diff options
Diffstat (limited to 'tools/ioemu/patches/serial-port-rate-limit')
| -rw-r--r-- | tools/ioemu/patches/serial-port-rate-limit | 116 |
1 files changed, 116 insertions, 0 deletions
diff --git a/tools/ioemu/patches/serial-port-rate-limit b/tools/ioemu/patches/serial-port-rate-limit new file mode 100644 index 0000000000..17eac33951 --- /dev/null +++ b/tools/ioemu/patches/serial-port-rate-limit @@ -0,0 +1,116 @@ +# HG changeset patch +# User Steven Smith <ssmith@xensource.com> +# Node ID 1d3f52eb256e3522edc12daca91039b319dbbbe5 +# Parent b7b653e36d20811831f26bb951ea66dca5854b17 +[HVM] Rate limit guest accesses to the qemu virtual serial port. This stops +grub's boot menu from hammering dom0. + +Signed-off-by: Steven Smith <sos22@cam.ac.uk> + +--- ioemu/hw/serial.c Mon Sep 25 16:31:02 2006 +0100 ++++ ioemu/hw/serial.c Mon Sep 25 17:27:18 2006 +0100 +@@ -22,6 +22,9 @@ + * THE SOFTWARE. + */ + #include "vl.h" ++#include <sys/time.h> ++#include <time.h> ++#include <assert.h> + + //#define DEBUG_SERIAL + +@@ -138,6 +141,67 @@ static void serial_update_parameters(Ser + printf("speed=%d parity=%c data=%d stop=%d\n", + speed, parity, data_bits, stop_bits); + #endif ++} ++ ++/* Rate limit serial requests so that e.g. grub on a serial console ++ doesn't kill dom0. Simple token bucket. If we get some actual ++ data from the user, instantly refil the bucket. */ ++ ++/* How long it takes to generate a token, in microseconds. */ ++#define TOKEN_PERIOD 1000 ++/* Maximum and initial size of token bucket */ ++#define TOKENS_MAX 100000 ++ ++static int tokens_avail; ++ ++static void serial_get_token(void) ++{ ++ static struct timeval last_refil_time; ++ static int started; ++ ++ assert(tokens_avail >= 0); ++ if (!tokens_avail) { ++ struct timeval delta, now; ++ int generated; ++ ++ if (!started) { ++ gettimeofday(&last_refil_time, NULL); ++ tokens_avail = TOKENS_MAX; ++ started = 1; ++ return; ++ } ++ retry: ++ gettimeofday(&now, NULL); ++ delta.tv_sec = now.tv_sec - last_refil_time.tv_sec; ++ delta.tv_usec = now.tv_usec - last_refil_time.tv_usec; ++ if (delta.tv_usec < 0) { ++ delta.tv_usec += 1000000; ++ delta.tv_sec--; ++ } ++ assert(delta.tv_usec >= 0 && delta.tv_sec >= 0); ++ if (delta.tv_usec < TOKEN_PERIOD) { ++ struct timespec ts; ++ /* Wait until at least one token is available. */ ++ ts.tv_sec = TOKEN_PERIOD / 1000000; ++ ts.tv_nsec = (TOKEN_PERIOD % 1000000) * 1000; ++ while (nanosleep(&ts, &ts) < 0 && errno == EINTR) ++ ; ++ goto retry; ++ } ++ generated = (delta.tv_sec * 1000000) / TOKEN_PERIOD; ++ generated += ++ ((delta.tv_sec * 1000000) % TOKEN_PERIOD + delta.tv_usec) / TOKEN_PERIOD; ++ assert(generated > 0); ++ ++ last_refil_time.tv_usec += (generated * TOKEN_PERIOD) % 1000000; ++ last_refil_time.tv_sec += last_refil_time.tv_usec / 1000000; ++ last_refil_time.tv_usec %= 1000000; ++ last_refil_time.tv_sec += (generated * TOKEN_PERIOD) / 1000000; ++ if (generated > TOKENS_MAX) ++ generated = TOKENS_MAX; ++ tokens_avail = generated; ++ } ++ tokens_avail--; + } + + static void serial_ioport_write(void *opaque, uint32_t addr, uint32_t val) +@@ -245,9 +309,11 @@ static uint32_t serial_ioport_read(void + ret = s->mcr; + break; + case 5: ++ serial_get_token(); + ret = s->lsr; + break; + case 6: ++ serial_get_token(); + if (s->mcr & UART_MCR_LOOP) { + /* in loopback, the modem output pins are connected to the + inputs */ +@@ -296,12 +362,14 @@ static void serial_receive1(void *opaque + static void serial_receive1(void *opaque, const uint8_t *buf, int size) + { + SerialState *s = opaque; ++ tokens_avail = TOKENS_MAX; + serial_receive_byte(s, buf[0]); + } + + static void serial_event(void *opaque, int event) + { + SerialState *s = opaque; ++ tokens_avail = TOKENS_MAX; + if (event == CHR_EVENT_BREAK) + serial_receive_break(s); + } |