Commit c21d54f0 authored by Vitaly Kuznetsov's avatar Vitaly Kuznetsov Committed by Paolo Bonzini
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KVM: x86: hyper-v: allow KVM_GET_SUPPORTED_HV_CPUID as a system ioctl 



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: default avatarVitaly Kuznetsov <vkuznets@redhat.com>
Message-Id: <20200929150944.1235688-2-vkuznets@redhat.com>
Signed-off-by: default avatarPaolo Bonzini <pbonzini@redhat.com>
parent b59e00dd

Documentation/virt/kvm/api.rst

+11 −5
Original line number Diff line number Diff line
@@ -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
@@ -4502,9 +4502,6 @@ Currently, the following list of CPUID leaves are returned: 
 - HYPERV_CPUID_SYNDBG_INTERFACE

 - HYPERV_CPUID_SYNDBG_PLATFORM_CAPABILITIES



HYPERV_CPUID_NESTED_FEATURES leaf is only exposed when Enlightened VMCS was

enabled on the corresponding vCPU (KVM_CAP_HYPERV_ENLIGHTENED_VMCS).



Userspace invokes KVM_GET_SUPPORTED_HV_CPUID by passing a kvm_cpuid2 structure

with the 'nent' field indicating the number of entries in the variable-size

array 'entries'.  If the number of entries is too low to describe all Hyper-V
@@ -4515,6 +4512,15 @@ number of valid entries in the 'entries' array, which is then filled. 
'index' and 'flags' fields in 'struct kvm_cpuid_entry2' are currently reserved,

userspace should not expect to get any particular value there.



Note, vcpu version of KVM_GET_SUPPORTED_HV_CPUID is currently deprecated. Unlike

system ioctl which exposes all supported feature bits unconditionally, vcpu

version has the following quirks:

- HYPERV_CPUID_NESTED_FEATURES leaf and HV_X64_ENLIGHTENED_VMCS_RECOMMENDED

  feature bit are only exposed when Enlightened VMCS was previously enabled

  on the corresponding vCPU (KVM_CAP_HYPERV_ENLIGHTENED_VMCS).

- HV_STIMER_DIRECT_MODE_AVAILABLE bit is only exposed with in-kernel LAPIC.

  (presumes KVM_CREATE_IRQCHIP has already been called).



4.119 KVM_ARM_VCPU_FINALIZE

---------------------------

arch/x86/kvm/hyperv.c

+3 −3
Original line number Diff line number Diff line
@@ -1951,7 +1951,7 @@ int kvm_vm_ioctl_hv_eventfd(struct kvm *kvm, struct kvm_hyperv_eventfd *args) 
	return kvm_hv_eventfd_assign(kvm, args->conn_id, args->fd);

}



int kvm_vcpu_ioctl_get_hv_cpuid(struct kvm_vcpu *vcpu, struct kvm_cpuid2 *cpuid,

int kvm_get_hv_cpuid(struct kvm_vcpu *vcpu, struct kvm_cpuid2 *cpuid,

		     struct kvm_cpuid_entry2 __user *entries)

{

	uint16_t evmcs_ver = 0;
@@ -2037,7 +2037,7 @@ int kvm_vcpu_ioctl_get_hv_cpuid(struct kvm_vcpu *vcpu, struct kvm_cpuid2 *cpuid, 
			 * Direct Synthetic timers only make sense with in-kernel

			 * LAPIC

			 */

			if (lapic_in_kernel(vcpu))

			if (!vcpu || lapic_in_kernel(vcpu))

				ent->edx |= HV_STIMER_DIRECT_MODE_AVAILABLE;



			break;

arch/x86/kvm/hyperv.h

+2 −2
Original line number Diff line number Diff line
@@ -126,7 +126,7 @@ void kvm_hv_setup_tsc_page(struct kvm *kvm, 
void kvm_hv_init_vm(struct kvm *kvm);

void kvm_hv_destroy_vm(struct kvm *kvm);

int kvm_vm_ioctl_hv_eventfd(struct kvm *kvm, struct kvm_hyperv_eventfd *args);

int kvm_vcpu_ioctl_get_hv_cpuid(struct kvm_vcpu *vcpu, struct kvm_cpuid2 *cpuid,

int kvm_get_hv_cpuid(struct kvm_vcpu *vcpu, struct kvm_cpuid2 *cpuid,

		     struct kvm_cpuid_entry2 __user *entries);



#endif

arch/x86/kvm/vmx/evmcs.c

+1 −2
Original line number Diff line number Diff line
@@ -326,7 +326,6 @@ bool nested_enlightened_vmentry(struct kvm_vcpu *vcpu, u64 *evmcs_gpa) 


uint16_t nested_get_evmcs_version(struct kvm_vcpu *vcpu)

{

	struct vcpu_vmx *vmx = to_vmx(vcpu);

	/*

	 * vmcs_version represents the range of supported Enlightened VMCS

	 * versions: lower 8 bits is the minimal version, higher 8 bits is the
@@ -334,7 +333,7 @@ uint16_t nested_get_evmcs_version(struct kvm_vcpu *vcpu) 
	 * KVM_EVMCS_VERSION.

	 */

	if (kvm_cpu_cap_get(X86_FEATURE_VMX) &&

	    vmx->nested.enlightened_vmcs_enabled)

	    (!vcpu || to_vmx(vcpu)->nested.enlightened_vmcs_enabled))

		return (KVM_EVMCS_VERSION << 8) | 1;



	return 0;

arch/x86/kvm/x86.c

+27 −18
Original line number Diff line number Diff line
@@ -3677,6 +3677,27 @@ 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_vcpu *vcpu,

					    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(vcpu, &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;
@@ -3713,6 +3734,7 @@ 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:
@@ -3898,6 +3920,9 @@ 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(NULL, argp);

		break;

	default:

		r = -EINVAL;

		break;
@@ -4974,25 +4999,9 @@ 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_vcpu_ioctl_get_hv_cpuid(vcpu, &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(vcpu, argp);

		break;

	}

	default:

		r = -EINVAL;

	}

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