On Tue, 17 Jul 2018, Julien Grall wrote:
> Hi Stefano,
>
> On 07/07/2018 00:12, Stefano Stabellini wrote:
> > Today Ctrl-AAA is used to switch between Xen and Dom0. Extend the
> > mechanism to allow for switching between Xen, Dom0, and any of the
> > initial DomU created from Xen alongside Dom0 out of information provided
> > via device tree.
> >
> > Signed-off-by: Stefano Stabellini <stefa...@xilinx.com>
> > CC: andrew.coop...@citrix.com
> > CC: george.dun...@eu.citrix.com
> > CC: ian.jack...@eu.citrix.com
> > CC: jbeul...@suse.com
> > CC: konrad.w...@oracle.com
> > CC: t...@xen.org
> > CC: wei.l...@citrix.com
> > ---
> > Changes in v2:
> > - only call vpl011_rx_char if the vpl011 has been initialized
> > ---
> > xen/drivers/char/console.c | 50
> > ++++++++++++++++++++++++++++++++--------------
> > 1 file changed, 35 insertions(+), 15 deletions(-)
> >
> > diff --git a/xen/drivers/char/console.c b/xen/drivers/char/console.c
> > index 0f05369..d590bc0 100644
> > --- a/xen/drivers/char/console.c
> > +++ b/xen/drivers/char/console.c
> > @@ -31,10 +31,13 @@
> > #include <xen/early_printk.h>
> > #include <xen/warning.h>
> > #include <xen/pv_console.h>
> > +#include <asm/setup.h>
> > #ifdef CONFIG_X86
> > #include <xen/consoled.h>
> > #include <asm/guest.h>
> > +#else
> > +#include <asm/vpl011.h>
> > #endif
> > /* console: comma-separated list of console outputs. */
> > @@ -389,29 +392,49 @@ static void dump_console_ring_key(unsigned char key)
> > free_xenheap_pages(buf, order);
> > }
> > -/* CTRL-<switch_char> switches input direction between Xen and DOM0. */
> > +/*
> > + * CTRL-<switch_char> switches input direction between Xen, Dom0 and
> > + * DomUs.
> > + */
> > #define switch_code (opt_conswitch[0]-'a'+1)
> > -static int __read_mostly xen_rx = 1; /* FALSE => input passed to domain 0.
> > */
> > +static int __read_mostly xen_rx = 1; /* 1 => input passed to domain 0. */
> > static void switch_serial_input(void)
> > {
> > - static char *input_str[2] = { "DOM0", "Xen" };
> > - xen_rx = !xen_rx;
> > - printk("*** Serial input -> %s", input_str[xen_rx]);
> > + xen_rx++;
> > + if ( xen_rx == max_init_domid + 1 )
> > + xen_rx = 0;
> > +
> > + if ( !xen_rx )
> > + printk("*** Serial input xen_rx=%d -> %s", xen_rx, "Xen");
> > + else
> > + printk("*** Serial input xen_rx=%d -> DOM%d", xen_rx, xen_rx - 1);
> > +
> > if ( switch_code )
> > - printk(" (type 'CTRL-%c' three times to switch input to %s)",
> > - opt_conswitch[0], input_str[!xen_rx]);
> > + printk(" (type 'CTRL-%c' three times to switch input)",
> > + opt_conswitch[0]);
> > printk("\n");
> > }
> > static void __serial_rx(char c, struct cpu_user_regs *regs)
> > {
> > - if ( xen_rx )
> > + if ( xen_rx == 0 )
> > return handle_keypress(c, regs);
> > - /* Deliver input to guest buffer, unless it is already full. */
> > - if ( (serial_rx_prod-serial_rx_cons) != SERIAL_RX_SIZE )
> > - serial_rx_ring[SERIAL_RX_MASK(serial_rx_prod++)] = c;
> > + if ( xen_rx == 1 )
> > + {
> > + /* Deliver input to guest buffer, unless it is already full. */
> > + if ( (serial_rx_prod-serial_rx_cons) != SERIAL_RX_SIZE )
> > + serial_rx_ring[SERIAL_RX_MASK(serial_rx_prod++)] = c;
> > + }
> > +#ifdef CONFIG_ARM
> > + else
> > + {
> > + struct domain *d = get_domain_by_id(xen_rx - 1);
> > + if ( !d->arch.vpl011.ring_enable && d->arch.vpl011.inring != NULL )
>
> It sounds like you want to provide a macro here. So would make clearer what
> you are actually checking.
I would rather add a in-code comment because it is the only instance of
this check in the codebase.
> > + vpl011_rx_char(d, c);
>
> What happen in the case vpl011 is not enabled for that domain?
Yes, that is a mistake in this version of the series. I have already
fixed the issue in my v3 dev branch.
> Shouldn't you at least warn there are no console available?
I'll add a warning
> > + }
> > +#endif
> > /* Always notify the guest: prevents receive path from getting stuck.
> > */
>
> This comment seems a bit wrong now, altough the comment seem to suggest may
> need to be taken care.
I'll update the comment, it is only relevant to the hardware domain
> > send_global_virq(VIRQ_CONSOLE);
> > @@ -923,7 +946,7 @@ void __init console_endboot(void)
> > * a useful 'how to switch' message.
> > */
> > if ( opt_conswitch[1] == 'x' )
> > - xen_rx = !xen_rx;
> > + xen_rx = 0;
> > register_keyhandler('w', dump_console_ring_key,
> > "synchronously dump console ring buffer (dmesg)",
> > 0);
> > @@ -933,9 +956,6 @@ void __init console_endboot(void)
> > "decrease log level threshold", 0);
> > register_irq_keyhandler('G', &do_toggle_guest,
> > "toggle host/guest log level adjustment", 0);
> > -
> > - /* Serial input is directed to DOM0 by default. */
> > - switch_serial_input();
> > }
> > int __init console_has(const char *device)
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