Re: [Qemu-devel] [PATCH v3 09/46] ivshmem: more qdev conversion

[Claudio Fontana]

On 15.09.2015 18:07, address@hidden wrote:
> From: Marc-André Lureau <address@hidden>
> 
> Use the latest qemu device modeling API, in particular, convert to
> realize to fix the error handling; right now a botched device_add
> ivhsmem command kills the VM.
> 
> Signed-off-by: Marc-André Lureau <address@hidden>
> ---
>  hw/misc/ivshmem.c | 119 
> +++++++++++++++++++++++++++++++-----------------------
>  1 file changed, 68 insertions(+), 51 deletions(-)
> 
> diff --git a/hw/misc/ivshmem.c b/hw/misc/ivshmem.c
> index 1b8204e..3af73a5 100644
> --- a/hw/misc/ivshmem.c
> +++ b/hw/misc/ivshmem.c
> @@ -319,22 +319,23 @@ static CharDriverState* create_eventfd_chr_device(void 
> * opaque, EventNotifier *
>  
>  }
>  
> -static int check_shm_size(IVShmemState *s, int fd) {
> +static int check_shm_size(IVShmemState *s, int fd, Error **errp)
> +{
>      /* check that the guest isn't going to try and map more memory than the
>       * the object has allocated return -1 to indicate error */
>  
>      struct stat buf;
>  
>      if (fstat(fd, &buf) < 0) {
> -        error_report("exiting: fstat on fd %d failed: %s",
> -                     fd, strerror(errno));
> +        error_setg(errp, "exiting: fstat on fd %d failed: %s",
> +                   fd, strerror(errno));
>          return -1;
>      }
>  
>      if (s->ivshmem_size > buf.st_size) {
> -        error_report("Requested memory size greater"
> -                     " than shared object size (%" PRIu64 " > %" PRIu64")",
> -                     s->ivshmem_size, (uint64_t)buf.st_size);
> +        error_setg(errp, "Requested memory size greater"
> +                   " than shared object size (%" PRIu64 " > %" PRIu64")",
> +                   s->ivshmem_size, (uint64_t)buf.st_size);
>          return -1;
>      } else {
>          return 0;
> @@ -343,13 +344,18 @@ static int check_shm_size(IVShmemState *s, int fd) {
>  
>  /* create the shared memory BAR when we are not using the server, so we can
>   * create the BAR and map the memory immediately */
> -static void create_shared_memory_BAR(IVShmemState *s, int fd, uint8_t attr) {
> -
> +static int create_shared_memory_BAR(IVShmemState *s, int fd, uint8_t attr,
> +                                    Error **errp)
> +{
>      void * ptr;
>  
> -    s->shm_fd = fd;
> -
>      ptr = mmap(0, s->ivshmem_size, PROT_READ|PROT_WRITE, MAP_SHARED, fd, 0);
> +    if (ptr == MAP_FAILED) {
> +        error_setg_errno(errp, errno, "Failed to mmap shared memory");
> +        return -1;
> +    }
> +
> +    s->shm_fd = fd;
>  
>      memory_region_init_ram_ptr(&s->ivshmem, OBJECT(s), "ivshmem.bar2",
>                                 s->ivshmem_size, ptr);
> @@ -358,6 +364,8 @@ static void create_shared_memory_BAR(IVShmemState *s, int 
> fd, uint8_t attr) {
>  
>      /* region for shared memory */
>      pci_register_bar(PCI_DEVICE(s), 2, attr, &s->bar);
> +
> +    return 0;
>  }
>  
>  static void ivshmem_add_eventfd(IVShmemState *s, int posn, int i)
> @@ -481,6 +489,7 @@ static void ivshmem_read(void *opaque, const uint8_t 
> *buf, int size)
>      int incoming_fd;
>      int guest_max_eventfd;
>      long incoming_posn;
> +    Error *err = NULL;
>  
>      if (!fifo_update_and_get(s, buf, size,
>                               &incoming_posn, sizeof(incoming_posn))) {
> @@ -524,18 +533,24 @@ static void ivshmem_read(void *opaque, const uint8_t 
> *buf, int size)
>  
>      /* if the position is -1, then it's shared memory region fd */
>      if (incoming_posn == -1) {
> -
>          void * map_ptr;
>  
>          s->max_peer = 0;
>  
> -        if (check_shm_size(s, incoming_fd) == -1) {
> -            exit(1);
> +        if (check_shm_size(s, incoming_fd, &err) == -1) {
> +            error_report_err(err);
> +            close(incoming_fd);
> +            return;
>          }
>  
>          /* mmap the region and map into the BAR2 */
>          map_ptr = mmap(0, s->ivshmem_size, PROT_READ|PROT_WRITE, MAP_SHARED,
>                                                              incoming_fd, 0);
> +        if (map_ptr == MAP_FAILED) {
> +            error_report("Failed to mmap shared memory %s", strerror(errno));
> +            close(incoming_fd);
> +            return;
> +        }
>          memory_region_init_ram_ptr(&s->ivshmem, OBJECT(s),
>                                     "ivshmem.bar2", s->ivshmem_size, map_ptr);
>          vmstate_register_ram(&s->ivshmem, DEVICE(s));
> @@ -610,7 +625,7 @@ static void ivshmem_reset(DeviceState *d)
>      ivshmem_use_msix(s);
>  }
>  
> -static uint64_t ivshmem_get_size(IVShmemState * s) {
> +static uint64_t ivshmem_get_size(IVShmemState * s, Error **errp) {
>  
>      uint64_t value;
>      char *ptr;
> @@ -624,24 +639,23 @@ static uint64_t ivshmem_get_size(IVShmemState * s) {
>              value <<= 30;
>              break;
>          default:
> -            error_report("invalid ram size: %s", s->sizearg);
> -            exit(1);
> +            error_setg(errp, "invalid ram size: %s", s->sizearg);
> +            return 0;
>      }
>  
>      /* BARs must be a power of 2 */
>      if (!is_power_of_two(value)) {
> -        error_report("size must be power of 2");
> -        exit(1);
> +        error_setg(errp, "size must be power of 2");
> +        return 0;
>      }
>  
>      return value;
>  }
>  
> -static void ivshmem_setup_msi(IVShmemState * s)
> +static int ivshmem_setup_msi(IVShmemState * s)
>  {
>      if (msix_init_exclusive_bar(PCI_DEVICE(s), s->vectors, 1)) {
> -        IVSHMEM_DPRINTF("msix initialization failed\n");
> -        exit(1);
> +        return -1;
>      }
>  
>      IVSHMEM_DPRINTF("msix initialized (%d vectors)\n", s->vectors);
> @@ -650,6 +664,7 @@ static void ivshmem_setup_msi(IVShmemState * s)
>      s->eventfd_table = g_malloc0(s->vectors * sizeof(EventfdEntry));
>  
>      ivshmem_use_msix(s);
> +    return 0;
>  }
>  
>  static void ivshmem_save(QEMUFile* f, void *opaque)
> @@ -703,34 +718,37 @@ static int ivshmem_load(QEMUFile* f, void *opaque, int 
> version_id)
>  }
>  
>  static void ivshmem_write_config(PCIDevice *pci_dev, uint32_t address,
> -                              uint32_t val, int len)
> +                                 uint32_t val, int len)
>  {
>      pci_default_write_config(pci_dev, address, val, len);
>  }
>  
> -static int pci_ivshmem_init(PCIDevice *dev)
> +static void pci_ivshmem_realize(PCIDevice *dev, Error **errp)
>  {
>      IVShmemState *s = IVSHMEM(dev);
>      uint8_t *pci_conf;
>      uint8_t attr = PCI_BASE_ADDRESS_SPACE_MEMORY |
>          PCI_BASE_ADDRESS_MEM_PREFETCH;;
> +    Error *local_err = NULL;
>  
> -    if (s->sizearg == NULL)
> +    if (s->sizearg == NULL) {
>          s->ivshmem_size = 4 << 20; /* 4 MB default */
> -    else {
> -        s->ivshmem_size = ivshmem_get_size(s);
> +    } else {
> +        s->ivshmem_size = ivshmem_get_size(s, &local_err);
> +        if (local_err) {
> +            error_propagate(errp, local_err);
> +            return;
> +        }
>      }
>  
>      fifo8_create(&s->incoming_fifo, sizeof(long));
> -
>      register_savevm(DEVICE(dev), "ivshmem", 0, 0, ivshmem_save, ivshmem_load,
>                                                                          dev);
> -
>      /* IRQFD requires MSI */
>      if (ivshmem_has_feature(s, IVSHMEM_IOEVENTFD) &&
>          !ivshmem_has_feature(s, IVSHMEM_MSI)) {
> -        error_report("ioeventfd/irqfd requires MSI");
> -        exit(1);
> +        error_setg(errp, "ioeventfd/irqfd requires MSI");
> +        return;
>      }
>  
>      /* check that role is reasonable */
> @@ -740,8 +758,8 @@ static int pci_ivshmem_init(PCIDevice *dev)
>          } else if (strncmp(s->role, "master", 7) == 0) {
>              s->role_val = IVSHMEM_MASTER;
>          } else {
> -            error_report("'role' must be 'peer' or 'master'");
> -            exit(1);
> +            error_setg(errp, "'role' must be 'peer' or 'master'");
> +            return;
>          }
>      } else {
>          s->role_val = IVSHMEM_MASTER; /* default */
> @@ -778,15 +796,18 @@ static int pci_ivshmem_init(PCIDevice *dev)
>           * to the ivshmem server to receive the memory region */
>  
>          if (s->shmobj != NULL) {
> -            error_report("WARNING: do not specify both 'chardev' "
> -                         "and 'shm' with ivshmem");
> +            error_setg(errp, "do not specify both 'chardev' "
> +                       "and 'shm' with ivshmem");
> +            return;
>          }
>  
>          IVSHMEM_DPRINTF("using shared memory server (socket = %s)\n",
>                          s->server_chr->filename);
>  
> -        if (ivshmem_has_feature(s, IVSHMEM_MSI)) {
> -            ivshmem_setup_msi(s);
> +        if (ivshmem_has_feature(s, IVSHMEM_MSI) &&
> +            ivshmem_setup_msi(s)) {
> +            error_setg(errp, "msix initialization failed");
> +            return;
>          }
>  
>          /* we allocate enough space for 16 guests and grow as needed */
> @@ -807,8 +828,8 @@ static int pci_ivshmem_init(PCIDevice *dev)
>          int fd;
>  
>          if (s->shmobj == NULL) {
> -            error_report("Must specify 'chardev' or 'shm' to ivshmem");
> -            exit(1);
> +            error_setg(errp, "Must specify 'chardev' or 'shm' to ivshmem");
> +            return;
>          }
>  
>          IVSHMEM_DPRINTF("using shm_open (shm object = %s)\n", s->shmobj);
> @@ -824,24 +845,19 @@ static int pci_ivshmem_init(PCIDevice *dev)
>  
>          } else if ((fd = shm_open(s->shmobj, O_CREAT|O_RDWR,
>                          S_IRWXU|S_IRWXG|S_IRWXO)) < 0) {
> -            error_report("could not open shared file");
> -            exit(1);
> -
> +            error_setg(errp, "could not open shared file");
> +            return;
>          }
>  
> -        if (check_shm_size(s, fd) == -1) {
> -            exit(1);
> +        if (check_shm_size(s, fd, errp) == -1) {
> +            return;
>          }
>  
> -        create_shared_memory_BAR(s, fd, attr);
> +        create_shared_memory_BAR(s, fd, attr, errp);
>      }
> -
> -    dev->config_write = ivshmem_write_config;
> -
> -    return 0;
>  }
>  
> -static void pci_ivshmem_uninit(PCIDevice *dev)
> +static void pci_ivshmem_exit(PCIDevice *dev)
>  {
>      IVShmemState *s = IVSHMEM(dev);
>  
> @@ -873,8 +889,9 @@ static void ivshmem_class_init(ObjectClass *klass, void 
> *data)
>      DeviceClass *dc = DEVICE_CLASS(klass);
>      PCIDeviceClass *k = PCI_DEVICE_CLASS(klass);
>  
> -    k->init = pci_ivshmem_init;
> -    k->exit = pci_ivshmem_uninit;
> +    k->realize = pci_ivshmem_realize;
> +    k->exit = pci_ivshmem_exit;
> +    k->config_write = ivshmem_write_config;
>      k->vendor_id = PCI_VENDOR_ID_IVSHMEM;
>      k->device_id = PCI_DEVICE_ID_IVSHMEM;
>      k->class_id = PCI_CLASS_MEMORY_RAM;
> 


As mentioned, have you checked this for leaking resources between _realize and 
_exit? Or do I misunderstand the interface?

Ciao,

Claudio