linux-kernel - Re: [RFC PATCH v2.1 01/30] x86/sgx: Add short descriptions to ENCLS wrappers

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Date:   Fri, 4 Mar 2022 11:40:31 +0200
From:   Jarkko Sakkinen <jarkko@...nel.org>
To:     linux-sgx@...r.kernel.org
Cc:     Nathaniel McCallum <nathaniel@...fian.com>,
        Reinette Chatre <reinette.chatre@...el.com>,
        Dave Hansen <dave.hansen@...ux.intel.com>,
        Thomas Gleixner <tglx@...utronix.de>,
        Ingo Molnar <mingo@...hat.com>, Borislav Petkov <bp@...en8.de>,
        "maintainer:X86 ARCHITECTURE (32-BIT AND 64-BIT)" <x86@...nel.org>,
        "H. Peter Anvin" <hpa@...or.com>,
        "open list:X86 ARCHITECTURE (32-BIT AND 64-BIT)" 
        <linux-kernel@...r.kernel.org>
Subject: Re: [RFC PATCH v2.1 01/30] x86/sgx: Add short descriptions to ENCLS
 wrappers

This is just a bug fixed version of v2, and also the requirement
to do obsolete round trip with EMODPE has been optimized away.
I hope that v3 is rolled out quickly because now there is no
comparison point. We can have speculative discussions whether
ioctl or #PF is better but no means to benchmark. Thus, a quick
patch set revision roll out would be such a great thing.

Based on https://lore.kernel.org/linux-sgx/20220304033918.361495-1-jarkko@kernel.org/T/#u

BR, Jarkko

On Fri, Mar 04, 2022 at 11:34:55AM +0200, Jarkko Sakkinen wrote:
> From: Reinette Chatre <reinette.chatre@...el.com>
> 
> The SGX ENCLS instruction uses EAX to specify an SGX function and
> may require additional registers, depending on the SGX function.
> ENCLS invokes the specified privileged SGX function for managing
> and debugging enclaves. Macros are used to wrap the ENCLS
> functionality and several wrappers are used to wrap the macros to
> make the different SGX functions accessible in the code.
> 
> The wrappers of the supported SGX functions are cryptic. Add short
> descriptions of each as a comment.
> 
> Suggested-by: Dave Hansen <dave.hansen@...ux.intel.com>
> Signed-off-by: Reinette Chatre <reinette.chatre@...el.com>
> ---
>  arch/x86/kernel/cpu/sgx/encls.h | 15 +++++++++++++++
>  1 file changed, 15 insertions(+)
> 
> diff --git a/arch/x86/kernel/cpu/sgx/encls.h b/arch/x86/kernel/cpu/sgx/encls.h
> index fa04a73daf9c..0e22fa8f77c5 100644
> --- a/arch/x86/kernel/cpu/sgx/encls.h
> +++ b/arch/x86/kernel/cpu/sgx/encls.h
> @@ -136,57 +136,71 @@ static inline bool encls_failed(int ret)
>  	ret;						\
>  	})
>  
> +/* Initialize an EPC page into an SGX Enclave Control Structure (SECS) page. */
>  static inline int __ecreate(struct sgx_pageinfo *pginfo, void *secs)
>  {
>  	return __encls_2(ECREATE, pginfo, secs);
>  }
>  
> +/* Hash a 256 byte region of an enclave page to SECS:MRENCLAVE. */
>  static inline int __eextend(void *secs, void *addr)
>  {
>  	return __encls_2(EEXTEND, secs, addr);
>  }
>  
> +/*
> + * Associate an EPC page to an enclave either as a REG or TCS page
> + * populated with the provided data.
> + */
>  static inline int __eadd(struct sgx_pageinfo *pginfo, void *addr)
>  {
>  	return __encls_2(EADD, pginfo, addr);
>  }
>  
> +/* Finalize enclave build, initialize enclave for user code execution. */
>  static inline int __einit(void *sigstruct, void *token, void *secs)
>  {
>  	return __encls_ret_3(EINIT, sigstruct, secs, token);
>  }
>  
> +/* Disassociate EPC page from its enclave and mark it as unused. */
>  static inline int __eremove(void *addr)
>  {
>  	return __encls_ret_1(EREMOVE, addr);
>  }
>  
> +/* Copy data to an EPC page belonging to a debug enclave. */
>  static inline int __edbgwr(void *addr, unsigned long *data)
>  {
>  	return __encls_2(EDGBWR, *data, addr);
>  }
>  
> +/* Copy data from an EPC page belonging to a debug enclave. */
>  static inline int __edbgrd(void *addr, unsigned long *data)
>  {
>  	return __encls_1_1(EDGBRD, *data, addr);
>  }
>  
> +/* Track that software has completed the required TLB address clears. */
>  static inline int __etrack(void *addr)
>  {
>  	return __encls_ret_1(ETRACK, addr);
>  }
>  
> +/* Load, verify, and unblock an EPC page. */
>  static inline int __eldu(struct sgx_pageinfo *pginfo, void *addr,
>  			 void *va)
>  {
>  	return __encls_ret_3(ELDU, pginfo, addr, va);
>  }
>  
> +/* Make EPC page inaccessible to enclave, ready to be written to memory. */
>  static inline int __eblock(void *addr)
>  {
>  	return __encls_ret_1(EBLOCK, addr);
>  }
>  
> +/* Initialize an EPC page into a Version Array (VA) page. */
>  static inline int __epa(void *addr)
>  {
>  	unsigned long rbx = SGX_PAGE_TYPE_VA;
> @@ -194,6 +208,7 @@ static inline int __epa(void *addr)
>  	return __encls_2(EPA, rbx, addr);
>  }
>  
> +/* Invalidate an EPC page and write it out to main memory. */
>  static inline int __ewb(struct sgx_pageinfo *pginfo, void *addr,
>  			void *va)
>  {
> -- 
> 2.35.1
>