linux-kernel - Re: [PATCH] x86/sgx: Add SGX

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Date:   Wed, 18 Aug 2021 15:29:59 +0200
From:   Jethro Beekman <jethro@...tanix.com>
To:     Jarkko Sakkinen <jarkko@...nel.org>, linux-sgx@...r.kernel.org
Cc:     Shuah Khan <shuah@...nel.org>,
        Dave Hansen <dave.hansen@...ux.intel.com>,
        Thomas Gleixner <tglx@...utronix.de>,
        Ingo Molnar <mingo@...hat.com>, Borislav Petkov <bp@...en8.de>,
        x86@...nel.org, "H. Peter Anvin" <hpa@...or.com>,
        Jonathan Corbet <corbet@....net>,
        Andy Lutomirski <luto@...nel.org>,
        Peter Zijlstra <peterz@...radead.org>,
        Andrew Morton <akpm@...ux-foundation.org>,
        Mike Rapoport <rppt@...nel.org>,
        "Kirill A. Shutemov" <kirill.shutemov@...ux.intel.com>,
        Saravanan D <saravanand@...com>,
        "Aneesh Kumar K.V" <aneesh.kumar@...ux.ibm.com>,
        Krish Sadhukhan <krish.sadhukhan@...cle.com>,
        linux-kernel@...r.kernel.org, linux-doc@...r.kernel.org
Subject: Re: [PATCH] x86/sgx: Add SGX_MemTotal to /proc/meminfo

On 2021-08-18 15:25, Jarkko Sakkinen wrote:
> The amount of SGX memory on the system is determined by the BIOS and it
> varies wildly between systems.  It can be from dozens of MB's on desktops
> or VM's, up to many GB's on servers.  Just like for regular memory, it is
> sometimes useful to know the amount of usable SGX memory in the system.
> 
> Add SGX_MemTotal field to /proc/meminfo, which shows the total amount of
> usable SGX memory in the system.  E.g. with 32 MB reserved for SGX from
> BIOS, the printout would be:
> 
> SGX_MemTotal:      22528 kB
> 
> It is less than 32 MB because some of the space is reserved for Enclave
> Page Cache Metadata (EPCM), which contains state variables for all the
> pages in the Enclave Page Cache (EPC).  The latter contains the pages,
> which applications can use to create enclaves.
> 
> Signed-off-by: Jarkko Sakkinen <jarkko@...nel.org>
> ---
>  Documentation/x86/sgx.rst      |  6 ++++++
>  arch/x86/include/asm/sgx.h     | 10 +++++++---
>  arch/x86/kernel/cpu/sgx/main.c |  7 ++++++-
>  arch/x86/mm/pat/set_memory.c   |  5 +++++
>  4 files changed, 24 insertions(+), 4 deletions(-)
> 
> diff --git a/Documentation/x86/sgx.rst b/Documentation/x86/sgx.rst
> index dd0ac96ff9ef..68ee171e1d8f 100644
> --- a/Documentation/x86/sgx.rst
> +++ b/Documentation/x86/sgx.rst
> @@ -250,3 +250,9 @@ user wants to deploy SGX applications both on the host and in guests
>  on the same machine, the user should reserve enough EPC (by taking out
>  total virtual EPC size of all SGX VMs from the physical EPC size) for
>  host SGX applications so they can run with acceptable performance.
> +
> +Supplemental fields for /proc/meminfo
> +=====================================
> +
> +SGX_MemTotal
> +	The total usable SGX protected memory in kilobytes.
> diff --git a/arch/x86/include/asm/sgx.h b/arch/x86/include/asm/sgx.h
> index 05f3e21f01a7..2ae9dc8c9411 100644
> --- a/arch/x86/include/asm/sgx.h
> +++ b/arch/x86/include/asm/sgx.h
> @@ -365,6 +365,13 @@ struct sgx_sigstruct {
>   * comment!
>   */
>  
> +#if defined(CONFIG_X86_SGX) || defined(CONFIG_X86_SGX_KVM)
> +extern unsigned long sgx_nr_all_pages;
> +
> +int sgx_set_attribute(unsigned long *allowed_attributes,
> +		      unsigned int attribute_fd);
> +#endif
> +
>  #ifdef CONFIG_X86_SGX_KVM
>  int sgx_virt_ecreate(struct sgx_pageinfo *pageinfo, void __user *secs,
>  		     int *trapnr);
> @@ -372,7 +379,4 @@ int sgx_virt_einit(void __user *sigstruct, void __user *token,
>  		   void __user *secs, u64 *lepubkeyhash, int *trapnr);
>  #endif
>  
> -int sgx_set_attribute(unsigned long *allowed_attributes,
> -		      unsigned int attribute_fd);
> -

This change seems unrelated?

>  #endif /* _ASM_X86_SGX_H */
> diff --git a/arch/x86/kernel/cpu/sgx/main.c b/arch/x86/kernel/cpu/sgx/main.c
> index 63d3de02bbcc..1fe26a8e80dc 100644
> --- a/arch/x86/kernel/cpu/sgx/main.c
> +++ b/arch/x86/kernel/cpu/sgx/main.c
> @@ -28,7 +28,10 @@ static DECLARE_WAIT_QUEUE_HEAD(ksgxd_waitq);
>  static LIST_HEAD(sgx_active_page_list);
>  static DEFINE_SPINLOCK(sgx_reclaimer_lock);
>  
> -/* The free page list lock protected variables prepend the lock. */
> +/* The number of usable EPC pages in the system. */
> +unsigned long sgx_nr_all_pages;
> +
> +/* The number of free EPC pages in all nodes. */
>  static unsigned long sgx_nr_free_pages;
>  
>  /* Nodes with one or more EPC sections. */
> @@ -656,6 +659,8 @@ static bool __init sgx_setup_epc_section(u64 phys_addr, u64 size,
>  		list_add_tail(&section->pages[i].list, &sgx_dirty_page_list);
>  	}
>  
> +	sgx_nr_all_pages += nr_pages;
> +
>  	return true;
>  }
>  
> diff --git a/arch/x86/mm/pat/set_memory.c b/arch/x86/mm/pat/set_memory.c
> index ad8a5c586a35..82bb09c298de 100644
> --- a/arch/x86/mm/pat/set_memory.c
> +++ b/arch/x86/mm/pat/set_memory.c
> @@ -29,6 +29,7 @@
>  #include <asm/proto.h>
>  #include <asm/memtype.h>
>  #include <asm/set_memory.h>
> +#include <asm/sgx.h>
>  
>  #include "../mm_internal.h"
>  
> @@ -116,6 +117,10 @@ void arch_report_meminfo(struct seq_file *m)
>  	if (direct_gbpages)
>  		seq_printf(m, "DirectMap1G:    %8lu kB\n",
>  			direct_pages_count[PG_LEVEL_1G] << 20);
> +
> +#if defined(CONFIG_X86_SGX) || defined(CONFIG_X86_SGX_KVM)
> +	seq_printf(m, "SGX_MemTotal:   %8lu kB\n", sgx_nr_all_pages << 2);
> +#endif
>  }
>  #else
>  static inline void split_page_count(int level) { }
> 


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