[PATCH v2 16/60] KVM: PPC: Book3S HV: POWER10 enable HAIL when running radix guests

[Nicholas Piggin]

HV interrupts may be taken with the MMU enabled when radix guests are
running. Enable LPCR[HAIL] on ISA v3.1 processors for radix guests.
Make this depend on the host LPCR[HAIL] being enabled. Currently that is
always enabled, but having this test means any issue that might require
LPCR[HAIL] to be disabled in the host will not have to be duplicated in
KVM.

This optimisation takes 1380 cycles off a NULL hcall entry+exit micro
benchmark on a POWER10.

Reviewed-by: Fabiano Rosas <farosas at linux.ibm.com>
Signed-off-by: Nicholas Piggin <npiggin at gmail.com>
---
 arch/powerpc/kvm/book3s_hv.c | 29 +++++++++++++++++++++++++----
 1 file changed, 25 insertions(+), 4 deletions(-)

diff --git a/arch/powerpc/kvm/book3s_hv.c b/arch/powerpc/kvm/book3s_hv.c
index 5e48a929d670..2fe01dc2062f 100644
--- a/arch/powerpc/kvm/book3s_hv.c
+++ b/arch/powerpc/kvm/book3s_hv.c
@@ -5034,6 +5034,8 @@ static int kvmppc_hv_setup_htab_rma(struct kvm_vcpu *vcpu)
  */
 int kvmppc_switch_mmu_to_hpt(struct kvm *kvm)
 {
+	unsigned long lpcr, lpcr_mask;
+
 	if (nesting_enabled(kvm))
 		kvmhv_release_all_nested(kvm);
 	kvmppc_rmap_reset(kvm);
@@ -5043,8 +5045,13 @@ int kvmppc_switch_mmu_to_hpt(struct kvm *kvm)
 	kvm->arch.radix = 0;
 	spin_unlock(&kvm->mmu_lock);
 	kvmppc_free_radix(kvm);
-	kvmppc_update_lpcr(kvm, LPCR_VPM1,
-			   LPCR_VPM1 | LPCR_UPRT | LPCR_GTSE | LPCR_HR);
+
+	lpcr = LPCR_VPM1;
+	lpcr_mask = LPCR_VPM1 | LPCR_UPRT | LPCR_GTSE | LPCR_HR;
+	if (cpu_has_feature(CPU_FTR_ARCH_31))
+		lpcr_mask |= LPCR_HAIL;
+	kvmppc_update_lpcr(kvm, lpcr, lpcr_mask);
+
 	return 0;
 }
 
@@ -5054,6 +5061,7 @@ int kvmppc_switch_mmu_to_hpt(struct kvm *kvm)
  */
 int kvmppc_switch_mmu_to_radix(struct kvm *kvm)
 {
+	unsigned long lpcr, lpcr_mask;
 	int err;
 
 	err = kvmppc_init_vm_radix(kvm);
@@ -5065,8 +5073,17 @@ int kvmppc_switch_mmu_to_radix(struct kvm *kvm)
 	kvm->arch.radix = 1;
 	spin_unlock(&kvm->mmu_lock);
 	kvmppc_free_hpt(&kvm->arch.hpt);
-	kvmppc_update_lpcr(kvm, LPCR_UPRT | LPCR_GTSE | LPCR_HR,
-			   LPCR_VPM1 | LPCR_UPRT | LPCR_GTSE | LPCR_HR);
+
+	lpcr = LPCR_UPRT | LPCR_GTSE | LPCR_HR;
+	lpcr_mask = LPCR_VPM1 | LPCR_UPRT | LPCR_GTSE | LPCR_HR;
+	if (cpu_has_feature(CPU_FTR_ARCH_31)) {
+		lpcr_mask |= LPCR_HAIL;
+		if (cpu_has_feature(CPU_FTR_HVMODE) &&
+				(kvm->arch.host_lpcr & LPCR_HAIL))
+			lpcr |= LPCR_HAIL;
+	}
+	kvmppc_update_lpcr(kvm, lpcr, lpcr_mask);
+
 	return 0;
 }
 
@@ -5230,6 +5247,10 @@ static int kvmppc_core_init_vm_hv(struct kvm *kvm)
 		kvm->arch.mmu_ready = 1;
 		lpcr &= ~LPCR_VPM1;
 		lpcr |= LPCR_UPRT | LPCR_GTSE | LPCR_HR;
+		if (cpu_has_feature(CPU_FTR_HVMODE) &&
+		    cpu_has_feature(CPU_FTR_ARCH_31) &&
+		    (kvm->arch.host_lpcr & LPCR_HAIL))
+			lpcr |= LPCR_HAIL;
 		ret = kvmppc_init_vm_radix(kvm);
 		if (ret) {
 			kvmppc_free_lpid(kvm->arch.lpid);
-- 
2.23.0