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From:   Thomas Gleixner <tglx@linutronix.de>
To:     Andrew Cooper <andrew.cooper3@citrix.com>,
        Juergen Gross <jgross@suse.com>,
        LKML <linux-kernel@vger.kernel.org>
Cc:     x86@kernel.org, Tom Lendacky <thomas.lendacky@amd.com>,
        Arjan van de Ven <arjan@linux.intel.com>,
        Huang Rui <ray.huang@amd.com>,
        Dimitri Sivanich <dimitri.sivanich@hpe.com>,
        Michael Kelley <mikelley@microsoft.com>,
        Sohil Mehta <sohil.mehta@intel.com>,
        K Prateek Nayak <kprateek.nayak@amd.com>,
        Kan Liang <kan.liang@linux.intel.com>,
        Zhang Rui <rui.zhang@intel.com>,
        "Paul E. McKenney" <paulmck@kernel.org>,
        Feng Tang <feng.tang@intel.com>,
        Andy Shevchenko <andy@infradead.org>
Subject: Re: [patch 00/53] x86/topology: The final installment
In-Reply-To: <a08e9457-cb8f-6b57-8f4d-4a1f856ce60e@citrix.com>
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 <8d650d5c-e7b8-99c3-e561-3d177e6189bd@suse.com>
 <a08e9457-cb8f-6b57-8f4d-4a1f856ce60e@citrix.com>
Date:   Tue, 08 Aug 2023 20:55:52 +0200
Message-ID: <87jzu5l5xj.ffs@tglx>
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On Tue, Aug 08 2023 at 12:20, Andrew Cooper wrote:
> On 08/08/2023 8:40 am, Juergen Gross wrote:
>> Tested on an Intel system with Xen:
>>
>> - PV dom0 is working fine. I couldn't test physical cpu hotplug, but
>> removing
>> =C2=A0 and then re-adding vcpus to dom0 worked.
>
> It turns out that physical CPU hotplug with XenPV is broken in at least
> two ways.
>
> It's dom0 (not Xen) that gets the hot-unplug event, after which the Xen
> code in Linux succumbs to a preempt-check failure while trying to
> offline the vCPU that aliases the pCPU wanting to go offline.

That should be gone by now :)