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From: Peter Zijlstra <peterz@infradead.org>
To: Boris Ostrovsky <boris.ostrovsky@oracle.com>
Cc: linux-kernel@vger.kernel.org, xen-devel@lists.xenproject.org,
	tglx@linutronix.de, bp@alien8.de, dave.hansen@linux.intel.com,
	x86@kernel.org, hpa@zytor.com, jgross@suse.com
Subject: Re: [PATCH] x86/smp: Factor out parts of native_smp_prepare_cpus()
Date: Mon, 8 Nov 2021 16:11:11 +0100	[thread overview]
Message-ID: <YYk+D17oIOGKWNtN@hirez.programming.kicks-ass.net> (raw)
In-Reply-To: <1635896196-18961-1-git-send-email-boris.ostrovsky@oracle.com>

On Tue, Nov 02, 2021 at 07:36:36PM -0400, Boris Ostrovsky wrote:
> Commit 66558b730f25 ("sched: Add cluster scheduler level for x86")
> introduced cpu_l2c_shared_map mask which is expected to be initialized
> by smp_op.smp_prepare_cpus(). That commit only updated
> native_smp_prepare_cpus() version but not xen_pv_smp_prepare_cpus().
> As result Xen PV guests crash in set_cpu_sibling_map().
> 
> While the new mask can be allocated in xen_pv_smp_prepare_cpus() one can
> see that both versions of smp_prepare_cpus ops share a number of common
> operations that can be factored out. So do that instead.
> 
> Fixes: 66558b730f25 ("sched: Add cluster scheduler level for x86")
> Signed-off-by: Boris Ostrovsky <boris.ostrovsky@oracle.com>

Thanks! I'll go stick that somewhere /urgent (I've had another report on
that here:

  https://lkml.kernel.org/r/20211105074139.GE174703@worktop.programming.kicks-ass.net
)

But looking at those functions; there seems to be more spurious
differences. For example, the whole sched_topology thing.

Should we re-architect this whole smp_prepare_cpus() thing instead? Have
a common function and a guest function? HyperV for instance seems to
call native_smp_prepare_cpus() and then does something extra (as does
xen_hvm).


  parent reply	other threads:[~2021-11-08 15:11 UTC|newest]

Thread overview: 10+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-11-02 23:36 [PATCH] x86/smp: Factor out parts of native_smp_prepare_cpus() Boris Ostrovsky
2021-11-03  5:45 ` Juergen Gross
2021-11-08 15:11 ` Peter Zijlstra [this message]
2021-11-08 17:20   ` Boris Ostrovsky
2021-11-09 15:10     ` Peter Zijlstra
2021-11-09 15:21       ` Juergen Gross
2021-11-09 15:28       ` Andrew Cooper
2021-11-10 21:52 ` Josef Johansson
2021-11-11 10:15   ` Peter Zijlstra
2021-11-11 12:39     ` Josef Johansson

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