[PATCH v2 2/3] virtio: increase VIRTQUEUE_MAX_SIZE to 32k

[Christian Schoenebeck <qemu_oss@crudebyte.com>]

Raise the maximum possible virtio transfer size to 128M
(more precisely: 32k * PAGE_SIZE). See previous commit for a
more detailed explanation for the reasons of this change.

For not breaking any virtio user, all virtio users transition
to using the new macro VIRTQUEUE_LEGACY_MAX_SIZE instead of
VIRTQUEUE_MAX_SIZE, so they are all still using the old value
of 1k with this commit.

On the long-term, each virtio user should subsequently either
switch from VIRTQUEUE_LEGACY_MAX_SIZE to VIRTQUEUE_MAX_SIZE
after checking that they support the new value of 32k, or
otherwise they should replace the VIRTQUEUE_LEGACY_MAX_SIZE
macro by an appropriate value supported by them.

Signed-off-by: Christian Schoenebeck <qemu_oss@crudebyte.com>
---
 hw/9pfs/virtio-9p-device.c     |  2 +-
 hw/block/vhost-user-blk.c      |  6 +++---
 hw/block/virtio-blk.c          |  6 +++---
 hw/char/virtio-serial-bus.c    |  2 +-
 hw/input/virtio-input.c        |  2 +-
 hw/net/virtio-net.c            | 12 ++++++------
 hw/scsi/virtio-scsi.c          |  2 +-
 hw/virtio/vhost-user-fs.c      |  6 +++---
 hw/virtio/vhost-user-i2c.c     |  2 +-
 hw/virtio/vhost-vsock-common.c |  2 +-
 hw/virtio/virtio-balloon.c     |  2 +-
 hw/virtio/virtio-crypto.c      |  2 +-
 hw/virtio/virtio-iommu.c       |  2 +-
 hw/virtio/virtio-mem.c         |  2 +-
 hw/virtio/virtio-mmio.c        |  4 ++--
 hw/virtio/virtio-pmem.c        |  2 +-
 hw/virtio/virtio-rng.c         |  3 ++-
 include/hw/virtio/virtio.h     | 20 +++++++++++++++++++-
 18 files changed, 49 insertions(+), 30 deletions(-)

diff --git a/hw/9pfs/virtio-9p-device.c b/hw/9pfs/virtio-9p-device.c
index cd5d95dd51..9013e7df6e 100644
--- a/hw/9pfs/virtio-9p-device.c
+++ b/hw/9pfs/virtio-9p-device.c
@@ -217,7 +217,7 @@ static void virtio_9p_device_realize(DeviceState *dev, Error **errp)
 
     v->config_size = sizeof(struct virtio_9p_config) + strlen(s->fsconf.tag);
     virtio_init(vdev, "virtio-9p", VIRTIO_ID_9P, v->config_size,
-                VIRTQUEUE_MAX_SIZE);
+                VIRTQUEUE_LEGACY_MAX_SIZE);
     v->vq = virtio_add_queue(vdev, MAX_REQ, handle_9p_output);
 }
 
diff --git a/hw/block/vhost-user-blk.c b/hw/block/vhost-user-blk.c
index 336f56705c..e5e45262ab 100644
--- a/hw/block/vhost-user-blk.c
+++ b/hw/block/vhost-user-blk.c
@@ -480,9 +480,9 @@ static void vhost_user_blk_device_realize(DeviceState *dev, Error **errp)
         error_setg(errp, "queue size must be non-zero");
         return;
     }
-    if (s->queue_size > VIRTQUEUE_MAX_SIZE) {
+    if (s->queue_size > VIRTQUEUE_LEGACY_MAX_SIZE) {
         error_setg(errp, "queue size must not exceed %d",
-                   VIRTQUEUE_MAX_SIZE);
+                   VIRTQUEUE_LEGACY_MAX_SIZE);
         return;
     }
 
@@ -491,7 +491,7 @@ static void vhost_user_blk_device_realize(DeviceState *dev, Error **errp)
     }
 
     virtio_init(vdev, "virtio-blk", VIRTIO_ID_BLOCK,
-                sizeof(struct virtio_blk_config), VIRTQUEUE_MAX_SIZE);
+                sizeof(struct virtio_blk_config), VIRTQUEUE_LEGACY_MAX_SIZE);
 
     s->virtqs = g_new(VirtQueue *, s->num_queues);
     for (i = 0; i < s->num_queues; i++) {
diff --git a/hw/block/virtio-blk.c b/hw/block/virtio-blk.c
index 9c0f46815c..5883e3e7db 100644
--- a/hw/block/virtio-blk.c
+++ b/hw/block/virtio-blk.c
@@ -1171,10 +1171,10 @@ static void virtio_blk_device_realize(DeviceState *dev, Error **errp)
         return;
     }
     if (!is_power_of_2(conf->queue_size) ||
-        conf->queue_size > VIRTQUEUE_MAX_SIZE) {
+        conf->queue_size > VIRTQUEUE_LEGACY_MAX_SIZE) {
         error_setg(errp, "invalid queue-size property (%" PRIu16 "), "
                    "must be a power of 2 (max %d)",
-                   conf->queue_size, VIRTQUEUE_MAX_SIZE);
+                   conf->queue_size, VIRTQUEUE_LEGACY_MAX_SIZE);
         return;
     }
 
@@ -1214,7 +1214,7 @@ static void virtio_blk_device_realize(DeviceState *dev, Error **errp)
     virtio_blk_set_config_size(s, s->host_features);
 
     virtio_init(vdev, "virtio-blk", VIRTIO_ID_BLOCK, s->config_size,
-                VIRTQUEUE_MAX_SIZE);
+                VIRTQUEUE_LEGACY_MAX_SIZE);
 
     s->blk = conf->conf.blk;
     s->rq = NULL;
diff --git a/hw/char/virtio-serial-bus.c b/hw/char/virtio-serial-bus.c
index 9ad9111115..2d4285ab53 100644
--- a/hw/char/virtio-serial-bus.c
+++ b/hw/char/virtio-serial-bus.c
@@ -1045,7 +1045,7 @@ static void virtio_serial_device_realize(DeviceState *dev, Error **errp)
         config_size = offsetof(struct virtio_console_config, emerg_wr);
     }
     virtio_init(vdev, "virtio-serial", VIRTIO_ID_CONSOLE,
-                config_size, VIRTQUEUE_MAX_SIZE);
+                config_size, VIRTQUEUE_LEGACY_MAX_SIZE);
 
     /* Spawn a new virtio-serial bus on which the ports will ride as devices */
     qbus_init(&vser->bus, sizeof(vser->bus), TYPE_VIRTIO_SERIAL_BUS,
diff --git a/hw/input/virtio-input.c b/hw/input/virtio-input.c
index 345eb2cce7..b6b77488f2 100644
--- a/hw/input/virtio-input.c
+++ b/hw/input/virtio-input.c
@@ -258,7 +258,7 @@ static void virtio_input_device_realize(DeviceState *dev, Error **errp)
     assert(vinput->cfg_size <= sizeof(virtio_input_config));
 
     virtio_init(vdev, "virtio-input", VIRTIO_ID_INPUT,
-                vinput->cfg_size, VIRTQUEUE_MAX_SIZE);
+                vinput->cfg_size, VIRTQUEUE_LEGACY_MAX_SIZE);
     vinput->evt = virtio_add_queue(vdev, 64, virtio_input_handle_evt);
     vinput->sts = virtio_add_queue(vdev, 64, virtio_input_handle_sts);
 }
diff --git a/hw/net/virtio-net.c b/hw/net/virtio-net.c
index f74b5f6268..5100978b07 100644
--- a/hw/net/virtio-net.c
+++ b/hw/net/virtio-net.c
@@ -636,7 +636,7 @@ static int virtio_net_max_tx_queue_size(VirtIONet *n)
         return VIRTIO_NET_TX_QUEUE_DEFAULT_SIZE;
     }
 
-    return VIRTQUEUE_MAX_SIZE;
+    return VIRTQUEUE_LEGACY_MAX_SIZE;
 }
 
 static int peer_attach(VirtIONet *n, int index)
@@ -3365,7 +3365,7 @@ static void virtio_net_device_realize(DeviceState *dev, Error **errp)
 
     virtio_net_set_config_size(n, n->host_features);
     virtio_init(vdev, "virtio-net", VIRTIO_ID_NET, n->config_size,
-                VIRTQUEUE_MAX_SIZE);
+                VIRTQUEUE_LEGACY_MAX_SIZE);
 
     /*
      * We set a lower limit on RX queue size to what it always was.
@@ -3373,23 +3373,23 @@ static void virtio_net_device_realize(DeviceState *dev, Error **errp)
      * help from us (using virtio 1 and up).
      */
     if (n->net_conf.rx_queue_size < VIRTIO_NET_RX_QUEUE_MIN_SIZE ||
-        n->net_conf.rx_queue_size > VIRTQUEUE_MAX_SIZE ||
+        n->net_conf.rx_queue_size > VIRTQUEUE_LEGACY_MAX_SIZE ||
         !is_power_of_2(n->net_conf.rx_queue_size)) {
         error_setg(errp, "Invalid rx_queue_size (= %" PRIu16 "), "
                    "must be a power of 2 between %d and %d.",
                    n->net_conf.rx_queue_size, VIRTIO_NET_RX_QUEUE_MIN_SIZE,
-                   VIRTQUEUE_MAX_SIZE);
+                   VIRTQUEUE_LEGACY_MAX_SIZE);
         virtio_cleanup(vdev);
         return;
     }
 
     if (n->net_conf.tx_queue_size < VIRTIO_NET_TX_QUEUE_MIN_SIZE ||
-        n->net_conf.tx_queue_size > VIRTQUEUE_MAX_SIZE ||
+        n->net_conf.tx_queue_size > VIRTQUEUE_LEGACY_MAX_SIZE ||
         !is_power_of_2(n->net_conf.tx_queue_size)) {
         error_setg(errp, "Invalid tx_queue_size (= %" PRIu16 "), "
                    "must be a power of 2 between %d and %d",
                    n->net_conf.tx_queue_size, VIRTIO_NET_TX_QUEUE_MIN_SIZE,
-                   VIRTQUEUE_MAX_SIZE);
+                   VIRTQUEUE_LEGACY_MAX_SIZE);
         virtio_cleanup(vdev);
         return;
     }
diff --git a/hw/scsi/virtio-scsi.c b/hw/scsi/virtio-scsi.c
index 5e5e657e1d..f204e8878a 100644
--- a/hw/scsi/virtio-scsi.c
+++ b/hw/scsi/virtio-scsi.c
@@ -973,7 +973,7 @@ void virtio_scsi_common_realize(DeviceState *dev,
     int i;
 
     virtio_init(vdev, "virtio-scsi", VIRTIO_ID_SCSI,
-                sizeof(VirtIOSCSIConfig), VIRTQUEUE_MAX_SIZE);
+                sizeof(VirtIOSCSIConfig), VIRTQUEUE_LEGACY_MAX_SIZE);
 
     if (s->conf.num_queues == VIRTIO_SCSI_AUTO_NUM_QUEUES) {
         s->conf.num_queues = 1;
diff --git a/hw/virtio/vhost-user-fs.c b/hw/virtio/vhost-user-fs.c
index ae1672d667..decc5def39 100644
--- a/hw/virtio/vhost-user-fs.c
+++ b/hw/virtio/vhost-user-fs.c
@@ -209,9 +209,9 @@ static void vuf_device_realize(DeviceState *dev, Error **errp)
         return;
     }
 
-    if (fs->conf.queue_size > VIRTQUEUE_MAX_SIZE) {
+    if (fs->conf.queue_size > VIRTQUEUE_LEGACY_MAX_SIZE) {
         error_setg(errp, "queue-size property must be %u or smaller",
-                   VIRTQUEUE_MAX_SIZE);
+                   VIRTQUEUE_LEGACY_MAX_SIZE);
         return;
     }
 
@@ -220,7 +220,7 @@ static void vuf_device_realize(DeviceState *dev, Error **errp)
     }
 
     virtio_init(vdev, "vhost-user-fs", VIRTIO_ID_FS,
-                sizeof(struct virtio_fs_config), VIRTQUEUE_MAX_SIZE);
+                sizeof(struct virtio_fs_config), VIRTQUEUE_LEGACY_MAX_SIZE);
 
     /* Hiprio queue */
     fs->hiprio_vq = virtio_add_queue(vdev, fs->conf.queue_size, vuf_handle_output);
diff --git a/hw/virtio/vhost-user-i2c.c b/hw/virtio/vhost-user-i2c.c
index eeb1d8853a..b248ddbe93 100644
--- a/hw/virtio/vhost-user-i2c.c
+++ b/hw/virtio/vhost-user-i2c.c
@@ -221,7 +221,7 @@ static void vu_i2c_device_realize(DeviceState *dev, Error **errp)
     }
 
     virtio_init(vdev, "vhost-user-i2c", VIRTIO_ID_I2C_ADAPTER, 0,
-                VIRTQUEUE_MAX_SIZE);
+                VIRTQUEUE_LEGACY_MAX_SIZE);
 
     i2c->vhost_dev.nvqs = 1;
     i2c->vq = virtio_add_queue(vdev, 4, vu_i2c_handle_output);
diff --git a/hw/virtio/vhost-vsock-common.c b/hw/virtio/vhost-vsock-common.c
index a81fa884a8..73e6b72bba 100644
--- a/hw/virtio/vhost-vsock-common.c
+++ b/hw/virtio/vhost-vsock-common.c
@@ -201,7 +201,7 @@ void vhost_vsock_common_realize(VirtIODevice *vdev, const char *name)
     VHostVSockCommon *vvc = VHOST_VSOCK_COMMON(vdev);
 
     virtio_init(vdev, name, VIRTIO_ID_VSOCK,
-                sizeof(struct virtio_vsock_config), VIRTQUEUE_MAX_SIZE);
+                sizeof(struct virtio_vsock_config), VIRTQUEUE_LEGACY_MAX_SIZE);
 
     /* Receive and transmit queues belong to vhost */
     vvc->recv_vq = virtio_add_queue(vdev, VHOST_VSOCK_QUEUE_SIZE,
diff --git a/hw/virtio/virtio-balloon.c b/hw/virtio/virtio-balloon.c
index 067c73223d..890fb15ed3 100644
--- a/hw/virtio/virtio-balloon.c
+++ b/hw/virtio/virtio-balloon.c
@@ -886,7 +886,7 @@ static void virtio_balloon_device_realize(DeviceState *dev, Error **errp)
     int ret;
 
     virtio_init(vdev, "virtio-balloon", VIRTIO_ID_BALLOON,
-                virtio_balloon_config_size(s), VIRTQUEUE_MAX_SIZE);
+                virtio_balloon_config_size(s), VIRTQUEUE_LEGACY_MAX_SIZE);
 
     ret = qemu_add_balloon_handler(virtio_balloon_to_target,
                                    virtio_balloon_stat, s);
diff --git a/hw/virtio/virtio-crypto.c b/hw/virtio/virtio-crypto.c
index 1e70d4d2a8..e13b6091d6 100644
--- a/hw/virtio/virtio-crypto.c
+++ b/hw/virtio/virtio-crypto.c
@@ -811,7 +811,7 @@ static void virtio_crypto_device_realize(DeviceState *dev, Error **errp)
     }
 
     virtio_init(vdev, "virtio-crypto", VIRTIO_ID_CRYPTO, vcrypto->config_size,
-                VIRTQUEUE_MAX_SIZE);
+                VIRTQUEUE_LEGACY_MAX_SIZE);
     vcrypto->curr_queues = 1;
     vcrypto->vqs = g_malloc0(sizeof(VirtIOCryptoQueue) * vcrypto->max_queues);
     for (i = 0; i < vcrypto->max_queues; i++) {
diff --git a/hw/virtio/virtio-iommu.c b/hw/virtio/virtio-iommu.c
index ca360e74eb..845df78842 100644
--- a/hw/virtio/virtio-iommu.c
+++ b/hw/virtio/virtio-iommu.c
@@ -974,7 +974,7 @@ static void virtio_iommu_device_realize(DeviceState *dev, Error **errp)
     VirtIOIOMMU *s = VIRTIO_IOMMU(dev);
 
     virtio_init(vdev, "virtio-iommu", VIRTIO_ID_IOMMU,
-                sizeof(struct virtio_iommu_config), VIRTQUEUE_MAX_SIZE);
+                sizeof(struct virtio_iommu_config), VIRTQUEUE_LEGACY_MAX_SIZE);
 
     memset(s->iommu_pcibus_by_bus_num, 0, sizeof(s->iommu_pcibus_by_bus_num));
 
diff --git a/hw/virtio/virtio-mem.c b/hw/virtio/virtio-mem.c
index 1d9d01b871..7a39550cde 100644
--- a/hw/virtio/virtio-mem.c
+++ b/hw/virtio/virtio-mem.c
@@ -738,7 +738,7 @@ static void virtio_mem_device_realize(DeviceState *dev, Error **errp)
     vmem->bitmap = bitmap_new(vmem->bitmap_size);
 
     virtio_init(vdev, TYPE_VIRTIO_MEM, VIRTIO_ID_MEM,
-                sizeof(struct virtio_mem_config), VIRTQUEUE_MAX_SIZE);
+                sizeof(struct virtio_mem_config), VIRTQUEUE_LEGACY_MAX_SIZE);
     vmem->vq = virtio_add_queue(vdev, 128, virtio_mem_handle_request);
 
     host_memory_backend_set_mapped(vmem->memdev, true);
diff --git a/hw/virtio/virtio-mmio.c b/hw/virtio/virtio-mmio.c
index 7b3ebca178..ae0cc223e9 100644
--- a/hw/virtio/virtio-mmio.c
+++ b/hw/virtio/virtio-mmio.c
@@ -174,7 +174,7 @@ static uint64_t virtio_mmio_read(void *opaque, hwaddr offset, unsigned size)
         if (!virtio_queue_get_num(vdev, vdev->queue_sel)) {
             return 0;
         }
-        return VIRTQUEUE_MAX_SIZE;
+        return VIRTQUEUE_LEGACY_MAX_SIZE;
     case VIRTIO_MMIO_QUEUE_PFN:
         if (!proxy->legacy) {
             qemu_log_mask(LOG_GUEST_ERROR,
@@ -348,7 +348,7 @@ static void virtio_mmio_write(void *opaque, hwaddr offset, uint64_t value,
         }
         break;
     case VIRTIO_MMIO_QUEUE_NUM:
-        trace_virtio_mmio_queue_write(value, VIRTQUEUE_MAX_SIZE);
+        trace_virtio_mmio_queue_write(value, VIRTQUEUE_LEGACY_MAX_SIZE);
         virtio_queue_set_num(vdev, vdev->queue_sel, value);
 
         if (proxy->legacy) {
diff --git a/hw/virtio/virtio-pmem.c b/hw/virtio/virtio-pmem.c
index 82b54b00c5..5f4d375b58 100644
--- a/hw/virtio/virtio-pmem.c
+++ b/hw/virtio/virtio-pmem.c
@@ -124,7 +124,7 @@ static void virtio_pmem_realize(DeviceState *dev, Error **errp)
 
     host_memory_backend_set_mapped(pmem->memdev, true);
     virtio_init(vdev, TYPE_VIRTIO_PMEM, VIRTIO_ID_PMEM,
-                sizeof(struct virtio_pmem_config), VIRTQUEUE_MAX_SIZE);
+                sizeof(struct virtio_pmem_config), VIRTQUEUE_LEGACY_MAX_SIZE);
     pmem->rq_vq = virtio_add_queue(vdev, 128, virtio_pmem_flush);
 }
 
diff --git a/hw/virtio/virtio-rng.c b/hw/virtio/virtio-rng.c
index 0e91d60106..ab075b22b6 100644
--- a/hw/virtio/virtio-rng.c
+++ b/hw/virtio/virtio-rng.c
@@ -215,7 +215,8 @@ static void virtio_rng_device_realize(DeviceState *dev, Error **errp)
         return;
     }
 
-    virtio_init(vdev, "virtio-rng", VIRTIO_ID_RNG, 0, VIRTQUEUE_MAX_SIZE);
+    virtio_init(vdev, "virtio-rng", VIRTIO_ID_RNG, 0,
+                VIRTQUEUE_LEGACY_MAX_SIZE);
 
     vrng->vq = virtio_add_queue(vdev, 8, handle_input);
     vrng->quota_remaining = vrng->conf.max_bytes;
diff --git a/include/hw/virtio/virtio.h b/include/hw/virtio/virtio.h
index a37d1f7d52..fe0f13266b 100644
--- a/include/hw/virtio/virtio.h
+++ b/include/hw/virtio/virtio.h
@@ -48,7 +48,25 @@ size_t virtio_feature_get_config_size(const VirtIOFeature *features,
 
 typedef struct VirtQueue VirtQueue;
 
-#define VIRTQUEUE_MAX_SIZE 1024
+/*
+ * This is meant as transitional measure for VIRTQUEUE_MAX_SIZE's old value
+ * of 1024 to its new value of 32768. On the long-term virtio users should
+ * either switch to VIRTQUEUE_MAX_SIZE, provided they support 32768,
+ * otherwise they should replace this macro on their side with an
+ * appropriate value actually supported by them.
+ *
+ * Once all virtio users switched, this macro will be removed.
+ */
+#define VIRTQUEUE_LEGACY_MAX_SIZE 1024
+
+/*
+ * Reflects the absolute theoretical maximum queue size (in amount of pages)
+ * ever possible, which is actually the maximum queue size allowed by the
+ * virtio protocol. This value therefore construes the maximum transfer size
+ * possible with virtio (multiplied by system dependent PAGE_SIZE); assuming
+ * a typical page size of 4k this would be a maximum transfer size of 128M.
+ */
+#define VIRTQUEUE_MAX_SIZE 32768
 
 typedef struct VirtQueueElement
 {
-- 
2.20.1