From: Thomas Gleixner <tglx@linutronix.de>
To: "Andrew Cooper" <andrew.cooper3@citrix.com>,
"Ingo Molnar" <mingo@redhat.com>,
"Borislav Petkov" <bp@alien8.de>,
"Dave Hansen" <dave.hansen@linux.intel.com>,
x86@kernel.org, "H. Peter Anvin" <hpa@zytor.com>,
"Steve Wahl" <steve.wahl@hpe.com>,
"Justin Ernst" <justin.ernst@hpe.com>,
"Kyle Meyer" <kyle.meyer@hpe.com>,
"Dimitri Sivanich" <dimitri.sivanich@hpe.com>,
"Russ Anderson" <russ.anderson@hpe.com>,
"Darren Hart" <dvhart@infradead.org>,
"Andy Shevchenko" <andy@infradead.org>,
"K. Y. Srinivasan" <kys@microsoft.com>,
"Haiyang Zhang" <haiyangz@microsoft.com>,
"Wei Liu" <wei.liu@kernel.org>,
"Dexuan Cui" <decui@microsoft.com>,
"Lorenzo Pieralisi" <lpieralisi@kernel.org>,
"Krzysztof Wilczyński" <kw@linux.com>,
"Rob Herring" <robh@kernel.org>,
"Bjorn Helgaas" <bhelgaas@google.com>
Cc: linux-kernel@vger.kernel.org,
platform-driver-x86@vger.kernel.org,
linux-hyperv@vger.kernel.org, linux-pci@vger.kernel.org
Subject: Re: Notes on BAD_APICID, Was: [PATCH 0/3] x86/apic: Misc pruning
Date: Sat, 04 Nov 2023 20:15:05 +0100 [thread overview]
Message-ID: <87zfztib46.ffs@tglx> (raw)
In-Reply-To: <36462e78-8014-4415-bc47-86fbb46d028b@citrix.com>
On Fri, Nov 03 2023 at 19:58, Andrew Cooper wrote:
> On 02/11/2023 12:26 pm, Andrew Cooper wrote:
> Another dodgy construct spotted while doing this work is
>
> #ifdef CONFIG_X86_32
> #define BAD_APICID 0xFFu
> #else
> #define BAD_APICID 0xFFFFu
> #endif
>
> considering that both of those "bad" values are legal APIC IDs in an
> x2APIC system.
>
> The majority use is as a sentential (of varying types - int, u16
> mostly), although the uses for NUM_APIC_CLUSTERS, and
> safe_smp_processor_id() look suspect.
>
> In particular, safe_smp_processor_id() *will* malfunction on some legal
> CPUs, and needs to use -1 (32 bits wide) to spot the intended error case
> of a bad xAPIC mapping.
>
> However, it's use in amd_pmu_cpu_starting() from topology_die_id() looks
> broken. Partly because the error handling is (only) a WARN_ON_ONCE(),
> and also because nb->nb_id's sentinel value is -1 of type int.
>
> I suspect there's a lot of cleaning to be done here too.
Sigh...
prev parent reply other threads:[~2023-11-04 19:15 UTC|newest]
Thread overview: 20+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-11-02 12:26 [PATCH 0/3] x86/apic: Misc pruning Andrew Cooper
2023-11-02 12:26 ` [PATCH 1/3] x86/apic: Drop apic::delivery_mode Andrew Cooper
2023-11-03 20:15 ` Steve Wahl
2023-11-04 19:13 ` Thomas Gleixner
2023-11-21 8:43 ` [tip: x86/apic] " tip-bot2 for Andrew Cooper
2023-11-21 12:04 ` Borislav Petkov
2023-11-21 12:18 ` x86/apic: Further apic::delivery_mode cleanup Andrew Cooper
2023-11-21 12:30 ` [PATCH RESEND] " Andrew Cooper
2023-11-21 18:04 ` [tip: x86/apic] x86/apic: Drop apic::delivery_mode tip-bot2 for Andrew Cooper
2023-11-02 12:26 ` [PATCH 2/3] x86/apic: Drop enum apic_delivery_modes Andrew Cooper
2023-11-03 20:15 ` Steve Wahl
2023-11-21 8:43 ` [tip: x86/apic] " tip-bot2 for Andrew Cooper
2023-11-21 18:04 ` tip-bot2 for Andrew Cooper
2023-11-02 12:26 ` [PATCH 3/3] x86/apic: Drop struct local_apic Andrew Cooper
2023-11-03 20:16 ` Steve Wahl
2023-11-14 11:32 ` Ilpo Järvinen
2023-11-21 8:43 ` [tip: x86/apic] " tip-bot2 for Andrew Cooper
2023-11-21 18:04 ` tip-bot2 for Andrew Cooper
2023-11-03 19:58 ` Notes on BAD_APICID, Was: [PATCH 0/3] x86/apic: Misc pruning Andrew Cooper
2023-11-04 19:15 ` Thomas Gleixner [this message]
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=87zfztib46.ffs@tglx \
--to=tglx@linutronix.de \
--cc=andrew.cooper3@citrix.com \
--cc=andy@infradead.org \
--cc=bhelgaas@google.com \
--cc=bp@alien8.de \
--cc=dave.hansen@linux.intel.com \
--cc=decui@microsoft.com \
--cc=dimitri.sivanich@hpe.com \
--cc=dvhart@infradead.org \
--cc=haiyangz@microsoft.com \
--cc=hpa@zytor.com \
--cc=justin.ernst@hpe.com \
--cc=kw@linux.com \
--cc=kyle.meyer@hpe.com \
--cc=kys@microsoft.com \
--cc=linux-hyperv@vger.kernel.org \
--cc=linux-kernel@vger.kernel.org \
--cc=linux-pci@vger.kernel.org \
--cc=lpieralisi@kernel.org \
--cc=mingo@redhat.com \
--cc=platform-driver-x86@vger.kernel.org \
--cc=robh@kernel.org \
--cc=russ.anderson@hpe.com \
--cc=steve.wahl@hpe.com \
--cc=wei.liu@kernel.org \
--cc=x86@kernel.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 an external index of several public inboxes,
see mirroring instructions on how to clone and mirror
all data and code used by this external index.