[+MarcZ - this patch needs IRQ maintainers vetting] On Tue, Sep 08, 2020 at 04:17:59PM -0700, Dexuan Cui wrote: > Hyper-V doesn't trap and emulate the accesses to the MSI/MSI-X registers, > and we must use hv_compose_msi_msg() to ask Hyper-V to create the IOMMU > Interrupt Remapping Table Entries. This is not an issue for a lot of > PCI device drivers (e.g. NVMe driver, Mellanox NIC drivers), which > destroy and re-create the interrupts across hibernation, so > hv_compose_msi_msg() is called automatically. However, some other PCI > device drivers (e.g. the Nvidia driver) may not destroy and re-create > the interrupts across hibernation, so hv_pci_resume() has to call > hv_compose_msi_msg(), otherwise the PCI device drivers can no longer > receive MSI/MSI-X interrupts after hibernation. This looks like drivers bugs and I don't think the HV controller driver is where you should fix them. Regardless, this commit log does not provide the information that it should. > Fixes: ac82fc832708 ("PCI: hv: Add hibernation support") > Signed-off-by: Dexuan Cui <decui@xxxxxxxxxxxxx> > Reviewed-by: Jake Oshins <jakeo@xxxxxxxxxxxxx> > > --- > > Changes in v2: > Fixed a typo in the comment in hv_irq_unmask. Thanks to Michael! > Added Jake's Reviewed-by. > > drivers/pci/controller/pci-hyperv.c | 44 +++++++++++++++++++++++++++++ > 1 file changed, 44 insertions(+) > > diff --git a/drivers/pci/controller/pci-hyperv.c b/drivers/pci/controller/pci-hyperv.c > index fc4c3a15e570..dd21afb5d62b 100644 > --- a/drivers/pci/controller/pci-hyperv.c > +++ b/drivers/pci/controller/pci-hyperv.c > @@ -1211,6 +1211,21 @@ static void hv_irq_unmask(struct irq_data *data) > pbus = pdev->bus; > hbus = container_of(pbus->sysdata, struct hv_pcibus_device, sysdata); > > + if (hbus->state == hv_pcibus_removing) { > + /* > + * During hibernation, when a CPU is offlined, the kernel tries > + * to move the interrupt to the remaining CPUs that haven't > + * been offlined yet. In this case, the below hv_do_hypercall() > + * always fails since the vmbus channel has been closed, so we > + * should not call the hypercall, but we still need > + * pci_msi_unmask_irq() to reset the mask bit in desc->masked: > + * see cpu_disable_common() -> fixup_irqs() -> > + * irq_migrate_all_off_this_cpu() -> migrate_one_irq(). > + */ > + pci_msi_unmask_irq(data); This is not appropriate - it looks like a plaster to paper over an issue with hyper-V hibernation code sequence. Fix that issue instead of papering over it here. Thanks, Lorenzo > + return; > + } > + > spin_lock_irqsave(&hbus->retarget_msi_interrupt_lock, flags); > > params = &hbus->retarget_msi_interrupt_params; > @@ -3372,6 +3387,33 @@ static int hv_pci_suspend(struct hv_device *hdev) > return 0; > } > > +static int hv_pci_restore_msi_msg(struct pci_dev *pdev, void *arg) > +{ > + struct msi_desc *entry; > + struct irq_data *irq_data; > + > + for_each_pci_msi_entry(entry, pdev) { > + irq_data = irq_get_irq_data(entry->irq); > + if (WARN_ON_ONCE(!irq_data)) > + return -EINVAL; > + > + hv_compose_msi_msg(irq_data, &entry->msg); > + } > + > + return 0; > +} > + > +/* > + * Upon resume, pci_restore_msi_state() -> ... -> __pci_write_msi_msg() > + * re-writes the MSI/MSI-X registers, but since Hyper-V doesn't trap and > + * emulate the accesses, we have to call hv_compose_msi_msg() to ask > + * Hyper-V to re-create the IOMMU Interrupt Remapping Table Entries. > + */ > +static void hv_pci_restore_msi_state(struct hv_pcibus_device *hbus) > +{ > + pci_walk_bus(hbus->pci_bus, hv_pci_restore_msi_msg, NULL); > +} > + > static int hv_pci_resume(struct hv_device *hdev) > { > struct hv_pcibus_device *hbus = hv_get_drvdata(hdev); > @@ -3405,6 +3447,8 @@ static int hv_pci_resume(struct hv_device *hdev) > > prepopulate_bars(hbus); > > + hv_pci_restore_msi_state(hbus); > + > hbus->state = hv_pcibus_installed; > return 0; > out: > -- > 2.19.1 >