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

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Date:	Fri, 26 Feb 2016 11:09:36 -0500
From:	Boris Ostrovsky <boris.ostrovsky@...cle.com>
To:	Stefano Stabellini <stefano.stabellini@...citrix.com>
Cc:	xen-devel@...ts.xensource.com, linux-kernel@...r.kernel.org,
	david.vrabel@...rix.com, konrad.wilk@...cle.com
Subject: Re: [PATCH v2 2/3] hvc_xen: fix xenboot for DomUs

On 02/26/2016 10:39 AM, Stefano Stabellini wrote:
> 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@...citrix.com>
>>>
>>> ---
>>> 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?

Sure, that sounds good.

(BTW, I didn't mean that my R-b was conditional on this)


-boris

>
>
>> Other than that:
>> Reviewed-by: Boris Ostrovsky <boris.ostrovsky@...cle.com>
> 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,
>>>    };