Re: [PATCH v2 2/3] hvc_xen: fix xenboot for DomUs

[Boris Ostrovsky]

On 02/26/2016 10:39 AM, Stefano Stabellini wrote:
> On Thu, 25 Feb 2016, Boris Ostrovsky wrote:
> > On 02/25/2016 07:10 AM, Stefano Stabellini wrote:
> > > The xenboot early console has been partially broken for DomU for a long
> > > time: the output would only go to the hypervisor via hypercall
> > > (HYPERVISOR_console_io), while it wouldn't actually go to the DomU
> > > console. The reason is that domU_write_console would return early as no
> > > xencons structs are configured for it.
> > >
> > > Add an appropriate xencons struct for xenboot from the xenboot setup
> > > callback.
> > >
> > > Signed-off-by: Stefano Stabellini <stefano.stabellini@xxxxxxxxxxxxx>
> > >
> > > ---
> > > Changes in v2:
> > > - add return to xenboot_setup_console
> > > ---
> > >    drivers/tty/hvc/hvc_xen.c |   32 ++++++++++++++++++++++++++------
> > >    1 file changed, 26 insertions(+), 6 deletions(-)
> > >
> > > diff --git a/drivers/tty/hvc/hvc_xen.c b/drivers/tty/hvc/hvc_xen.c
> > > index 68b8ec8..bf787aa 100644
> > > --- a/drivers/tty/hvc/hvc_xen.c
> > > +++ b/drivers/tty/hvc/hvc_xen.c
> > > @@ -246,6 +246,18 @@ err:
> > >    	return -ENODEV;
> > >    }
> > >    +static int xen_early_pv_console_init(struct xencons_info *info, int
> > > vtermno)
> > Nit: not sure whether "early" is the right word to use here: when called from
> > xen_pv_console_init() it's not really on the early path.
> What about xencons_info_pv_init?

Sure, that sounds good.

(BTW, I didn't mean that my R-b was conditional on this)


-boris

> > Other than that:
> > Reviewed-by: Boris Ostrovsky <boris.ostrovsky@xxxxxxxxxx>
> Thanks!
>
>
> > > +{
> > > +	info->evtchn = xen_start_info->console.domU.evtchn;
> > > +	/* GFN == MFN for PV guest */
> > > +	info->intf = gfn_to_virt(xen_start_info->console.domU.mfn);
> > > +	info->vtermno = vtermno;
> > > +
> > > +	list_add_tail(&info->list, &xenconsoles);
> > > +
> > > +	return 0;
> > > +}
> > > +
> > >    static int xen_pv_console_init(void)
> > >    {
> > >    	struct xencons_info *info;
> > > @@ -265,13 +277,8 @@ static int xen_pv_console_init(void)
> > >    		/* already configured */
> > >    		return 0;
> > >    	}
> > > -	info->evtchn = xen_start_info->console.domU.evtchn;
> > > -	/* GFN == MFN for PV guest */
> > > -	info->intf = gfn_to_virt(xen_start_info->console.domU.mfn);
> > > -	info->vtermno = HVC_COOKIE;
> > > -
> > >    	spin_lock(&xencons_lock);
> > > -	list_add_tail(&info->list, &xenconsoles);
> > > +	xen_early_pv_console_init(info, HVC_COOKIE);
> > >    	spin_unlock(&xencons_lock);
> > >      	return 0;
> > > @@ -599,6 +606,18 @@ static int xen_cons_init(void)
> > >    console_initcall(xen_cons_init);
> > >      #ifdef CONFIG_EARLY_PRINTK
> > > +static int __init xenboot_setup_console(struct console *console, char
> > > *string)
> > > +{
> > > +	static struct xencons_info xenboot;
> > > +
> > > +	if (xen_initial_domain())
> > > +		return 0;
> > > +	if (!xen_pv_domain())
> > > +		return -ENODEV;
> > > +
> > > +	return xen_early_pv_console_init(&xenboot, 0);
> > > +}
> > > +
> > >    static void xenboot_write_console(struct console *console, const char
> > > *string,
> > >    				  unsigned len)
> > >    {
> > > @@ -629,6 +648,7 @@ static void xenboot_write_console(struct console
> > > *console, const char *string,
> > >    struct console xenboot_console = {
> > >    	.name		= "xenboot",
> > >    	.write		= xenboot_write_console,
> > > +	.setup		= xenboot_setup_console,
> > >    	.flags		= CON_PRINTBUFFER | CON_BOOT | CON_ANYTIME,
> > >    	.index		= -1,
> > >    };