On Sun, Aug 07, 2022 at 03:01:04PM -0700, isaku.yamahata@xxxxxxxxx wrote:
> From: Isaku Yamahata <isaku.yamahata@xxxxxxxxx>
>
> TDX private host key id is assigned to guest TD. The memory controller
> encrypts guest TD memory with the assigned TDX private host key id (HIKD).
> Add helper functions to allocate/free TDX private host key id so that TDX
> KVM manage it.
>
> Also export the global TDX private host key id that is used to encrypt TDX
> module, its memory and some dynamic data (TDR). When VMM releasing
> encrypted page to reuse it, the page needs to be flushed with the used host
> key id. VMM needs the global TDX private host key id to flush such pages
> TDX module accesses with the global TDX private host key id.
>
> Signed-off-by: Isaku Yamahata <isaku.yamahata@xxxxxxxxx>
> ---
> arch/x86/include/asm/tdx.h | 12 ++++++++++++
> arch/x86/virt/vmx/tdx/tdx.c | 28 +++++++++++++++++++++++++++-
> 2 files changed, 39 insertions(+), 1 deletion(-)
>
> diff --git a/arch/x86/include/asm/tdx.h b/arch/x86/include/asm/tdx.h
> index c887618e3cec..a32e8881e758 100644
> --- a/arch/x86/include/asm/tdx.h
> +++ b/arch/x86/include/asm/tdx.h
> @@ -144,6 +144,16 @@ struct tdsysinfo_struct {
> bool platform_tdx_enabled(void);
> int tdx_init(void);
> const struct tdsysinfo_struct *tdx_get_sysinfo(void);
> +/*
> + * Key id globally used by TDX module: TDX module maps TDR with this TDX global
> + * key id. TDR includes key id assigned to the TD. Then TDX module maps other
> + * TD-related pages with the assigned key id. TDR requires this TDX global key
> + * id for cache flush unlike other TD-related pages.
> + */
> +extern u32 tdx_global_keyid __read_mostly;
> +int tdx_keyid_alloc(void);
> +void tdx_keyid_free(int keyid);
> +
> u64 __seamcall(u64 op, u64 rcx, u64 rdx, u64 r8, u64 r9,
> struct tdx_module_output *out);
> #else /* !CONFIG_INTEL_TDX_HOST */
> @@ -151,6 +161,8 @@ static inline bool platform_tdx_enabled(void) { return false; }
> static inline int tdx_init(void) { return -ENODEV; }
> struct tdsysinfo_struct;
> static inline const struct tdsysinfo_struct *tdx_get_sysinfo(void) { return NULL; }
> +static inline int tdx_keyid_alloc(void) { return -EOPNOTSUPP; }
> +static inline void tdx_keyid_free(int keyid) { }
> #endif /* CONFIG_INTEL_TDX_HOST */
>
> #endif /* !__ASSEMBLY__ */
> diff --git a/arch/x86/virt/vmx/tdx/tdx.c b/arch/x86/virt/vmx/tdx/tdx.c
> index 918e79159bbf..2168e6133d45 100644
> --- a/arch/x86/virt/vmx/tdx/tdx.c
> +++ b/arch/x86/virt/vmx/tdx/tdx.c
> @@ -56,7 +56,8 @@ static struct cmr_info tdx_cmr_array[MAX_CMRS] __aligned(CMR_INFO_ARRAY_ALIGNMEN
> static int tdx_cmr_num;
>
> /* TDX module global KeyID. Used in TDH.SYS.CONFIG ABI. */
> -static u32 tdx_global_keyid;
> +u32 tdx_global_keyid __read_mostly;
> +EXPORT_SYMBOL_GPL(tdx_global_keyid);
>
> /* Detect whether CPU supports SEAM */
> static int detect_seam(void)
> @@ -80,6 +81,31 @@ static int detect_seam(void)
> return 0;
> }
>
> +/* TDX KeyID pool */
> +static DEFINE_IDA(tdx_keyid_pool);
> +
> +int tdx_keyid_alloc(void)
> +{
> + if (WARN_ON_ONCE(!tdx_keyid_start || !tdx_keyid_num))
> + return -EINVAL;
> +
> + /* The first keyID is reserved for the global key. */
> + return ida_alloc_range(&tdx_keyid_pool, tdx_keyid_start + 1,
> + tdx_keyid_start + tdx_keyid_num - 1,
> + GFP_KERNEL);
> +}
> +EXPORT_SYMBOL_GPL(tdx_keyid_alloc);
> +
> +void tdx_keyid_free(int keyid)
> +{
> + /* keyid = 0 is reserved. */
> + if (!keyid || keyid <= 0)
keyid <=0 covers !keyid.
> + return;
> +
> + ida_free(&tdx_keyid_pool, keyid);
> +}
> +EXPORT_SYMBOL_GPL(tdx_keyid_free);
> +
> static int detect_tdx_keyids(void)
> {
> u64 keyid_part;
> --
> 2.25.1
>
