Re: [PATCH v3 2/7] nitro_enclaves: Update documentation for Arm64 support

George-Aurelian Popescu
2021-08-30T15:57:09Z

On Fri, Aug 27, 2021 at 06:49:25PM +0300, Andra Paraschiv wrote:
> Add references for hugepages and booting steps for Arm64.
>
> Include info about the current supported architectures for the
> NE kernel driver.
>
> Signed-off-by: Andra Paraschiv <andraprs@amazon.com>
> ---
> Changelog
>
> v1 -> v2
>
> * Add information about supported architectures for the NE kernel
> driver.
>
> v2 -> v3
>
> * Move changelog after the "---" line.
> ---
> Documentation/virt/ne_overview.rst | 21 +++++++++++++--------
> 1 file changed, 13 insertions(+), 8 deletions(-)
>
> diff --git a/Documentation/virt/ne_overview.rst b/Documentation/virt/ne_overview.rst
> index 39b0c8fe2654a..74c2f5919c886 100644
> --- a/Documentation/virt/ne_overview.rst
> +++ b/Documentation/virt/ne_overview.rst
> @@ -14,12 +14,15 @@ instances [1].
> For example, an application that processes sensitive data and runs in a VM,
> can be separated from other applications running in the same VM. This
> application then runs in a separate VM than the primary VM, namely an enclave.
> +It runs alongside the VM that spawned it. This setup matches low latency
> +applications needs.
>
> -An enclave runs alongside the VM that spawned it. This setup matches low latency
> -applications needs. The resources that are allocated for the enclave, such as
> -memory and CPUs, are carved out of the primary VM. Each enclave is mapped to a
> -process running in the primary VM, that communicates with the NE driver via an
> -ioctl interface.
> +The current supported architectures for the NE kernel driver, available in the
> +upstream Linux kernel, are x86 and ARM64.
> +
> +The resources that are allocated for the enclave, such as memory and CPUs, are
> +carved out of the primary VM. Each enclave is mapped to a process running in the
> +primary VM, that communicates with the NE kernel driver via an ioctl interface.
>
> In this sense, there are two components:
>
> @@ -43,8 +46,8 @@ for the enclave VM. An enclave does not have persistent storage attached.
> The memory regions carved out of the primary VM and given to an enclave need to
> be aligned 2 MiB / 1 GiB physically contiguous memory regions (or multiple of
> this size e.g. 8 MiB). The memory can be allocated e.g. by using hugetlbfs from
> -user space [2][3]. The memory size for an enclave needs to be at least 64 MiB.
> -The enclave memory and CPUs need to be from the same NUMA node.
> +user space [2][3][7]. The memory size for an enclave needs to be at least
> +64 MiB. The enclave memory and CPUs need to be from the same NUMA node.
>
> An enclave runs on dedicated cores. CPU 0 and its CPU siblings need to remain
> available for the primary VM. A CPU pool has to be set for NE purposes by an
> @@ -61,7 +64,7 @@ device is placed in memory below the typical 4 GiB.
> The application that runs in the enclave needs to be packaged in an enclave
> image together with the OS ( e.g. kernel, ramdisk, init ) that will run in the
> enclave VM. The enclave VM has its own kernel and follows the standard Linux
> -boot protocol [6].
> +boot protocol [6][8].
>
> The kernel bzImage, the kernel command line, the ramdisk(s) are part of the
> Enclave Image Format (EIF); plus an EIF header including metadata such as magic
> @@ -93,3 +96,5 @@ enclave process can exit.
> [4] https://www.kernel.org/doc/html/latest/admin-guide/kernel-parameters.html
> [5] https://man7.org/linux/man-pages/man7/vsock.7.html
> [6] https://www.kernel.org/doc/html/latest/x86/boot.html
> +[7] https://www.kernel.org/doc/html/latest/arm64/hugetlbpage.html
> +[8] https://www.kernel.org/doc/html/latest/arm64/booting.html
> --
> 2.20.1 (Apple Git-117)
>

Reviewed-by: George-Aurelian Popescu <popegeo@amazon.com>

Looks good,
George