paravirt: clean up lazy mode handling

Currently, the set_lazy_mode pv_op is overloaded with 5 functions:
 1. enter lazy cpu mode
 2. leave lazy cpu mode
 3. enter lazy mmu mode
 4. leave lazy mmu mode
 5. flush pending batched operations

This complicates each paravirt backend, since it needs to deal with
all the possible state transitions, handling flushing, etc. In
particular, flushing is quite distinct from the other 4 functions, and
seems to just cause complication.

This patch removes the set_lazy_mode operation, and adds "enter" and
"leave" lazy mode operations on mmu_ops and cpu_ops.  All the logic
associated with enter and leaving lazy states is now in common code
(basically BUG_ONs to make sure that no mode is current when entering
a lazy mode, and make sure that the mode is current when leaving).
Also, flush is handled in a common way, by simply leaving and
re-entering the lazy mode.

The result is that the Xen, lguest and VMI lazy mode implementations
are much simpler.

Signed-off-by: Jeremy Fitzhardinge <jeremy@xensource.com>
Cc: Andi Kleen <ak@suse.de>
Cc: Zach Amsden <zach@vmware.com>
Cc: Rusty Russell <rusty@rustcorp.com.au>
Cc: Avi Kivity <avi@qumranet.com>
Cc: Anthony Liguory <aliguori@us.ibm.com>
Cc: "Glauber de Oliveira Costa" <glommer@gmail.com>
Cc: Jun Nakajima <jun.nakajima@intel.com>

1 files changed, 23 insertions, 16 deletions

diff --git a/arch/x86/kernel/vmi_32.c b/arch/x86/kernel/vmi_32.c
index 67cea5c2e3e..f02bad68aba 100644
--- a/arch/x86/kernel/vmi_32.c
+++ b/arch/x86/kernel/vmi_32.c
@@ -552,24 +552,22 @@ vmi_startup_ipi_hook(int phys_apicid, unsigned long start_eip,
 }
 #endif
 
-static void vmi_set_lazy_mode(enum paravirt_lazy_mode mode)
+static void vmi_enter_lazy_cpu(void)
 {
-	static DEFINE_PER_CPU(enum paravirt_lazy_mode, lazy_mode);
-
-	if (!vmi_ops.set_lazy_mode)
-		return;
+	paravirt_enter_lazy_cpu();
+	vmi_ops.set_lazy_mode(2);
+}
 
-	/* Modes should never nest or overlap */
-	BUG_ON(__get_cpu_var(lazy_mode) && !(mode == PARAVIRT_LAZY_NONE ||
-					     mode == PARAVIRT_LAZY_FLUSH));
+static void vmi_enter_lazy_mmu(void)
+{
+	paravirt_enter_lazy_mmu();
+	vmi_ops.set_lazy_mode(1);
+}
 
-	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;
-	}
+static void vmi_leave_lazy(void)
+{
+	paravirt_leave_lazy(paravirt_get_lazy_mode());
+	vmi_ops.set_lazy_mode(0);
 }
 
 static inline int __init check_vmi_rom(struct vrom_header *rom)
@@ -798,7 +796,16 @@ static inline int __init activate_vmi(void)
 	para_wrap(pv_cpu_ops.load_esp0, vmi_load_esp0, set_kernel_stack, UpdateKernelStack);
 	para_fill(pv_cpu_ops.set_iopl_mask, SetIOPLMask);
 	para_fill(pv_cpu_ops.io_delay, IODelay);
-	para_wrap(pv_misc_ops.set_lazy_mode, vmi_set_lazy_mode, set_lazy_mode, SetLazyMode);
+
+	para_wrap(pv_cpu_ops.lazy_mode.enter, vmi_enter_lazy_cpu,
+		  set_lazy_mode, SetLazyMode);
+	para_wrap(pv_cpu_ops.lazy_mode.leave, vmi_leave_lazy,
+		  set_lazy_mode, SetLazyMode);
+
+	para_wrap(pv_mmu_ops.lazy_mode.enter, vmi_enter_lazy_mmu,
+		  set_lazy_mode, SetLazyMode);
+	para_wrap(pv_mmu_ops.lazy_mode.leave, vmi_leave_lazy,
+		  set_lazy_mode, SetLazyMode);
 
 	/* user and kernel flush are just handled with different flags to FlushTLB */
 	para_wrap(pv_mmu_ops.flush_tlb_user, vmi_flush_tlb_user, _flush_tlb, FlushTLB);