From ff1d2ac949dc94d8a0e71fd46939fb69c2ef075b Mon Sep 17 00:00:00 2001 From: Greg Ungerer Date: Tue, 28 Jul 2015 11:02:54 +1000 Subject: [PATCH 1/2] hw/net: handle flow control in mcf_fec driver receiver The network mcf_fec driver emulated receive side method is not dealing with network queue flow control properly. Modify the receive side to check if we have enough space in the descriptors to store the current packet. If not we process none of it and return 0. When the guest frees up some buffers through its descriptors we signal the qemu net layer to send more packets. [Fixed coding style: 4-space indent and curly braces on if statement. --Stefan] Signed-off-by: Greg Ungerer Message-id: 1438045374-10358-1-git-send-email-gerg@uclinux.org Signed-off-by: Stefan Hajnoczi --- hw/net/mcf_fec.c | 44 ++++++++++++++++++++++++++++++++++---------- 1 file changed, 34 insertions(+), 10 deletions(-) diff --git a/hw/net/mcf_fec.c b/hw/net/mcf_fec.c index 4e6939f9a2..21928f9f3f 100644 --- a/hw/net/mcf_fec.c +++ b/hw/net/mcf_fec.c @@ -196,12 +196,14 @@ static void mcf_fec_do_tx(mcf_fec_state *s) static void mcf_fec_enable_rx(mcf_fec_state *s) { + NetClientState *nc = qemu_get_queue(s->nic); mcf_fec_bd bd; mcf_fec_read_bd(&bd, s->rx_descriptor); s->rx_enabled = ((bd.flags & FEC_BD_E) != 0); - if (!s->rx_enabled) - DPRINTF("RX buffer full\n"); + if (s->rx_enabled) { + qemu_flush_queued_packets(nc); + } } static void mcf_fec_reset(mcf_fec_state *s) @@ -397,6 +399,32 @@ static void mcf_fec_write(void *opaque, hwaddr addr, mcf_fec_update(s); } +static int mcf_fec_have_receive_space(mcf_fec_state *s, size_t want) +{ + mcf_fec_bd bd; + uint32_t addr; + + /* Walk descriptor list to determine if we have enough buffer */ + addr = s->rx_descriptor; + while (want > 0) { + mcf_fec_read_bd(&bd, addr); + if ((bd.flags & FEC_BD_E) == 0) { + return 0; + } + if (want < s->emrbr) { + return 1; + } + want -= s->emrbr; + /* Advance to the next descriptor. */ + if ((bd.flags & FEC_BD_W) != 0) { + addr = s->erdsr; + } else { + addr += 8; + } + } + return 0; +} + static ssize_t mcf_fec_receive(NetClientState *nc, const uint8_t *buf, size_t size) { mcf_fec_state *s = qemu_get_nic_opaque(nc); @@ -426,18 +454,14 @@ static ssize_t mcf_fec_receive(NetClientState *nc, const uint8_t *buf, size_t si if (size > (s->rcr >> 16)) { flags |= FEC_BD_LG; } + /* Check if we have enough space in current descriptors */ + if (!mcf_fec_have_receive_space(s, size)) { + return 0; + } addr = s->rx_descriptor; retsize = size; while (size > 0) { mcf_fec_read_bd(&bd, addr); - if ((bd.flags & FEC_BD_E) == 0) { - /* No descriptors available. Bail out. */ - /* FIXME: This is wrong. We should probably either save the - remainder for when more RX buffers are available, or - flag an error. */ - fprintf(stderr, "mcf_fec: Lost end of frame\n"); - break; - } buf_len = (size <= s->emrbr) ? size: s->emrbr; bd.length = buf_len; size -= buf_len; From 7bba83bf80eae9c9e323319ff40d0ca477b0a77a Mon Sep 17 00:00:00 2001 From: Fam Zheng Date: Tue, 28 Jul 2015 17:52:56 +0800 Subject: [PATCH 2/2] xen: Drop net_rx_ok Let net_rx_packet() (which checks the same conditions) drops the packet if the device is not ready. Drop net_xen_info.can_receive and update the return value for the buffer full case. We rely on the qemu_flush_queued_packets() in net_event() to wake up the peer when the buffer becomes available again. Signed-off-by: Fam Zheng Message-id: 1438077176-378-1-git-send-email-famz@redhat.com Signed-off-by: Stefan Hajnoczi --- hw/net/xen_nic.c | 25 +------------------------ 1 file changed, 1 insertion(+), 24 deletions(-) diff --git a/hw/net/xen_nic.c b/hw/net/xen_nic.c index 19ecfc4ccf..d7cbfc1033 100644 --- a/hw/net/xen_nic.c +++ b/hw/net/xen_nic.c @@ -234,27 +234,6 @@ static void net_rx_response(struct XenNetDev *netdev, #define NET_IP_ALIGN 2 -static int net_rx_ok(NetClientState *nc) -{ - struct XenNetDev *netdev = qemu_get_nic_opaque(nc); - RING_IDX rc, rp; - - if (netdev->xendev.be_state != XenbusStateConnected) { - return 0; - } - - rc = netdev->rx_ring.req_cons; - rp = netdev->rx_ring.sring->req_prod; - xen_rmb(); - - if (rc == rp || RING_REQUEST_CONS_OVERFLOW(&netdev->rx_ring, rc)) { - xen_be_printf(&netdev->xendev, 2, "%s: no rx buffers (%d/%d)\n", - __FUNCTION__, rc, rp); - return 0; - } - return 1; -} - static ssize_t net_rx_packet(NetClientState *nc, const uint8_t *buf, size_t size) { struct XenNetDev *netdev = qemu_get_nic_opaque(nc); @@ -271,8 +250,7 @@ static ssize_t net_rx_packet(NetClientState *nc, const uint8_t *buf, size_t size xen_rmb(); /* Ensure we see queued requests up to 'rp'. */ if (rc == rp || RING_REQUEST_CONS_OVERFLOW(&netdev->rx_ring, rc)) { - xen_be_printf(&netdev->xendev, 2, "no buffer, drop packet\n"); - return -1; + return 0; } if (size > XC_PAGE_SIZE - NET_IP_ALIGN) { xen_be_printf(&netdev->xendev, 0, "packet too big (%lu > %ld)", @@ -304,7 +282,6 @@ static ssize_t net_rx_packet(NetClientState *nc, const uint8_t *buf, size_t size static NetClientInfo net_xen_info = { .type = NET_CLIENT_OPTIONS_KIND_NIC, .size = sizeof(NICState), - .can_receive = net_rx_ok, .receive = net_rx_packet, };