Re: [PATCH 33/33] KVM: TDX: Register TDX host key IDs to cgroup misc controller

[Chenyi Qiang <chenyi.qiang@intel.com>]

On 2/27/2025 2:14 AM, Paolo Bonzini wrote:
> From: Zhiming Hu <zhiming.hu@intel.com>
> 
> TDX host key IDs (HKID) are limit resources in a machine, and the misc
> cgroup lets the machine owner track their usage and limits the possibility
> of abusing them outside the owner's control.
> 
> The cgroup v2 miscellaneous subsystem was introduced to control the
> resource of AMD SEV & SEV-ES ASIDs.  Likewise introduce HKIDs as a misc
> resource.
> 
> Signed-off-by: Zhiming Hu <zhiming.hu@intel.com>
> Signed-off-by: Isaku Yamahata <isaku.yamahata@intel.com>
> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
> ---
>  arch/x86/include/asm/tdx.h  |  2 ++
>  arch/x86/kvm/vmx/tdx.c      | 14 ++++++++++++++
>  arch/x86/kvm/vmx/tdx.h      |  1 +
>  arch/x86/virt/vmx/tdx/tdx.c |  6 ++++++
>  include/linux/misc_cgroup.h |  4 ++++
>  kernel/cgroup/misc.c        |  4 ++++
>  6 files changed, 31 insertions(+)
> 
> diff --git a/arch/x86/include/asm/tdx.h b/arch/x86/include/asm/tdx.h
> index 52a21075c0a6..7dd71ca3eb57 100644
> --- a/arch/x86/include/asm/tdx.h
> +++ b/arch/x86/include/asm/tdx.h
> @@ -124,6 +124,7 @@ const char *tdx_dump_mce_info(struct mce *m);
>  const struct tdx_sys_info *tdx_get_sysinfo(void);
>  
>  int tdx_guest_keyid_alloc(void);
> +u32 tdx_get_nr_guest_keyids(void);
>  void tdx_guest_keyid_free(unsigned int keyid);
>  
>  struct tdx_td {
> @@ -179,6 +180,7 @@ u64 tdh_phymem_page_wbinvd_tdr(struct tdx_td *td);
>  static inline void tdx_init(void) { }
>  static inline int tdx_cpu_enable(void) { return -ENODEV; }
>  static inline int tdx_enable(void)  { return -ENODEV; }
> +static u32 tdx_get_nr_guest_keyids(void) { return 0; }

static inline ...

Otherwise will trigger build error when !TDX_HOST

>  static inline const char *tdx_dump_mce_info(struct mce *m) { return NULL; }
>  static inline const struct tdx_sys_info *tdx_get_sysinfo(void) { return NULL; }
>  #endif	/* CONFIG_INTEL_TDX_HOST */