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KVM: PPC: Graciously fail broken LE hypercalls

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There are LE Linux guests out there that don't handle hypercalls correctly.
Instead of interpreting the instruction stream from device tree as big endian
they assume it's a little endian instruction stream and fail.

When we see an illegal instruction from such a byte reversed instruction stream,
bail out graciously and just declare every hcall as error.

Signed-off-by: Alexander Graf <agraf@suse.de>
This commit is contained in:
Alexander Graf 2014-05-13 17:05:51 +02:00
parent 235959be9a
commit 42188365f9
1 changed files with 17 additions and 0 deletions
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17
arch/powerpc/kvm/book3s_emulate.c
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@ -94,8 +94,25 @@ int kvmppc_core_emulate_op_pr(struct kvm_run *run, struct kvm_vcpu *vcpu,
int rs = get_rs(inst);
int ra = get_ra(inst);
int rb = get_rb(inst);
u32 inst_sc = 0x44000002;
switch (get_op(inst)) {
case 0:
emulated = EMULATE_FAIL;
if ((kvmppc_get_msr(vcpu) & MSR_LE) &&
(inst == swab32(inst_sc))) {
/*
* This is the byte reversed syscall instruction of our
* hypercall handler. Early versions of LE Linux didn't
* swap the instructions correctly and ended up in
* illegal instructions.
* Just always fail hypercalls on these broken systems.
*/
kvmppc_set_gpr(vcpu, 3, EV_UNIMPLEMENTED);
kvmppc_set_pc(vcpu, kvmppc_get_pc(vcpu) + 4);
emulated = EMULATE_DONE;
}
break;
case 19:
switch (get_xop(inst)) {
case OP_19_XOP_RFID: