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

[liu ping fan <qemulist@gmail.com>]

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But it seems outdated, after fixing the unlocked_ioctl, and vm-id bits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).

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
>>