From: "Gautham R. Shenoy" <ego@xxxxxxxxxxxxxxxxxx>
If a guest executes a stop instruction when the hypervisor has set the
PSSCR[ESL|EC] bits, the processor will throw an Hypervisor Facility
Unavailable exception. Currently when we receive this exception, we
only check if the exeception is generated due to a doorbell
instruction, in which case we emulate it. For all other cases,
including the case when the guest executes a stop-instruction, the
hypervisor sends a PROGILL to the guest program, which results in a
guest crash.
This patch adds code to handle the case when the hypervisor receives a
H_FAC_UNAVAIL exception due to guest executing the stop
instruction. The hypervisor increments the pc to the next instruction
and resumes the guest as expected by the semantics of the
PSSCR[ESL|EC] = 0 stop instruction.
Signed-off-by: Gautham R. Shenoy <ego@xxxxxxxxxxxxxxxxxx>
---
arch/powerpc/include/asm/reg.h | 1 +
arch/powerpc/kvm/book3s_hv.c | 6 +++++-
2 files changed, 6 insertions(+), 1 deletion(-)
diff --git a/arch/powerpc/include/asm/reg.h b/arch/powerpc/include/asm/reg.h
index da5cab0..2568c18 100644
--- a/arch/powerpc/include/asm/reg.h
+++ b/arch/powerpc/include/asm/reg.h
@@ -399,6 +399,7 @@
/* HFSCR and FSCR bit numbers are the same */
#define FSCR_SCV_LG 12 /* Enable System Call Vectored */
#define FSCR_MSGP_LG 10 /* Enable MSGP */
+#define FSCR_STOP_LG 9 /* Enable stop states */
#define FSCR_TAR_LG 8 /* Enable Target Address Register */
#define FSCR_EBB_LG 7 /* Enable Event Based Branching */
#define FSCR_TM_LG 5 /* Enable Transactional Memory */
diff --git a/arch/powerpc/kvm/book3s_hv.c b/arch/powerpc/kvm/book3s_hv.c
index 33be4d9..cdb7224 100644
--- a/arch/powerpc/kvm/book3s_hv.c
+++ b/arch/powerpc/kvm/book3s_hv.c
@@ -1419,7 +1419,11 @@ static int kvmppc_handle_exit_hv(struct kvm_run *run, struct kvm_vcpu *vcpu,
if (((vcpu->arch.hfscr >> 56) == FSCR_MSGP_LG) &&
cpu_has_feature(CPU_FTR_ARCH_300))
r = kvmppc_emulate_doorbell_instr(vcpu);
- if (r == EMULATE_FAIL) {
+ else if (((vcpu->arch.hfscr >> 56) == FSCR_STOP_LG) &&
+ cpu_has_feature(CPU_FTR_ARCH_300)) {
+ kvmppc_set_pc(vcpu, kvmppc_get_pc(vcpu) + 4);
+ r = RESUME_GUEST;
+ } else if (r == EMULATE_FAIL) {
kvmppc_core_queue_program(vcpu, SRR1_PROGILL);
r = RESUME_GUEST;
}
--
1.9.4
