On 8/25/23 05:14, Kai Huang wrote:
> Some SEAMCALLs use the RDRAND hardware and can fail for the same reasons
> as RDRAND. Use the kernel RDRAND retry logic for them.
>
> There are three __seamcall*() variants. Add a macro to do the SEAMCALL
> retry in the common code and define a wrapper for each __seamcall*()
> variant.
>
> Signed-off-by: Kai Huang <kai.huang@xxxxxxxxx>
> ---
>
> v12 -> v13:
> - New implementation due to TDCALL assembly series.
>
> ---
> arch/x86/include/asm/tdx.h | 27 +++++++++++++++++++++++++++
> 1 file changed, 27 insertions(+)
>
> diff --git a/arch/x86/include/asm/tdx.h b/arch/x86/include/asm/tdx.h
> index a252328734c7..cfae8b31a2e9 100644
> --- a/arch/x86/include/asm/tdx.h
> +++ b/arch/x86/include/asm/tdx.h
> @@ -24,6 +24,11 @@
> #define TDX_SEAMCALL_GP (TDX_SW_ERROR | X86_TRAP_GP)
> #define TDX_SEAMCALL_UD (TDX_SW_ERROR | X86_TRAP_UD)
>
> +/*
> + * TDX module SEAMCALL leaf function error codes
> + */
> +#define TDX_RND_NO_ENTROPY 0x8000020300000000ULL
> +
> #ifndef __ASSEMBLY__
>
> /*
> @@ -82,6 +87,28 @@ u64 __seamcall(u64 fn, struct tdx_module_args *args);
> u64 __seamcall_ret(u64 fn, struct tdx_module_args *args);
> u64 __seamcall_saved_ret(u64 fn, struct tdx_module_args *args);
>
> +#include <asm/archrandom.h>
> +
> +#define SEAMCALL_NO_ENTROPY_RETRY(__seamcall_func, __fn, __args) \
> +({ \
> + int ___retry = RDRAND_RETRY_LOOPS; \
> + u64 ___sret; \
> + \
> + do { \
> + ___sret = __seamcall_func((__fn), (__args)); \
> + } while (___sret == TDX_RND_NO_ENTROPY && --___retry); \
> + ___sret; \
> +})
This is a *LOT* less eye-bleedy if you do it without macros:
typedef u64 (*sc_func_t)(u64 fn, struct tdx_module_args *args);
static inline
u64 sc_retry(sc_func_t func, u64 fn, struct tdx_module_args *args)
{
int retry = RDRAND_RETRY_LOOPS;
u64 ret;
do {
ret = func(fn, args);
} while (ret == TDX_RND_NO_ENTROPY && --retry);
return ret;
}
#define seamcall(_fn, _args) sc_retry(_seamcall,
(_fn), (_args))
#define seamcall_ret(_fn, _args) sc_retry(_seamcall_ret,
(_fn), (_args))
#define seamcall_saved_ret(_fn, _args) sc_retry(_seamcall_saved_ret,
(_fn), (_args))
The compiler can figure it out and avoid making func() an indirect call
since it knows the call location at compile time.
You can also do the seamcall() #define as a static inline, but it does
take up more screen real estate. Oh, and going a wee bit over 80
columns is OK for those #defines.
