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Re: [Qemu-devel] [PATCH v2 2/2] ivshmem: use irqfd to interrupt among VM


From: Cam Macdonell
Subject: Re: [Qemu-devel] [PATCH v2 2/2] ivshmem: use irqfd to interrupt among VMs
Date: Thu, 29 Nov 2012 10:33:38 -0700

On Thu, Nov 29, 2012 at 1:34 AM, liu ping fan <address@hidden> wrote:
> On Thu, Nov 29, 2012 at 12:42 PM, Cam Macdonell <address@hidden> wrote:
>> On Tue, Nov 27, 2012 at 7:53 PM, liu ping fan <address@hidden> wrote:
>>> On Wed, Nov 28, 2012 at 5:48 AM, Cam Macdonell <address@hidden> wrote:
>>>> On Sat, Nov 24, 2012 at 8:51 PM, Liu Ping Fan <address@hidden> wrote:
>>>>> From: Liu Ping Fan <address@hidden>
>>>>>
>>>>> Using irqfd, so we can avoid switch between kernel and user when
>>>>> VMs interrupts each other.
>>>>
>>>> Nice work.  Due to a hardware failure, there will be a small delay in
>>>> me being able to test this.  I'll follow up as soon as I can.
>>>>
>>> BTW where can I find the latest guest code for test?
>>> I got the guest code from git://gitorious.org/nahanni/guest-code.git.
>>> But it seems outdated, after fixing the unlocked_ioctl, and vm-id bits
>>> position (the codes conflict with ivshmem spec), it works (I have
>>> tested for V1).
>>
>> Hello,
>>
>> Which device driver are you using?
>>
> guest-code/kernel_module/standard/kvm_ivshmem.c

The uio driver is the recommended one, however if you want to use the
kvm_ivshmem one and have it working, then feel free to continue.

I had deleted it form the repo, but some users had based solutions off
it, so I added it back.

btw, my hardware issue has been resolved, so I'll get to testing your
patch soon.

Sincerely,
Cam

>
>> Cam
>>
>>>
>>> Regards,
>>> Pingfan
>>>
>>>>>
>>>>> Signed-off-by: Liu Ping Fan <address@hidden>
>>>>> ---
>>>>>  hw/ivshmem.c |   54 
>>>>> +++++++++++++++++++++++++++++++++++++++++++++++++++++-
>>>>>  1 files changed, 53 insertions(+), 1 deletions(-)
>>>>>
>>>>> diff --git a/hw/ivshmem.c b/hw/ivshmem.c
>>>>> index 7c8630c..5709e89 100644
>>>>> --- a/hw/ivshmem.c
>>>>> +++ b/hw/ivshmem.c
>>>>> @@ -19,6 +19,7 @@
>>>>>  #include "hw.h"
>>>>>  #include "pc.h"
>>>>>  #include "pci.h"
>>>>> +#include "msi.h"
>>>>>  #include "msix.h"
>>>>>  #include "kvm.h"
>>>>>  #include "migration.h"
>>>>> @@ -83,6 +84,7 @@ typedef struct IVShmemState {
>>>>>      uint32_t vectors;
>>>>>      uint32_t features;
>>>>>      EventfdEntry *eventfd_table;
>>>>> +    int *vector_virqs;
>>>>>
>>>>>      Error *migration_blocker;
>>>>>
>>>>> @@ -625,16 +627,62 @@ static int ivshmem_load(QEMUFile* f, void *opaque, 
>>>>> int version_id)
>>>>>      return 0;
>>>>>  }
>>>>>
>>>>> +static int ivshmem_vector_use(PCIDevice *dev, unsigned vector,
>>>>> +                                     MSIMessage msg)
>>>>> +{
>>>>> +    IVShmemState *s = DO_UPCAST(IVShmemState, dev, dev);
>>>>> +    int virq;
>>>>> +    EventNotifier *n = &s->peers[s->vm_id].eventfds[vector];
>>>>> +
>>>>> +    virq = kvm_irqchip_add_msi_route(kvm_state, msg);
>>>>> +    if (virq >= 0 && kvm_irqchip_add_irqfd_notifier(kvm_state, n, virq) 
>>>>> >= 0) {
>>>>> +        s->vector_virqs[vector] = virq;
>>>>> +        qemu_chr_add_handlers(s->eventfd_chr[vector], NULL, NULL, NULL, 
>>>>> NULL);
>>>>> +    } else if (virq >= 0) {
>>>>> +        kvm_irqchip_release_virq(kvm_state, virq);
>>>>> +        error_report("ivshmem, can not setup irqfd\n");
>>>>> +        return -1;
>>>>> +    } else {
>>>>> +        error_report("ivshmem, no enough msi route to setup irqfd\n");
>>>>> +        return -1;
>>>>> +    }
>>>>> +
>>>>> +    return 0;
>>>>> +}
>>>>> +
>>>>> +static void ivshmem_vector_release(PCIDevice *dev, unsigned vector)
>>>>> +{
>>>>> +    IVShmemState *s = DO_UPCAST(IVShmemState, dev, dev);
>>>>> +    EventNotifier *n = &s->peers[s->vm_id].eventfds[vector];
>>>>> +    int virq = s->vector_virqs[vector];
>>>>> +
>>>>> +    if (s->vector_virqs[vector] >= 0) {
>>>>> +        kvm_irqchip_remove_irqfd_notifier(kvm_state, n, virq);
>>>>> +        kvm_irqchip_release_virq(kvm_state, virq);
>>>>> +        s->vector_virqs[vector] = -1;
>>>>> +    }
>>>>> +}
>>>>> +
>>>>>  static void ivshmem_write_config(PCIDevice *pci_dev, uint32_t address,
>>>>>                                  uint32_t val, int len)
>>>>>  {
>>>>> +    bool is_enabled, was_enabled = msi_enabled(pci_dev);
>>>>> +
>>>>>      pci_default_write_config(pci_dev, address, val, len);
>>>>> +    is_enabled = msi_enabled(pci_dev);
>>>>> +    if (!was_enabled && is_enabled) {
>>>>> +        msix_set_vector_notifiers(pci_dev, ivshmem_vector_use,
>>>>> +            ivshmem_vector_release);
>>>>> +    } else if (was_enabled && !is_enabled) {
>>>>> +        msix_unset_vector_notifiers(pci_dev);
>>>>> +    }
>>>>>  }
>>>>>
>>>>>  static int pci_ivshmem_init(PCIDevice *dev)
>>>>>  {
>>>>>      IVShmemState *s = DO_UPCAST(IVShmemState, dev, dev);
>>>>>      uint8_t *pci_conf;
>>>>> +    int i;
>>>>>
>>>>>      if (s->sizearg == NULL)
>>>>>          s->ivshmem_size = 4 << 20; /* 4 MB default */
>>>>> @@ -758,7 +806,10 @@ static int pci_ivshmem_init(PCIDevice *dev)
>>>>>      }
>>>>>
>>>>>      s->dev.config_write = ivshmem_write_config;
>>>>> -
>>>>> +    s->vector_virqs = g_new0(int, s->vectors);
>>>>> +    for (i = 0; i < s->vectors; i++) {
>>>>> +        s->vector_virqs[i] = -1;
>>>>> +    }
>>>>>      return 0;
>>>>>  }
>>>>>
>>>>> @@ -770,6 +821,7 @@ static void pci_ivshmem_uninit(PCIDevice *dev)
>>>>>          migrate_del_blocker(s->migration_blocker);
>>>>>          error_free(s->migration_blocker);
>>>>>      }
>>>>> +    g_free(s->vector_virqs);
>>>>>
>>>>>      memory_region_destroy(&s->ivshmem_mmio);
>>>>>      memory_region_del_subregion(&s->bar, &s->ivshmem);
>>>>> --
>>>>> 1.7.4.4
>>>>>
>>>
>



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