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Subject[PATCH v2 6/7] KVM: x86: hyper-v: allow KVM_GET_SUPPORTED_HV_CPUID as a system ioctl
Date
KVM_GET_SUPPORTED_HV_CPUID is a vCPU ioctl but its output is now
independent from vCPU and in some cases VMMs may want to use it as a system
ioctl instead. In particular, QEMU doesn CPU feature expansion before any
vCPU gets created so KVM_GET_SUPPORTED_HV_CPUID can't be used.

Convert KVM_GET_SUPPORTED_HV_CPUID to 'dual' system/vCPU ioctl with the
same meaning.

Signed-off-by: Vitaly Kuznetsov <vkuznets@redhat.com>
---
Documentation/virt/kvm/api.rst | 4 ++--
arch/x86/kvm/x86.c | 43 ++++++++++++++++++++--------------
include/uapi/linux/kvm.h | 3 ++-
3 files changed, 30 insertions(+), 20 deletions(-)

diff --git a/Documentation/virt/kvm/api.rst b/Documentation/virt/kvm/api.rst
index a552d41308e1..c323b346f001 100644
--- a/Documentation/virt/kvm/api.rst
+++ b/Documentation/virt/kvm/api.rst
@@ -4455,9 +4455,9 @@ that KVM_CAP_MANUAL_DIRTY_LOG_PROTECT2 is present.
4.118 KVM_GET_SUPPORTED_HV_CPUID
--------------------------------

-:Capability: KVM_CAP_HYPERV_CPUID
+:Capability: KVM_CAP_HYPERV_CPUID (vcpu), KVM_CAP_SYS_HYPERV_CPUID (system)
:Architectures: x86
-:Type: vcpu ioctl
+:Type: system ioctl, vcpu ioctl
:Parameters: struct kvm_cpuid2 (in/out)
:Returns: 0 on success, -1 on error

diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
index 4b1a092d9e51..6170489bb823 100644
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -3453,6 +3453,26 @@ static inline bool kvm_can_mwait_in_guest(void)
boot_cpu_has(X86_FEATURE_ARAT);
}

+static int kvm_ioctl_get_supported_hv_cpuid(struct kvm_cpuid2 __user *cpuid_arg)
+{
+ struct kvm_cpuid2 cpuid;
+ int r;
+
+ r = -EFAULT;
+ if (copy_from_user(&cpuid, cpuid_arg, sizeof(cpuid)))
+ return r;
+
+ r = kvm_get_hv_cpuid(&cpuid, cpuid_arg->entries);
+ if (r)
+ return r;
+
+ r = -EFAULT;
+ if (copy_to_user(cpuid_arg, &cpuid, sizeof(cpuid)))
+ return r;
+
+ return 0;
+}
+
int kvm_vm_ioctl_check_extension(struct kvm *kvm, long ext)
{
int r = 0;
@@ -3489,6 +3509,7 @@ int kvm_vm_ioctl_check_extension(struct kvm *kvm, long ext)
case KVM_CAP_HYPERV_TLBFLUSH:
case KVM_CAP_HYPERV_SEND_IPI:
case KVM_CAP_HYPERV_CPUID:
+ case KVM_CAP_SYS_HYPERV_CPUID:
case KVM_CAP_PCI_SEGMENT:
case KVM_CAP_DEBUGREGS:
case KVM_CAP_X86_ROBUST_SINGLESTEP:
@@ -3671,6 +3692,9 @@ long kvm_arch_dev_ioctl(struct file *filp,
case KVM_GET_MSRS:
r = msr_io(NULL, argp, do_get_msr_feature, 1);
break;
+ case KVM_GET_SUPPORTED_HV_CPUID:
+ r = kvm_ioctl_get_supported_hv_cpuid(argp);
+ break;
default:
r = -EINVAL;
break;
@@ -4740,24 +4764,9 @@ long kvm_arch_vcpu_ioctl(struct file *filp,
srcu_read_unlock(&vcpu->kvm->srcu, idx);
break;
}
- case KVM_GET_SUPPORTED_HV_CPUID: {
- struct kvm_cpuid2 __user *cpuid_arg = argp;
- struct kvm_cpuid2 cpuid;
-
- r = -EFAULT;
- if (copy_from_user(&cpuid, cpuid_arg, sizeof(cpuid)))
- goto out;
-
- r = kvm_get_hv_cpuid(&cpuid, cpuid_arg->entries);
- if (r)
- goto out;
-
- r = -EFAULT;
- if (copy_to_user(cpuid_arg, &cpuid, sizeof(cpuid)))
- goto out;
- r = 0;
+ case KVM_GET_SUPPORTED_HV_CPUID:
+ r = kvm_ioctl_get_supported_hv_cpuid(argp);
break;
- }
default:
r = -EINVAL;
}
diff --git a/include/uapi/linux/kvm.h b/include/uapi/linux/kvm.h
index 7d8eced6f459..3ebd48e72cdd 100644
--- a/include/uapi/linux/kvm.h
+++ b/include/uapi/linux/kvm.h
@@ -1037,6 +1037,7 @@ struct kvm_ppc_resize_hpt {
#define KVM_CAP_SMALLER_MAXPHYADDR 185
#define KVM_CAP_S390_DIAG318 186
#define KVM_CAP_STEAL_TIME 187
+#define KVM_CAP_SYS_HYPERV_CPUID 188

#ifdef KVM_CAP_IRQ_ROUTING

@@ -1495,7 +1496,7 @@ struct kvm_enc_region {
/* Available with KVM_CAP_MANUAL_DIRTY_LOG_PROTECT_2 */
#define KVM_CLEAR_DIRTY_LOG _IOWR(KVMIO, 0xc0, struct kvm_clear_dirty_log)

-/* Available with KVM_CAP_HYPERV_CPUID */
+/* Available with KVM_CAP_HYPERV_CPUID (vcpu) / KVM_CAP_SYS_HYPERV_CPUID (system) */
#define KVM_GET_SUPPORTED_HV_CPUID _IOWR(KVMIO, 0xc1, struct kvm_cpuid2)

/* Available with KVM_CAP_ARM_SVE */
--
2.25.4
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