MIPS: KVM: Add CP0_UserLocal KVM register access

Implement KVM_{GET,SET}_ONE_REG ioctl based access to the guest CP0
UserLocal register. This is so that userland can save and restore its
value.

Signed-off-by: James Hogan <james.hogan@imgtec.com>
Cc: Paolo Bonzini <pbonzini@redhat.com>
Cc: Gleb Natapov <gleb@kernel.org>
Cc: kvm@vger.kernel.org
Cc: Ralf Baechle <ralf@linux-mips.org>
Cc: linux-mips@linux-mips.org
Cc: David Daney <david.daney@cavium.com>
Cc: Sanjay Lal <sanjayl@kymasys.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

arch/mips/include/asm/kvm_host.h

@@ -442,6 +442,7 @@ struct kvm_vcpu_arch {
 #define kvm_read_c0_guest_context(cop0)		(cop0->reg[MIPS_CP0_TLB_CONTEXT][0])
 #define kvm_write_c0_guest_context(cop0, val)	(cop0->reg[MIPS_CP0_TLB_CONTEXT][0] = (val))
 #define kvm_read_c0_guest_userlocal(cop0)	(cop0->reg[MIPS_CP0_TLB_CONTEXT][2])
+#define kvm_write_c0_guest_userlocal(cop0, val)	(cop0->reg[MIPS_CP0_TLB_CONTEXT][2] = (val))
 #define kvm_read_c0_guest_pagemask(cop0)	(cop0->reg[MIPS_CP0_TLB_PG_MASK][0])
 #define kvm_write_c0_guest_pagemask(cop0, val)	(cop0->reg[MIPS_CP0_TLB_PG_MASK][0] = (val))
 #define kvm_read_c0_guest_wired(cop0)		(cop0->reg[MIPS_CP0_TLB_WIRED][0])

arch/mips/kvm/kvm_mips.c

@@ -526,6 +526,7 @@ static u64 kvm_mips_get_one_regs[] = {
 
 	KVM_REG_MIPS_CP0_INDEX,
 	KVM_REG_MIPS_CP0_CONTEXT,
+	KVM_REG_MIPS_CP0_USERLOCAL,
 	KVM_REG_MIPS_CP0_PAGEMASK,
 	KVM_REG_MIPS_CP0_WIRED,
 	KVM_REG_MIPS_CP0_BADVADDR,
@@ -570,6 +571,9 @@ static int kvm_mips_get_reg(struct kvm_vcpu *vcpu,
 	case KVM_REG_MIPS_CP0_CONTEXT:
 		v = (long)kvm_read_c0_guest_context(cop0);
 		break;
+	case KVM_REG_MIPS_CP0_USERLOCAL:
+		v = (long)kvm_read_c0_guest_userlocal(cop0);
+		break;
 	case KVM_REG_MIPS_CP0_PAGEMASK:
 		v = (long)kvm_read_c0_guest_pagemask(cop0);
 		break;
@@ -678,6 +682,9 @@ static int kvm_mips_set_reg(struct kvm_vcpu *vcpu,
 	case KVM_REG_MIPS_CP0_CONTEXT:
 		kvm_write_c0_guest_context(cop0, v);
 		break;
+	case KVM_REG_MIPS_CP0_USERLOCAL:
+		kvm_write_c0_guest_userlocal(cop0, v);
+		break;
 	case KVM_REG_MIPS_CP0_PAGEMASK:
 		kvm_write_c0_guest_pagemask(cop0, v);
 		break;