RE: [PATCH 1/2] pci-hyperv: Fix a bug in specifying CPU affinity

[Long Li <longli@microsoft.com>]

> -----Original Message-----
> From: devel [mailto:driverdev-devel-bounces@linuxdriverproject.org] On
> Behalf Of kys@exchange.microsoft.com
> Sent: Friday, March 24, 2017 11:07 AM
> To: helgaas@kernel.org; linux-pci@vger.kernel.org; linux-
> kernel@vger.kernel.org; devel@linuxdriverproject.org; olaf@aepfle.de;
> apw@canonical.com; vkuznets@redhat.com; jasowang@redhat.com;
> leann.ogasawara@canonical.com; marcelo.cerri@canonical.com; Stephen
> Hemminger <sthemmin@microsoft.com>
> Cc: stable@vger.kernel.org
> Subject: [PATCH 1/2] pci-hyperv: Fix a bug in specifying CPU affinity
> 
> From: K. Y. Srinivasan <kys@microsoft.com>
> 
> When we have 32 or more CPUs in the affinity mask, we should use a special
> constant to specify that to the host. Fix this issue.
> 
> Signed-off-by: K. Y. Srinivasan <kys@microsoft.com>
> Cc: <stable@vger.kernel.org>

Reviewed-by: Long Li <longli@microsoft.com>

> ---
>  drivers/pci/host/pci-hyperv.c |   11 ++++++++---
>  1 files changed, 8 insertions(+), 3 deletions(-)
> 
> diff --git a/drivers/pci/host/pci-hyperv.c b/drivers/pci/host/pci-hyperv.c
> index ada9856..32a16fb 100644
> --- a/drivers/pci/host/pci-hyperv.c
> +++ b/drivers/pci/host/pci-hyperv.c
> @@ -72,6 +72,7 @@ enum {
>         PCI_PROTOCOL_VERSION_CURRENT = PCI_PROTOCOL_VERSION_1_1  };
> 
> +#define CPU_AFFINITY_ALL       -1ULL
>  #define PCI_CONFIG_MMIO_LENGTH 0x2000
>  #define CFG_PAGE_OFFSET 0x1000
>  #define CFG_PAGE_SIZE (PCI_CONFIG_MMIO_LENGTH -
> CFG_PAGE_OFFSET) @@ -897,9 +898,13 @@ static void
> hv_compose_msi_msg(struct irq_data *data, struct msi_msg *msg)
>          * processors because Hyper-V only supports 64 in a guest.
>          */
>         affinity = irq_data_get_affinity_mask(data);
> -       for_each_cpu_and(cpu, affinity, cpu_online_mask) {
> -               int_pkt->int_desc.cpu_mask |=
> -                       (1ULL << vmbus_cpu_number_to_vp_number(cpu));
> +       if (cpumask_weight(affinity) >= 32) {
> +               int_pkt->int_desc.cpu_mask = CPU_AFFINITY_ALL;
> +       } else {
> +               for_each_cpu_and(cpu, affinity, cpu_online_mask) {
> +                       int_pkt->int_desc.cpu_mask |=
> +                               (1ULL << vmbus_cpu_number_to_vp_number(cpu));
> +               }
>         }
> 
>         ret = vmbus_sendpacket(hpdev->hbus->hdev->channel, int_pkt,
> --
> 1.7.1
> 
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