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

[Greg KH]

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

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

From: Jeremy Fitzhardinge <jeremy@xxxxxxxx>

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@xxxxxxxxxx>
Signed-off-by: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxx>

---
 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,


--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/