Re: [PATCH v3 02/10] xen: remap GSIs as pirqs when running as initial domain

[Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>]

On Tue, Oct 12, 2010 at 05:42:42PM +0100, Stefano Stabellini wrote:
> From: Jeremy Fitzhardinge <jeremy.fitzhardinge@citrix.com>
> 
> Implement xen_register_gsi to setup the correct triggering and polarity
> properties of a gsi.
> Implement xen_register_pirq to register a particular gsi as pirq and
> receive interrupts as events.
> Call xen_setup_pirqs to register all the legacy ISA irqs as pirqs.
> 
> Signed-off-by: Jeremy Fitzhardinge <jeremy.fitzhardinge@citrix.com>
> Signed-off-by: Stefano Stabellini <stefano.stabellini@eu.citrix.com>
> ---
>  arch/x86/include/asm/xen/pci.h  |    7 ++
>  arch/x86/pci/xen.c              |  132 +++++++++++++++++++++++++++++++++++++++
>  drivers/xen/events.c            |   13 ++++
>  include/xen/interface/physdev.h |   10 +++
>  4 files changed, 162 insertions(+), 0 deletions(-)
> 
> diff --git a/arch/x86/include/asm/xen/pci.h b/arch/x86/include/asm/xen/pci.h
> index f89a42a..2329b3e 100644
> --- a/arch/x86/include/asm/xen/pci.h
> +++ b/arch/x86/include/asm/xen/pci.h
> @@ -13,6 +13,13 @@ static inline int pci_xen_hvm_init(void)
>  	return -1;
>  }
>  #endif
> +#if defined(CONFIG_XEN_DOM0)
> +void __init xen_setup_pirqs(void);
> +#else
> +static inline void __init xen_setup_pirqs(void)
> +{
> +}
> +#endif
>  
>  #if defined(CONFIG_PCI_MSI)
>  #if defined(CONFIG_PCI_XEN)
> diff --git a/arch/x86/pci/xen.c b/arch/x86/pci/xen.c
> index fb20d05..5d87774 100644
> --- a/arch/x86/pci/xen.c
> +++ b/arch/x86/pci/xen.c
> @@ -262,3 +262,135 @@ int __init pci_xen_hvm_init(void)
>  #endif
>  	return 0;
>  }
> +
> +#ifdef CONFIG_XEN_DOM0
> +static int xen_register_pirq(u32 gsi, int triggering)
> +{
> +	int rc, irq;
> +	struct physdev_map_pirq map_irq;
> +	int shareable = 0;
> +	char *name;
> +
> +	if (!xen_pv_domain())
> +		return -1;
> +
> +	if (triggering == ACPI_EDGE_SENSITIVE) {
> +		shareable = 0;
> +		name = "ioapic-edge";
> +	} else {
> +		shareable = 1;
> +		name = "ioapic-level";
> +	}
> +
> +	irq = xen_allocate_pirq(gsi, shareable, name);
> +
> +	printk(KERN_DEBUG "xen: --> irq=%d\n", irq);
> +
> +	if (irq < 0)
> +		goto out;
> +
> +	map_irq.domid = DOMID_SELF;
> +	map_irq.type = MAP_PIRQ_TYPE_GSI;
> +	map_irq.index = gsi;
> +	map_irq.pirq = irq;
> +
> +	rc = HYPERVISOR_physdev_op(PHYSDEVOP_map_pirq, &map_irq);
> +	if (rc) {
> +		printk(KERN_WARNING "xen map irq failed %d\n", rc);
> +		return -1;
> +	}
> +
> +out:
> +	return irq;
> +}
> +
> +static int xen_register_gsi(u32 gsi, int triggering, int polarity)
> +{
> +	int rc, irq;
> +	struct physdev_setup_gsi setup_gsi;
> +
> +	if (!xen_pv_domain())
> +		return -1;
> +
> +	printk(KERN_DEBUG "xen: registering gsi %u triggering %d polarity %d\n",
> +			gsi, triggering, polarity);
> +
> +	irq = xen_register_pirq(gsi, triggering);
> +
> +	setup_gsi.gsi = gsi;
> +	setup_gsi.triggering = (triggering == ACPI_EDGE_SENSITIVE ? 0 : 1);
> +	setup_gsi.polarity = (polarity == ACPI_ACTIVE_HIGH ? 0 : 1);
> +
> +	rc = HYPERVISOR_physdev_op(PHYSDEVOP_setup_gsi, &setup_gsi);
> +	if (rc == -EEXIST)
> +		printk(KERN_INFO "Already setup the GSI :%d\n", gsi);
> +	else if (rc) {
> +		printk(KERN_ERR "Failed to setup GSI :%d, err_code:%d\n",
> +				gsi, rc);
> +	}
> +
> +	return irq;
> +}
> +
> +static __init void xen_setup_acpi_sci(void)
> +{
> +	int rc;
> +	int trigger, polarity;
> +	int gsi = acpi_sci_override_gsi;
> +
> +	if (!gsi)
> +		return;

Should this be 'if (gsi >= 0)' ? I haven't seen any machine
with the GSI at IRQ 0, but perhaps it would be possible?

> +
> +	rc = acpi_get_override_irq(gsi, &trigger, &polarity);
> +	if (rc)
> +		return;

We don't want to report the error? Say a printk?

> +	trigger = trigger ? ACPI_LEVEL_SENSITIVE : ACPI_EDGE_SENSITIVE;
> +	polarity = polarity ? ACPI_ACTIVE_LOW : ACPI_ACTIVE_HIGH;
> +	
> +	printk("xen: sci override: global_irq=%d trigger=%d polarity=%d\n",
> +			gsi, trigger, polarity);
> +
> +	gsi = xen_register_gsi(gsi, trigger, polarity);
> +	printk("xen: acpi sci %d\n", gsi);

KERN_INFO ?
> +
> +	return;
> +}
> +
> +static int acpi_register_gsi_xen(struct device *dev, u32 gsi,
> +				 int trigger, int polarity)
> +{
> +	return xen_register_gsi(gsi, trigger, polarity);
> +}
> +
> +static int __init pci_xen_initial_domain(void)
> +{
> +	xen_setup_acpi_sci();
> +	__acpi_register_gsi = acpi_register_gsi_xen;
> +
> +	return 0;
> +}
> +
> +void __init xen_setup_pirqs(void)
> +{
> +	int irq;
> +
> +	pci_xen_initial_domain();
> +
> +	if (0 == nr_ioapics) {

This function is only called for the Dom0 case, so under
what conditions would we have a machine with zero IO APICs?

And do we actually support machines with no IO APICs?
(would Xen run under such ancient hardware?)

> +		for (irq = 0; irq < NR_IRQS_LEGACY; irq++)
> +			xen_allocate_pirq(irq, 0, "xt-pic");
> +		return;
> +	}
> +