Merge tag 'kvm-x86-fixes-6.16-rc7' of https://github.com/kvm-x86/linux into HEAD

KVM TDX fixes for 6.16

 - Fix a formatting goof in the TDX documentation.

 - Reject KVM_SET_TSC_KHZ for guests with a protected TSC (currently only TDX).

 - Ensure struct kvm_tdx_capabilities fields that are not explicitly set by KVM
   are zeroed.

Author: bonzini

Documentation/virt/kvm/api.rst

@@ -2008,6 +2008,13 @@ If the KVM_CAP_VM_TSC_CONTROL capability is advertised, this can also
 be used as a vm ioctl to set the initial tsc frequency of subsequently
 created vCPUs.
 
+For TSC protected Confidential Computing (CoCo) VMs where TSC frequency
+is configured once at VM scope and remains unchanged during VM's
+lifetime, the vm ioctl should be used to configure the TSC frequency
+and the vcpu ioctl is not supported.
+
+Example of such CoCo VMs: TDX guests.
+
 4.56 KVM_GET_TSC_KHZ
 --------------------
 
@@ -7230,8 +7237,8 @@ inputs and outputs of the TDVMCALL.  Currently the following values of
    placed in fields from ``r11`` to ``r14`` of the ``get_tdvmcall_info``
    field of the union.
 
-* ``TDVMCALL_SETUP_EVENT_NOTIFY_INTERRUPT``: the guest has requested to
-set up a notification interrupt for vector ``vector``.
+ * ``TDVMCALL_SETUP_EVENT_NOTIFY_INTERRUPT``: the guest has requested to
+   set up a notification interrupt for vector ``vector``.
 
 KVM may add support for more values in the future that may cause a userspace
 exit, even without calls to ``KVM_ENABLE_CAP`` or similar.  In this case,

arch/x86/kvm/vmx/tdx.c

@@ -2269,25 +2269,26 @@ static int tdx_get_capabilities(struct kvm_tdx_cmd *cmd)
 	const struct tdx_sys_info_td_conf *td_conf = &tdx_sysinfo->td_conf;
 	struct kvm_tdx_capabilities __user *user_caps;
 	struct kvm_tdx_capabilities *caps = NULL;
+	u32 nr_user_entries;
 	int ret = 0;
 
 	/* flags is reserved for future use */
 	if (cmd->flags)
 		return -EINVAL;
 
-	caps = kmalloc(sizeof(*caps) +
+	caps = kzalloc(sizeof(*caps) +
 		       sizeof(struct kvm_cpuid_entry2) * td_conf->num_cpuid_config,
 		       GFP_KERNEL);
 	if (!caps)
 		return -ENOMEM;
 
 	user_caps = u64_to_user_ptr(cmd->data);
-	if (copy_from_user(caps, user_caps, sizeof(*caps))) {
+	if (get_user(nr_user_entries, &user_caps->cpuid.nent)) {
 		ret = -EFAULT;
 		goto out;
 	}
 
-	if (caps->cpuid.nent < td_conf->num_cpuid_config) {
+	if (nr_user_entries < td_conf->num_cpuid_config) {
 		ret = -E2BIG;
 		goto out;
 	}

arch/x86/kvm/x86.c

@@ -6188,6 +6188,10 @@ long kvm_arch_vcpu_ioctl(struct file *filp,
 		u32 user_tsc_khz;
 
 		r = -EINVAL;
+
+		if (vcpu->arch.guest_tsc_protected)
+			goto out;
+
 		user_tsc_khz = (u32)arg;
 
 		if (kvm_caps.has_tsc_control &&