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KVM: PPC: Book3S HV: Fix incorrect userspace exit on ioeventfd write

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When the guest does an MMIO write which is handled successfully by an
ioeventfd, ioeventfd_write() returns 0 (success) and
kvmppc_handle_store() returns EMULATE_DONE.  Then
kvmppc_emulate_mmio() converts EMULATE_DONE to RESUME_GUEST_NV and
this causes an exit from the loop in kvmppc_vcpu_run_hv(), causing an
exit back to userspace with a bogus exit reason code, typically
causing userspace (e.g. qemu) to crash with a message about an unknown
exit code.

This adds handling of RESUME_GUEST_NV in kvmppc_vcpu_run_hv() in order
to fix that.  For generality, we define a helper to check for either
of the return-to-guest codes we use, RESUME_GUEST and RESUME_GUEST_NV,
to make it easy to check for either and provide one place to update if
any other return-to-guest code gets defined in future.

Since it only affects Book3S HV for now, the helper is added to
the kvm_book3s.h header file.

We use the helper in two places in kvmppc_run_core() as well for
future-proofing, though we don't see RESUME_GUEST_NV in either place
at present.

[paulus@samba.org - combined 4 patches into one, rewrote description]

Suggested-by: Paul Mackerras <paulus@samba.org>
Signed-off-by: Alexey Kardashevskiy <aik@ozlabs.ru>
Signed-off-by: Greg Kurz <gkurz@linux.vnet.ibm.com>
Signed-off-by: Paul Mackerras <paulus@samba.org>
This commit is contained in:
Greg Kurz 2014-02-06 17:36:56 +01:00 committed by Paul Mackerras
parent e724f080f5
commit e59d24e612
2 changed files with 8 additions and 3 deletions
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5
arch/powerpc/include/asm/kvm_book3s.h
View file

@ -304,6 +304,11 @@ static inline ulong kvmppc_get_fault_dar(struct kvm_vcpu *vcpu)
return vcpu->arch.fault_dar;
}
static inline bool is_kvmppc_resume_guest(int r)
{
return (r == RESUME_GUEST || r == RESUME_GUEST_NV);
}
/* Magic register values loaded into r3 and r4 before the 'sc' assembly
* instruction for the OSI hypercalls */
#define OSI_SC_MAGIC_R3 0x113724FA

6
arch/powerpc/kvm/book3s_hv.c
View file

@ -1530,7 +1530,7 @@ static void kvmppc_run_core(struct kvmppc_vcore *vc)
vcpu->arch.trap = 0;
if (vcpu->arch.ceded) {
if (ret != RESUME_GUEST)
if (!is_kvmppc_resume_guest(ret))
kvmppc_end_cede(vcpu);
else
kvmppc_set_timer(vcpu);
@ -1541,7 +1541,7 @@ static void kvmppc_run_core(struct kvmppc_vcore *vc)
vc->vcore_state = VCORE_INACTIVE;
list_for_each_entry_safe(vcpu, vnext, &vc->runnable_threads,
arch.run_list) {
if (vcpu->arch.ret != RESUME_GUEST) {
if (!is_kvmppc_resume_guest(vcpu->arch.ret)) {
kvmppc_remove_runnable(vc, vcpu);
wake_up(&vcpu->arch.cpu_run);
}
@ -1731,7 +1731,7 @@ static int kvmppc_vcpu_run_hv(struct kvm_run *run, struct kvm_vcpu *vcpu)
vcpu->arch.fault_dar, vcpu->arch.fault_dsisr);
srcu_read_unlock(&vcpu->kvm->srcu, srcu_idx);
}
} while (r == RESUME_GUEST);
} while (is_kvmppc_resume_guest(r));
out:
vcpu->arch.state = KVMPPC_VCPU_NOTREADY;