Enable dom0less guests on ARM to use console_io hypercalls:
- set input_allow = true for dom0less domains
- update the in-code comment in console.c
- prioritize the VUART check to retain the same behavior as today
Signed-off-by: Stefano Stabellini <stefano.stabellini@amd.com>
---
Changes in v8:
- move in-code comment update to previous patch
- add in-code comment about is_focus_domain() check
---
xen/common/device-tree/dom0less-build.c | 2 ++
xen/drivers/char/console.c | 16 ++++++++++------
2 files changed, 12 insertions(+), 6 deletions(-)
diff --git a/xen/common/device-tree/dom0less-build.c b/xen/common/device-tree/dom0less-build.c
index 840d14419d..cb7026fa7e 100644
--- a/xen/common/device-tree/dom0less-build.c
+++ b/xen/common/device-tree/dom0less-build.c
@@ -829,6 +829,8 @@ static int __init construct_domU(struct kernel_info *kinfo,
rangeset_destroy(kinfo->xen_reg_assigned);
+ d->console->input_allowed = true;
+
return rc;
}
diff --git a/xen/drivers/char/console.c b/xen/drivers/char/console.c
index ed8f1ad8f2..418d194cef 100644
--- a/xen/drivers/char/console.c
+++ b/xen/drivers/char/console.c
@@ -613,11 +613,20 @@ static void __serial_rx(char c)
if ( console_rx == 0 )
return handle_keypress(c, false);
+ /* Includes an is_focus_domain() check. */
d = console_get_domain();
if ( !d )
return;
- if ( is_hardware_domain(d) )
+#ifdef CONFIG_SBSA_VUART_CONSOLE
+ /* Prioritize vpl011 if enabled for this domain */
+ if ( d->arch.vpl011.base_addr )
+ {
+ /* Deliver input to the emulated UART. */
+ rc = vpl011_rx_char_xen(d, c);
+ }
+ else
+#endif
{
unsigned long flags;
@@ -636,11 +645,6 @@ static void __serial_rx(char c)
*/
send_global_virq(VIRQ_CONSOLE);
}
-#ifdef CONFIG_SBSA_VUART_CONSOLE
- else
- /* Deliver input to the emulated UART. */
- rc = vpl011_rx_char_xen(d, c);
-#endif
if ( consoled_is_enabled() )
/* Deliver input to the PV shim console. */
--
2.25.1On 2026-01-29 17:08, Stefano Stabellini wrote:
> Enable dom0less guests on ARM to use console_io hypercalls:
> - set input_allow = true for dom0less domains
> - update the in-code comment in console.c
> - prioritize the VUART check to retain the same behavior as today
>
> Signed-off-by: Stefano Stabellini <stefano.stabellini@amd.com>
> ---
> Changes in v8:
> - move in-code comment update to previous patch
> - add in-code comment about is_focus_domain() check
> ---
> xen/common/device-tree/dom0less-build.c | 2 ++
> xen/drivers/char/console.c | 16 ++++++++++------
> 2 files changed, 12 insertions(+), 6 deletions(-)
>
> diff --git a/xen/common/device-tree/dom0less-build.c b/xen/common/device-tree/dom0less-build.c
> index 840d14419d..cb7026fa7e 100644
> --- a/xen/common/device-tree/dom0less-build.c
> +++ b/xen/common/device-tree/dom0less-build.c
> @@ -829,6 +829,8 @@ static int __init construct_domU(struct kernel_info *kinfo,
>
> rangeset_destroy(kinfo->xen_reg_assigned);
>
> + d->console->input_allowed = true;
> +
> return rc;
> }
>
> diff --git a/xen/drivers/char/console.c b/xen/drivers/char/console.c
> index ed8f1ad8f2..418d194cef 100644
> --- a/xen/drivers/char/console.c
> +++ b/xen/drivers/char/console.c
> @@ -613,11 +613,20 @@ static void __serial_rx(char c)
> if ( console_rx == 0 )
> return handle_keypress(c, false);
>
> + /* Includes an is_focus_domain() check. */
> d = console_get_domain();
> if ( !d )
> return;
>
> - if ( is_hardware_domain(d) )
> +#ifdef CONFIG_SBSA_VUART_CONSOLE
> + /* Prioritize vpl011 if enabled for this domain */
> + if ( d->arch.vpl011.base_addr )
> + {
> + /* Deliver input to the emulated UART. */
> + rc = vpl011_rx_char_xen(d, c);
> + }
> + else
> +#endif
> {
> unsigned long flags;
>
> @@ -636,11 +645,6 @@ static void __serial_rx(char c)
> */
> send_global_virq(VIRQ_CONSOLE);
I think we need an additional patch, or included in one of these two, to
change VIRQ_CONSOLE to a VIRQ_DOMAIN. Otherwise only hwdom could bind
to the virq, I think? It would be the two changes below:
Regards,
Jason
diff --git a/xen/common/event_channel.c b/xen/common/event_channel.c
index 67700b050a..dab123f20d 100644
--- a/xen/common/event_channel.c
+++ b/xen/common/event_channel.c
@@ -138,6 +138,7 @@ static enum virq_type get_virq_type(unsigned int virq)
return VIRQ_VCPU;
case VIRQ_ARGO:
+ case VIRQ_CONSOLE:
return VIRQ_DOMAIN;
case VIRQ_ARCH_0 ... VIRQ_ARCH_7:
diff --git a/xen/drivers/char/console.c b/xen/drivers/char/console.c
index 903ad912cc..138eeaa14d 100644
--- a/xen/drivers/char/console.c
+++ b/xen/drivers/char/console.c
@@ -611,7 +611,7 @@ static void __serial_rx(char c)
* Always notify the hardware domain: prevents receive path from
* getting stuck.
*/
- send_global_virq(VIRQ_CONSOLE);
+ send_guest_domain_virq(d, VIRQ_CONSOLE);
}
#ifdef CONFIG_SBSA_VUART_CONSOLE
else
On Thu, 29 Jan 2026, Jason Andryuk wrote:
> On 2026-01-29 17:08, Stefano Stabellini wrote:
> > Enable dom0less guests on ARM to use console_io hypercalls:
> > - set input_allow = true for dom0less domains
> > - update the in-code comment in console.c
> > - prioritize the VUART check to retain the same behavior as today
> >
> > Signed-off-by: Stefano Stabellini <stefano.stabellini@amd.com>
> > ---
> > Changes in v8:
> > - move in-code comment update to previous patch
> > - add in-code comment about is_focus_domain() check
> > ---
> > xen/common/device-tree/dom0less-build.c | 2 ++
> > xen/drivers/char/console.c | 16 ++++++++++------
> > 2 files changed, 12 insertions(+), 6 deletions(-)
> >
> > diff --git a/xen/common/device-tree/dom0less-build.c
> > b/xen/common/device-tree/dom0less-build.c
> > index 840d14419d..cb7026fa7e 100644
> > --- a/xen/common/device-tree/dom0less-build.c
> > +++ b/xen/common/device-tree/dom0less-build.c
> > @@ -829,6 +829,8 @@ static int __init construct_domU(struct kernel_info
> > *kinfo,
> > rangeset_destroy(kinfo->xen_reg_assigned);
> > + d->console->input_allowed = true;
> > +
> > return rc;
> > }
> > diff --git a/xen/drivers/char/console.c b/xen/drivers/char/console.c
> > index ed8f1ad8f2..418d194cef 100644
> > --- a/xen/drivers/char/console.c
> > +++ b/xen/drivers/char/console.c
> > @@ -613,11 +613,20 @@ static void __serial_rx(char c)
> > if ( console_rx == 0 )
> > return handle_keypress(c, false);
> > + /* Includes an is_focus_domain() check. */
> > d = console_get_domain();
> > if ( !d )
> > return;
> > - if ( is_hardware_domain(d) )
> > +#ifdef CONFIG_SBSA_VUART_CONSOLE
> > + /* Prioritize vpl011 if enabled for this domain */
> > + if ( d->arch.vpl011.base_addr )
> > + {
> > + /* Deliver input to the emulated UART. */
> > + rc = vpl011_rx_char_xen(d, c);
> > + }
> > + else
> > +#endif
> > {
> > unsigned long flags;
> > @@ -636,11 +645,6 @@ static void __serial_rx(char c)
> > */
> > send_global_virq(VIRQ_CONSOLE);
>
> I think we need an additional patch, or included in one of these two, to
> change VIRQ_CONSOLE to a VIRQ_DOMAIN. Otherwise only hwdom could bind to the
> virq, I think? It would be the two changes below:
Thank you Jason. I didn't notice this problem because Linux is able to
silently fallback to polling which works surprisingly well. I didn't
notice the difference.
I confirm that the error you highlighted is real and that with the patch
below the error goes away.
My preference is to submit it as a separate patch, it can still be part
of this series. Especially as the other two patches have already been
reviewed and tested independently a few times. But I am happy either
way.
Jan, what do you think?
> diff --git a/xen/common/event_channel.c b/xen/common/event_channel.c
> index 67700b050a..dab123f20d 100644
> --- a/xen/common/event_channel.c
> +++ b/xen/common/event_channel.c
> @@ -138,6 +138,7 @@ static enum virq_type get_virq_type(unsigned int virq)
> return VIRQ_VCPU;
>
> case VIRQ_ARGO:
> + case VIRQ_CONSOLE:
> return VIRQ_DOMAIN;
>
> case VIRQ_ARCH_0 ... VIRQ_ARCH_7:
> diff --git a/xen/drivers/char/console.c b/xen/drivers/char/console.c
> index 903ad912cc..138eeaa14d 100644
> --- a/xen/drivers/char/console.c
> +++ b/xen/drivers/char/console.c
> @@ -611,7 +611,7 @@ static void __serial_rx(char c)
> * Always notify the hardware domain: prevents receive path from
> * getting stuck.
> */
> - send_global_virq(VIRQ_CONSOLE);
> + send_guest_domain_virq(d, VIRQ_CONSOLE);
> }
> #ifdef CONFIG_SBSA_VUART_CONSOLE
> else
>
On 03.02.2026 01:11, Stefano Stabellini wrote:
> On Thu, 29 Jan 2026, Jason Andryuk wrote:
>> On 2026-01-29 17:08, Stefano Stabellini wrote:
>>> --- a/xen/drivers/char/console.c
>>> +++ b/xen/drivers/char/console.c
>>> @@ -613,11 +613,20 @@ static void __serial_rx(char c)
>>> if ( console_rx == 0 )
>>> return handle_keypress(c, false);
>>> + /* Includes an is_focus_domain() check. */
>>> d = console_get_domain();
>>> if ( !d )
>>> return;
>>> - if ( is_hardware_domain(d) )
>>> +#ifdef CONFIG_SBSA_VUART_CONSOLE
>>> + /* Prioritize vpl011 if enabled for this domain */
>>> + if ( d->arch.vpl011.base_addr )
>>> + {
>>> + /* Deliver input to the emulated UART. */
>>> + rc = vpl011_rx_char_xen(d, c);
>>> + }
>>> + else
>>> +#endif
>>> {
>>> unsigned long flags;
>>> @@ -636,11 +645,6 @@ static void __serial_rx(char c)
>>> */
>>> send_global_virq(VIRQ_CONSOLE);
>>
>> I think we need an additional patch, or included in one of these two, to
>> change VIRQ_CONSOLE to a VIRQ_DOMAIN. Otherwise only hwdom could bind to the
>> virq, I think? It would be the two changes below:
>
> Thank you Jason. I didn't notice this problem because Linux is able to
> silently fallback to polling which works surprisingly well. I didn't
> notice the difference.
>
> I confirm that the error you highlighted is real and that with the patch
> below the error goes away.
>
> My preference is to submit it as a separate patch, it can still be part
> of this series. Especially as the other two patches have already been
> reviewed and tested independently a few times. But I am happy either
> way.
>
> Jan, what do you think?
Imo this wants to be a separate change, yes. Likely a prereq one.
Jan
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