linux-kernel - Re: [Xen-devel] [PATCH] xen/hvc-console: Make it work with HVM guests.

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Date:	Sat, 26 Oct 2013 09:27:08 +0100
From:	Ian Campbell <ian.campbell@...rix.com>
To:	Konrad Rzeszutek Wilk <konrad.wilk@...cle.com>
CC:	Julien Grall <julien.grall@...aro.org>,
	<linux-kernel@...r.kernel.org>, <xen-devel@...ts.xenproject.org>
Subject: Re: [Xen-devel] [PATCH] xen/hvc-console: Make it work with HVM
 guests.

On Fri, 2013-10-25 at 15:38 -0400, Konrad Rzeszutek Wilk wrote:
> On Thu, Oct 24, 2013 at 05:43:54PM +0100, Ian Campbell wrote:
> > But stepping back how/why is this function called on x86 when not
> > running under Xen? Wouldn't the use have to be using console=hvc or
> > earlyprintk=xen or something -- which strikes me as user error... IOW
> > can we not just nuke the check
> 
> It shouldn't - ever. On x86 it is called from the early PV bootup code.
> 
> I occasionaly use it when developing/debugging and as such want it working
> in HVM even during early bootup.

Does earlyprintk=ttyS0,cough not Just Work for HVM guests? That would
avoid all of this stuff and assuming it works would be preferable IMHO.

Anyway, if not, then given that the xen_cpuid_base case is entirely x86
specific perhaps we can abstract this as something like:

	if (xen_arch_raw_console(str))
		return

	dom0_write_console(...)

Then ARM:
	#define xen_arch_raw_console 0
and x86
	static inline int xen_arch_raw_console(str)
	{
		if (xen_domain())
			return 0;

		/* Do the outb thing */
		return 1;
	}

This would also avoid the need for #ifdef x86 in the main function which
Julien pointed out.

Ian.

--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/