KVM: x86: accessors for guest registers

As suggested by Avi, introduce accessors to read/write guest registers.
This simplifies the ->cache_regs/->decache_regs interface, and improves
register caching which is important for VMX, where the cost of
vmcs_read/vmcs_write is significant.

[avi: fix warnings]

Signed-off-by: Marcelo Tosatti <mtosatti@redhat.com>
Signed-off-by: Avi Kivity <avi@qumranet.com>
diff --git a/arch/x86/kvm/lapic.c b/arch/x86/kvm/lapic.c
index 73f43de..9fde0ac 100644
--- a/arch/x86/kvm/lapic.c
+++ b/arch/x86/kvm/lapic.c
@@ -32,6 +32,7 @@
 #include <asm/current.h>
 #include <asm/apicdef.h>
 #include <asm/atomic.h>
+#include "kvm_cache_regs.h"
 #include "irq.h"
 
 #define PRId64 "d"
@@ -558,8 +559,7 @@
 	struct kvm_run *run = vcpu->run;
 
 	set_bit(KVM_REQ_REPORT_TPR_ACCESS, &vcpu->requests);
-	kvm_x86_ops->cache_regs(vcpu);
-	run->tpr_access.rip = vcpu->arch.rip;
+	run->tpr_access.rip = kvm_rip_read(vcpu);
 	run->tpr_access.is_write = write;
 }