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SubjectRe: [PATCH v14 07/23] x86/virt/tdx: Add skeleton to enable TDX on demand
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<snip>
> ---
> arch/x86/include/asm/tdx.h | 4 +
> arch/x86/virt/vmx/tdx/tdx.c | 167 ++++++++++++++++++++++++++++++++++++
> arch/x86/virt/vmx/tdx/tdx.h | 30 +++++++
> 3 files changed, 201 insertions(+)
> create mode 100644 arch/x86/virt/vmx/tdx/tdx.h
>
> diff --git a/arch/x86/include/asm/tdx.h b/arch/x86/include/asm/tdx.h
> index 984efd3114ed..3cfd64f8a2b5 100644
> --- a/arch/x86/include/asm/tdx.h
> +++ b/arch/x86/include/asm/tdx.h
> @@ -110,8 +110,12 @@ static inline u64 sc_retry(sc_func_t func, u64 fn,
> #define seamcall_saved_ret(_fn, _args) sc_retry(__seamcall_saved_ret, (_fn), (_args))
>
> bool platform_tdx_enabled(void);
> +int tdx_cpu_enable(void);
> +int tdx_enable(void);
> #else
> static inline bool platform_tdx_enabled(void) { return false; }
> +static inline int tdx_cpu_enable(void) { return -ENODEV; }
> +static inline int tdx_enable(void) { return -ENODEV; }
> #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 52fb14e0195f..36db33133cd5 100644
> --- a/arch/x86/virt/vmx/tdx/tdx.c
> +++ b/arch/x86/virt/vmx/tdx/tdx.c
> @@ -12,14 +12,24 @@
> #include <linux/init.h>
> #include <linux/errno.h>
> #include <linux/printk.h>
> +#include <linux/cpu.h>
> +#include <linux/spinlock.h>
> +#include <linux/percpu-defs.h>
> +#include <linux/mutex.h>
> #include <asm/msr-index.h>
> #include <asm/msr.h>
> #include <asm/tdx.h>
> +#include "tdx.h"
>
> static u32 tdx_global_keyid __ro_after_init;
> static u32 tdx_guest_keyid_start __ro_after_init;
> static u32 tdx_nr_guest_keyids __ro_after_init;
>
> +static DEFINE_PER_CPU(bool, tdx_lp_initialized);
> +
> +static enum tdx_module_status_t tdx_module_status;
> +static DEFINE_MUTEX(tdx_module_lock);
> +
> typedef void (*sc_err_func_t)(u64 fn, u64 err, struct tdx_module_args *args);
>
> static inline void seamcall_err(u64 fn, u64 err, struct tdx_module_args *args)
> @@ -72,6 +82,163 @@ static inline int sc_retry_prerr(sc_func_t func, sc_err_func_t err_func,
> #define seamcall_prerr_ret(__fn, __args) \
> sc_retry_prerr(__seamcall_ret, seamcall_err_ret, (__fn), (__args))
>
> +/*
> + * Do the module global initialization once and return its result.
> + * It can be done on any cpu. It's always called with interrupts
> + * disabled.
> + */
> +static int try_init_module_global(void)
> +{

Any particular reason why this function is not called from the tdx
module's tdx_init? It's global and must be called once when the module
is initialised. Subsequently kvm which is supposed to call
tdx_cpu_enable() must be sequenced _after_ tdx which shouldn't be that
hard, no? This will eliminate the spinlock as well.

<snip>

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