Re: [PATCH 1/2] hvc_xen: support PV on HVM consoles

[Jeremy Fitzhardinge <jeremy@goop.org>]

  On 08/09/2010 08:10 AM, stefano.stabellini@eu.citrix.com wrote:
> From: Stefano Stabellini<stefano.stabellini@eu.citrix.com>

How does this work?  Should "console=hvc0" just work, along with "xl 
create -c"?

Does it work with earlyprintk=xen?

     J

> Signed-off-by: Stefano Stabellini<stefano.stabellini@eu.citrix.com>
> ---
>   drivers/char/hvc_xen.c             |   63 ++++++++++++++++++++++++++++++-----
>   include/xen/interface/hvm/params.h |    6 +++-
>   2 files changed, 59 insertions(+), 10 deletions(-)
>
> diff --git a/drivers/char/hvc_xen.c b/drivers/char/hvc_xen.c
> index 60446f8..454a9cd 100644
> --- a/drivers/char/hvc_xen.c
> +++ b/drivers/char/hvc_xen.c
> @@ -24,9 +24,12 @@
>   #include<linux/init.h>
>   #include<linux/types.h>
>
> +#include<asm/io.h>
>   #include<asm/xen/hypervisor.h>
>
>   #include<xen/xen.h>
> +#include<xen/interface/xen.h>
> +#include<xen/hvm.h>
>   #include<xen/page.h>
>   #include<xen/events.h>
>   #include<xen/interface/io/console.h>
> @@ -42,9 +45,13 @@ static int xencons_irq;
>   /* ------------------------------------------------------------------ */
>
>   static unsigned long console_pfn = ~0ul;
> +static unsigned int console_evtchn = xen_start_info->console.domU.evtchn;
> +static struct xencons_interface *xencons_if = NULL;
>
>   static inline struct xencons_interface *xencons_interface(void)
>   {
> +	if (xencons_if != NULL)
> +		return xencons_if;
>   	if (console_pfn == ~0ul)
>   		return mfn_to_virt(xen_start_info->console.domU.mfn);
>   	else
> @@ -54,7 +61,7 @@ static inline struct xencons_interface *xencons_interface(void)
>   static inline void notify_daemon(void)
>   {
>   	/* Use evtchn: this is called early, before irq is set up. */
> -	notify_remote_via_evtchn(xen_start_info->console.domU.evtchn);
> +	notify_remote_via_evtchn(console_evtchn);
>   }
>
>   static int __write_console(const char *data, int len)
> @@ -130,16 +137,53 @@ static const struct hv_ops hvc_ops = {
>   	.notifier_hangup = notifier_hangup_irq,
>   };
>
> +static int xen_hvm_console_init(void)
> +{
> +	int r;
> +	uint64_t v = 0;
> +	unsigned long mfn;
> +
> +	if (!xen_hvm_domain())
> +		return -ENODEV;
> +
> +	if (xencons_if != NULL)
> +		return -EBUSY;
> +
> +	r = hvm_get_parameter(HVM_PARAM_CONSOLE_EVTCHN,&v);
> +	if (r<  0)
> +		return -ENODEV;
> +	console_evtchn = v;
> +	hvm_get_parameter(HVM_PARAM_CONSOLE_PFN,&v);
> +	if (r<  0)
> +		return -ENODEV;
> +	mfn = v;
> +	xencons_if = ioremap(mfn<<  PAGE_SHIFT, PAGE_SIZE);
> +	if (xencons_if == NULL)
> +		return -ENODEV;
> +
> +	return 0;
> +}
> +
>   static int __init xen_init(void)
>   {
>   	struct hvc_struct *hp;
> +	int r;
> +
> +	if (!xen_domain() || xen_initial_domain())
> +		return -ENODEV;
>
> -	if (!xen_pv_domain() ||
> -	    xen_initial_domain() ||
> -	    !xen_start_info->console.domU.evtchn)
> +	if (xen_pv_domain()&&  !xen_start_info->console.domU.evtchn)
>   		return -ENODEV;
>
> -	xencons_irq = bind_evtchn_to_irq(xen_start_info->console.domU.evtchn);
> +	if (xen_pv_domain())
> +		console_pfn = mfn_to_pfn(xen_start_info->console.domU.mfn);
> +	else {
> +		r = xen_hvm_console_init();
> +		if (r<  0)
> +			return r;
> +	}
> +
> +	xencons_irq = bind_evtchn_to_irq(console_evtchn);
>   	if (xencons_irq<  0)
>   		xencons_irq = 0; /* NO_IRQ */
>
> @@ -149,15 +193,13 @@ static int __init xen_init(void)
>
>   	hvc = hp;
>
> -	console_pfn = mfn_to_pfn(xen_start_info->console.domU.mfn);
> -
>   	return 0;
>   }
>
>   void xen_console_resume(void)
>   {
>   	if (xencons_irq)
> -		rebind_evtchn_irq(xen_start_info->console.domU.evtchn, xencons_irq);
> +		rebind_evtchn_irq(console_evtchn, xencons_irq);
>   }
>
>   static void __exit xen_fini(void)
> @@ -168,9 +210,12 @@ static void __exit xen_fini(void)
>
>   static int xen_cons_init(void)
>   {
> -	if (!xen_pv_domain())
> +	if (!xen_domain())
>   		return 0;
>
> +	if (xen_hvm_domain())
> +		xen_hvm_console_init();
> +
>   	hvc_instantiate(HVC_COOKIE, 0,&hvc_ops);
>   	return 0;
>   }
> diff --git a/include/xen/interface/hvm/params.h b/include/xen/interface/hvm/params.h
> index 1888d8c..1b4f923 100644
> --- a/include/xen/interface/hvm/params.h
> +++ b/include/xen/interface/hvm/params.h
> @@ -90,6 +90,10 @@
>   /* Boolean: Enable aligning all periodic vpts to reduce interrupts */
>   #define HVM_PARAM_VPT_ALIGN    16
>
> -#define HVM_NR_PARAMS          17
> +/* Console debug shared memory ring and event channel */
> +#define HVM_PARAM_CONSOLE_PFN    17
> +#define HVM_PARAM_CONSOLE_EVTCHN 18
> +
> +#define HVM_NR_PARAMS          19
>
>   #endif /* __XEN_PUBLIC_HVM_PARAMS_H__ */