[PATCH 3/3] [PREVIEW] Resurrect the VMI lazy mode fixes.

[Zachary Amsden <zach@vmware.com>]

Code changes and cleanup in the paravirt-ops queue caused the original
fix for this in 2.6.21 to create conflicts.  The easiest thing to do was
back it out before applying the queue.  In that case, this fix brings it
back with the newly tidied up paravirt-ops code.

PREVIEW-ONLY: Do not apply.  This is dependent on changes which have not
yet been merged.

Signed-off-by: Zachary Amsden <zach@vmware.com>

diff -r ecb571084874 arch/i386/kernel/vmi.c
--- a/arch/i386/kernel/vmi.c	Fri Apr 06 12:31:06 2007 -0700
+++ b/arch/i386/kernel/vmi.c	Fri Apr 06 12:31:06 2007 -0700
@@ -69,6 +69,7 @@ static struct {
 	void (*flush_tlb)(int);
 	void (*set_initial_ap_state)(int, int);
 	void (*halt)(void);
+  	void (*set_lazy_mode)(int mode);
 } vmi_ops;
 
 /*
@@ -545,6 +546,26 @@ vmi_startup_ipi_hook(int phys_apicid, un
 }
 #endif
 
+static void vmi_set_lazy_mode(int mode)
+{
+	static DEFINE_PER_CPU(int, 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(new_mode);
+		per_cpu(mode, cpu) = new_mode;
+	}
+}
+
 static inline int __init check_vmi_rom(struct vrom_header *rom)
 {
 	struct pci_header *pci;
@@ -769,7 +790,7 @@ static inline int __init activate_vmi(vo
 	para_wrap(load_esp0, vmi_load_esp0, set_kernel_stack, UpdateKernelStack);
 	para_fill(set_iopl_mask, SetIOPLMask);
 	para_fill(io_delay, IODelay);
-	para_fill(set_lazy_mode, SetLazyMode);
+	para_wrap(set_lazy_mode, vmi_set_lazy_mode, set_lazy_mode, SetLazyMode);
 
 	/* user and kernel flush are just handled with different flags to FlushTLB */
 	para_wrap(flush_tlb_user, vmi_flush_tlb_user, flush_tlb, FlushTLB);