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>

1 files changed, 16 insertions, 0 deletions

diff --git a/drivers/kvm/kvm_main.c b/drivers/kvm/kvm_main.c
index a044856bd02..50fd040b9ea 100644
--- a/drivers/kvm/kvm_main.c
+++ b/drivers/kvm/kvm_main.c
@@ -2661,6 +2661,16 @@ static int create_vcpu_fd(struct kvm_vcpu *vcpu)
         return fd;
 }
 
+static int kvm_vm_ioctl_set_tss_addr(struct kvm *kvm, unsigned long addr)
+{
+        int ret;
+
+        if (addr > (unsigned int)(-3 * PAGE_SIZE))
+                return -1;
+        ret = kvm_x86_ops->set_tss_addr(kvm, addr);
+        return ret;
+}
+
 /*
  * Creates some virtual cpus.  Good luck creating more than one.
  */
@@ -2957,6 +2967,11 @@ static long kvm_vm_ioctl(struct file *filp,
         int r = -EINVAL;
 
         switch (ioctl) {
+        case KVM_SET_TSS_ADDR:
+                r = kvm_vm_ioctl_set_tss_addr(kvm, arg);
+                if (r < 0)
+                        goto out;
+                break;
         case KVM_CREATE_VCPU:
                 r = kvm_vm_ioctl_create_vcpu(kvm, arg);
                 if (r < 0)
@@ -3183,6 +3198,7 @@ static long kvm_dev_ioctl(struct file *filp,
                 case KVM_CAP_HLT:
                 case KVM_CAP_MMU_SHADOW_CACHE_CONTROL:
                 case KVM_CAP_USER_MEMORY:
+                case KVM_CAP_SET_TSS_ADDR:
                         r = 1;
                         break;
                 default: