linux-kernel - Re: [PATCH v14 06/23] x86/virt/tdx: Add SEAMCALL error printing for module initialization

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Date:   Wed, 18 Oct 2023 10:40:10 +0300
From:   Nikolay Borisov <nik.borisov@...e.com>
To:     Kai Huang <kai.huang@...el.com>, linux-kernel@...r.kernel.org,
        kvm@...r.kernel.org
Cc:     x86@...nel.org, dave.hansen@...el.com,
        kirill.shutemov@...ux.intel.com, peterz@...radead.org,
        tony.luck@...el.com, tglx@...utronix.de, bp@...en8.de,
        mingo@...hat.com, hpa@...or.com, seanjc@...gle.com,
        pbonzini@...hat.com, rafael@...nel.org, david@...hat.com,
        dan.j.williams@...el.com, len.brown@...el.com, ak@...ux.intel.com,
        isaku.yamahata@...el.com, ying.huang@...el.com, chao.gao@...el.com,
        sathyanarayanan.kuppuswamy@...ux.intel.com, bagasdotme@...il.com,
        sagis@...gle.com, imammedo@...hat.com
Subject: Re: [PATCH v14 06/23] x86/virt/tdx: Add SEAMCALL error printing for
 module initialization



On 17.10.23 г. 13:14 ч., Kai Huang wrote:
> The SEAMCALLs involved during the TDX module initialization are not
> expected to fail.  In fact, they are not expected to return any non-zero
> code (except the "running out of entropy error", which can be handled
> internally already).
> 
> Add yet another set of SEAMCALL wrappers, which treats all non-zero
> return code as error, to support printing SEAMCALL error upon failure
> for module initialization.  Note the TDX module initialization doesn't
> use the _saved_ret() variant thus no wrapper is added for it.
> 
> SEAMCALL assembly can also return kernel-defined error codes for three
> special cases: 1) TDX isn't enabled by the BIOS; 2) TDX module isn't
> loaded; 3) CPU isn't in VMX operation.  Whether they can legally happen
> depends on the caller, so leave to the caller to print error message
> when desired.
> 
> Also convert the SEAMCALL error codes to the kernel error codes in the
> new wrappers so that each SEAMCALL caller doesn't have to repeat the
> conversion.
> 
> Signed-off-by: Kai Huang <kai.huang@...el.com>
> Reviewed-by: Kirill A. Shutemov <kirill.shutemov@...ux.intel.com>
> ---
> 
> v13 -> v14:
>   - Use real functions to replace macros. (Dave)
>   - Moved printing error message for special error code to the caller
>     (internal)
>   - Added Kirill's tag
> 
> v12 -> v13:
>   - New implementation due to TDCALL assembly series.
> 
> ---
>   arch/x86/include/asm/tdx.h  |  1 +
>   arch/x86/virt/vmx/tdx/tdx.c | 52 +++++++++++++++++++++++++++++++++++++
>   2 files changed, 53 insertions(+)
> 
> diff --git a/arch/x86/include/asm/tdx.h b/arch/x86/include/asm/tdx.h
> index d624aa25aab0..984efd3114ed 100644
> --- a/arch/x86/include/asm/tdx.h
> +++ b/arch/x86/include/asm/tdx.h
> @@ -27,6 +27,7 @@
>   /*
>    * TDX module SEAMCALL leaf function error codes
>    */
> +#define TDX_SUCCESS		0ULL
>   #define TDX_RND_NO_ENTROPY	0x8000020300000000ULL
>   
>   #ifndef __ASSEMBLY__
> diff --git a/arch/x86/virt/vmx/tdx/tdx.c b/arch/x86/virt/vmx/tdx/tdx.c
> index 13d22ea2e2d9..52fb14e0195f 100644
> --- a/arch/x86/virt/vmx/tdx/tdx.c
> +++ b/arch/x86/virt/vmx/tdx/tdx.c
> @@ -20,6 +20,58 @@ 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;
>   
> +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)
> +{
> +	pr_err("SEAMCALL (0x%llx) failed: 0x%llx\n", fn, err);
> +}
> +
> +static inline void seamcall_err_ret(u64 fn, u64 err,
> +				    struct tdx_module_args *args)
> +{
> +	seamcall_err(fn, err, args);
> +	pr_err("RCX 0x%llx RDX 0x%llx R8 0x%llx R9 0x%llx R10 0x%llx R11 0x%llx\n",
> +			args->rcx, args->rdx, args->r8, args->r9,
> +			args->r10, args->r11);
> +}
> +
> +static inline void seamcall_err_saved_ret(u64 fn, u64 err,
> +					  struct tdx_module_args *args)

This function remains unused throughout the whole series, remove it and 
add it later when it's actually going to be useful.

<snip>