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Date: Thu, 17 Aug 2023 13:49:06 +0200
From: Michael Mueller <mimu@...ux.ibm.com>
To: Steffen Eiden <seiden@...ux.ibm.com>, linux-kernel@...r.kernel.org,
linux-s390@...r.kernel.org, kvm@...r.kernel.org
Cc: Janosch Frank <frankja@...ux.ibm.com>,
Claudio Imbrenda <imbrenda@...ux.ibm.com>,
David Hildenbrand <david@...hat.com>,
Michael Mueller <mimu@...ux.vnet.ibm.com>,
Marc Hartmayer <mhartmay@...ux.ibm.com>,
Christian Borntraeger <borntraeger@...ux.ibm.com>,
Viktor Mihajlovski <mihajlov@...ux.ibm.com>
Subject: Re: [PATCH v4 3/4] KVM: s390: Add UV feature negotiation
On 15.08.23 17:14, 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@...ux.ibm.com>
> Reviewed-by: Janosch Frank <frankja@...ux.ibm.com>
Reviewed-by: Michael Mueller <mimu@...ux.ibm.com>
but a minor comment, see below.
> ---
> arch/s390/include/asm/kvm_host.h | 2 +
> arch/s390/include/uapi/asm/kvm.h | 16 +++++++
> arch/s390/kvm/kvm-s390.c | 73 ++++++++++++++++++++++++++++++++
> 3 files changed, 91 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..b3f17e014cab 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() fails the uv feature bits in "filter" are
calculated in vain
> + if (get_user(data, &ptr->feat))
> + return -EFAULT;
could be done here, but that's really minor to me
> + 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:
> @@ -3296,6 +3367,8 @@ 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 = 0;
> +
> kvm_s390_crypto_init(kvm);
>
> if (IS_ENABLED(CONFIG_VFIO_PCI_ZDEV_KVM)) {
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