From: Chao Gao <chao.gao@intel.com>
To: Jan Beulich <jbeulich@suse.com>
Cc: xen-devel@lists.xenproject.org,
"Roger Pau Monné" <roger.pau@citrix.com>,
"Ashok Raj" <ashok.raj@intel.com>, "Wei Liu" <wl@xen.org>,
"Andrew Cooper" <andrew.cooper3@citrix.com>
Subject: Re: [Xen-devel] [PATCH v9 15/15] microcode: block #NMI handling when loading an ucode
Date: Fri, 30 Aug 2019 14:33:27 +0800 [thread overview]
Message-ID: <20190830063326.GC31905@gao-cwp> (raw)
In-Reply-To: <e5eae8a9-1348-45a3-6f2b-b3bf75077312@suse.com>
On Thu, Aug 29, 2019 at 02:22:47PM +0200, Jan Beulich wrote:
>On 19.08.2019 03:25, Chao Gao wrote:
>> @@ -481,12 +478,28 @@ static int do_microcode_update(void *patch)
>> return ret;
>> }
>>
>> +static int microcode_nmi_callback(const struct cpu_user_regs *regs, int cpu)
>> +{
>> + /* The first thread of a core is to load an update. Don't block it. */
>> + if ( cpu == cpumask_first(per_cpu(cpu_sibling_mask, cpu)) ||
>> + loading_state != LOADING_CALLIN )
>> + return 0;
>> +
>> + cpumask_set_cpu(cpu, &cpu_callin_map);
>> +
>> + while ( loading_state != LOADING_EXIT )
>> + cpu_relax();
>> +
>> + return 0;
>> +}
>
>By returning 0 you tell do_nmi() to continue processing the NMI.
>Since you can't tell whether a non-IPI NMI has surfaced at about
>the same time this is generally the right thing imo, but how do
>you prevent unknown_nmi_error() from getting entered when do_nmi()
>ends up setting handle_unknown to true? (The question is mostly
>rhetorical, but there's a disconnect between do_nmi() checking
>"cpu == 0" and the control thread running on
>cpumask_first(&cpu_online_map), i.e. you introduce a well hidden
>dependency on CPU 0 never going offline. IOW my request is to at
>least make this less well hidden, such that it can be noticed if
>and when someone endeavors to remove said limitation.)
Seems the issue is that we couldn't send IPI NMI to BSP, otherwise
unknown_nmi_error() would be trigger. And loading ucode after
rendezvousing all CPUs in NMI handler expects all CPUs to receive IPI
NMI. So this approach always has such issue.
Considering self_nmi is called at another place, could we provide a
way to temporarily suppress or (force) ignore unknown nmi error?
Thanks
Chao
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next prev parent reply other threads:[~2019-08-30 6:29 UTC|newest]
Thread overview: 57+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-08-19 1:25 [Xen-devel] [PATCH v9 00/15] improve late microcode loading Chao Gao
2019-08-19 1:25 ` [Xen-devel] [PATCH v9 01/15] microcode/intel: extend microcode_update_match() Chao Gao
2019-08-28 15:12 ` Jan Beulich
2019-08-29 7:15 ` Chao Gao
2019-08-29 7:14 ` Jan Beulich
2019-08-19 1:25 ` [Xen-devel] [PATCH v9 02/15] microcode/amd: fix memory leak Chao Gao
2019-08-19 1:25 ` [Xen-devel] [PATCH v9 03/15] microcode/amd: distinguish old and mismatched ucode in microcode_fits() Chao Gao
2019-08-19 1:25 ` [Xen-devel] [PATCH v9 04/15] microcode: introduce a global cache of ucode patch Chao Gao
2019-08-22 11:11 ` Roger Pau Monné
2019-08-28 15:21 ` Jan Beulich
2019-08-29 10:18 ` Jan Beulich
2019-08-19 1:25 ` [Xen-devel] [PATCH v9 05/15] microcode: clean up microcode_resume_cpu Chao Gao
2019-08-19 1:25 ` [Xen-devel] [PATCH v9 06/15] microcode: remove struct ucode_cpu_info Chao Gao
2019-08-19 1:25 ` [Xen-devel] [PATCH v9 07/15] microcode: remove pointless 'cpu' parameter Chao Gao
2019-08-19 1:25 ` [Xen-devel] [PATCH v9 08/15] microcode/amd: call svm_host_osvw_init() in common code Chao Gao
2019-08-22 13:08 ` Roger Pau Monné
2019-08-28 15:26 ` Jan Beulich
2019-08-19 1:25 ` [Xen-devel] [PATCH v9 09/15] microcode: pass a patch pointer to apply_microcode() Chao Gao
2019-08-19 1:25 ` [Xen-devel] [PATCH v9 10/15] microcode: split out apply_microcode() from cpu_request_microcode() Chao Gao
2019-08-22 13:59 ` Roger Pau Monné
2019-08-29 10:06 ` Jan Beulich
2019-08-30 3:22 ` Chao Gao
2019-08-30 7:25 ` Jan Beulich
2019-08-29 10:19 ` Jan Beulich
2019-08-19 1:25 ` [Xen-devel] [PATCH v9 11/15] microcode: unify loading update during CPU resuming and AP wakeup Chao Gao
2019-08-22 14:10 ` Roger Pau Monné
2019-08-22 16:44 ` Chao Gao
2019-08-23 9:09 ` Roger Pau Monné
2019-08-29 7:37 ` Chao Gao
2019-08-29 8:16 ` Roger Pau Monné
2019-08-29 10:26 ` Jan Beulich
2019-08-29 10:29 ` Jan Beulich
2019-08-19 1:25 ` [Xen-devel] [PATCH v9 12/15] microcode: reduce memory allocation and copy when creating a patch Chao Gao
2019-08-23 8:11 ` Roger Pau Monné
2019-08-26 7:03 ` Chao Gao
2019-08-26 8:11 ` Roger Pau Monné
2019-08-29 10:47 ` Jan Beulich
2019-08-19 1:25 ` [Xen-devel] [PATCH v9 13/15] x86/microcode: Synchronize late microcode loading Chao Gao
2019-08-19 10:27 ` Sergey Dyasli
2019-08-19 14:49 ` Chao Gao
2019-08-29 12:06 ` Jan Beulich
2019-08-30 3:30 ` Chao Gao
2019-08-19 1:25 ` [Xen-devel] [PATCH v9 14/15] microcode: remove microcode_update_lock Chao Gao
2019-08-19 1:25 ` [Xen-devel] [PATCH v9 15/15] microcode: block #NMI handling when loading an ucode Chao Gao
2019-08-23 8:46 ` Sergey Dyasli
2019-08-26 8:07 ` Chao Gao
2019-08-27 4:52 ` Chao Gao
2019-08-28 8:52 ` Sergey Dyasli
2019-08-29 12:11 ` Jan Beulich
2019-08-30 6:35 ` Chao Gao
2019-09-09 5:52 ` Chao Gao
2019-09-09 6:16 ` Jan Beulich
2019-08-29 12:22 ` Jan Beulich
2019-08-30 6:33 ` Chao Gao [this message]
2019-08-30 7:30 ` Jan Beulich
2019-08-22 7:51 ` [Xen-devel] [PATCH v9 00/15] improve late microcode loading Sergey Dyasli
2019-08-22 15:39 ` Chao Gao
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