From fb4188bad02f4871b26cf19b98e8d92499ca5d31 Mon Sep 17 00:00:00 2001 From: Alexander Graf Date: Mon, 9 Jun 2014 01:16:32 +0200 Subject: [PATCH] KVM: PPC: Book3s PR: Disable AIL mode with OPAL When we're using PR KVM we must not allow the CPU to take interrupts in virtual mode, as the SLB does not contain host kernel mappings when running inside the guest context. To make sure we get good performance for non-KVM tasks but still properly functioning PR KVM, let's just disable AIL whenever a vcpu is scheduled in. This is fundamentally different from how we deal with AIL on pSeries type machines where we disable AIL for the whole machine as soon as a single KVM VM is up. The reason for that is easy - on pSeries we do not have control over per-cpu configuration of AIL. We also don't want to mess with CPU hotplug races and AIL configuration, so setting it per CPU is easier and more flexible. This patch fixes running PR KVM on POWER8 bare metal for me. Signed-off-by: Alexander Graf Acked-by: Paul Mackerras --- arch/powerpc/kvm/book3s_pr.c | 12 ++++++++++++ 1 file changed, 12 insertions(+) diff --git a/arch/powerpc/kvm/book3s_pr.c b/arch/powerpc/kvm/book3s_pr.c index 3da412e16b3a..8ea7da4b5649 100644 --- a/arch/powerpc/kvm/book3s_pr.c +++ b/arch/powerpc/kvm/book3s_pr.c @@ -71,6 +71,12 @@ static void kvmppc_core_vcpu_load_pr(struct kvm_vcpu *vcpu, int cpu) svcpu->in_use = 0; svcpu_put(svcpu); #endif + + /* Disable AIL if supported */ + if (cpu_has_feature(CPU_FTR_HVMODE) && + cpu_has_feature(CPU_FTR_ARCH_207S)) + mtspr(SPRN_LPCR, mfspr(SPRN_LPCR) & ~LPCR_AIL); + vcpu->cpu = smp_processor_id(); #ifdef CONFIG_PPC_BOOK3S_32 current->thread.kvm_shadow_vcpu = vcpu->arch.shadow_vcpu; @@ -91,6 +97,12 @@ static void kvmppc_core_vcpu_put_pr(struct kvm_vcpu *vcpu) kvmppc_giveup_ext(vcpu, MSR_FP | MSR_VEC | MSR_VSX); kvmppc_giveup_fac(vcpu, FSCR_TAR_LG); + + /* Enable AIL if supported */ + if (cpu_has_feature(CPU_FTR_HVMODE) && + cpu_has_feature(CPU_FTR_ARCH_207S)) + mtspr(SPRN_LPCR, mfspr(SPRN_LPCR) | LPCR_AIL_3); + vcpu->cpu = -1; }