KVM: Add coalesced MMIO support (x86 part)

This patch enables coalesced MMIO for x86 architecture.
It defines KVM_MMIO_PAGE_OFFSET and KVM_CAP_COALESCED_MMIO.
It enables the compilation of coalesced_mmio.c.

Signed-off-by: Laurent Vivier <Laurent.Vivier@bull.net>
Signed-off-by: Avi Kivity <avi@qumranet.com>
diff --git a/include/asm-x86/kvm_host.h b/include/asm-x86/kvm_host.h
index cd6a4bb..c64d124 100644
--- a/include/asm-x86/kvm_host.h
+++ b/include/asm-x86/kvm_host.h
@@ -27,6 +27,7 @@
 #define KVM_PRIVATE_MEM_SLOTS 4
 
 #define KVM_PIO_PAGE_OFFSET 1
+#define KVM_COALESCED_MMIO_PAGE_OFFSET 2
 
 #define CR3_PAE_RESERVED_BITS ((X86_CR3_PWT | X86_CR3_PCD) - 1)
 #define CR3_NONPAE_RESERVED_BITS ((PAGE_SIZE-1) & ~(X86_CR3_PWT | X86_CR3_PCD))