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Re: [PATCH v10 3/5] xen/console: add locking for serial_rx ring buffer access
- To: Stefano Stabellini <stefano.stabellini@xxxxxxx>
- From: dmukhin@xxxxxxxx
- Date: Fri, 6 Feb 2026 14:24:16 -0800
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- Delivery-date: Fri, 06 Feb 2026 22:24:56 +0000
- List-id: Xen developer discussion <xen-devel.lists.xenproject.org>
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On Wed, Feb 04, 2026 at 03:37:10PM -0800, Stefano Stabellini wrote:
> Guard every mutation of serial_rx_cons/prod with console_lock so that
> cross-domain reads can't see stale data:
>
> - In console_switch_input(): protect console_rx assignment with the lock
> using irqsave/irqrestore variants since this can be called from
> interrupt context
>
> - In __serial_rx(): protect the ring buffer write operation when
> delivering input to the hardware domain
>
> - In do_console_io() CONSOLEIO_read: hold the lock around the entire
> read loop, using a local buffer copy to avoid holding the lock during
> copy_to_guest_offset()
>
> This is preparatory work for allowing multiple domains to use the
> console_io hypercalls where proper synchronization is required.
>
> Signed-off-by: Stefano Stabellini <stefano.stabellini@xxxxxxx>
Reviewed-by: Denis Mukhin <dmukhin@xxxxxxxx>
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