Subject: Re: [Xen-devel] [RFC PATCH 01/20] x86/xen/MSI: Eliminate arch_msix_mask_irq() and arch_msi_mask_irq()

From: Yijing Wang <[email-masked]>
Date: Tue, 12 Aug 2014 19:11:53 +0800

On 2014/8/12 17:09, David Vrabel wrote:
> On 12/08/14 08:25, Yijing Wang wrote:
>> Commit 0e4ccb150 added two __weak arch functions arch_msix_mask_irq()
>> and arch_msi_mask_irq() to fix a bug found when running xen in x86.
>> Introduced these two funcntions make MSI code complex. This patch
>> reverted commit 0e4ccb150 and add #ifdef for x86 msi_chip to fix this
>> bug for simplicity. Also this is preparation for using struct
>> msi_chip instead of weak arch MSI functions in all platforms.
> [...]
>>  static struct irq_chip msi_chip = {
>>  	.name			= "PCI-MSI",
>> +#ifdef CONFIG_XEN
>> +	.irq_unmask		= nop_unmask_msi_irq,
>> +	.irq_mask		= nop_mask_msi_irq,
>> +#else
>>  	.irq_unmask		= unmask_msi_irq,
>>  	.irq_mask		= mask_msi_irq,
>> +#endif
> 
> No.  CONFIG_XEN kernels can run on Xen and bare metal so this must be a
> runtime option.

Hi David, that's my mistake, what about export struct irq_chip msi_chip, then
change the msi_chip->irq_mask/irq_unmask() in xen init functions.

Eg.

diff --git a/arch/x86/include/asm/apic.h b/arch/x86/include/asm/apic.h
index 19b0eba..bb6af00 100644
--- a/arch/x86/include/asm/apic.h
+++ b/arch/x86/include/asm/apic.h
@@ -43,6 +43,10 @@ static inline void generic_apic_probe(void)
 }
 #endif

+#ifdef CONFIG_PCI_MSI
+extern struct irq_chip msi_chip;
+#endif
+
 #ifdef CONFIG_X86_LOCAL_APIC
[...]
+
+#ifdef CONFIG_PCI_MSI
+void xen_nop_msi_mask(struct irq_data *data)
 {
-       return 0;
 }
 #endif

@@ -424,8 +423,8 @@ int __init pci_xen_init(void)
        x86_msi.setup_msi_irqs = xen_setup_msi_irqs;
        x86_msi.teardown_msi_irq = xen_teardown_msi_irq;
        x86_msi.teardown_msi_irqs = xen_teardown_msi_irqs;
-       x86_msi.msi_mask_irq = xen_nop_msi_mask_irq;
-       x86_msi.msix_mask_irq = xen_nop_msix_mask_irq;
+       msi_chip.irq_mask = xen_nop_msi_mask;
+       msi_chip.irq_unmask = xen_nop_msi_mask;
 #endif
        return 0;
 }
@@ -505,8 +504,8 @@ int __init pci_xen_initial_domain(void)
        x86_msi.setup_msi_irqs = xen_initdom_setup_msi_irqs;
        x86_msi.teardown_msi_irq = xen_teardown_msi_irq;
        x86_msi.restore_msi_irqs = xen_initdom_restore_msi_irqs;
-       x86_msi.msi_mask_irq = xen_nop_msi_mask_irq;
-       x86_msi.msix_mask_irq = xen_nop_msix_mask_irq;
+       msi_chip.irq_mask = xen_nop_msi_mask;
+       msi_chip.irq_unmask = xen_nop_msi_mask;
 #endif
        xen_setup_acpi_sci();

> David
> .

-- 
Thanks!
Yijing