Re: [Qemu-devel] [PATCH] ivshmem: fix guest unable to start with ioeventfd

[Cam Macdonell]

2011/11/30 Zang Hongyong <address@hidden>:
> Can this bug fix patch be applied yet?

Sorry, for not replying yet.  I'll test your patch within the next day.

> With this bug, guest os cannot successfully boot with ioeventfd.
> Thus the new PIO DoorBell patch cannot be posted.

Well, you can certainly post the new patch, just clarify that it's
dependent on this patch.

Sincerely,
Cam

>
> Thanks,
> Hongyong
>
> 于 2011/11/24,星期四 18:05, address@hidden 写道:
>> From: Hongyong Zang <address@hidden>
>>
>> When a guest boots with ioeventfd, an error (by gdb) occurs:
>>   Program received signal SIGSEGV, Segmentation fault.
>>   0x00000000006009cc in setup_ioeventfds (s=0x171dc40)
>>       at /home/louzhengwei/git_source/qemu-kvm/hw/ivshmem.c:363
>>   363             for (j = 0; j < s->peers[i].nb_eventfds; j++) {
>> The bug is due to accessing s->peers which is NULL.
>>
>> This patch uses the memory region API to replace the old one 
>> kvm_set_ioeventfd_mmio_long().
>> And this patch makes memory_region_add_eventfd() called in ivshmem_read() 
>> when qemu receives
>> eventfd information from ivshmem_server.
>>
>> Signed-off-by: Hongyong Zang <address@hidden>
>> ---
>>  hw/ivshmem.c |   41 ++++++++++++++---------------------------
>>  1 files changed, 14 insertions(+), 27 deletions(-)
>>
>> diff --git a/hw/ivshmem.c b/hw/ivshmem.c
>> index 242fbea..be26f03 100644
>> --- a/hw/ivshmem.c
>> +++ b/hw/ivshmem.c
>> @@ -58,7 +58,6 @@ typedef struct IVShmemState {
>>      CharDriverState *server_chr;
>>      MemoryRegion ivshmem_mmio;
>>
>> -    pcibus_t mmio_addr;
>>      /* We might need to register the BAR before we actually have the memory.
>>       * So prepare a container MemoryRegion for the BAR immediately and
>>       * add a subregion when we have the memory.
>> @@ -346,8 +345,14 @@ static void close_guest_eventfds(IVShmemState *s, int 
>> posn)
>>      guest_curr_max = s->peers[posn].nb_eventfds;
>>
>>      for (i = 0; i < guest_curr_max; i++) {
>> -        kvm_set_ioeventfd_mmio_long(s->peers[posn].eventfds[i],
>> -                    s->mmio_addr + DOORBELL, (posn << 16) | i, 0);
>> +        if (ivshmem_has_feature(s, IVSHMEM_IOEVENTFD)) {
>> +            memory_region_del_eventfd(&s->ivshmem_mmio,
>> +                                     DOORBELL,
>> +                                     4,
>> +                                     true,
>> +                                     (posn << 16) | i,
>> +                                     s->peers[posn].eventfds[i]);
>> +        }
>>          close(s->peers[posn].eventfds[i]);
>>      }
>>
>> @@ -355,22 +360,6 @@ static void close_guest_eventfds(IVShmemState *s, int 
>> posn)
>>      s->peers[posn].nb_eventfds = 0;
>>  }
>>
>> -static void setup_ioeventfds(IVShmemState *s) {
>> -
>> -    int i, j;
>> -
>> -    for (i = 0; i <= s->max_peer; i++) {
>> -        for (j = 0; j < s->peers[i].nb_eventfds; j++) {
>> -            memory_region_add_eventfd(&s->ivshmem_mmio,
>> -                                      DOORBELL,
>> -                                      4,
>> -                                      true,
>> -                                      (i << 16) | j,
>> -                                      s->peers[i].eventfds[j]);
>> -        }
>> -    }
>> -}
>> -
>>  /* this function increase the dynamic storage need to store data about other
>>   * guests */
>>  static void increase_dynamic_storage(IVShmemState *s, int new_min_size) {
>> @@ -491,10 +480,12 @@ static void ivshmem_read(void *opaque, const uint8_t * 
>> buf, int flags)
>>      }
>>
>>      if (ivshmem_has_feature(s, IVSHMEM_IOEVENTFD)) {
>> -        if (kvm_set_ioeventfd_mmio_long(incoming_fd, s->mmio_addr + 
>> DOORBELL,
>> -                        (incoming_posn << 16) | guest_max_eventfd, 1) < 0) {
>> -            fprintf(stderr, "ivshmem: ioeventfd not available\n");
>> -        }
>> +        memory_region_add_eventfd(&s->ivshmem_mmio,
>> +                                  DOORBELL,
>> +                                  4,
>> +                                  true,
>> +                                  (incoming_posn << 16) | guest_max_eventfd,
>> +                                  incoming_fd);
>>      }
>>
>>      return;
>> @@ -659,10 +650,6 @@ static int pci_ivshmem_init(PCIDevice *dev)
>>      memory_region_init_io(&s->ivshmem_mmio, &ivshmem_mmio_ops, s,
>>                            "ivshmem-mmio", IVSHMEM_REG_BAR_SIZE);
>>
>> -    if (ivshmem_has_feature(s, IVSHMEM_IOEVENTFD)) {
>> -        setup_ioeventfds(s);
>> -    }
>> -
>>      /* region for registers*/
>>      pci_register_bar(&s->dev, 0, PCI_BASE_ADDRESS_SPACE_MEMORY,
>>                       &s->ivshmem_mmio);
>
>