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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 <agraf@suse.de>
Acked-by: Paul Mackerras <paulus@samba.org>
This commit is contained in:
Alexander Graf 2014-06-09 01:16:32 +02:00
parent 06da28e76b
commit fb4188bad0
1 changed files with 12 additions and 0 deletions
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12
arch/powerpc/kvm/book3s_pr.c
View File

@ -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;
}