On Wednesday, October 16, 2013 3:33 PM, Zhenzhong Duan wrote: > > Driver init call graph under baremetal: > driver_init-> > msix_capability_init-> > msix_program_entries-> > msix_mask_irq-> > entry->masked = 1 > request_irq-> > __setup_irq-> > irq_startup-> > unmask_msi_irq-> > msix_mask_irq-> > entry->masked = 0; > > So entry->masked is always updated with newest value and its value could be used > to restore to mask register in device. > > But in initial domain (aka priviliged guest), it's different. > Driver init call graph under initial domain: > driver_init-> > msix_capability_init-> > msix_program_entries-> > msix_mask_irq-> > entry->masked = 1 > request_irq-> > __setup_irq-> > irq_startup-> > __startup_pirq-> > EVTCHNOP_bind_pirq hypercall (trap into Xen) > [Xen:] > pirq_guest_bind-> > startup_msi_irq-> > unmask_msi_irq-> > msi_set_mask_bit-> > entry->msi_attrib.masked = 0; > > So entry->msi_attrib.masked in xen side always has newest value. entry->masked > in initial domain is untouched and is 1 after msix_capability_init. > > Based on above, it's Xen's duty to restore entry->msi_attrib.masked to device, > but with current code, entry->masked is used and MSI-x interrupt is masked. > > Before patch, restore call graph under initial domain: > pci_reset_function-> > pci_restore_state-> > __pci_restore_msix_state-> > arch_restore_msi_irqs-> > xen_initdom_restore_msi_irqs-> > PHYSDEVOP_restore_msi hypercall (first mask restore) > msix_mask_irq(entry, entry->masked) (second mask restore) > > So msix_mask_irq call in initial domain call graph needs to be removed. > > Based on this we can move the restore of the mask in default_restore_msi_irqs > which would avoid restoring the invalid mask under Xen. Furthermore this > simplifies the API by making everything related to restoring an MSI be in the > platform specific APIs instead of just parts of it. > > After patch, restore call graph under initial domain: > pci_reset_function-> > pci_restore_state-> > __pci_restore_msix_state-> > arch_restore_msi_irqs-> > xen_initdom_restore_msi_irqs-> > PHYSDEVOP_restore_msi hypercall (first mask restore) > > Logic for baremetal is not changed. > Before patch, restore call graph under baremetal: > pci_reset_function-> > pci_restore_state-> > __pci_restore_msix_state-> > arch_restore_msi_irqs-> > default_restore_msi_irqs-> > msix_mask_irq(entry, entry->masked) (first mask restore) > > After patch, restore call graph under baremetal: > pci_reset_function-> > pci_restore_state-> > __pci_restore_msix_state-> > arch_restore_msi_irqs-> > default_restore_msi_irqs-> > msix_mask_irq(entry, entry->masked) (first mask restore) > > The process for MSI code is similiar. > > Tested-by: Sucheta Chakraborty <sucheta.chakraborty@xxxxxxxxxx> > Signed-off-by: Zhenzhong Duan <zhenzhong.duan@xxxxxxxxxx> > Acked-by: Konrad Rzeszutek Wilk <konrad.wilk@xxxxxxxxxx> Reviewed-by: Jingoo Han <jg1.han@xxxxxxxxxxx> It looks good. Also, I tested this patch on Exynos5440. Best regards, Jingoo Han -- To unsubscribe from this list: send the line "unsubscribe linux-pci" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
