KVM: Add ioctl to tss address from userspace,

Currently kvm has a wart in that it requires three extra pages for use
as a tss when emulating real mode on Intel.  This patch moves the allocation
internally, only requiring userspace to tell us where in the physical address
space we can place the tss.

Signed-off-by: Izik Eidus <izike@qumranet.com>
Signed-off-by: Avi Kivity <avi@qumranet.com>
diff --git a/drivers/kvm/svm.c b/drivers/kvm/svm.c
index 953c111..beb1e68 100644
--- a/drivers/kvm/svm.c
+++ b/drivers/kvm/svm.c
@@ -1439,6 +1439,11 @@
 		control->intercept &= ~(1ULL << INTERCEPT_VINTR);
 }
 
+static int svm_set_tss_addr(struct kvm *kvm, unsigned int addr)
+{
+	return 0;
+}
+
 static void save_db_regs(unsigned long *db_regs)
 {
 	asm volatile ("mov %%dr0, %0" : "=r"(db_regs[0]));
@@ -1744,6 +1749,8 @@
 	.set_irq = svm_set_irq,
 	.inject_pending_irq = svm_intr_assist,
 	.inject_pending_vectors = do_interrupt_requests,
+
+	.set_tss_addr = svm_set_tss_addr,
 };
 
 static int __init svm_init(void)