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SubjectRe: [RFC PATCH v5 023/104] x86/cpu: Add helper functions to allocate/free MKTME keyid
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On 3/4/22 20:48, isaku.yamahata@intel.com wrote:
> From: Isaku Yamahata <isaku.yamahata@intel.com>
>
> MKTME keyid is assigned to guest TD. The memory controller encrypts guest
> TD memory with key id. Add helper functions to allocate/free MKTME keyid
> so that TDX KVM assign keyid.
>
> Also export MKTME global keyid that is used to encrypt TDX module and its
> memory.
>
> Signed-off-by: Isaku Yamahata <isaku.yamahata@intel.com>
> ---
> arch/x86/include/asm/tdx.h | 6 ++++++
> arch/x86/virt/vmx/tdx.c | 33 ++++++++++++++++++++++++++++++++-
> 2 files changed, 38 insertions(+), 1 deletion(-)
>
> diff --git a/arch/x86/include/asm/tdx.h b/arch/x86/include/asm/tdx.h
> index 9a8dc6afcb63..73bb472bd515 100644
> --- a/arch/x86/include/asm/tdx.h
> +++ b/arch/x86/include/asm/tdx.h
> @@ -139,6 +139,9 @@ int tdx_detect(void);
> int tdx_init(void);
> bool platform_has_tdx(void);
> const struct tdsysinfo_struct *tdx_get_sysinfo(void);
> +u32 tdx_get_global_keyid(void);
> +int tdx_keyid_alloc(void);
> +void tdx_keyid_free(int keyid);
> #else
> static inline void tdx_detect_cpu(struct cpuinfo_x86 *c) { }
> static inline int tdx_detect(void) { return -ENODEV; }
> @@ -146,6 +149,9 @@ static inline int tdx_init(void) { return -ENODEV; }
> static inline bool platform_has_tdx(void) { return false; }
> struct tdsysinfo_struct;
> static inline const struct tdsysinfo_struct *tdx_get_sysinfo(void) { return NULL; }
> +static inline u32 tdx_get_global_keyid(void) { return 0; };
> +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.c b/arch/x86/virt/vmx/tdx.c
> index e45f188479cb..d714106321d4 100644
> --- a/arch/x86/virt/vmx/tdx.c
> +++ b/arch/x86/virt/vmx/tdx.c
> @@ -113,7 +113,13 @@ static int tdx_cmr_num;
> static struct tdsysinfo_struct tdx_sysinfo;
>
> /* TDX global KeyID to protect TDX metadata */
> -static u32 tdx_global_keyid;
> +static u32 __read_mostly tdx_global_keyid;
> +
> +u32 tdx_get_global_keyid(void)
> +{
> + return tdx_global_keyid;
> +}
> +EXPORT_SYMBOL_GPL(tdx_get_global_keyid);
>
> static bool enable_tdx_host;
>
> @@ -189,6 +195,31 @@ static void detect_seam(struct cpuinfo_x86 *c)
> detect_seam_ap(c);
> }
>
> +/* 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)
> + return;
> +
> + ida_free(&tdx_keyid_pool, keyid);
> +}
> +EXPORT_SYMBOL_GPL(tdx_keyid_free);
> +
> static void detect_tdx_keyids_bsp(struct cpuinfo_x86 *c)
> {
> u64 keyid_part;

Reviewed-by: Paolo Bonzini <pbonzini@redhat.com>

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