On Tue, 2007-09-04 at 14:42 +0100, Jeremy Fitzhardinge wrote:

quoted

Rusty Russell wrote:

quoted

 static inline void arch_flush_lazy_mmu_mode(void)
 {
-	PVOP_VCALL1(set_lazy_mode, PARAVIRT_LAZY_FLUSH);
+	if (unlikely(__get_cpu_var(paravirt_lazy_mode) == PARAVIRT_LAZY_MMU))
+		arch_leave_lazy_mmu_mode();
 }
  

This changes the semantics a bit; previously "flush" would flush
anything pending but leave us in lazy mode.  This just drops lazymode
altogether?

I guess if we assume that flushing is a rare event then its OK, but I
think the name's a bit misleading.  How does it differ from plain
arch_leave_lazy_mmu_mode()?

Whether it's likely or unlikely to be in lazy mode, basically.  But
you're right, this should be folded, since we don't want to "leave" lazy
mode twice.

===
Hoist per-cpu lazy_mode variable up into common code.

VMI, Xen and lguest all track paravirt_lazy_mode individually, meaning
we hand a "magic" value for set_lazy_mode() to say "flush if currently
active".

We can simplify the logic by hoisting this variable into common code.

Signed-off-by: Rusty Russell <redacted>

---
 arch/i386/kernel/vmi.c      |   16 ++++------------
 arch/i386/xen/enlighten.c   |   15 +++------------
 arch/i386/xen/multicalls.h  |    2 +-
 arch/i386/xen/xen-ops.h     |    7 -------
 drivers/lguest/lguest.c     |   25 ++++++-------------------
 include/asm-i386/paravirt.h |   29 ++++++++++++++++-------------
 6 files changed, 30 insertions(+), 64 deletions(-)

diff -r 072a0b3924fb arch/i386/kernel/vmi.c

--- a/arch/i386/kernel/vmi.c	Thu Aug 30 04:47:43 2007 +1000
+++ b/arch/i386/kernel/vmi.c	Wed Sep 05 04:06:20 2007 +1000

@@ -554,22 +554,14 @@ vmi_startup_ipi_hook(int phys_apicid, un
 
 static void vmi_set_lazy_mode(enum paravirt_lazy_mode mode)
 {
-	static DEFINE_PER_CPU(enum paravirt_lazy_mode, lazy_mode);
-
 	if (!vmi_ops.set_lazy_mode)
 		return;
 
 	/* Modes should never nest or overlap */
-	BUG_ON(__get_cpu_var(lazy_mode) && !(mode == PARAVIRT_LAZY_NONE ||
-					     mode == PARAVIRT_LAZY_FLUSH));
-
-	if (mode == PARAVIRT_LAZY_FLUSH) {
-		vmi_ops.set_lazy_mode(0);
-		vmi_ops.set_lazy_mode(__get_cpu_var(lazy_mode));
-	} else {
-		vmi_ops.set_lazy_mode(mode);
-		__get_cpu_var(lazy_mode) = mode;
-	}
+	BUG_ON(get_lazy_mode() && !(mode == PARAVIRT_LAZY_NONE |
+				    | mode == PARAVIRT_LAZY_FLUSH));