KVM: PPC: Book3S HV: Introduce new capability for 2nd DAWR

Introduce KVM_CAP_PPC_DAWR1 which can be used by QEMU to query whether
KVM supports 2nd DAWR or not. The capability is by default disabled
even when the underlying CPU supports 2nd DAWR. QEMU needs to check
and enable it manually to use the feature.

Signed-off-by: Ravi Bangoria <ravi.bangoria@linux.ibm.com>
Signed-off-by: Paul Mackerras <paulus@ozlabs.org>

6 files changed, 35 insertions, 0 deletions

diff --git a/Documentation/virt/kvm/api.rst b/Documentation/virt/kvm/api.rst
index a783a8da818b..45fd862ac128 100644
--- a/Documentation/virt/kvm/api.rst
+++ b/Documentation/virt/kvm/api.rst
@@ -6215,6 +6215,16 @@ the bus lock vm exit can be preempted by a higher priority VM exit, the exit
 notifications to userspace can be KVM_EXIT_BUS_LOCK or other reasons.
 KVM_RUN_BUS_LOCK flag is used to distinguish between them.
 
+7.22 KVM_CAP_PPC_DAWR1
+----------------------
+
+:Architectures: ppc
+:Parameters: none
+:Returns: 0 on success, -EINVAL when CPU doesn't support 2nd DAWR
+
+This capability can be used to check / enable 2nd DAWR feature provided
+by POWER10 processor.
+
 8. Other capabilities.
 ======================
 
diff --git a/arch/powerpc/include/asm/kvm_ppc.h b/arch/powerpc/include/asm/kvm_ppc.h
index 0a056c64c317..13c39d24dda5 100644
--- a/arch/powerpc/include/asm/kvm_ppc.h
+++ b/arch/powerpc/include/asm/kvm_ppc.h
@@ -314,6 +314,7 @@ struct kvmppc_ops {
 			      int size);
 	int (*enable_svm)(struct kvm *kvm);
 	int (*svm_off)(struct kvm *kvm);
+	int (*enable_dawr1)(struct kvm *kvm);
 };
 
 extern struct kvmppc_ops *kvmppc_hv_ops;
diff --git a/arch/powerpc/kvm/book3s_hv.c b/arch/powerpc/kvm/book3s_hv.c
index b37bddfead1b..dffbfd1ab47b 100644
--- a/arch/powerpc/kvm/book3s_hv.c
+++ b/arch/powerpc/kvm/book3s_hv.c
@@ -5642,6 +5642,17 @@ out:
 	return ret;
 }
 
+static int kvmhv_enable_dawr1(struct kvm *kvm)
+{
+	if (!cpu_has_feature(CPU_FTR_DAWR1))
+		return -ENODEV;
+
+	/* kvm == NULL means the caller is testing if the capability exists */
+	if (kvm)
+		kvm->arch.dawr1_enabled = true;
+	return 0;
+}
+
 static struct kvmppc_ops kvm_ops_hv = {
 	.get_sregs = kvm_arch_vcpu_ioctl_get_sregs_hv,
 	.set_sregs = kvm_arch_vcpu_ioctl_set_sregs_hv,
@@ -5685,6 +5696,7 @@ static struct kvmppc_ops kvm_ops_hv = {
 	.store_to_eaddr = kvmhv_store_to_eaddr,
 	.enable_svm = kvmhv_enable_svm,
 	.svm_off = kvmhv_svm_off,
+	.enable_dawr1 = kvmhv_enable_dawr1,
 };
 
 static int kvm_init_subcore_bitmap(void)
diff --git a/arch/powerpc/kvm/powerpc.c b/arch/powerpc/kvm/powerpc.c
index cf52d26f49cd..5914c32d9ef3 100644
--- a/arch/powerpc/kvm/powerpc.c
+++ b/arch/powerpc/kvm/powerpc.c
@@ -678,6 +678,10 @@ int kvm_vm_ioctl_check_extension(struct kvm *kvm, long ext)
 		r = hv_enabled && kvmppc_hv_ops->enable_svm &&
 			!kvmppc_hv_ops->enable_svm(NULL);
 		break;
+	case KVM_CAP_PPC_DAWR1:
+		r = !!(hv_enabled && kvmppc_hv_ops->enable_dawr1 &&
+		       !kvmppc_hv_ops->enable_dawr1(NULL));
+		break;
 #endif
 	default:
 		r = 0;
@@ -2187,6 +2191,12 @@ int kvm_vm_ioctl_enable_cap(struct kvm *kvm,
 			break;
 		r = kvm->arch.kvm_ops->enable_svm(kvm);
 		break;
+	case KVM_CAP_PPC_DAWR1:
+		r = -EINVAL;
+		if (!is_kvmppc_hv_enabled(kvm) || !kvm->arch.kvm_ops->enable_dawr1)
+			break;
+		r = kvm->arch.kvm_ops->enable_dawr1(kvm);
+		break;
 #endif
 	default:
 		r = -EINVAL;
diff --git a/include/uapi/linux/kvm.h b/include/uapi/linux/kvm.h
index 63f8f6e95648..8b281f722e5b 100644
--- a/include/uapi/linux/kvm.h
+++ b/include/uapi/linux/kvm.h
@@ -1077,6 +1077,7 @@ struct kvm_ppc_resize_hpt {
 #define KVM_CAP_SYS_HYPERV_CPUID 191
 #define KVM_CAP_DIRTY_LOG_RING 192
 #define KVM_CAP_X86_BUS_LOCK_EXIT 193
+#define KVM_CAP_PPC_DAWR1 194
 
 #ifdef KVM_CAP_IRQ_ROUTING
 
diff --git a/tools/include/uapi/linux/kvm.h b/tools/include/uapi/linux/kvm.h
index 886802b8ffba..9c284a9c3ac5 100644
--- a/tools/include/uapi/linux/kvm.h
+++ b/tools/include/uapi/linux/kvm.h
@@ -1056,6 +1056,7 @@ struct kvm_ppc_resize_hpt {
 #define KVM_CAP_ENFORCE_PV_FEATURE_CPUID 190
 #define KVM_CAP_SYS_HYPERV_CPUID 191
 #define KVM_CAP_DIRTY_LOG_RING 192
+#define KVM_CAP_PPC_DAWR1 194
 
 #ifdef KVM_CAP_IRQ_ROUTING