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

[Cam Macdonell <cam@cs.ualberta.ca>]

On Tue, Nov 27, 2012 at 7:53 PM, liu ping fan <qemulist@gmail.com> wrote:
> On Wed, Nov 28, 2012 at 5:48 AM, Cam Macdonell <cam@cs.ualberta.ca> wrote:
>> On Sat, Nov 24, 2012 at 8:51 PM, Liu Ping Fan <qemulist@gmail.com> wrote:
>>> From: Liu Ping Fan <pingfank@linux.vnet.ibm.com>
>>>
>>> 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 But it seems outdated, after fixing the unlocked_ioctl, and vm-id bits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?

Cam

>
> Regards,
> Pingfan
>
>>>
>>> Signed-off-by: Liu Ping Fan <pingfank@linux.vnet.ibm.com>
>>> ---
>>>  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
>>>
>