From: Jarkko Sakkinen <firstname.lastname@example.org>
To: Dave Hansen <email@example.com>, Borislav Petkov <firstname.lastname@example.org>
Cc: Thomas Gleixner <email@example.com>,
Ingo Molnar <firstname.lastname@example.org>,
Dave Hansen <email@example.com>,
firstname.lastname@example.org, "H. Peter Anvin" <email@example.com>,
Greg Kroah-Hartman <firstname.lastname@example.org>,
"Rafael J. Wysocki" <email@example.com>,
Subject: Re: [PATCH v13 2/2] x86/sgx: Add an attribute for the amount of SGX memory in a NUMA node
Date: Sat, 11 Dec 2021 17:37:46 +0200 [thread overview]
Message-ID: <firstname.lastname@example.org> (raw)
On Wed, 2021-12-08 at 11:38 -0800, Dave Hansen wrote:
> I reworked the changelog quite a bit, addressing some of Borislav's
> questions. No code changes, though.
> The result is below. I've retained Greg's ack. I'll stick this in
> tip/x86/sgx if this looks OK to everyone.
> From: Jarkko Sakkinen <email@example.com>
> == Problem ==
> The amount of SGX memory on a system is determined by the BIOS and it
> varies wildly between systems. It can be as small as dozens of MB's
> and as large as many GB's on servers. Just like how applications need
> to know how much regular RAM is available, enclave builders need to
> know how much SGX memory an enclave can consume.
> == Solution ==
> Introduce a new sysfs file:
> to enumerate the amount of SGX memory available in each NUMA node.
> This serves the same function for SGX as /proc/meminfo or
> /sys/devices/system/node/nodeX/meminfo does for normal RAM.
> 'sgx_total_bytes' is needed today to help drive the SGX selftests.
> SGX-specific swap code is exercised by creating overcommitted enclaves
> which are larger than the physical SGX memory on the system. They
> currently use a CPUID-based approach which can diverge from the actual
> amount of SGX memory available. 'sgx_total_bytes' ensures that the
> selftests can work efficiently and do not attempt stupid things like
> creating a 100,000 MB enclave on a system with 128 MB of SGX memory.
> == Implementation Details ==
> Introduce CONFIG_HAVE_ARCH_NODE_DEV_GROUP opt-in flag to expose an
> arch specific attribute group, and add an attribute for the amount of
> SGX memory in bytes to each NUMA node:
> == ABI Design Discussion ==
> As opposed to the per-node ABI, a single, global ABI was considered.
> However, this would prevent enclaves from being able to size
> themselves so that they fit on a single NUMA node. Essentially, a
> single value would rule out NUMA optimizations for enclaves.
> Create a new "x86/" directory inside each "nodeX/" sysfs directory.
> 'sgx_total_bytes' is expected to be the first of at least a few
> sgx-specific files to be placed in the new directory. Just scanning
> /proc/meminfo, these are the no-brainers that we have for RAM, but we
> need for SGX:
> MemTotal: xxxx kB // sgx_total_bytes (implemented here)
> MemFree: yyyy kB // sgx_free_bytes
> SwapTotal: zzzz kB // sgx_swapped_bytes
> So, at *least* three. I think we will eventually end up needing
> something more along the lines of a dozen. A new directory (as
> opposed to being in the nodeX/ "root") directory avoids cluttering the
> root with several "sgx_*" files.
> Place the new file in a new "nodeX/x86/" directory because SGX is
> highly x86-specific. It is very unlikely that any other architecture
> (or even non-Intel x86 vendor) will ever implement SGX. Using "sgx/"
> as opposed to "x86/" was also considered. But, there is a real chance
> this can get used for other arch-specific purposes.
> [ dhansen: rewrite changelog ]
> Signed-off-by: Jarkko Sakkinen <firstname.lastname@example.org>
> Signed-off-by: Dave Hansen <email@example.com>
> Acked-by: Greg Kroah-Hartman <firstname.lastname@example.org>
> Link: https://email@example.com
> Documentation/ABI/stable/sysfs-devices-node | 6 ++++++
> arch/Kconfig | 4 ++++
> arch/x86/Kconfig | 1 +
> arch/x86/kernel/cpu/sgx/main.c | 20 ++++++++++++++++++++
> arch/x86/kernel/cpu/sgx/sgx.h | 1 +
> drivers/base/node.c | 3 +++
> include/linux/numa.h | 4 ++++
> 7 files changed, 39 insertions(+)
Thank you! Looks good to me.
next prev parent reply other threads:[~2021-12-11 15:37 UTC|newest]
Thread overview: 19+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-11-16 16:21 [PATCH v13 1/2] x86/sgx: Rename fallback labels in sgx_init() Jarkko Sakkinen
2021-11-16 16:21 ` [PATCH v13 2/2] x86/sgx: Add an attribute for the amount of SGX memory in a NUMA node Jarkko Sakkinen
2021-12-04 23:51 ` Jarkko Sakkinen
2021-12-07 19:36 ` Dave Hansen
2021-12-08 10:10 ` Borislav Petkov
2021-12-08 19:38 ` Dave Hansen
2021-12-09 12:08 ` Borislav Petkov
2021-12-11 15:37 ` Jarkko Sakkinen [this message]
2021-12-11 15:36 ` Jarkko Sakkinen
2021-12-09 15:35 ` [tip: x86/sgx] " tip-bot2 for Jarkko Sakkinen
2021-12-17 19:12 ` [PATCH v13 2/2] " Nathan Chancellor
2021-12-17 21:17 ` Dave Hansen
2021-12-17 22:04 ` Nathan Chancellor
2021-12-28 23:45 ` Jarkko Sakkinen
2022-01-02 4:54 ` Dave Hansen
2022-01-02 23:20 ` Nathan Chancellor
2022-01-04 16:52 ` Dave Hansen
2022-01-06 19:18 ` Jarkko Sakkinen
2022-01-07 11:42 ` Jarkko Sakkinen
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