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authorJames Hogan <james.hogan@imgtec.com>2014-03-14 13:06:07 +0000
committerGreg Kroah-Hartman <gregkh@linuxfoundation.org>2014-05-13 13:32:48 +0200
commit2981534733f5deaa4ed86bc7f91f3bd18152abe0 (patch)
treeea0ef98046339579ae8a5322bea80566adde101b /arch/mips
parentf8944acc97ceebf902e5b26b900aefef987ab4be (diff)
MIPS: KVM: Pass reserved instruction exceptions to guest
commit 15505679362270d02c449626385cb74af8905514 upstream. Previously a reserved instruction exception while in guest code would cause a KVM internal error if kvm_mips_handle_ri() didn't recognise the instruction (including a RDHWR from an unrecognised hardware register). However the guest OS should really have the opportunity to catch the exception so that it can take the appropriate actions such as sending a SIGILL to the guest user process or emulating the instruction itself. Therefore in these cases emulate a guest RI exception and only return EMULATE_FAIL if that fails, being careful to revert the PC first in case the exception occurred in a branch delay slot in which case the PC will already point to the branch target. Also turn the printk messages relating to these cases into kvm_debug messages so that they aren't usually visible. This allows crashme to run in the guest without killing the entire VM. Signed-off-by: James Hogan <james.hogan@imgtec.com> Cc: Ralf Baechle <ralf@linux-mips.org> Cc: Gleb Natapov <gleb@kernel.org> Cc: Paolo Bonzini <pbonzini@redhat.com> Cc: Sanjay Lal <sanjayl@kymasys.com> Cc: linux-mips@linux-mips.org Cc: kvm@vger.kernel.org Signed-off-by: Paolo Bonzini <pbonzini@redhat.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Diffstat (limited to 'arch/mips')
-rw-r--r--arch/mips/kvm/kvm_mips_emul.c7
1 files changed, 4 insertions, 3 deletions
diff --git a/arch/mips/kvm/kvm_mips_emul.c b/arch/mips/kvm/kvm_mips_emul.c
index 4b6274b47f33..e75ef8219caf 100644
--- a/arch/mips/kvm/kvm_mips_emul.c
+++ b/arch/mips/kvm/kvm_mips_emul.c
@@ -1571,17 +1571,17 @@ kvm_mips_handle_ri(unsigned long cause, uint32_t *opc,
arch->gprs[rt] = kvm_read_c0_guest_userlocal(cop0);
#else
/* UserLocal not implemented */
- er = kvm_mips_emulate_ri_exc(cause, opc, run, vcpu);
+ er = EMULATE_FAIL;
#endif
break;
default:
- printk("RDHWR not supported\n");
+ kvm_debug("RDHWR %#x not supported @ %p\n", rd, opc);
er = EMULATE_FAIL;
break;
}
} else {
- printk("Emulate RI not supported @ %p: %#x\n", opc, inst);
+ kvm_debug("Emulate RI not supported @ %p: %#x\n", opc, inst);
er = EMULATE_FAIL;
}
@@ -1590,6 +1590,7 @@ kvm_mips_handle_ri(unsigned long cause, uint32_t *opc,
*/
if (er == EMULATE_FAIL) {
vcpu->arch.pc = curr_pc;
+ er = kvm_mips_emulate_ri_exc(cause, opc, run, vcpu);
}
return er;
}