[patch 099/114] x86/paravirt: make arch_flush_lazy_mmu/cpu disable preemption

Greg KH
2009-03-14T01:57:59Z

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[-- Type: text/plain, Size: 2772 bytes --]

2.6.28-stable review patch. If anyone has any objections, please let us know.

------------------

From: Jeremy Fitzhardinge <jeremy@goop.org>

commit d85cf93da66977dbc645352be1b2084a659d8a0b upstream.

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: Jeremy Fitzhardinge <jeremy.fitzhardinge@citrix.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

---
arch/x86/include/asm/paravirt.h | 17 ++---------------
arch/x86/kernel/paravirt.c | 24 ++++++++++++++++++++++++
2 files changed, 26 insertions(+), 15 deletions(-)

--- a/arch/x86/include/asm/paravirt.h
+++ b/arch/x86/include/asm/paravirt.h
@@ -1352,14 +1352,7 @@ static inline void arch_leave_lazy_cpu_m
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_m
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)
--- a/arch/x86/kernel/paravirt.c
+++ b/arch/x86/kernel/paravirt.c
@@ -268,6 +268,30 @@ enum paravirt_lazy_mode paravirt_get_laz
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,