On Mon, Nov 14, 2022 at 09:07:52AM +0100, Cédric Le Goater wrote: > When a virtio console port is initialized, it is registered as an hvc > console using a virtual console number. If a KVM guest is started with > multiple virtio console devices, the same vtermno (or virtual console > number) can be used to allocate different hvc consoles, which leads to > various communication problems later on. > > This is also reported in debugfs : > > # grep vtermno /sys/kernel/debug/virtio-ports/* > /sys/kernel/debug/virtio-ports/vport1p1:console_vtermno: 1 > /sys/kernel/debug/virtio-ports/vport2p1:console_vtermno: 1 > /sys/kernel/debug/virtio-ports/vport3p1:console_vtermno: 2 > /sys/kernel/debug/virtio-ports/vport4p1:console_vtermno: 3 > > Fix the issue with an atomic variable and start the first console > number at 1 as it is today. > > Signed-off-by: Cédric Le Goater <[email protected]> > --- > drivers/char/virtio_console.c | 8 ++++---- > 1 file changed, 4 insertions(+), 4 deletions(-) > > diff --git a/drivers/char/virtio_console.c b/drivers/char/virtio_console.c > index 9fa3c76a267f..253574f41e57 100644 > --- a/drivers/char/virtio_console.c > +++ b/drivers/char/virtio_console.c > @@ -58,12 +58,13 @@ struct ports_driver_data { > * We also just assume the first console being initialised was > * the first one that got used as the initial console. > */ > - unsigned int next_vtermno; > + atomic_t next_vtermno; > > /* All the console devices handled by this driver */ > struct list_head consoles; > }; > -static struct ports_driver_data pdrvdata = { .next_vtermno = 1}; > + > +static struct ports_driver_data pdrvdata = { .next_vtermno = ATOMIC_INIT(0) > }; > > static DEFINE_SPINLOCK(pdrvdata_lock); > static DECLARE_COMPLETION(early_console_added); > @@ -1244,7 +1245,7 @@ static int init_port_console(struct port *port) > * pointers. The final argument is the output buffer size: we > * can do any size, so we put PAGE_SIZE here. > */ > - port->cons.vtermno = pdrvdata.next_vtermno; > + port->cons.vtermno = atomic_inc_return(&pdrvdata.next_vtermno);
Why not use a normal ida/idr structure here? And why is this never decremented? and finally, why not use the value that created the "vportN" number instead? thanks, greg k-h _______________________________________________ Virtualization mailing list [email protected] https://lists.linuxfoundation.org/mailman/listinfo/virtualization
