x86/pvops: replace arch_enter_lazy_cpu_mode with arch_start_context_switch

Impact: simplification, prepare for later changes

Make lazy cpu mode more specific to context switching, so that
it makes sense to do more context-switch specific things in
the callbacks.

Signed-off-by: Jeremy Fitzhardinge <jeremy.fitzhardinge@citrix.com>
Acked-by: Peter Zijlstra <a.p.zijlstra@chello.nl>

5 files changed, 6 insertions, 24 deletions

diff --git a/arch/x86/include/asm/paravirt.h b/arch/x86/include/asm/paravirt.h
index 0617d5cc971..7b28abac323 100644
--- a/arch/x86/include/asm/paravirt.h
+++ b/arch/x86/include/asm/paravirt.h
@@ -1420,19 +1420,17 @@ void paravirt_enter_lazy_mmu(void);
 void paravirt_leave_lazy_mmu(void);
 void paravirt_leave_lazy(enum paravirt_lazy_mode mode);
 
-#define  __HAVE_ARCH_ENTER_LAZY_CPU_MODE
-static inline void arch_enter_lazy_cpu_mode(void)
+#define  __HAVE_ARCH_START_CONTEXT_SWITCH
+static inline void arch_start_context_switch(void)
 {
         PVOP_VCALL0(pv_cpu_ops.lazy_mode.enter);
 }
 
-static inline void arch_leave_lazy_cpu_mode(void)
+static inline void arch_end_context_switch(void)
 {
         PVOP_VCALL0(pv_cpu_ops.lazy_mode.leave);
 }
 
-void arch_flush_lazy_cpu_mode(void);
-
 #define  __HAVE_ARCH_ENTER_LAZY_MMU_MODE
 static inline void arch_enter_lazy_mmu_mode(void)
 {
diff --git a/arch/x86/kernel/paravirt.c b/arch/x86/kernel/paravirt.c
index 8ab250ac498..5eea9548216 100644
--- a/arch/x86/kernel/paravirt.c
+++ b/arch/x86/kernel/paravirt.c
@@ -301,19 +301,6 @@ void arch_flush_lazy_mmu_mode(void)
         preempt_enable();
 }
 
-void arch_flush_lazy_cpu_mode(void)
-{
-        preempt_disable();
-
-        if (paravirt_get_lazy_mode() == PARAVIRT_LAZY_CPU) {
-                WARN_ON(preempt_count() == 1);
-                arch_leave_lazy_cpu_mode();
-                arch_enter_lazy_cpu_mode();
-        }
-
-        preempt_enable();
-}
-
 struct pv_info pv_info = {
         .name = "bare hardware",
         .paravirt_enabled = 0,
diff --git a/arch/x86/kernel/process_32.c b/arch/x86/kernel/process_32.c
index 14014d766ca..57e49a8278a 100644
--- a/arch/x86/kernel/process_32.c
+++ b/arch/x86/kernel/process_32.c
@@ -407,7 +407,7 @@ __switch_to(struct task_struct *prev_p, struct task_struct *next_p)
          * done before math_state_restore, so the TS bit is up
          * to date.
          */
-        arch_leave_lazy_cpu_mode();
+        arch_end_context_switch();
 
         /* If the task has used fpu the last 5 timeslices, just do a full
          * restore of the math state immediately to avoid the trap; the
diff --git a/arch/x86/kernel/process_64.c b/arch/x86/kernel/process_64.c
index abb7e6a7f0c..7115e608532 100644
--- a/arch/x86/kernel/process_64.c
+++ b/arch/x86/kernel/process_64.c
@@ -428,7 +428,7 @@ __switch_to(struct task_struct *prev_p, struct task_struct *next_p)
          * done before math_state_restore, so the TS bit is up
          * to date.
          */
-        arch_leave_lazy_cpu_mode();
+        arch_end_context_switch();
 
         /*
          * Switch FS and GS.
diff --git a/arch/x86/xen/mmu.c b/arch/x86/xen/mmu.c
index cb6afa4ec95..6b98f87232a 100644
--- a/arch/x86/xen/mmu.c
+++ b/arch/x86/xen/mmu.c
@@ -1119,10 +1119,8 @@ static void drop_other_mm_ref(void *info)
 
         /* If this cpu still has a stale cr3 reference, then make sure
            it has been flushed. */
-        if (percpu_read(xen_current_cr3) == __pa(mm->pgd)) {
+        if (percpu_read(xen_current_cr3) == __pa(mm->pgd))
                 load_cr3(swapper_pg_dir);
-                arch_flush_lazy_cpu_mode();
-        }
 }
 
 static void xen_drop_mm_ref(struct mm_struct *mm)
@@ -1135,7 +1133,6 @@ static void xen_drop_mm_ref(struct mm_struct *mm)
                         load_cr3(swapper_pg_dir);
                 else
                         leave_mm(smp_processor_id());
-                arch_flush_lazy_cpu_mode();
         }
 
         /* Get the "official" set of cpus referring to our pagetable. */