[PATCH v3 4/4] KVM: PPC: Introduce new capability for 2nd DAWR

[Ravi Bangoria]

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 at linux.ibm.com>
---
 Documentation/virt/kvm/api.rst     | 10 ++++++++++
 arch/powerpc/include/asm/kvm_ppc.h |  1 +
 arch/powerpc/kvm/book3s_hv.c       | 12 ++++++++++++
 arch/powerpc/kvm/powerpc.c         | 10 ++++++++++
 include/uapi/linux/kvm.h           |  1 +
 tools/include/uapi/linux/kvm.h     |  1 +
 6 files changed, 35 insertions(+)

diff --git a/Documentation/virt/kvm/api.rst b/Documentation/virt/kvm/api.rst
index abb24575bdf9..049f07ebf197 100644
--- a/Documentation/virt/kvm/api.rst
+++ b/Documentation/virt/kvm/api.rst
@@ -6016,6 +6016,16 @@ KVM_EXIT_X86_RDMSR and KVM_EXIT_X86_WRMSR exit notifications which user space
 can then handle to implement model specific MSR handling and/or user notifications
 to inform a user that an MSR was not handled.
 
+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 b7a30c0692a7..04c02344bd3f 100644
--- a/arch/powerpc/kvm/book3s_hv.c
+++ b/arch/powerpc/kvm/book3s_hv.c
@@ -5625,6 +5625,17 @@ static int kvmhv_svm_off(struct kvm *kvm)
 	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,
@@ -5668,6 +5679,7 @@ 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 13999123b735..380656528b5b 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 ca41220b40b8..f1210f99a52d 100644
--- a/include/uapi/linux/kvm.h
+++ b/include/uapi/linux/kvm.h
@@ -1053,6 +1053,7 @@ struct kvm_ppc_resize_hpt {
 #define KVM_CAP_X86_USER_SPACE_MSR 188
 #define KVM_CAP_X86_MSR_FILTER 189
 #define KVM_CAP_ENFORCE_PV_FEATURE_CPUID 190
+#define KVM_CAP_PPC_DAWR1 191
 
 #ifdef KVM_CAP_IRQ_ROUTING
 
diff --git a/tools/include/uapi/linux/kvm.h b/tools/include/uapi/linux/kvm.h
index ca41220b40b8..f1210f99a52d 100644
--- a/tools/include/uapi/linux/kvm.h
+++ b/tools/include/uapi/linux/kvm.h
@@ -1053,6 +1053,7 @@ struct kvm_ppc_resize_hpt {
 #define KVM_CAP_X86_USER_SPACE_MSR 188
 #define KVM_CAP_X86_MSR_FILTER 189
 #define KVM_CAP_ENFORCE_PV_FEATURE_CPUID 190
+#define KVM_CAP_PPC_DAWR1 191
 
 #ifdef KVM_CAP_IRQ_ROUTING
 
-- 
2.26.2