>+static int vt_max_vcpus(struct kvm *kvm)
>+{
>+ if (!kvm)
>+ return KVM_MAX_VCPUS;
>+
>+ if (is_td(kvm))
>+ return min(kvm->max_vcpus, TDX_MAX_VCPUS);
I suppose kvm->max_vcpus should be always smaller than TDX_MAX_VCPUS, right?
if that's the case, the min() is pointless.
I don't get why kvm->max_vcpus is concerned. do you want to enable userspace to
read back the max_vcpus configured last time? this looks useless because userspace
can keep track of that value. how about:
/*
* TDX module imposes additional restrictions on the maximum number of
* vCPUs of a TD guest.
*/
if (kvm && is_td(kvm))
return min(TDX_MAX_VCPUS, KVM_MAX_VCPUS);
else
return KVM_MAX_VCPUS;
>+
>+ return kvm->max_vcpus;
>+}
>+
> static int vt_hardware_enable(void)
> {
> int ret;
>@@ -54,6 +66,14 @@ static void vt_hardware_unsetup(void)
> vmx_hardware_unsetup();
> }
>
>+static int vt_vm_enable_cap(struct kvm *kvm, struct kvm_enable_cap *cap)
>+{
>+ if (is_td(kvm))
>+ return tdx_vm_enable_cap(kvm, cap);
>+
>+ return -EINVAL;
>+}
>+
> static int vt_vm_init(struct kvm *kvm)
> {
> if (is_td(kvm))
>@@ -91,7 +111,9 @@ struct kvm_x86_ops vt_x86_ops __initdata = {
> .has_emulated_msr = vmx_has_emulated_msr,
>
> .is_vm_type_supported = vt_is_vm_type_supported,
>+ .max_vcpus = vt_max_vcpus,
> .vm_size = sizeof(struct kvm_vmx),
>+ .vm_enable_cap = vt_vm_enable_cap,
> .vm_init = vt_vm_init,
> .vm_destroy = vmx_vm_destroy,
>
>diff --git a/arch/x86/kvm/vmx/tdx.c b/arch/x86/kvm/vmx/tdx.c
>index 8c463407f8a8..876ad7895b88 100644
>--- a/arch/x86/kvm/vmx/tdx.c
>+++ b/arch/x86/kvm/vmx/tdx.c
>@@ -100,6 +100,35 @@ struct tdx_info {
> /* Info about the TDX module. */
> static struct tdx_info *tdx_info;
>
>+int tdx_vm_enable_cap(struct kvm *kvm, struct kvm_enable_cap *cap)
>+{
>+ int r;
>+
>+ switch (cap->cap) {
>+ case KVM_CAP_MAX_VCPUS: {
>+ if (cap->flags || cap->args[0] == 0)
>+ return -EINVAL;
>+ if (cap->args[0] > KVM_MAX_VCPUS ||
>+ cap->args[0] > TDX_MAX_VCPUS)
>+ return -E2BIG;
>+
>+ mutex_lock(&kvm->lock);
>+ if (kvm->created_vcpus)
>+ r = -EBUSY;
Curly brackets are missing.
And -EBUSY looks improper because it isn't a temporary error.
>+ else {
>+ kvm->max_vcpus = cap->args[0];
>+ r = 0;
>+ }
>+ mutex_unlock(&kvm->lock);
>+ break;
