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

From: Stefano Stabellini
Date: Fri Feb 26 2016 - 10:40:58 EST


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?


> 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,
> > };
>