From: Jan Beulich <jbeulich@suse.com>
To: Andrew Cooper <andrew.cooper3@citrix.com>
Cc: Xen-devel <xen-devel@lists.xenproject.org>,
"Wei Liu" <wl@xen.org>, "Roger Pau Monné" <roger.pau@citrix.com>
Subject: Re: [Xen-devel] [PATCH 1/7] x86/ucode: Document the behaviour of the microcode_ops hooks
Date: Mon, 23 Mar 2020 13:33:04 +0100 [thread overview]
Message-ID: <3a2b459d-2d44-55fc-d72f-3f65afaf02af@suse.com> (raw)
In-Reply-To: <20200323101724.15655-2-andrew.cooper3@citrix.com>
On 23.03.2020 11:17, Andrew Cooper wrote:
> ... and struct cpu_signature for good measure.
>
> No comment is passed on the suitability of the behaviour...
>
> Signed-off-by: Andrew Cooper <andrew.cooper3@citrix.com>
> ---
> CC: Jan Beulich <JBeulich@suse.com>
> CC: Wei Liu <wl@xen.org>
> CC: Roger Pau Monné <roger.pau@citrix.com>
> ---
> xen/arch/x86/cpu/microcode/private.h | 46 ++++++++++++++++++++++++++++++++++++
> xen/include/asm-x86/microcode.h | 5 ++++
> 2 files changed, 51 insertions(+)
>
> diff --git a/xen/arch/x86/cpu/microcode/private.h b/xen/arch/x86/cpu/microcode/private.h
> index e64168a502..a2aec53047 100644
> --- a/xen/arch/x86/cpu/microcode/private.h
> +++ b/xen/arch/x86/cpu/microcode/private.h
> @@ -14,14 +14,60 @@ enum microcode_match_result {
> struct microcode_patch; /* Opaque */
>
> struct microcode_ops {
> + /*
> + * Parse a microcode container. Format is vendor-specific.
> + *
> + * Search within the container for the patch, suitable for the current
> + * CPU, which has the highest revision. (Note: May be a patch which is
> + * older that what is running in the CPU. This is a feature, to better
> + * cope with corner cases from buggy firmware.)
> + *
> + * If one is found, allocate and return a struct microcode_patch
> + * encapsulating the appropriate microcode patch. Does not alias the
> + * original buffer.
> + *
> + * If one is not found, (nothing matches the current CPU), return NULL.
> + * Also may return ERR_PTR(-err), e.g. bad container, out of memory.
> + */
> struct microcode_patch *(*cpu_request_microcode)(const void *buf,
> size_t size);
> +
> + /* Obtain microcode-relevant details for the current CPU. */
> int (*collect_cpu_info)(struct cpu_signature *csig);
> +
> + /*
> + * Attempt to load the provided patch into the CPU. Returns -EIO if
> + * anything didn't go as expected.
> + */
> int (*apply_microcode)(const struct microcode_patch *patch);
While at present -EIO may be the only error that may come back here, do
we want to risk the comment going stale when another error return gets
added? IOW - perhaps add "e.g." or some such?
> --- a/xen/include/asm-x86/microcode.h
> +++ b/xen/include/asm-x86/microcode.h
> @@ -7,8 +7,13 @@
> #include <public/xen.h>
>
> struct cpu_signature {
> + /* CPU signature (CPUID.1.EAX). Only written on Intel. */
> unsigned int sig;
> +
> + /* Platform Flags (only actually 1 bit). Only applicable to Intel. */
> unsigned int pf;
To me "only actually 1 bit" makes it an implication that this is the
lowest bit (like in a bool represented in a 32-bit memory location).
I didn't think this was the case though, so unless I'm wrong, could
you clarify this a little?
Jan
_______________________________________________
Xen-devel mailing list
Xen-devel@lists.xenproject.org
https://lists.xenproject.org/mailman/listinfo/xen-devel
next prev parent reply other threads:[~2020-03-23 12:33 UTC|newest]
Thread overview: 29+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-03-23 10:17 [Xen-devel] [PATCH 0/7] x86/ucode: Cleanup and fixes - Part 3/n (Intel) Andrew Cooper
2020-03-23 10:17 ` [Xen-devel] [PATCH 1/7] x86/ucode: Document the behaviour of the microcode_ops hooks Andrew Cooper
2020-03-23 12:33 ` Jan Beulich [this message]
2020-03-23 13:26 ` Andrew Cooper
2020-03-23 14:24 ` Jan Beulich
2020-03-23 10:17 ` [Xen-devel] [PATCH 2/7] x86/ucode/intel: Adjust microcode_sanity_check() to not take void * Andrew Cooper
2020-03-25 13:23 ` Jan Beulich
2020-03-23 10:17 ` [Xen-devel] [PATCH 3/7] x86/ucode/intel: Remove gratuitous memory allocations from cpu_request_microcode() Andrew Cooper
2020-03-25 13:34 ` Jan Beulich
2020-03-23 10:17 ` [Xen-devel] [PATCH 4/7] x86/ucode/intel: Reimplement get_{data, total}size() helpers Andrew Cooper
2020-03-25 13:41 ` Jan Beulich
2020-03-26 14:35 ` Andrew Cooper
2020-03-26 14:56 ` Jan Beulich
2020-03-26 15:09 ` Andrew Cooper
2020-03-26 15:19 ` Jan Beulich
2020-03-23 10:17 ` [Xen-devel] [PATCH 5/7] x86/ucode/intel: Clean up microcode_update_match() Andrew Cooper
2020-03-25 13:51 ` Jan Beulich
2020-03-26 14:36 ` Andrew Cooper
2020-03-23 10:17 ` [Xen-devel] [PATCH 6/7] x86/ucode/intel: Clean up microcode_sanity_check() Andrew Cooper
2020-03-25 14:07 ` Jan Beulich
2020-03-26 14:41 ` Andrew Cooper
2020-03-26 15:02 ` Jan Beulich
2020-03-23 10:17 ` [Xen-devel] [PATCH 7/7] x86/ucode/intel: Fold structures together Andrew Cooper
2020-03-25 14:16 ` Jan Beulich
2020-03-25 14:32 ` Andrew Cooper
2020-03-26 12:24 ` Jan Beulich
2020-03-26 14:50 ` Andrew Cooper
2020-03-26 15:05 ` Jan Beulich
2020-03-27 12:40 ` Andrew Cooper
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=3a2b459d-2d44-55fc-d72f-3f65afaf02af@suse.com \
--to=jbeulich@suse.com \
--cc=andrew.cooper3@citrix.com \
--cc=roger.pau@citrix.com \
--cc=wl@xen.org \
--cc=xen-devel@lists.xenproject.org \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).