From: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
To: linux-kernel@vger.kernel.org, x86@kernel.org,
xen-devel@lists.xenproject.org
Cc: Thomas Gleixner <tglx@linutronix.de>,
Longpeng <longpeng2@huawei.com>,
Gonglei <arei.gonglei@huawei.com>,
Peter Zijlstra <peterz@infradead.org>,
Ingo Molnar <mingo@kernel.org>,
Valentin Schneider <valentin.schneider@arm.com>,
Juergen Gross <jgross@suse.com>,
Stefano Stabellini <sstabellini@kernel.org>,
Ingo Molnar <mingo@redhat.com>, Borislav Petkov <bp@alien8.de>,
Dave Hansen <dave.hansen@linux.intel.com>,
"H . Peter Anvin" <hpa@zytor.com>,
Sebastian Andrzej Siewior <bigeasy@linutronix.de>,
Dongli Zhang <dongli.zhang@oracle.com>,
Henry Wang <Henry.Wang@arm.com>
Subject: [PATCH REPOST v2 2/2] cpu/hotplug: Allow the CPU in CPU_UP_PREPARE state to be brought up again.
Date: Wed, 9 Feb 2022 09:02:14 +0100 [thread overview]
Message-ID: <20220209080214.1439408-3-bigeasy@linutronix.de> (raw)
In-Reply-To: <20220209080214.1439408-1-bigeasy@linutronix.de>
From: "Longpeng(Mike)" <longpeng2@huawei.com>
A CPU will not show up in virtualized environment which includes an
Enclave. The VM splits its resources into a primary VM and a Enclave
VM. While the Enclave is active, the hypervisor will ignore all requests
to bring up a CPU and this CPU will remain in CPU_UP_PREPARE state.
The kernel will wait up to ten seconds for CPU to show up
(do_boot_cpu()) and then rollback the hotplug state back to
CPUHP_OFFLINE leaving the CPU state in CPU_UP_PREPARE. The CPU state is
set back to CPUHP_TEARDOWN_CPU during the CPU_POST_DEAD stage.
After the Enclave VM terminates, the primary VM can bring up the CPU
again.
Allow to bring up the CPU if it is in the CPU_UP_PREPARE state.
[bigeasy: Rewrite commit description.]
Signed-off-by: Longpeng(Mike) <longpeng2@huawei.com>
Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Link: https://lore.kernel.org/r/20210901051143.2752-1-longpeng2@huawei.com
Reviewed-by: Valentin Schneider <valentin.schneider@arm.com>
Tested-by: Dongli Zhang <dongli.zhang@oracle.com>
Reviewed-by: Henry Wang <Henry.Wang@arm.com>
Link: https://lore.kernel.org/r/20211122154714.xaoxok3fpk5bgznz@linutronix.de
Link: https://lore.kernel.org/r/20211206152034.2150770-3-bigeasy@linutronix.de
---
kernel/smpboot.c | 7 +++++++
1 file changed, 7 insertions(+)
diff --git a/kernel/smpboot.c b/kernel/smpboot.c
index f6bc0bc8a2aab..b9f54544e7499 100644
--- a/kernel/smpboot.c
+++ b/kernel/smpboot.c
@@ -392,6 +392,13 @@ int cpu_check_up_prepare(int cpu)
*/
return -EAGAIN;
+ case CPU_UP_PREPARE:
+ /*
+ * Timeout while waiting for the CPU to show up. Allow to try
+ * again later.
+ */
+ return 0;
+
default:
/* Should not happen. Famous last words. */
--
2.34.1
next prev parent reply other threads:[~2022-02-09 8:02 UTC|newest]
Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-02-09 8:02 [PATCH REPOST v2 0/2 v2] cpu/hotplug: Allow the CPU in CPU_UP_PREPARE state to be brought up again Sebastian Andrzej Siewior
2022-02-09 8:02 ` [PATCH REPOST v2 1/2] x86/xen: Allow to retry if cpu_initialize_context() failed Sebastian Andrzej Siewior
2022-04-12 12:19 ` [tip: smp/core] " tip-bot2 for Boris Ostrovsky
2022-02-09 8:02 ` Sebastian Andrzej Siewior [this message]
2022-04-12 12:19 ` [tip: smp/core] cpu/hotplug: Allow the CPU in CPU_UP_PREPARE state to be brought up again tip-bot2 for Longpeng(Mike)
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=20220209080214.1439408-3-bigeasy@linutronix.de \
--to=bigeasy@linutronix.de \
--cc=Henry.Wang@arm.com \
--cc=arei.gonglei@huawei.com \
--cc=bp@alien8.de \
--cc=dave.hansen@linux.intel.com \
--cc=dongli.zhang@oracle.com \
--cc=hpa@zytor.com \
--cc=jgross@suse.com \
--cc=linux-kernel@vger.kernel.org \
--cc=longpeng2@huawei.com \
--cc=mingo@kernel.org \
--cc=mingo@redhat.com \
--cc=peterz@infradead.org \
--cc=sstabellini@kernel.org \
--cc=tglx@linutronix.de \
--cc=valentin.schneider@arm.com \
--cc=x86@kernel.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).