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KVM: MIPS: Improve kvm_get_inst() error return

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Currently kvm_get_inst() returns KVM_INVALID_INST in the event of a
fault reading the guest instruction. This has the rather arbitrary magic
value 0xdeadbeef. This API isn't very robust, and in fact 0xdeadbeef is
a valid MIPS64 instruction encoding, namely "ld t1,-16657(s5)".

Therefore change the kvm_get_inst() API to return 0 or -EFAULT, and to
return the instruction via a u32 *out argument. We can then drop the
KVM_INVALID_INST definition entirely.

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
This commit is contained in:
James Hogan
2016-11-28 17:23:14 +00:00
parent a1ecc54d7e
commit 122e51d474
4 changed files with 56 additions and 53 deletions
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7
arch/mips/kvm/mips.c
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@@ -1343,6 +1343,7 @@ int kvm_mips_handle_exit(struct kvm_run *run, struct kvm_vcpu *vcpu)
u32 __user *opc = (u32 __user *) vcpu->arch.pc;
unsigned long badvaddr = vcpu->arch.host_cp0_badvaddr;
enum emulation_result er = EMULATE_DONE;
u32 inst;
int ret = RESUME_GUEST;
/* re-enable HTW before enabling interrupts */
@@ -1467,8 +1468,12 @@ int kvm_mips_handle_exit(struct kvm_run *run, struct kvm_vcpu *vcpu)
break;
default:
if (cause & CAUSEF_BD)
opc += 1;
inst = 0;
kvm_get_inst(opc, vcpu, &inst);
kvm_err("Exception Code: %d, not yet handled, @ PC: %p, inst: 0x%08x BadVaddr: %#lx Status: %#lx\n",
exccode, opc, kvm_get_inst(opc, vcpu), badvaddr,
exccode, opc, inst, badvaddr,
kvm_read_c0_guest_status(vcpu->arch.cop0));
kvm_arch_vcpu_dump_regs(vcpu);
run->exit_reason = KVM_EXIT_INTERNAL_ERROR;