linux-kernel - Re: Can't boot as Xen dom0 due to commit fe055896

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Date:   Thu, 15 Dec 2016 20:23:05 +0100
From:   Borislav Petkov <bp@...e.de>
To:     Boris Ostrovsky <boris.ostrovsky@...cle.com>
Cc:     Juergen Gross <jgross@...e.com>,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
        xen-devel <xen-devel@...ts.xenproject.org>
Subject: Re: Can't boot as Xen dom0 due to commit fe055896

On Thu, Dec 15, 2016 at 02:08:50PM -0500, Boris Ostrovsky wrote:
> This fixes my PV boot problem. I am still failing to boot HVM, will
> need to look at this some more.

No, no more stabbing in the dark and no more brown paper bags.

Please check whether CPUID(4) works that early in any xen guest and
let's add that check to a function which does something like:

bool loader_disabled(void)
{
	if (running_on_a_xen_guest)
		return true;

        if (check_loader_disabled_bsp())
                return true;

        if (!have_cpuid_p())
                return true;

	return false;

}

and call that at the entry points and be done with it.

Or if there's some other clean method to detect I'm running on a xen
guest.

Thanks.

-- 
Regards/Gruss,
    Boris.

SUSE Linux GmbH, GF: Felix Imendörffer, Jane Smithard, Graham Norton, HRB 21284 (AG Nürnberg)
--