Re: [PATCH 3.18 129/151] x86/xen: Treat SCI interrupt as normal GSI interrupt

[Stefan Bader <stefan.bader@canonical.com>]

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On 04.03.2015 07:14, Greg Kroah-Hartman wrote:
> 3.18-stable review patch.  If anyone has any objections, please let me know.

I thought I replied earlier today but I cannot seem to find it coming back via
the mailing list. Hope this is not duplicating too much... There was a
regression with that patch and it requires the below commit as well to prevent that:

commit 1ea76fbadd667b19c4fa4466f3a3b55a505e83d9
Author: Jiang Liu <jiang.liu@linux.intel.com>
Date:   Mon Feb 16 10:11:13 2015 +0800

    x86/irq: Fix regression caused by commit b568b8601f05

    Commit b568b8601f05 ("Treat SCI interrupt as normal GSI interrupt")
    accidently removes support of legacy PIC interrupt when fixing a
    regression for Xen, which causes a nasty regression on HP/Compaq
    nc6000 where we fail to register the ACPI interrupt, and thus
    lose eg. thermal notifications leading a potentially overheated
    machine.

-Stefan


> 
> ------------------
> 
> From: Jiang Liu <jiang.liu@linux.intel.com>
> 
> commit b568b8601f05a591a7ff09d8ee1cedb5b2e815fe upstream.
> 
> Currently Xen Domain0 has special treatment for ACPI SCI interrupt,
> that is initialize irq for ACPI SCI at early stage in a special way as:
> xen_init_IRQ()
> 	->pci_xen_initial_domain()
> 		->xen_setup_acpi_sci()
> 			Allocate and initialize irq for ACPI SCI
> 
> Function xen_setup_acpi_sci() calls acpi_gsi_to_irq() to get an irq
> number for ACPI SCI. But unfortunately acpi_gsi_to_irq() depends on
> IOAPIC irqdomains through following path
> acpi_gsi_to_irq()
> 	->mp_map_gsi_to_irq()
> 		->mp_map_pin_to_irq()
> 			->check IOAPIC irqdomain
> 
> For PV domains, it uses Xen event based interrupt manangement and
> doesn't make uses of native IOAPIC, so no irqdomains created for IOAPIC.
> This causes Xen domain0 fail to install interrupt handler for ACPI SCI
> and all ACPI events will be lost. Please refer to:
> https://lkml.org/lkml/2014/12/19/178
> 
> So the fix is to get rid of special treatment for ACPI SCI, just treat
> ACPI SCI as normal GSI interrupt as:
> acpi_gsi_to_irq()
> 	->acpi_register_gsi()
> 		->acpi_register_gsi_xen()
> 			->xen_register_gsi()
> 
> With above change, there's no need for xen_setup_acpi_sci() anymore.
> The above change also works with bare metal kernel too.
> 
> Signed-off-by: Jiang Liu <jiang.liu@linux.intel.com>
> Tested-by: Sander Eikelenboom <linux@eikelenboom.it>
> Cc: Tony Luck <tony.luck@intel.com>
> Cc: xen-devel@lists.xenproject.org
> Cc: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
> Cc: David Vrabel <david.vrabel@citrix.com>
> Cc: Rafael J. Wysocki <rjw@rjwysocki.net>
> Cc: Len Brown <len.brown@intel.com>
> Cc: Pavel Machek <pavel@ucw.cz>
> Cc: Bjorn Helgaas <bhelgaas@google.com>
> Link: http://lkml.kernel.org/r/1421720467-7709-2-git-send-email-jiang.liu@linux.intel.com
> Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
> Signed-off-by: Stefan Bader <stefan.bader@canonical.com>
> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
> 
> ---
>  arch/x86/kernel/acpi/boot.c |   21 ++++++++++---------
>  arch/x86/pci/xen.c          |   47 --------------------------------------------
>  2 files changed, 11 insertions(+), 57 deletions(-)
> 
> --- a/arch/x86/kernel/acpi/boot.c
> +++ b/arch/x86/kernel/acpi/boot.c
> @@ -604,18 +604,19 @@ void __init acpi_pic_sci_set_trigger(uns
>  
>  int acpi_gsi_to_irq(u32 gsi, unsigned int *irqp)
>  {
> -	int irq;
> +	int rc, irq, trigger, polarity;
>  
> -	if (acpi_irq_model == ACPI_IRQ_MODEL_PIC) {
> -		*irqp = gsi;
> -	} else {
> -		irq = mp_map_gsi_to_irq(gsi,
> -					IOAPIC_MAP_ALLOC | IOAPIC_MAP_CHECK);
> -		if (irq < 0)
> -			return -1;
> -		*irqp = irq;
> +	rc = acpi_get_override_irq(gsi, &trigger, &polarity);
> +	if (rc == 0) {
> +		trigger = trigger ? ACPI_LEVEL_SENSITIVE : ACPI_EDGE_SENSITIVE;
> +		polarity = polarity ? ACPI_ACTIVE_LOW : ACPI_ACTIVE_HIGH;
> +		irq = acpi_register_gsi(NULL, gsi, trigger, polarity);
> +		if (irq >= 0) {
> +			*irqp = irq;
> +			return 0;
> +		}
>  	}
> -	return 0;
> +	return -1;
>  }
>  EXPORT_SYMBOL_GPL(acpi_gsi_to_irq);
>  
> --- a/arch/x86/pci/xen.c
> +++ b/arch/x86/pci/xen.c
> @@ -452,52 +452,6 @@ int __init pci_xen_hvm_init(void)
>  }
>  
>  #ifdef CONFIG_XEN_DOM0
> -static __init void xen_setup_acpi_sci(void)
> -{
> -	int rc;
> -	int trigger, polarity;
> -	int gsi = acpi_sci_override_gsi;
> -	int irq = -1;
> -	int gsi_override = -1;
> -
> -	if (!gsi)
> -		return;
> -
> -	rc = acpi_get_override_irq(gsi, &trigger, &polarity);
> -	if (rc) {
> -		printk(KERN_WARNING "xen: acpi_get_override_irq failed for acpi"
> -				" sci, rc=%d\n", rc);
> -		return;
> -	}
> -	trigger = trigger ? ACPI_LEVEL_SENSITIVE : ACPI_EDGE_SENSITIVE;
> -	polarity = polarity ? ACPI_ACTIVE_LOW : ACPI_ACTIVE_HIGH;
> -
> -	printk(KERN_INFO "xen: sci override: global_irq=%d trigger=%d "
> -			"polarity=%d\n", gsi, trigger, polarity);
> -
> -	/* Before we bind the GSI to a Linux IRQ, check whether
> -	 * we need to override it with bus_irq (IRQ) value. Usually for
> -	 * IRQs below IRQ_LEGACY_IRQ this holds IRQ == GSI, as so:
> -	 *  ACPI: INT_SRC_OVR (bus 0 bus_irq 9 global_irq 9 low level)
> -	 * but there are oddballs where the IRQ != GSI:
> -	 *  ACPI: INT_SRC_OVR (bus 0 bus_irq 9 global_irq 20 low level)
> -	 * which ends up being: gsi_to_irq[9] == 20
> -	 * (which is what acpi_gsi_to_irq ends up calling when starting the
> -	 * the ACPI interpreter and keels over since IRQ 9 has not been
> -	 * setup as we had setup IRQ 20 for it).
> -	 */
> -	if (acpi_gsi_to_irq(gsi, &irq) == 0) {
> -		/* Use the provided value if it's valid. */
> -		if (irq >= 0)
> -			gsi_override = irq;
> -	}
> -
> -	gsi = xen_register_gsi(gsi, gsi_override, trigger, polarity);
> -	printk(KERN_INFO "xen: acpi sci %d\n", gsi);
> -
> -	return;
> -}
> -
>  int __init pci_xen_initial_domain(void)
>  {
>  	int irq;
> @@ -509,7 +463,6 @@ int __init pci_xen_initial_domain(void)
>  	x86_msi.msi_mask_irq = xen_nop_msi_mask_irq;
>  	x86_msi.msix_mask_irq = xen_nop_msix_mask_irq;
>  #endif
> -	xen_setup_acpi_sci();
>  	__acpi_register_gsi = acpi_register_gsi_xen;
>  	/* Pre-allocate legacy irqs */
>  	for (irq = 0; irq < nr_legacy_irqs(); irq++) {
> 
> 



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