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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: Jeremy Fitzhardinge <jeremy.fitzhardinge@citrix.com>
Acked-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
This commit is contained in:
Jeremy Fitzhardinge 2009-02-17 23:53:19 -08:00
parent 224101ed69
commit 2829b44927
2 changed files with 5 additions and 10 deletions
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7
arch/x86/kernel/paravirt.c
View File

@ -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) static inline void enter_lazy(enum paravirt_lazy_mode mode)
{ {
BUG_ON(__get_cpu_var(paravirt_lazy_mode) != PARAVIRT_LAZY_NONE); BUG_ON(__get_cpu_var(paravirt_lazy_mode) != PARAVIRT_LAZY_NONE);
BUG_ON(preemptible());
__get_cpu_var(paravirt_lazy_mode) = mode; __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) static void leave_lazy(enum paravirt_lazy_mode mode)
{ {
BUG_ON(__get_cpu_var(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; __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) void paravirt_start_context_switch(struct task_struct *prev)
{ {
BUG_ON(preemptible());
if (percpu_read(paravirt_lazy_mode) == PARAVIRT_LAZY_MMU) { if (percpu_read(paravirt_lazy_mode) == PARAVIRT_LAZY_MMU) {
arch_leave_lazy_mmu_mode(); arch_leave_lazy_mmu_mode();
set_ti_thread_flag(task_thread_info(prev), TIF_LAZY_MMU_UPDATES); 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) void paravirt_end_context_switch(struct task_struct *next)
{ {
BUG_ON(preemptible());
leave_lazy(PARAVIRT_LAZY_CPU); leave_lazy(PARAVIRT_LAZY_CPU);
if (test_and_clear_ti_thread_flag(task_thread_info(next), TIF_LAZY_MMU_UPDATES)) 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(); preempt_disable();
if (paravirt_get_lazy_mode() == PARAVIRT_LAZY_MMU) { if (paravirt_get_lazy_mode() == PARAVIRT_LAZY_MMU) {
WARN_ON(preempt_count() == 1);
arch_leave_lazy_mmu_mode(); arch_leave_lazy_mmu_mode();
arch_enter_lazy_mmu_mode(); arch_enter_lazy_mmu_mode();
} }

8
arch/x86/xen/mmu.c
View File

@ -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, void xen_set_pte_at(struct mm_struct *mm, unsigned long addr,
pte_t *ptep, pte_t pteval) 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, 1);
// ADD_STATS(set_pte_at_pinned, xen_page_pinned(ptep)); // ADD_STATS(set_pte_at_pinned, xen_page_pinned(ptep));
ADD_STATS(set_pte_at_current, mm == current->mm); 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); xen_set_pte(ptep, pteval);
out: out: return;
if (mm == &init_mm)
preempt_enable();
} }
pte_t xen_ptep_modify_prot_start(struct mm_struct *mm, pte_t xen_ptep_modify_prot_start(struct mm_struct *mm,