[PATCH v3 0/3] KVM: s390: Enable AP instructions for PV-guests

[PATCH v3 0/3] KVM: s390: Enable AP instructions for PV-guests

[Steffen Eiden]

This series enables general KVM support for AP-passthrough for Secure
Execution guests (PV-guests).

To enable AP inside PV-guests two things have to be done/considered:
	1) set corresponding flags in the Create Secure Configuration UVC if
     firmware supports AP for PV-guests (patch 3).
	2) enable/disable AP in PV-guests if the VMM wants this (patch 2).

since v2:
  - applied styling recommendations from Heiko

since v1:
  - PATCH 1: r-b from Claudio
  - PATCH 2: fixed formatting issues (Claudio)
  - PATCH 3: removed unnecessary checks (Claudio)

Steffen

Steffen Eiden (3):
  s390: uv: UV feature check utility
  KVM: s390: Add UV feature negotiation
  KVM: s390: pv:  Allow AP-instructions for pv-guests

 arch/s390/include/asm/kvm_host.h |  2 +
 arch/s390/include/asm/uv.h       | 17 ++++++-
 arch/s390/include/uapi/asm/kvm.h | 16 +++++++
 arch/s390/kernel/uv.c            |  2 +-
 arch/s390/kvm/kvm-s390.c         | 76 +++++++++++++++++++++++++++++++-
 arch/s390/kvm/pv.c               |  6 ++-
 arch/s390/mm/fault.c             |  2 +-
 7 files changed, 115 insertions(+), 6 deletions(-)

-- 
2.40.1

[PATCH v3 1/3] s390: uv: UV feature check utility

[Steffen Eiden]

Introduces a function to check the existence of an UV feature.
Refactor feature bit checks to use the new function.

Reviewed-by: Claudio Imbrenda <imbrenda@linux.ibm.com>
Signed-off-by: Steffen Eiden <seiden@linux.ibm.com>
---
 arch/s390/include/asm/uv.h | 5 +++++
 arch/s390/kernel/uv.c      | 2 +-
 arch/s390/kvm/kvm-s390.c   | 2 +-
 arch/s390/mm/fault.c       | 2 +-
 4 files changed, 8 insertions(+), 3 deletions(-)

diff --git a/arch/s390/include/asm/uv.h b/arch/s390/include/asm/uv.h
index d2cd42bb2c26..f76b2747b648 100644
--- a/arch/s390/include/asm/uv.h
+++ b/arch/s390/include/asm/uv.h
@@ -397,6 +397,11 @@ struct uv_info {
 
 extern struct uv_info uv_info;
 
+static inline bool uv_has_feature(u8 feature_bit)
+{
+	return test_bit_inv(feature_bit, &uv_info.uv_feature_indications);
+}
+
 #ifdef CONFIG_PROTECTED_VIRTUALIZATION_GUEST
 extern int prot_virt_guest;
 
diff --git a/arch/s390/kernel/uv.c b/arch/s390/kernel/uv.c
index b771f1b4cdd1..fc07bc39e698 100644
--- a/arch/s390/kernel/uv.c
+++ b/arch/s390/kernel/uv.c
@@ -258,7 +258,7 @@ static bool should_export_before_import(struct uv_cb_header *uvcb, struct mm_str
 	 * shared page from a different protected VM will automatically also
 	 * transfer its ownership.
 	 */
-	if (test_bit_inv(BIT_UV_FEAT_MISC, &uv_info.uv_feature_indications))
+	if (uv_has_feature(BIT_UV_FEAT_MISC))
 		return false;
 	if (uvcb->cmd == UVC_CMD_UNPIN_PAGE_SHARED)
 		return false;
diff --git a/arch/s390/kvm/kvm-s390.c b/arch/s390/kvm/kvm-s390.c
index e6511608280c..813cc3d59c90 100644
--- a/arch/s390/kvm/kvm-s390.c
+++ b/arch/s390/kvm/kvm-s390.c
@@ -2406,7 +2406,7 @@ static int kvm_s390_cpus_to_pv(struct kvm *kvm, u16 *rc, u16 *rrc)
 	struct kvm_vcpu *vcpu;
 
 	/* Disable the GISA if the ultravisor does not support AIV. */
-	if (!test_bit_inv(BIT_UV_FEAT_AIV, &uv_info.uv_feature_indications))
+	if (!uv_has_feature(BIT_UV_FEAT_AIV))
 		kvm_s390_gisa_disable(kvm);
 
 	kvm_for_each_vcpu(i, vcpu, kvm) {
diff --git a/arch/s390/mm/fault.c b/arch/s390/mm/fault.c
index b5e1bea9194c..8a86dd725870 100644
--- a/arch/s390/mm/fault.c
+++ b/arch/s390/mm/fault.c
@@ -599,7 +599,7 @@ void do_secure_storage_access(struct pt_regs *regs)
 	 * reliable without the misc UV feature so we need to check
 	 * for that as well.
 	 */
-	if (test_bit_inv(BIT_UV_FEAT_MISC, &uv_info.uv_feature_indications) &&
+	if (uv_has_feature(BIT_UV_FEAT_MISC) &&
 	    !test_bit_inv(61, &regs->int_parm_long)) {
 		/*
 		 * When this happens, userspace did something that it
-- 
2.40.1

[PATCH v3 2/3] KVM: s390: Add UV feature negotiation

[Steffen Eiden]

Add a uv_feature list for pv-guests to the KVM cpu-model.
The feature bits 'AP-interpretation for secure guests' and
'AP-interrupt for secure guests' are available.

Signed-off-by: Steffen Eiden <seiden@linux.ibm.com>
---
 arch/s390/include/asm/kvm_host.h |  2 +
 arch/s390/include/uapi/asm/kvm.h | 16 +++++++
 arch/s390/kvm/kvm-s390.c         | 74 ++++++++++++++++++++++++++++++++
 3 files changed, 92 insertions(+)

diff --git a/arch/s390/include/asm/kvm_host.h b/arch/s390/include/asm/kvm_host.h
index 91bfecb91321..427f9528a7b6 100644
--- a/arch/s390/include/asm/kvm_host.h
+++ b/arch/s390/include/asm/kvm_host.h
@@ -817,6 +817,8 @@ struct kvm_s390_cpu_model {
 	__u64 *fac_list;
 	u64 cpuid;
 	unsigned short ibc;
+	/* subset of available UV-features for pv-guests enabled by user space */
+	struct kvm_s390_vm_cpu_uv_feat uv_feat_guest;
 };
 
 typedef int (*crypto_hook)(struct kvm_vcpu *vcpu);
diff --git a/arch/s390/include/uapi/asm/kvm.h b/arch/s390/include/uapi/asm/kvm.h
index a73cf01a1606..abe926d43cbe 100644
--- a/arch/s390/include/uapi/asm/kvm.h
+++ b/arch/s390/include/uapi/asm/kvm.h
@@ -159,6 +159,22 @@ struct kvm_s390_vm_cpu_subfunc {
 	__u8 reserved[1728];
 };
 
+#define KVM_S390_VM_CPU_PROCESSOR_UV_FEAT_GUEST	6
+#define KVM_S390_VM_CPU_MACHINE_UV_FEAT_GUEST	7
+
+#define KVM_S390_VM_CPU_UV_FEAT_NR_BITS	64
+struct kvm_s390_vm_cpu_uv_feat {
+	union {
+		struct {
+			__u64 : 4;
+			__u64 ap : 1;		/* bit 4 */
+			__u64 ap_intr : 1;	/* bit 5 */
+			__u64 : 58;
+		};
+		__u64 feat;
+	};
+};
+
 /* kvm attributes for crypto */
 #define KVM_S390_VM_CRYPTO_ENABLE_AES_KW	0
 #define KVM_S390_VM_CRYPTO_ENABLE_DEA_KW	1
diff --git a/arch/s390/kvm/kvm-s390.c b/arch/s390/kvm/kvm-s390.c
index 813cc3d59c90..80c1449fd358 100644
--- a/arch/s390/kvm/kvm-s390.c
+++ b/arch/s390/kvm/kvm-s390.c
@@ -1531,6 +1531,39 @@ static int kvm_s390_set_processor_subfunc(struct kvm *kvm,
 	return 0;
 }
 
+#define KVM_S390_VM_CPU_UV_FEAT_GUEST_MASK	\
+(						\
+	((struct kvm_s390_vm_cpu_uv_feat){	\
+		.ap = 1,			\
+		.ap_intr = 1,			\
+	})					\
+	.feat					\
+)
+
+static int kvm_s390_set_uv_feat(struct kvm *kvm, struct kvm_device_attr *attr)
+{
+	struct kvm_s390_vm_cpu_uv_feat __user *ptr = (void __user *)attr->addr;
+	unsigned long data, filter;
+
+	filter = uv_info.uv_feature_indications & KVM_S390_VM_CPU_UV_FEAT_GUEST_MASK;
+	if (get_user(data, &ptr->feat))
+		return -EFAULT;
+	if (!bitmap_subset(&data, &filter, KVM_S390_VM_CPU_UV_FEAT_NR_BITS))
+		return -EINVAL;
+
+	mutex_lock(&kvm->lock);
+	if (kvm->created_vcpus) {
+		mutex_unlock(&kvm->lock);
+		return -EBUSY;
+	}
+	kvm->arch.model.uv_feat_guest.feat = data;
+	mutex_unlock(&kvm->lock);
+
+	VM_EVENT(kvm, 3, "SET: guest UV-feat: 0x%16.16lx", data);
+
+	return 0;
+}
+
 static int kvm_s390_set_cpu_model(struct kvm *kvm, struct kvm_device_attr *attr)
 {
 	int ret = -ENXIO;
@@ -1545,6 +1578,9 @@ static int kvm_s390_set_cpu_model(struct kvm *kvm, struct kvm_device_attr *attr)
 	case KVM_S390_VM_CPU_PROCESSOR_SUBFUNC:
 		ret = kvm_s390_set_processor_subfunc(kvm, attr);
 		break;
+	case KVM_S390_VM_CPU_PROCESSOR_UV_FEAT_GUEST:
+		ret = kvm_s390_set_uv_feat(kvm, attr);
+		break;
 	}
 	return ret;
 }
@@ -1777,6 +1813,33 @@ static int kvm_s390_get_machine_subfunc(struct kvm *kvm,
 	return 0;
 }
 
+static int kvm_s390_get_processor_uv_feat(struct kvm *kvm, struct kvm_device_attr *attr)
+{
+	struct kvm_s390_vm_cpu_uv_feat __user *dst = (void __user *)attr->addr;
+	unsigned long feat = kvm->arch.model.uv_feat_guest.feat;
+
+	if (put_user(feat, &dst->feat))
+		return -EFAULT;
+	VM_EVENT(kvm, 3, "GET: guest UV-feat: 0x%16.16lx", feat);
+
+	return 0;
+}
+
+static int kvm_s390_get_machine_uv_feat(struct kvm *kvm, struct kvm_device_attr *attr)
+{
+	struct kvm_s390_vm_cpu_uv_feat __user *dst = (void __user *)attr->addr;
+	unsigned long feat;
+
+	BUILD_BUG_ON(sizeof(*dst) != sizeof(uv_info.uv_feature_indications));
+
+	feat = uv_info.uv_feature_indications & KVM_S390_VM_CPU_UV_FEAT_GUEST_MASK;
+	if (put_user(feat, &dst->feat))
+		return -EFAULT;
+	VM_EVENT(kvm, 3, "GET: guest UV-feat: 0x%16.16lx", feat);
+
+	return 0;
+}
+
 static int kvm_s390_get_cpu_model(struct kvm *kvm, struct kvm_device_attr *attr)
 {
 	int ret = -ENXIO;
@@ -1800,6 +1863,12 @@ static int kvm_s390_get_cpu_model(struct kvm *kvm, struct kvm_device_attr *attr)
 	case KVM_S390_VM_CPU_MACHINE_SUBFUNC:
 		ret = kvm_s390_get_machine_subfunc(kvm, attr);
 		break;
+	case KVM_S390_VM_CPU_PROCESSOR_UV_FEAT_GUEST:
+		ret = kvm_s390_get_processor_uv_feat(kvm, attr);
+		break;
+	case KVM_S390_VM_CPU_MACHINE_UV_FEAT_GUEST:
+		ret = kvm_s390_get_machine_uv_feat(kvm, attr);
+		break;
 	}
 	return ret;
 }
@@ -1952,6 +2021,8 @@ static int kvm_s390_vm_has_attr(struct kvm *kvm, struct kvm_device_attr *attr)
 		case KVM_S390_VM_CPU_MACHINE_FEAT:
 		case KVM_S390_VM_CPU_MACHINE_SUBFUNC:
 		case KVM_S390_VM_CPU_PROCESSOR_SUBFUNC:
+		case KVM_S390_VM_CPU_MACHINE_UV_FEAT_GUEST:
+		case KVM_S390_VM_CPU_PROCESSOR_UV_FEAT_GUEST:
 			ret = 0;
 			break;
 		default:
@@ -3216,6 +3287,7 @@ void kvm_arch_free_vm(struct kvm *kvm)
 	__kvm_arch_free_vm(kvm);
 }
 
+#define KVM_S390_VM_CPU_UV_FEAT_GUEST_DEFAULT 0
 int kvm_arch_init_vm(struct kvm *kvm, unsigned long type)
 {
 	gfp_t alloc_flags = GFP_KERNEL_ACCOUNT;
@@ -3296,6 +3368,8 @@ int kvm_arch_init_vm(struct kvm *kvm, unsigned long type)
 	kvm->arch.model.cpuid = kvm_s390_get_initial_cpuid();
 	kvm->arch.model.ibc = sclp.ibc & 0x0fff;
 
+	kvm->arch.model.uv_feat_guest.feat = KVM_S390_VM_CPU_UV_FEAT_GUEST_DEFAULT;
+
 	kvm_s390_crypto_init(kvm);
 
 	if (IS_ENABLED(CONFIG_VFIO_PCI_ZDEV_KVM)) {
-- 
2.40.1

[PATCH v3 3/3] KVM: s390: pv: Allow AP-instructions for pv-guests

[Steffen Eiden]

Introduces new feature bits and enablement flags for AP and AP IRQ
support.

Signed-off-by: Steffen Eiden <seiden@linux.ibm.com>
---
 arch/s390/include/asm/uv.h | 12 +++++++++++-
 arch/s390/kvm/pv.c         |  6 ++++--
 2 files changed, 15 insertions(+), 3 deletions(-)

diff --git a/arch/s390/include/asm/uv.h b/arch/s390/include/asm/uv.h
index f76b2747b648..680654ff6d17 100644
--- a/arch/s390/include/asm/uv.h
+++ b/arch/s390/include/asm/uv.h
@@ -99,6 +99,8 @@ enum uv_cmds_inst {
 enum uv_feat_ind {
 	BIT_UV_FEAT_MISC = 0,
 	BIT_UV_FEAT_AIV = 1,
+	BIT_UV_FEAT_AP = 4,
+	BIT_UV_FEAT_AP_INTR = 5,
 };
 
 struct uv_cb_header {
@@ -159,7 +161,15 @@ struct uv_cb_cgc {
 	u64 guest_handle;
 	u64 conf_base_stor_origin;
 	u64 conf_virt_stor_origin;
-	u64 reserved30;
+	u8  reserved30[6];
+	union {
+		struct {
+			u16 : 14;
+			u16 ap_instr_intr : 1;
+			u16 ap_allow_instr : 1;
+		};
+		u16 raw;
+	} flags;
 	u64 guest_stor_origin;
 	u64 guest_stor_len;
 	u64 guest_sca;
diff --git a/arch/s390/kvm/pv.c b/arch/s390/kvm/pv.c
index 8d3f39a8a11e..bbd3a93db341 100644
--- a/arch/s390/kvm/pv.c
+++ b/arch/s390/kvm/pv.c
@@ -575,12 +575,14 @@ int kvm_s390_pv_init_vm(struct kvm *kvm, u16 *rc, u16 *rrc)
 	uvcb.conf_base_stor_origin =
 		virt_to_phys((void *)kvm->arch.pv.stor_base);
 	uvcb.conf_virt_stor_origin = (u64)kvm->arch.pv.stor_var;
+	uvcb.flags.ap_allow_instr = kvm->arch.model.uv_feat_guest.ap;
+	uvcb.flags.ap_instr_intr = kvm->arch.model.uv_feat_guest.ap_intr;
 
 	cc = uv_call_sched(0, (u64)&uvcb);
 	*rc = uvcb.header.rc;
 	*rrc = uvcb.header.rrc;
-	KVM_UV_EVENT(kvm, 3, "PROTVIRT CREATE VM: handle %llx len %llx rc %x rrc %x",
-		     uvcb.guest_handle, uvcb.guest_stor_len, *rc, *rrc);
+	KVM_UV_EVENT(kvm, 3, "PROTVIRT CREATE VM: handle %llx len %llx rc %x rrc %x flags %04x",
+		     uvcb.guest_handle, uvcb.guest_stor_len, *rc, *rrc, uvcb.flags.raw);
 
 	/* Outputs */
 	kvm->arch.pv.handle = uvcb.guest_handle;
-- 
2.40.1

Re: [PATCH v3 1/3] s390: uv: UV feature check utility

[Janosch Frank]

On 8/10/23 13:32, Steffen Eiden wrote:
> Introduces a function to check the existence of an UV feature.
> Refactor feature bit checks to use the new function.
> 
> Reviewed-by: Claudio Imbrenda <imbrenda@linux.ibm.com>
> Signed-off-by: Steffen Eiden <seiden@linux.ibm.com>

Please add a bounds check, then:
Reviewed-by: Janosch Frank <frankja@linux.ibm.com>

> ---
>   arch/s390/include/asm/uv.h | 5 +++++
>   arch/s390/kernel/uv.c      | 2 +-
>   arch/s390/kvm/kvm-s390.c   | 2 +-
>   arch/s390/mm/fault.c       | 2 +-
>   4 files changed, 8 insertions(+), 3 deletions(-)
> 
> diff --git a/arch/s390/include/asm/uv.h b/arch/s390/include/asm/uv.h
> index d2cd42bb2c26..f76b2747b648 100644
> --- a/arch/s390/include/asm/uv.h
> +++ b/arch/s390/include/asm/uv.h
> @@ -397,6 +397,11 @@ struct uv_info {
>   
>   extern struct uv_info uv_info;
>   
> +static inline bool uv_has_feature(u8 feature_bit)
> +{

if (feature_bit >= sizeof(uv_info.uv_feature_indications) * 8)
	return false;

> +	return test_bit_inv(feature_bit, &uv_info.uv_feature_indications);
> +}
> +
>   #ifdef CONFIG_PROTECTED_VIRTUALIZATION_GUEST
>   extern int prot_virt_guest;
>   
> diff --git a/arch/s390/kernel/uv.c b/arch/s390/kernel/uv.c
> index b771f1b4cdd1..fc07bc39e698 100644
> --- a/arch/s390/kernel/uv.c
> +++ b/arch/s390/kernel/uv.c
> @@ -258,7 +258,7 @@ static bool should_export_before_import(struct uv_cb_header *uvcb, struct mm_str
>   	 * shared page from a different protected VM will automatically also
>   	 * transfer its ownership.
>   	 */
> -	if (test_bit_inv(BIT_UV_FEAT_MISC, &uv_info.uv_feature_indications))
> +	if (uv_has_feature(BIT_UV_FEAT_MISC))
>   		return false;
>   	if (uvcb->cmd == UVC_CMD_UNPIN_PAGE_SHARED)
>   		return false;
> diff --git a/arch/s390/kvm/kvm-s390.c b/arch/s390/kvm/kvm-s390.c
> index e6511608280c..813cc3d59c90 100644
> --- a/arch/s390/kvm/kvm-s390.c
> +++ b/arch/s390/kvm/kvm-s390.c
> @@ -2406,7 +2406,7 @@ static int kvm_s390_cpus_to_pv(struct kvm *kvm, u16 *rc, u16 *rrc)
>   	struct kvm_vcpu *vcpu;
>   
>   	/* Disable the GISA if the ultravisor does not support AIV. */
> -	if (!test_bit_inv(BIT_UV_FEAT_AIV, &uv_info.uv_feature_indications))
> +	if (!uv_has_feature(BIT_UV_FEAT_AIV))
>   		kvm_s390_gisa_disable(kvm);
>   
>   	kvm_for_each_vcpu(i, vcpu, kvm) {
> diff --git a/arch/s390/mm/fault.c b/arch/s390/mm/fault.c
> index b5e1bea9194c..8a86dd725870 100644
> --- a/arch/s390/mm/fault.c
> +++ b/arch/s390/mm/fault.c
> @@ -599,7 +599,7 @@ void do_secure_storage_access(struct pt_regs *regs)
>   	 * reliable without the misc UV feature so we need to check
>   	 * for that as well.
>   	 */
> -	if (test_bit_inv(BIT_UV_FEAT_MISC, &uv_info.uv_feature_indications) &&
> +	if (uv_has_feature(BIT_UV_FEAT_MISC) &&
>   	    !test_bit_inv(61, &regs->int_parm_long)) {
>   		/*
>   		 * When this happens, userspace did something that it

Re: [PATCH v3 3/3] KVM: s390: pv: Allow AP-instructions for pv-guests

[Janosch Frank]

On 8/10/23 13:32, Steffen Eiden wrote:
> Introduces new feature bits and enablement flags for AP and AP IRQ
> support.
> 
> Signed-off-by: Steffen Eiden <seiden@linux.ibm.com>

Reviewed-by: Janosch Frank <frankja@linux.ibm.com>

> ---
>   arch/s390/include/asm/uv.h | 12 +++++++++++-
>   arch/s390/kvm/pv.c         |  6 ++++--
>   2 files changed, 15 insertions(+), 3 deletions(-)
> 
> diff --git a/arch/s390/include/asm/uv.h b/arch/s390/include/asm/uv.h
> index f76b2747b648..680654ff6d17 100644
> --- a/arch/s390/include/asm/uv.h
> +++ b/arch/s390/include/asm/uv.h
> @@ -99,6 +99,8 @@ enum uv_cmds_inst {
>   enum uv_feat_ind {
>   	BIT_UV_FEAT_MISC = 0,
>   	BIT_UV_FEAT_AIV = 1,
> +	BIT_UV_FEAT_AP = 4,
> +	BIT_UV_FEAT_AP_INTR = 5,
>   };
>   
>   struct uv_cb_header {
> @@ -159,7 +161,15 @@ struct uv_cb_cgc {
>   	u64 guest_handle;
>   	u64 conf_base_stor_origin;
>   	u64 conf_virt_stor_origin;
> -	u64 reserved30;
> +	u8  reserved30[6];
> +	union {
> +		struct {
> +			u16 : 14;
> +			u16 ap_instr_intr : 1;
> +			u16 ap_allow_instr : 1;
> +		};
> +		u16 raw;
> +	} flags;
>   	u64 guest_stor_origin;
>   	u64 guest_stor_len;
>   	u64 guest_sca;
> diff --git a/arch/s390/kvm/pv.c b/arch/s390/kvm/pv.c
> index 8d3f39a8a11e..bbd3a93db341 100644
> --- a/arch/s390/kvm/pv.c
> +++ b/arch/s390/kvm/pv.c
> @@ -575,12 +575,14 @@ int kvm_s390_pv_init_vm(struct kvm *kvm, u16 *rc, u16 *rrc)
>   	uvcb.conf_base_stor_origin =
>   		virt_to_phys((void *)kvm->arch.pv.stor_base);
>   	uvcb.conf_virt_stor_origin = (u64)kvm->arch.pv.stor_var;
> +	uvcb.flags.ap_allow_instr = kvm->arch.model.uv_feat_guest.ap;
> +	uvcb.flags.ap_instr_intr = kvm->arch.model.uv_feat_guest.ap_intr;
>   
>   	cc = uv_call_sched(0, (u64)&uvcb);
>   	*rc = uvcb.header.rc;
>   	*rrc = uvcb.header.rrc;
> -	KVM_UV_EVENT(kvm, 3, "PROTVIRT CREATE VM: handle %llx len %llx rc %x rrc %x",
> -		     uvcb.guest_handle, uvcb.guest_stor_len, *rc, *rrc);
> +	KVM_UV_EVENT(kvm, 3, "PROTVIRT CREATE VM: handle %llx len %llx rc %x rrc %x flags %04x",
> +		     uvcb.guest_handle, uvcb.guest_stor_len, *rc, *rrc, uvcb.flags.raw);
>   
>   	/* Outputs */
>   	kvm->arch.pv.handle = uvcb.guest_handle;

Re: [PATCH v3 2/3] KVM: s390: Add UV feature negotiation

[Janosch Frank]

On 8/10/23 13:32, Steffen Eiden wrote:
> Add a uv_feature list for pv-guests to the KVM cpu-model.
> The feature bits 'AP-interpretation for secure guests' and
> 'AP-interrupt for secure guests' are available.
> 
> Signed-off-by: Steffen Eiden <seiden@linux.ibm.com>
[...]
>   
> +#define KVM_S390_VM_CPU_UV_FEAT_GUEST_DEFAULT 0

Reviewed-by: Janosch Frank <frankja@linux.ibm.com>

I don't think that's needed, just set it to 0 (and even that's not 
really needed since it's kzalloced but I'm fine with making this explicit).

>   int kvm_arch_init_vm(struct kvm *kvm, unsigned long type)
>   {
>   	gfp_t alloc_flags = GFP_KERNEL_ACCOUNT;
> @@ -3296,6 +3368,8 @@ int kvm_arch_init_vm(struct kvm *kvm, unsigned long type)
>   	kvm->arch.model.cpuid = kvm_s390_get_initial_cpuid();
>   	kvm->arch.model.ibc = sclp.ibc & 0x0fff;
>   
> +	kvm->arch.model.uv_feat_guest.feat = KVM_S390_VM_CPU_UV_FEAT_GUEST_DEFAULT;
> +
>   	kvm_s390_crypto_init(kvm);
>   
>   	if (IS_ENABLED(CONFIG_VFIO_PCI_ZDEV_KVM)) {