[PATCH] PCI: hv: use effective affinity mask

Adrian Suhov (Cloudbase Solutions SRL) v-adsuho at microsoft.com
Fri Nov 10 08:55:07 UTC 2017


Hi,

I've also tested this and it's working good. Kernels tested:
 - next-20171109 on top of Ubuntu 16.04
 - MSFT kernel - 4.14.0-rc5 with patch applied - on top of RHEL 7.3

Adrian

-----Original Message-----
From: Bjorn Helgaas [mailto:helgaas at kernel.org] 
Sent: Wednesday, November 8, 2017 3:08 AM
To: Dexuan Cui <decui at microsoft.com>
Cc: Bjorn Helgaas <bhelgaas at google.com>; linux-pci at vger.kernel.org; Jake Oshins <jakeo at microsoft.com>; KY Srinivasan <kys at microsoft.com>; Stephen Hemminger <sthemmin at microsoft.com>; devel at linuxdriverproject.org; linux-kernel at vger.kernel.org; Haiyang Zhang <haiyangz at microsoft.com>; Jork Loeser <Jork.Loeser at microsoft.com>; Chris Valean (Cloudbase Solutions SRL) <v-chvale at microsoft.com>; Adrian Suhov (Cloudbase Solutions SRL) <v-adsuho at microsoft.com>; Simon Xiao <sixiao at microsoft.com>; 'Eyal Mizrachi' <eyalmi at mellanox.com>; Jack Morgenstein <jackm at mellanox.com>; Armen Guezalian <armeng at mellanox.com>; Firas Mahameed <firas at mellanox.com>; Tziporet Koren <tziporet at mellanox.com>; Daniel Jurgens <danielj at mellanox.com>
Subject: Re: [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 at microsoft.com>
> Cc: Jake Oshins <jakeo at microsoft.com>
> Cc: Jork Loeser <jloeser at microsoft.com>
> Cc: Stephen Hemminger <sthemmin at microsoft.com>
> Cc: K. Y. Srinivasan <kys at 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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