KVM: PPC: Book3S HV P9: implement hash guest support
Implement hash guest support. Guest entry/exit has to restore and
save/clear the SLB, plus several other bits to accommodate hash guests
in the P9 path. Radix host, hash guest support is removed from the P7/8
path.
The HPT hcalls and faults are not handled in real mode, which is a
performance regression. A worst-case fork/exit microbenchmark takes 3x
longer after this patch. kbuild benchmark performance is in the noise,
but the slowdown is likely to be noticed somewhere.
For now, accept this penalty for the benefit of simplifying the P7/8
paths and unifying P9 hash with the new code, because hash is a less
important configuration than radix on processors that support it. Hash
will benefit from future optimisations to this path, including possibly
a faster path to handle such hcalls and interrupts without doing a full
exit.
Signed-off-by: Nicholas Piggin <npiggin@gmail.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20210528090752.3542186-31-npiggin@gmail.com
diff --git a/arch/powerpc/kvm/book3s_hv.c b/arch/powerpc/kvm/book3s_hv.c
index 493f67f..662f599 100644
--- a/arch/powerpc/kvm/book3s_hv.c
+++ b/arch/powerpc/kvm/book3s_hv.c
@@ -3875,7 +3875,8 @@ static int kvmhv_p9_guest_entry(struct kvm_vcpu *vcpu, u64 time_limit,
}
kvmppc_xive_pull_vcpu(vcpu);
- vcpu->arch.slb_max = 0;
+ if (kvm_is_radix(vcpu->kvm))
+ vcpu->arch.slb_max = 0;
}
dec = mfspr(SPRN_DEC);
@@ -4110,7 +4111,6 @@ static void kvmppc_vcore_blocked(struct kvmppc_vcore *vc)
/*
* This never fails for a radix guest, as none of the operations it does
* for a radix guest can fail or have a way to report failure.
- * kvmhv_run_single_vcpu() relies on this fact.
*/
static int kvmhv_setup_mmu(struct kvm_vcpu *vcpu)
{
@@ -4289,8 +4289,15 @@ int kvmhv_run_single_vcpu(struct kvm_vcpu *vcpu, u64 time_limit,
vc->runner = vcpu;
/* See if the MMU is ready to go */
- if (!kvm->arch.mmu_ready)
- kvmhv_setup_mmu(vcpu);
+ if (!kvm->arch.mmu_ready) {
+ r = kvmhv_setup_mmu(vcpu);
+ if (r) {
+ run->exit_reason = KVM_EXIT_FAIL_ENTRY;
+ run->fail_entry.hardware_entry_failure_reason = 0;
+ vcpu->arch.ret = r;
+ return r;
+ }
+ }
if (need_resched())
cond_resched();
@@ -4303,7 +4310,8 @@ int kvmhv_run_single_vcpu(struct kvm_vcpu *vcpu, u64 time_limit,
preempt_disable();
pcpu = smp_processor_id();
vc->pcpu = pcpu;
- kvmppc_prepare_radix_vcpu(vcpu, pcpu);
+ if (kvm_is_radix(kvm))
+ kvmppc_prepare_radix_vcpu(vcpu, pcpu);
local_irq_disable();
hard_irq_disable();
@@ -4503,7 +4511,7 @@ static int kvmppc_vcpu_run_hv(struct kvm_vcpu *vcpu)
vcpu->arch.state = KVMPPC_VCPU_BUSY_IN_HOST;
do {
- if (kvm_is_radix(kvm))
+ if (radix_enabled())
r = kvmhv_run_single_vcpu(vcpu, ~(u64)0,
vcpu->arch.vcore->lpcr);
else