Hi,
Is it bad if the olatch counts up if the host's wall clock
is set backward? Or if the olatch makes a big jump for
the same reason?
Serious question: I don't have any EPT hardware to test
this (sorry).
While here, it looks like we can (a) roll the olatch-writing
parts of i8253_do_readback into a loop, and (b) use the
timespecsub macro from sys/time.h, to make the code briefer.
Anyone down to test?
--
Scott Cheloha
Index: usr.sbin/vmd/i8253.c
===================================================================
RCS file: /cvs/src/usr.sbin/vmd/i8253.c,v
retrieving revision 1.17
diff -u -p -r1.17 i8253.c
--- usr.sbin/vmd/i8253.c 14 Aug 2017 19:46:44 -0000 1.17
+++ usr.sbin/vmd/i8253.c 18 Feb 2018 17:53:48 -0000
@@ -25,6 +25,7 @@
#include <event.h>
#include <string.h>
#include <stddef.h>
+#include <time.h>
#include <unistd.h>
#include "i8253.h"
@@ -53,7 +54,7 @@ void
i8253_init(uint32_t vm_id)
{
memset(&i8253_channel, 0, sizeof(struct i8253_channel));
- gettimeofday(&i8253_channel[0].tv, NULL);
+ clock_gettime(CLOCK_MONOTONIC, &i8253_channel[0].ts);
i8253_channel[0].start = 0xFFFF;
i8253_channel[0].mode = TIMER_INTTC;
i8253_channel[0].last_r = 1;
@@ -86,8 +87,10 @@ i8253_init(uint32_t vm_id)
void
i8253_do_readback(uint32_t data)
{
- struct timeval now, delta;
+ struct timespec now, delta;
uint64_t ns, ticks;
+ int readback_channel[3] = { TIMER_RB_C0, TIMER_RB_C1, TIMER_RB_C2 };
+ int i;
/* bits are inverted here - !TIMER_RB_STATUS == enable chan readback */
if (data & ~TIMER_RB_STATUS) {
@@ -98,73 +101,19 @@ i8253_do_readback(uint32_t data)
/* !TIMER_RB_COUNT == enable counter readback */
if (data & ~TIMER_RB_COUNT) {
- if (data & TIMER_RB_C0) {
- gettimeofday(&now, NULL);
- delta.tv_sec = now.tv_sec - i8253_channel[0].tv.tv_sec;
- delta.tv_usec = now.tv_usec -
- i8253_channel[0].tv.tv_usec;
- if (delta.tv_usec < 0) {
- delta.tv_sec--;
- delta.tv_usec += 1000000;
+ for (i = 0; i < 3; i++) {
+ if (data & readback_channel[i]) {
+ clock_gettime(CLOCK_MONOTONIC, &now);
+ timespecsub(&now, &i8253_channel[i].ts, &delta);
+ ns = delta.tv_sec * 1000000000 + delta.tv_nsec;
+ ticks = ns / NS_PER_TICK;
+ if (i8253_channel[i].start)
+ i8253_channel[i].olatch =
+ i8253_channel[i].start -
+ ticks % i8253_channel[i].start;
+ else
+ i8253_channel[i].olatch = 0;
}
- if (delta.tv_usec > 1000000) {
- delta.tv_sec++;
- delta.tv_usec -= 1000000;
- }
- ns = delta.tv_usec * 1000 + delta.tv_sec * 1000000000;
- ticks = ns / NS_PER_TICK;
- if (i8253_channel[0].start)
- i8253_channel[0].olatch =
- i8253_channel[0].start -
- ticks % i8253_channel[0].start;
- else
- i8253_channel[0].olatch = 0;
- }
-
- if (data & TIMER_RB_C1) {
- gettimeofday(&now, NULL);
- delta.tv_sec = now.tv_sec - i8253_channel[1].tv.tv_sec;
- delta.tv_usec = now.tv_usec -
- i8253_channel[1].tv.tv_usec;
- if (delta.tv_usec < 0) {
- delta.tv_sec--;
- delta.tv_usec += 1000000;
- }
- if (delta.tv_usec > 1000000) {
- delta.tv_sec++;
- delta.tv_usec -= 1000000;
- }
- ns = delta.tv_usec * 1000 + delta.tv_sec * 1000000000;
- ticks = ns / NS_PER_TICK;
- if (i8253_channel[1].start)
- i8253_channel[1].olatch =
- i8253_channel[1].start -
- ticks % i8253_channel[1].start;
- else
- i8253_channel[1].olatch = 0;
- }
-
- if (data & TIMER_RB_C2) {
- gettimeofday(&now, NULL);
- delta.tv_sec = now.tv_sec - i8253_channel[2].tv.tv_sec;
- delta.tv_usec = now.tv_usec -
- i8253_channel[2].tv.tv_usec;
- if (delta.tv_usec < 0) {
- delta.tv_sec--;
- delta.tv_usec += 1000000;
- }
- if (delta.tv_usec > 1000000) {
- delta.tv_sec++;
- delta.tv_usec -= 1000000;
- }
- ns = delta.tv_usec * 1000 + delta.tv_sec * 1000000000;
- ticks = ns / NS_PER_TICK;
- if (i8253_channel[2].start)
- i8253_channel[2].olatch =
- i8253_channel[2].start -
- ticks % i8253_channel[2].start;
- else
- i8253_channel[2].olatch = 0;
}
}
}
@@ -188,7 +137,7 @@ vcpu_exit_i8253(struct vm_run_params *vr
uint32_t out_data;
uint8_t sel, rw, data, mode;
uint64_t ns, ticks;
- struct timeval now, delta;
+ struct timespec now, delta;
union vm_exit *vei = vrp->vrp_exit;
get_input_data(vei, &out_data);
@@ -216,21 +165,9 @@ vcpu_exit_i8253(struct vm_run_params *vr
* rate.
*/
if (rw == TIMER_LATCH) {
- gettimeofday(&now, NULL);
- delta.tv_sec = now.tv_sec -
- i8253_channel[sel].tv.tv_sec;
- delta.tv_usec = now.tv_usec -
- i8253_channel[sel].tv.tv_usec;
- if (delta.tv_usec < 0) {
- delta.tv_sec--;
- delta.tv_usec += 1000000;
- }
- if (delta.tv_usec > 1000000) {
- delta.tv_sec++;
- delta.tv_usec -= 1000000;
- }
- ns = delta.tv_usec * 1000 +
- delta.tv_sec * 1000000000;
+ clock_gettime(CLOCK_MONOTONIC, &now);
+ timespecsub(&now, &i8253_channel[sel].ts,
&delta);
+ ns = delta.tv_sec * 1000000000 + delta.tv_nsec;
ticks = ns / NS_PER_TICK;
if (i8253_channel[sel].start) {
i8253_channel[sel].olatch =
Index: usr.sbin/vmd/i8253.h
===================================================================
RCS file: /cvs/src/usr.sbin/vmd/i8253.h,v
retrieving revision 1.7
diff -u -p -r1.7 i8253.h
--- usr.sbin/vmd/i8253.h 9 Jul 2017 00:51:40 -0000 1.7
+++ usr.sbin/vmd/i8253.h 18 Feb 2018 17:53:48 -0000
@@ -29,7 +29,7 @@
/* i8253 registers */
struct i8253_channel {
- struct timeval tv; /* timer start time */
+ struct timespec ts; /* timer start time */
uint16_t start; /* starting value */
uint16_t olatch; /* output latch */
uint16_t ilatch; /* input latch */
