Re: [PATCH] PCI: hv: use effective affinity mask

[Bjorn Helgaas]

On Wed, Nov 01, 2017 at 08:52:56PM +0000, Jake Oshins wrote:
> > -----Original Message-----
> > From: Dexuan Cui
> > Sent: Wednesday, November 1, 2017 1:31 PM
> > To: Bjorn Helgaas <bhelgaas@xxxxxxxxxx>; linux-pci@xxxxxxxxxxxxxxx; Jake
> > Oshins <jakeo@xxxxxxxxxxxxx>; KY Srinivasan <kys@xxxxxxxxxxxxx>;
> > Stephen Hemminger <sthemmin@xxxxxxxxxxxxx>
> > Cc: devel@xxxxxxxxxxxxxxxxxxxxxx; linux-kernel@xxxxxxxxxxxxxxx; Haiyang
> > Zhang <haiyangz@xxxxxxxxxxxxx>; Jork Loeser
> > <Jork.Loeser@xxxxxxxxxxxxx>; Chris Valean (Cloudbase Solutions SRL) <v-
> > chvale@xxxxxxxxxxxxx>; Adrian Suhov (Cloudbase Solutions SRL) <v-
> > adsuho@xxxxxxxxxxxxx>; Simon Xiao <sixiao@xxxxxxxxxxxxx>; 'Eyal
> > Mizrachi' <eyalmi@xxxxxxxxxxxx>; Jack Morgenstein
> > <jackm@xxxxxxxxxxxx>; Armen Guezalian <armeng@xxxxxxxxxxxx>; Firas
> > Mahameed <firas@xxxxxxxxxxxx>; Tziporet Koren
> > <tziporet@xxxxxxxxxxxx>; Daniel Jurgens <danielj@xxxxxxxxxxxx>
> > Subject: [PATCH] PCI: hv: use effective affinity mask
> > 
> > 
> > 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@xxxxxxxxxxxxx>
> > Cc: Jake Oshins <jakeo@xxxxxxxxxxxxx>
> > Cc: Jork Loeser <jloeser@xxxxxxxxxxxxx>
> > Cc: Stephen Hemminger <sthemmin@xxxxxxxxxxxxx>
> > Cc: K. Y. Srinivasan <kys@xxxxxxxxxxxxx>
> > ---
> > 
> > Please consider this for v4.14, if it's not too late.
> > 
> >  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
> 
> Signed-off-by: Jake Oshins <jakeo@xxxxxxxxxxxxx>

I'm not sure what this means.

Per Documentation/process/submitting-patches.rst, "Signed-off-by"
means you were "involved in the development of the patch, or that
he/she was in the patch's delivery path."  You weren't in the delivery
path (I got it from Dexuan), and if you were involved in development,
your Signed-off-by would normally appear in the original posting.

Should this be a Reviewed-by tag?