MIPS: KVM: Don't unwind PC when emulating CACHE
authorJames Hogan <james.hogan@imgtec.com>
Thu, 9 Jun 2016 09:50:45 +0000 (10:50 +0100)
committerPaolo Bonzini <pbonzini@redhat.com>
Tue, 14 Jun 2016 08:59:45 +0000 (10:59 +0200)
commitcc81e9486202345d6ca56495cf8b5f3d03fbc563
treedf76b2d7c4766a0f2c07c8d41d7517191e97a122
parent7f5a1ddc792901249c2060e165bcb3ca779cde35
MIPS: KVM: Don't unwind PC when emulating CACHE

When a CACHE instruction is emulated by kvm_mips_emulate_cache(), the PC
is first updated to point to the next instruction, and afterwards it
falls through the "dont_update_pc" label, which rewinds the PC back to
its original address.

This works when dynamic translation of emulated instructions is enabled,
since the CACHE instruction is replaced with a SYNCI which works without
trapping, however when dynamic translation is disabled the guest hangs
on CACHE instructions as they always trap and are never stepped over.

Roughly swap the meanings of the "done" and "dont_update_pc" to match
kvm_mips_emulate_CP0(), so that "done" will roll back the PC on failure,
and "dont_update_pc" won't change PC at all (for the sake of exceptions
that have already modified the PC).

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: kvm@vger.kernel.org
Cc: linux-mips@linux-mips.org
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
arch/mips/kvm/emulate.c