Subject: [PATCH v5 38/48] KVM: PPC: Book3S HV: Remove support for dependent threads mode on P9

From: Nicholas Piggin <[email-masked]>
Date: Fri, 2 Apr 2021 01:03:15 +1000

Radix guest support will be removed from the P7/8 path, so disallow
dependent threads mode on P9.

Signed-off-by: Nicholas Piggin <[email-masked]>
---
 arch/powerpc/include/asm/kvm_host.h |  1 -
 arch/powerpc/kvm/book3s_hv.c        | 27 +++++----------------------
 2 files changed, 5 insertions(+), 23 deletions(-)

diff --git a/arch/powerpc/include/asm/kvm_host.h b/arch/powerpc/include/asm/kvm_host.h
index 05fb00d37609..dd017dfa4e65 100644
--- a/arch/powerpc/include/asm/kvm_host.h
+++ b/arch/powerpc/include/asm/kvm_host.h
@@ -304,7 +304,6 @@ struct kvm_arch {
 	u8 fwnmi_enabled;
 	u8 secure_guest;
 	u8 svm_enabled;
-	bool threads_indep;
 	bool nested_enable;
 	bool dawr1_enabled;
 	pgd_t *pgtable;
diff --git a/arch/powerpc/kvm/book3s_hv.c b/arch/powerpc/kvm/book3s_hv.c
index 50022c29a0fe..ae5ad93a623f 100644
--- a/arch/powerpc/kvm/book3s_hv.c
+++ b/arch/powerpc/kvm/book3s_hv.c
@@ -103,13 +103,9 @@ static int target_smt_mode;
 module_param(target_smt_mode, int, 0644);
 MODULE_PARM_DESC(target_smt_mode, "Target threads per core (0 = max)");
 
-static bool indep_threads_mode = true;
-module_param(indep_threads_mode, bool, S_IRUGO | S_IWUSR);
-MODULE_PARM_DESC(indep_threads_mode, "Independent-threads mode (only on POWER9)");
-
 static bool one_vm_per_core;
 module_param(one_vm_per_core, bool, S_IRUGO | S_IWUSR);
-MODULE_PARM_DESC(one_vm_per_core, "Only run vCPUs from the same VM on a core (requires indep_threads_mode=N)");
+MODULE_PARM_DESC(one_vm_per_core, "Only run vCPUs from the same VM on a core (requires POWER8 or older)");
 
 #ifdef CONFIG_KVM_XICS
 static const struct kernel_param_ops module_param_ops = {
@@ -2258,7 +2254,7 @@ static int kvmppc_set_one_reg_hv(struct kvm_vcpu *vcpu, u64 id,
  */
 static int threads_per_vcore(struct kvm *kvm)
 {
-	if (kvm->arch.threads_indep)
+	if (cpu_has_feature(CPU_FTR_ARCH_300))
 		return 1;
 	return threads_per_subcore;
 }
@@ -4354,7 +4350,7 @@ static int kvmppc_vcpu_run_hv(struct kvm_vcpu *vcpu)
 	vcpu->arch.state = KVMPPC_VCPU_BUSY_IN_HOST;
 
 	do {
-		if (kvm->arch.threads_indep && kvm_is_radix(kvm))
+		if (kvm_is_radix(kvm))
 			r = kvmhv_run_single_vcpu(vcpu, ~(u64)0,
 						  vcpu->arch.vcore->lpcr);
 		else
@@ -4978,21 +4974,8 @@ static int kvmppc_core_init_vm_hv(struct kvm *kvm)
 	/*
 	 * Track that we now have a HV mode VM active. This blocks secondary
 	 * CPU threads from coming online.
-	 * On POWER9, we only need to do this if the "indep_threads_mode"
-	 * module parameter has been set to N.
 	 */
-	if (cpu_has_feature(CPU_FTR_ARCH_300)) {
-		if (!indep_threads_mode && !cpu_has_feature(CPU_FTR_HVMODE)) {
-			pr_warn("KVM: Ignoring indep_threads_mode=N in nested hypervisor\n");
-			kvm->arch.threads_indep = true;
-		} else if (!indep_threads_mode && cpu_has_feature(CPU_FTR_P9_RADIX_PREFETCH_BUG)) {
-			pr_warn("KVM: Ignoring indep_threads_mode=N on pre-DD2.2 POWER9\n");
-			kvm->arch.threads_indep = true;
-		} else {
-			kvm->arch.threads_indep = indep_threads_mode;
-		}
-	}
-	if (!kvm->arch.threads_indep)
+	if (!cpu_has_feature(CPU_FTR_ARCH_300))
 		kvm_hv_vm_activated();
 
 	/*
@@ -5033,7 +5016,7 @@ static void kvmppc_core_destroy_vm_hv(struct kvm *kvm)
 {
 	debugfs_remove_recursive(kvm->arch.debugfs_dir);
 
-	if (!kvm->arch.threads_indep)
+	if (!cpu_has_feature(CPU_FTR_ARCH_300))
 		kvm_hv_vm_deactivated();
 
 	kvmppc_free_vcores(kvm);
-- 
2.23.0