KVM: MIPS/T&E: Ignore user writes to CP0_Config7

Ignore userland writes to CP0_Config7 rather than reporting an error,
since we do allow reads of this register and it is claimed to exist in
the ioctl API.

This allows userland to blindly save and restore KVM registers without
having to special case certain registers as not being writable, for
example during live migration once dirty page logging is fixed.

Signed-off-by: James Hogan <james.hogan@imgtec.com>
Cc: Paolo Bonzini <pbonzini@redhat.com>
Cc: "Radim Krčmář" <rkrcmar@redhat.com>
Cc: Ralf Baechle <ralf@linux-mips.org>
Cc: linux-mips@linux-mips.org
Cc: kvm@vger.kernel.org

diff --git a/arch/mips/kvm/trap_emul.c b/arch/mips/kvm/trap_emul.c
index 1efe78d4bda891b7f0ecbc12e06d7796f31f9a2e..d0b6409cb4a328756cb7b994df9fc3b5fe323616 100644 (file)
--- a/arch/mips/kvm/trap_emul.c
+++ b/arch/mips/kvm/trap_emul.c
@@ -705,6 +705,9 @@ static int kvm_trap_emul_set_one_reg(struct kvm_vcpu *vcpu,
                        kvm_write_c0_guest_config5(cop0, v);
                }
                break;
+       case KVM_REG_MIPS_CP0_CONFIG7:
+               /* writes ignored */
+               break;
        case KVM_REG_MIPS_COUNT_CTL:
                ret = kvm_mips_set_count_ctl(vcpu, v);
                break;