On 2019-06-05 12:48, Sean Christopherson wrote:
> ...to improve performance when building enclaves by reducing the number
> of user<->system transitions.  Rather than provide arbitrary batching,
> e.g. with per-page SECINFO and mrmask, take advantage of the fact that
> any sane enclave will have large swaths of pages with identical
> properties, e.g. code vs. data sections.
> 
> For simplicity and stability in the initial implementation, loop over
> the existing add page flow instead of taking a more agressive approach,
> which would require tracking transitions between VMAs and holding
> mmap_sem for an extended duration.
> 
> On an error, update the userspace struct to reflect progress made, e.g.
> so that the ioctl can be re-invoked to finish adding pages after a non-
> fatal error.
> 
> Signed-off-by: Sean Christopherson <sean.j.christopherson@intel.com>
> ---
>   Documentation/x86/sgx/3.API.rst        |   2 +-
>   arch/x86/include/uapi/asm/sgx.h        |  21 ++--
>   arch/x86/kernel/cpu/sgx/driver/ioctl.c | 128 +++++++++++++++++--------
>   3 files changed, 98 insertions(+), 53 deletions(-)
> 
> diff --git a/Documentation/x86/sgx/3.API.rst b/Documentation/x86/sgx/3.API.rst
> index b113aeb05f54..44550aa41073 100644
> --- a/Documentation/x86/sgx/3.API.rst
> +++ b/Documentation/x86/sgx/3.API.rst
> @@ -22,6 +22,6 @@ controls the `PROVISON_KEY` attribute.
>   
>   .. kernel-doc:: arch/x86/kernel/cpu/sgx/driver/ioctl.c
>      :functions: sgx_ioc_enclave_create
> -               sgx_ioc_enclave_add_page
> +               sgx_ioc_enclave_add_region
>                  sgx_ioc_enclave_init
>                  sgx_ioc_enclave_set_attribute
> diff --git a/arch/x86/include/uapi/asm/sgx.h b/arch/x86/include/uapi/asm/sgx.h
> index 9ed690a38c70..30d114f6b3bd 100644
> --- a/arch/x86/include/uapi/asm/sgx.h
> +++ b/arch/x86/include/uapi/asm/sgx.h
> @@ -12,8 +12,8 @@
>   
>   #define SGX_IOC_ENCLAVE_CREATE \
>   	_IOW(SGX_MAGIC, 0x00, struct sgx_enclave_create)
> -#define SGX_IOC_ENCLAVE_ADD_PAGE \
> -	_IOW(SGX_MAGIC, 0x01, struct sgx_enclave_add_page)
> +#define SGX_IOC_ENCLAVE_ADD_REGION \
> +	_IOWR(SGX_MAGIC, 0x01, struct sgx_enclave_add_region)
>   #define SGX_IOC_ENCLAVE_INIT \
>   	_IOW(SGX_MAGIC, 0x02, struct sgx_enclave_init)
>   #define SGX_IOC_ENCLAVE_SET_ATTRIBUTE \
> @@ -32,21 +32,22 @@ struct sgx_enclave_create  {
>   };
>   
>   /**
> - * struct sgx_enclave_add_page - parameter structure for the
> - *                               %SGX_IOC_ENCLAVE_ADD_PAGE ioctl
> - * @addr:	address within the ELRANGE
> - * @src:	address for the page data
> - * @secinfo:	address for the SECINFO data
> - * @mrmask:	bitmask for the measured 256 byte chunks
> + * struct sgx_enclave_add_region - parameter structure for the
> + *                                 %SGX_IOC_ENCLAVE_ADD_REGION ioctl
> + * @addr:	start address within the ELRANGE
> + * @src:	start address for the pages' data
> + * @size:	size of region, in bytes
> + * @secinfo:	address of the SECINFO data (common to the entire region)
> + * @mrmask:	bitmask of 256 byte chunks to measure (applied per 4k page)
>    */
> -struct sgx_enclave_add_page {
> +struct sgx_enclave_add_region {
>   	__u64	addr;
>   	__u64	src;
> +	__u64	size;
>   	__u64	secinfo;
>   	__u16	mrmask;

Considering:

1. I might want to load multiple pages that are not consecutive in memory.
2. Repeating mrmask (other than 0 or ~0) doesn't really make sense for 
ranges.

I'd be in favor of an approach that passes an array of 
sgx_enclave_add_page instead.

Somewhat unrelated: have you considered optionally "gifting" enclave 
source pages to the kernel (as in vmsplice)? That would avoid the 
copy_from_user.

--
Jethro Beekman | Fortanix