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authorJason Wang <jasowang@redhat.com>2018-10-16 17:40:45 +0800
committerJason Wang <jasowang@redhat.com>2018-10-19 11:15:04 +0800
commit1001cf45a7ca22d990e19a81029319ca763cad4f (patch)
treef2a8bb1c7b8e3e9318fae5e9f72f453037598955 /hw/net
parent1592a9947036d60dde5404204a5d45975133caf5 (diff)
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e1000: indicate dropped packets in HW counters
The e1000 emulation silently discards RX packets if there's insufficient space in the ring buffer. This leads to errors on higher-level protocols in the guest, with no indication about the error cause. This patch increments the "Missed Packets Count" (MPC) and "Receive No Buffers Count" (RNBC) HW counters in this case. As the emulation has no FIFO for buffering packets that can't immediately be pushed to the guest, these two registers are practically equivalent (see 10.2.7.4, 10.2.7.33 in https://www.intel.com/content/www/us/en/embedded/products/networking/82574l-gbe-controller-datasheet.html). On a Linux guest, the register content will be reflected in the "rx_missed_errors" and "rx_no_buffer_count" stats from "ethtool -S", and in the "missed" stat from "ip -s -s link show", giving at least some hint about the error cause inside the guest. If the cause is known, problems like this can often be avoided easily, by increasing the number of RX descriptors in the guest e1000 driver (e.g under Linux, "e1000.RxDescriptors=1024"). The patch also adds a qemu trace message for this condition. Signed-off-by: Martin Wilck <mwilck@suse.com> Signed-off-by: Jason Wang <jasowang@redhat.com>
Diffstat (limited to 'hw/net')
-rw-r--r--hw/net/e1000.c16
-rw-r--r--hw/net/trace-events3
2 files changed, 16 insertions, 3 deletions
diff --git a/hw/net/e1000.c b/hw/net/e1000.c
index 13a9494..5e144cb 100644
--- a/hw/net/e1000.c
+++ b/hw/net/e1000.c
@@ -36,6 +36,7 @@
#include "qemu/range.h"
#include "e1000x_common.h"
+#include "trace.h"
static const uint8_t bcast[] = {0xff, 0xff, 0xff, 0xff, 0xff, 0xff};
@@ -847,6 +848,15 @@ static uint64_t rx_desc_base(E1000State *s)
return (bah << 32) + bal;
}
+static void
+e1000_receiver_overrun(E1000State *s, size_t size)
+{
+ trace_e1000_receiver_overrun(size, s->mac_reg[RDH], s->mac_reg[RDT]);
+ e1000x_inc_reg_if_not_full(s->mac_reg, RNBC);
+ e1000x_inc_reg_if_not_full(s->mac_reg, MPC);
+ set_ics(s, 0, E1000_ICS_RXO);
+}
+
static ssize_t
e1000_receive_iov(NetClientState *nc, const struct iovec *iov, int iovcnt)
{
@@ -916,8 +926,8 @@ e1000_receive_iov(NetClientState *nc, const struct iovec *iov, int iovcnt)
desc_offset = 0;
total_size = size + e1000x_fcs_len(s->mac_reg);
if (!e1000_has_rxbufs(s, total_size)) {
- set_ics(s, 0, E1000_ICS_RXO);
- return -1;
+ e1000_receiver_overrun(s, total_size);
+ return -1;
}
do {
desc_size = total_size - desc_offset;
@@ -969,7 +979,7 @@ e1000_receive_iov(NetClientState *nc, const struct iovec *iov, int iovcnt)
rdh_start >= s->mac_reg[RDLEN] / sizeof(desc)) {
DBGOUT(RXERR, "RDH wraparound @%x, RDT %x, RDLEN %x\n",
rdh_start, s->mac_reg[RDT], s->mac_reg[RDLEN]);
- set_ics(s, 0, E1000_ICS_RXO);
+ e1000_receiver_overrun(s, total_size);
return -1;
}
} while (desc_offset < total_size);
diff --git a/hw/net/trace-events b/hw/net/trace-events
index c1dea4b..9d49f62 100644
--- a/hw/net/trace-events
+++ b/hw/net/trace-events
@@ -98,6 +98,9 @@ net_rx_pkt_rss_ip6_ex(void) "Calculating IPv6/EX RSS hash"
net_rx_pkt_rss_hash(size_t rss_length, uint32_t rss_hash) "RSS hash for %zu bytes: 0x%X"
net_rx_pkt_rss_add_chunk(void* ptr, size_t size, size_t input_offset) "Add RSS chunk %p, %zu bytes, RSS input offset %zu bytes"
+# hw/net/e1000.c
+e1000_receiver_overrun(size_t s, uint32_t rdh, uint32_t rdt) "Receiver overrun: dropped packet of %zu bytes, RDH=%u, RDT=%u"
+
# hw/net/e1000x_common.c
e1000x_rx_can_recv_disabled(bool link_up, bool rx_enabled, bool pci_master) "link_up: %d, rx_enabled %d, pci_master %d"
e1000x_vlan_is_vlan_pkt(bool is_vlan_pkt, uint16_t eth_proto, uint16_t vet) "Is VLAN packet: %d, ETH proto: 0x%X, VET: 0x%X"