MIPS: kvm: Fix ioctl error handling.

Calling return copy_to_user(...) or return copy_from_user in an ioctl
will not do the right thing if there's a pagefault:
copy_to_user/copy_from_user return the number of bytes not copied in
this case.

Fix up kvm on mips to do
	return copy_to_user(...)) ?  -EFAULT : 0;
and
	return copy_from_user(...)) ?  -EFAULT : 0;

everywhere.

Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
Cc: Paolo Bonzini <pbonzini@redhat.com>
Cc: James Hogan <james.hogan@imgtec.com>
Cc: linux-kernel@vger.kernel.org
Cc: linux-mips@linux-mips.org
Cc: stable@vger.kernel.org
Cc: kvm@vger.kernel.org
Patchwork: https://patchwork.linux-mips.org/patch/12709/
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>

diff --git a/arch/mips/kvm/mips.c b/arch/mips/kvm/mips.c
index 8bc3977..3110447 100644 (file)
--- a/arch/mips/kvm/mips.c
+++ b/arch/mips/kvm/mips.c
@@ -702,7 +702,7 @@ static int kvm_mips_get_reg(struct kvm_vcpu *vcpu,
        } else if ((reg->id & KVM_REG_SIZE_MASK) == KVM_REG_SIZE_U128) {
                void __user *uaddr = (void __user *)(long)reg->addr;
 
-               return copy_to_user(uaddr, vs, 16);
+               return copy_to_user(uaddr, vs, 16) ? -EFAULT : 0;
        } else {
                return -EINVAL;
        }
@@ -732,7 +732,7 @@ static int kvm_mips_set_reg(struct kvm_vcpu *vcpu,
        } else if ((reg->id & KVM_REG_SIZE_MASK) == KVM_REG_SIZE_U128) {
                void __user *uaddr = (void __user *)(long)reg->addr;
 
-               return copy_from_user(vs, uaddr, 16);
+               return copy_from_user(vs, uaddr, 16) ? -EFAULT : 0;
        } else {
                return -EINVAL;
        }