Re: [PATCH 09/25] KVM: TDX: Get system-wide info about TDX module on initialization

Xu Yilun
2024-08-15T08:01:41Z

> diff --git a/arch/x86/kvm/vmx/tdx.c b/arch/x86/kvm/vmx/tdx.c
> index de14e80d8f3a..90b44ebaf864 100644
> --- a/arch/x86/kvm/vmx/tdx.c
> +++ b/arch/x86/kvm/vmx/tdx.c
> @@ -3,6 +3,7 @@
> #include <asm/tdx.h>
> #include "capabilities.h"
> #include "x86_ops.h"
> +#include "mmu.h"

Is the header file still needed?

> #include "tdx.h"
>
> #undef pr_fmt
> @@ -30,6 +31,72 @@ static void __used tdx_guest_keyid_free(int keyid)
> ida_free(&tdx_guest_keyid_pool, keyid);
> }
>
> +static int tdx_get_capabilities(struct kvm_tdx_cmd *cmd)
> +{
> + const struct tdx_sysinfo_td_conf *td_conf = &tdx_sysinfo->td_conf;
> + struct kvm_tdx_capabilities __user *user_caps;
> + struct kvm_tdx_capabilities *caps = NULL;
> + int i, ret = 0;
> +
> + /* flags is reserved for future use */
> + if (cmd->flags)
> + return -EINVAL;
> +
> + caps = kmalloc(sizeof(*caps), GFP_KERNEL);
> + if (!caps)
> + return -ENOMEM;
> +
> + user_caps = u64_to_user_ptr(cmd->data);
> + if (copy_from_user(caps, user_caps, sizeof(*caps))) {
> + ret = -EFAULT;
> + goto out;
> + }
> +
> + if (caps->nr_cpuid_configs < td_conf->num_cpuid_config) {
> + ret = -E2BIG;

How about output the correct num_cpuid_config to userspace as a hint,
to avoid user blindly retries.

> + goto out;
> + }
> +
> + *caps = (struct kvm_tdx_capabilities) {
> + .attrs_fixed0 = td_conf->attributes_fixed0,
> + .attrs_fixed1 = td_conf->attributes_fixed1,
> + .xfam_fixed0 = td_conf->xfam_fixed0,
> + .xfam_fixed1 = td_conf->xfam_fixed1,
> + .supported_gpaw = TDX_CAP_GPAW_48 |
> + ((kvm_host.maxphyaddr >= 52 &&
> + cpu_has_vmx_ept_5levels()) ? TDX_CAP_GPAW_52 : 0),
> + .nr_cpuid_configs = td_conf->num_cpuid_config,
> + .padding = 0,
> + };
> +
> + if (copy_to_user(user_caps, caps, sizeof(*caps))) {
> + ret = -EFAULT;
> + goto out;
> + }
> +
> + for (i = 0; i < td_conf->num_cpuid_config; i++) {
> + struct kvm_tdx_cpuid_config cpuid_config = {
> + .leaf = (u32)td_conf->cpuid_config_leaves[i],
> + .sub_leaf = td_conf->cpuid_config_leaves[i] >> 32,
> + .eax = (u32)td_conf->cpuid_config_values[i].eax_ebx,
> + .ebx = td_conf->cpuid_config_values[i].eax_ebx >> 32,
> + .ecx = (u32)td_conf->cpuid_config_values[i].ecx_edx,
> + .edx = td_conf->cpuid_config_values[i].ecx_edx >> 32,
> + };
> +
> + if (copy_to_user(&(user_caps->cpuid_configs[i]), &cpuid_config,
^ ^

I think the brackets could be removed.

> + sizeof(struct kvm_tdx_cpuid_config))) {

sizeof(cpuid_config) could be better.

Thanks,
Yilun