linux-kernel - Re: [PATCH] xen: setup pv irq ops vector earlier

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Message-ID: <405aaefe-b7d2-5971-166b-25f5bf366e71@oracle.com>
Date:   Wed, 11 Jul 2018 11:31:33 -0400
From:   Boris Ostrovsky <boris.ostrovsky@...cle.com>
To:     Juergen Gross <jgross@...e.com>, linux-kernel@...r.kernel.org,
        xen-devel@...ts.xenproject.org, x86@...nel.org
Cc:     hpa@...or.com, tglx@...utronix.de, mingo@...hat.com,
        stable@...r.kernel.org
Subject: Re: [PATCH] xen: setup pv irq ops vector earlier

On 07/11/2018 01:08 AM, Juergen Gross wrote:
> On 11/07/18 00:26, Boris Ostrovsky wrote:
>> On 07/02/2018 06:00 AM, Juergen Gross wrote:
>>> Setting pv_irq_ops for Xen PV domains should be done as early as
>>> possible in order to support e.g. very early printk() usage.
>> Will printk() work as result of this move? We still, for example,
>> haven't set up console.
> It will print to the kernel print buffer, so the output will be
> available later.

Right, haven't thought about it.


>
>> This will (probably) allow us not to crash (due to STI and such) but I
>> am not sure "support" is the right term here.
> Not crashing is big plus IMO. :-)

Actually, no, this is not sufficient.

You need to move xen_vcpu_info_reset(0) up as well. Otherwise you will
not be able to dereference the percpu xen_vcpu in xen_save_fl().


-boris