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Date:   Thu, 17 Dec 2020 20:10:12 -0800
From:   Ira Weiny <ira.weiny@intel.com>
To:     Dave Hansen <dave.hansen@intel.com>
Cc:     Thomas Gleixner <tglx@linutronix.de>,
        Ingo Molnar <mingo@redhat.com>, Borislav Petkov <bp@alien8.de>,
        Andy Lutomirski <luto@kernel.org>,
        Peter Zijlstra <peterz@infradead.org>,
        Dave Hansen <dave.hansen@linux.intel.com>,
        Fenghua Yu <fenghua.yu@intel.com>, x86@kernel.org,
        linux-kernel@vger.kernel.org,
        Andrew Morton <akpm@linux-foundation.org>,
        linux-doc@vger.kernel.org, linux-nvdimm@lists.01.org,
        linux-mm@kvack.org, linux-kselftest@vger.kernel.org,
        Dan Williams <dan.j.williams@intel.com>,
        Greg KH <gregkh@linuxfoundation.org>
Subject: Re: [NEEDS-REVIEW] [PATCH V3 04/10] x86/pks: Preserve the PKRS MSR
 on context switch
Message-ID: <20201218041012.GC2506510@iweiny-DESK2.sc.intel.com>
References: <20201106232908.364581-1-ira.weiny@intel.com>
 <20201106232908.364581-5-ira.weiny@intel.com>
 <ff685068-6821-ca35-7fa8-732a66cbf266@intel.com>
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On Thu, Dec 17, 2020 at 12:41:50PM -0800, Dave Hansen wrote:
> On 11/6/20 3:29 PM, ira.weiny@intel.com wrote:
> >  void disable_TSC(void)
> > @@ -644,6 +668,8 @@ void __switch_to_xtra(struct task_struct *prev_p, struct task_struct *next_p)
> >  
> >  	if ((tifp ^ tifn) & _TIF_SLD)
> >  		switch_to_sld(tifn);
> > +
> > +	pks_sched_in();
> >  }
> 
> Does the selftest for this ever actually schedule()?

At this point I'm not sure.  This code has been in since the beginning.  So its
seen a lot of soak time.

> 
> I see it talking about context switching, but I don't immediately see
> how it would.

We were trying to force parent and child to run on the same CPU.  I suspect
something is wrong in the timing of that test.

Ira