diff options
Diffstat (limited to 'arch/powerpc/platforms/pseries/smp.c')
| -rw-r--r-- | arch/powerpc/platforms/pseries/smp.c | 38 |
1 files changed, 23 insertions, 15 deletions
diff --git a/arch/powerpc/platforms/pseries/smp.c b/arch/powerpc/platforms/pseries/smp.c index a1cb861154e9..92922491a81c 100644 --- a/arch/powerpc/platforms/pseries/smp.c +++ b/arch/powerpc/platforms/pseries/smp.c @@ -210,24 +210,32 @@ static __init void pSeries_smp_probe(void) if (!cpu_has_feature(CPU_FTR_SMT)) return; - /* - * KVM emulates doorbells by disabling FSCR[MSGP] so msgsndp faults - * to the hypervisor which then reads the instruction from guest - * memory. This can't be done if the guest is secure, so don't use - * doorbells in secure guests. - * - * Under PowerVM, FSCR[MSGP] is enabled so doorbells could be used - * by secure guests if we distinguished this from KVM. - */ - if (is_secure_guest()) - return; + if (is_kvm_guest()) { + /* + * KVM emulates doorbells by disabling FSCR[MSGP] so msgsndp + * faults to the hypervisor which then reads the instruction + * from guest memory, which tends to be slower than using XIVE. + */ + if (xive_enabled()) + return; + + /* + * XICS hcalls aren't as fast, so we can use msgsndp (which + * also helps exercise KVM emulation), however KVM can't + * emulate secure guests because it can't read the instruction + * out of their memory. + */ + if (is_secure_guest()) + return; + } /* - * The guest can use doobells for SMT sibling IPIs, which stay in - * the core rather than going to the interrupt controller. This - * tends to be slower under KVM where doorbells are emulated, but - * faster for PowerVM where they're enabled. + * Under PowerVM, FSCR[MSGP] is enabled as guest vCPU siblings are + * gang scheduled on the same physical core, so doorbells are always + * faster than the interrupt controller, and they can be used by + * secure guests. */ + ic_cause_ipi = smp_ops->cause_ipi; smp_ops->cause_ipi = dbell_or_ic_cause_ipi; } |