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    SubjectRe: [PATCH] PCI: hv: use effective affinity mask
    On Wed, Nov 01, 2017 at 08:30:53PM +0000, Dexuan Cui wrote:
    >
    > The effective_affinity_mask is always set when an interrupt is assigned in
    > __assign_irq_vector() -> apic->cpu_mask_to_apicid(), e.g. for struct apic
    > apic_physflat: -> default_cpu_mask_to_apicid() ->
    > irq_data_update_effective_affinity(), but it looks d->common->affinity
    > remains all-1's before the user space or the kernel changes it later.
    >
    > In the early allocation/initialization phase of an irq, we should use the
    > effective_affinity_mask, otherwise Hyper-V may not deliver the interrupt
    > to the expected cpu. Without the patch, if we assign 7 Mellanox ConnectX-3
    > VFs to a 32-vCPU VM, one of the VFs may fail to receive interrupts.
    >
    > Signed-off-by: Dexuan Cui <decui@microsoft.com>
    > Cc: Jake Oshins <jakeo@microsoft.com>
    > Cc: Jork Loeser <jloeser@microsoft.com>
    > Cc: Stephen Hemminger <sthemmin@microsoft.com>
    > Cc: K. Y. Srinivasan <kys@microsoft.com>
    > ---
    >
    > Please consider this for v4.14, if it's not too late.

    What would be the rationale for putting it in v4.14? After the merge
    window, I usually only merge fixes for problems introduced during the
    merge window, or for serious regressions. I can't tell if this fits
    into that or not.

    > drivers/pci/host/pci-hyperv.c | 8 +++++---
    > 1 file changed, 5 insertions(+), 3 deletions(-)
    >
    > diff --git a/drivers/pci/host/pci-hyperv.c b/drivers/pci/host/pci-hyperv.c
    > index 5ccb47d..8b5f66d 100644
    > --- a/drivers/pci/host/pci-hyperv.c
    > +++ b/drivers/pci/host/pci-hyperv.c
    > @@ -879,7 +879,7 @@ static void hv_irq_unmask(struct irq_data *data)
    > int cpu;
    > u64 res;
    >
    > - dest = irq_data_get_affinity_mask(data);
    > + dest = irq_data_get_effective_affinity_mask(data);
    > pdev = msi_desc_to_pci_dev(msi_desc);
    > pbus = pdev->bus;
    > hbus = container_of(pbus->sysdata, struct hv_pcibus_device, sysdata);
    > @@ -1042,6 +1042,7 @@ static void hv_compose_msi_msg(struct irq_data *data, struct msi_msg *msg)
    > struct hv_pci_dev *hpdev;
    > struct pci_bus *pbus;
    > struct pci_dev *pdev;
    > + struct cpumask *dest;
    > struct compose_comp_ctxt comp;
    > struct tran_int_desc *int_desc;
    > struct {
    > @@ -1056,6 +1057,7 @@ static void hv_compose_msi_msg(struct irq_data *data, struct msi_msg *msg)
    > int ret;
    >
    > pdev = msi_desc_to_pci_dev(irq_data_get_msi_desc(data));
    > + dest = irq_data_get_effective_affinity_mask(data);
    > pbus = pdev->bus;
    > hbus = container_of(pbus->sysdata, struct hv_pcibus_device, sysdata);
    > hpdev = get_pcichild_wslot(hbus, devfn_to_wslot(pdev->devfn));
    > @@ -1081,14 +1083,14 @@ static void hv_compose_msi_msg(struct irq_data *data, struct msi_msg *msg)
    > switch (pci_protocol_version) {
    > case PCI_PROTOCOL_VERSION_1_1:
    > size = hv_compose_msi_req_v1(&ctxt.int_pkts.v1,
    > - irq_data_get_affinity_mask(data),
    > + dest,
    > hpdev->desc.win_slot.slot,
    > cfg->vector);
    > break;
    >
    > case PCI_PROTOCOL_VERSION_1_2:
    > size = hv_compose_msi_req_v2(&ctxt.int_pkts.v2,
    > - irq_data_get_affinity_mask(data),
    > + dest,
    > hpdev->desc.win_slot.slot,
    > cfg->vector);
    > break;
    > --
    > 2.7.4
    >

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