMU_UPDATES))
@@ -300,7 +302,6 @@ void arch_flush_lazy_mmu_mode(void) 
	preempt_disable();



	if (paravirt_get_lazy_mode() == PARAVIRT_LAZY_MMU) {

		WARN_ON(preempt_count() == 1);

		arch_leave_lazy_mmu_mode();

		arch_enter_lazy_mmu_mode();

	}

arch/x86/xen/mmu.c

+1 −7
Original line number Diff line number Diff line
@@ -419,10 +419,6 @@ void set_pte_mfn(unsigned long vaddr, unsigned long mfn, pgprot_t flags) 
void xen_set_pte_at(struct mm_struct *mm, unsigned long addr,

		    pte_t *ptep, pte_t pteval)

{

	/* updates to init_mm may be done without lock */

	if (mm == &init_mm)

		preempt_disable();



	ADD_STATS(set_pte_at, 1);

//	ADD_STATS(set_pte_at_pinned, xen_page_pinned(ptep));

	ADD_STATS(set_pte_at_current, mm == current->mm);
@@ -443,9 +439,7 @@ void xen_set_pte_at(struct mm_struct *mm, unsigned long addr, 
	}

	xen_set_pte(ptep, pteval);



out:

	if (mm == &init_mm)

		preempt_enable();

out:	return;

}



pte_t xen_ptep_modify_prot_start(struct mm_struct *mm,