RE: [Xen-devel] IRQ SMP affinity problems in domU with vcpus > 4 on HP ProLiant G6 with dual Xeon 5540 (Nehalem)

["Zhang, Xiantao" <xiantao.zhang@xxxxxxxxx>]

Cinco, Dante wrote:
> Xiantao,
> With vcpus=16 (all CPUs) in domU, I'm able to change the IRQ
> smp_affinity to any one-hot value and see the interrupts routed to
> the specified CPU. Every now and then though, both domU and dom0 will
> permanently lockup (cold reboot required) after changing the
> smp_affinity. If I change it manually via command-line, it seems to
> be okay but if I change it within a script (such as shifting-left a
> walking "1" to test all 16 CPUs), it will lockup part way through the
> script. 

I can't reproduce the failure at my side after applying the patches even with a 
similar script which changes irq's affinity.  Could you share your script with 
me ? 



> Other observations:
> 
> In the above log, I had changed the smp_affinity for IRQ 66 but IRQ
> 68 and 69 got masked. 

We can see the warning as "No irq handler for vector" but it shouldn't hang 
host, and it maybe related to another potential issue, and maybe need further 
investigation.  

Xiantao

> -----Original Message-----
> From: Zhang, Xiantao [mailto:xiantao.zhang@xxxxxxxxx]
> Sent: Friday, October 16, 2009 5:59 PM
> To: Cinco, Dante; He, Qing
> Cc: xen-devel@xxxxxxxxxxxxxxxxxxx; Fraser; Fraser
> Subject: RE: [Xen-devel] IRQ SMP affinity problems in domU with vcpus
> > 4 on HP ProLiant G6 with dual Xeon 5540 (Nehalem) 
> 
>  Dante
>  It should be another issue as you described.  Can you try the
> following code to see whether it works for you ?  Just a try. 
> Xiantao
> 
> diff -r 0705efd9c69e xen/arch/x86/hvm/hvm.c
> --- a/xen/arch/x86/hvm/hvm.c    Fri Oct 16 09:04:53 2009 +0100
> +++ b/xen/arch/x86/hvm/hvm.c    Sat Oct 17 08:48:23 2009 +0800
> @@ -243,7 +243,7 @@ void hvm_migrate_pirqs(struct vcpu *v)
>              continue;
>          irq = desc - irq_desc;
>          ASSERT(MSI_IRQ(irq));
> -        desc->handler->set_affinity(irq, *cpumask_of(v->processor));
> +        //desc->handler->set_affinity(irq,
>          *cpumask_of(v->processor)); spin_unlock_irq(&desc->lock);
>      }
>      spin_unlock(&d->event_lock);
> 
> -----Original Message-----
> From: xen-devel-bounces@xxxxxxxxxxxxxxxxxxx
> [mailto:xen-devel-bounces@xxxxxxxxxxxxxxxxxxx] On Behalf Of Cinco,
> Dante  
> Sent: Saturday, October 17, 2009 2:24 AM
> To: Zhang, Xiantao; He, Qing
> Cc: Keir; xen-devel@xxxxxxxxxxxxxxxxxxx; Fraser
> Subject: RE: [Xen-devel] IRQ SMP affinity problems in domU with vcpus
> > 4 on HP ProLiant G6 with dual Xeon 5540 (Nehalem) 
> 
> Xiantao,
> I'm still losing the interrupts with your patch but I see some
> differences. To simplifiy the data, I'm only going to focus on the
> first function of my 4-function PCI device.  
> 
> After changing the IRQ affinity, the IRQ is not masked anymore
> (unlike before the patch). What stands out for me is the new vector
> (219) as reported by "guest interrupt information" does not match the
> vector (187) in dom0 lspci. Before the patch, the new vector in
> "guest interrupt information" matched the new vector in dom0 lspci
> (dest ID in dom0 lspci was unchanged). I also saw this message pop on
> the Xen console when I changed smp_affinity:      
> 
> (XEN) do_IRQ: 1.187 No irq handler for vector (irq -1).
> 
> 187 is the vector from dom0 lspci before and after the smp_affinity
> change but "guest interrupt information" reports the new vector is
> 219. To me, this looks like the new MSI message data (with
> vector=219) did not get written into the PCI device, right?   
> 
> Here's a comparison before and after changing smp_affinity from ffff
> to 2 (dom0 is pvops 2.6.31.1, domU is 2.6.30.1): 
> 
> ------------------------------------------------------------------------
> 
> /proc/irq/48/smp_affinity=ffff (default):
> 
> dom0 lspci: Address: 00000000fee00000  Data: 40bb (vector=187)
> 
> domU lspci: Address: 00000000fee00000  Data: 4071 (vector=113)
> 
> qemu-dm-dpm.log: pt_msi_setup: msi mapped with pirq 4f (79)
>                  pt_msi_update: Update msi with pirq 4f gvec 71
> gflags 0 
> 
> Guest interrupt information: (XEN) IRQ: 74, IRQ affinity:0x00000001,
> Vec:187 type=PCI-MSI status=00000010 in-flight=0 domain-list=1:
> 79(----)  
> 
> Xen console: (XEN) [VT-D]iommu.c:1289:d0 domain_context_unmap:PCIe:
>              bdf = 7:0.0 (XEN) [VT-D]iommu.c:1175:d0
>              domain_context_mapping:PCIe: bdf = 7:0.0 (XEN)
>              [VT-D]io.c:301:d0 VT-d irq bind: m_irq = 4f device = 5
>              intx = 0 (XEN) io.c:326:d0 pt_irq_destroy_bind_vtd:
> machine_gsi=79 guest_gsi=36, device=5, intx=0 (XEN) io.c:381:d0
> XEN_DOMCTL_irq_unmapping: m_irq = 0x4f device = 0x5 intx = 0x0  
> 
> ------------------------------------------------------------------------
> 
> /proc/irq/48/smp_affinity=2:
> 
> dom0 lspci: Address: 00000000fee10000  Data: 40bb (dest ID changed
> from 0 (APIC ID of CPU0) to 16 (APIC ID of CPU1), vector unchanged) 
> 
> domU lspci: Address: 00000000fee02000  Data: 40b1 (dest ID changed
> from 0 (APIC ID of CPU0) to 2 (APIC ID of CPU1), new vector=177) 
> 
> Guest interrupt information: (XEN) IRQ: 74, IRQ affinity:0x00000002,
> Vec:219 type=PCI-MSI status=00000010 in-flight=0 domain-list=1:
> 79(----)  
> 
> qemu-dm-dpm.log: pt_msi_update: Update msi with pirq 4f gvec 71
>                  gflags 2 pt_msi_update: Update msi with pirq 4f gvec
> b1 gflags 2 


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