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Pop pending events after pausing vm #1026

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merged 3 commits into from Jun 2, 2022
Merged

Pop pending events after pausing vm #1026

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5130eb3
Remove unused includes
May 9, 2022
4b4f064
Remove unnecessary indirections
May 9, 2022
bc35816
Make sure all pause events are popped for resuming
May 9, 2022
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75 changes: 23 additions & 52 deletions libvmi/driver/kvm/kvm.c
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Expand Up @@ -31,24 +31,13 @@
#include <stdio.h>
#include <stdint.h>
#include <stdlib.h>
#include <sys/un.h>
#include <sys/mman.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <sys/socket.h>
#include <sys/time.h>
#include <unistd.h>
#include <fcntl.h>
#include <glib.h>
#include <math.h>
#include <glib/gstdio.h>
#include <libvirt/libvirt.h>
#include <libvirt/virterror.h>
#include <libkvmi.h>

#include "private.h"
#include "msr-index.h"
#include "driver/driver_wrapper.h"
#include "driver/memory_cache.h"
#include "driver/kvm/kvm.h"
#include "driver/kvm/kvm_private.h"
Expand Down Expand Up @@ -1004,7 +993,7 @@ kvm_pause_vm(
{
kvm_instance_t *kvm = kvm_get_instance(vmi);
// already paused ?
if (kvm->expected_pause_count)
if (kvm->paused)
return VMI_SUCCESS;

// pause vcpus
Expand All @@ -1013,9 +1002,9 @@ kvm_pause_vm(
return VMI_FAILURE;
}

kvm->expected_pause_count = vmi->num_vcpus;
kvm->paused = true;

dbprint(VMI_DEBUG_KVM, "--We should receive %u pause events\n", kvm->expected_pause_count);
dbprint(VMI_DEBUG_KVM, "--We should receive %u pause events\n", vmi->num_vcpus);

return VMI_SUCCESS;
}
Expand All @@ -1027,54 +1016,36 @@ kvm_resume_vm(
kvm_instance_t *kvm = kvm_get_instance(vmi);

// already resumed ?
if (!kvm->expected_pause_count)
if (!kvm->paused)
return VMI_SUCCESS;

// wait to receive pause events
while (kvm->expected_pause_count) {
// iterate over pause_events_list and unpause every single vcpu by sending a continue reply for each pause event
for (unsigned int vcpu = 0; vcpu < vmi->num_vcpus; vcpu++) {
struct kvmi_dom_event *ev = NULL;
unsigned int ev_id = 0;

// check pause events poped by vmi_events_listen first
for (unsigned int vcpu = 0; vcpu < vmi->num_vcpus; vcpu++) {
if (kvm->pause_events_list[vcpu]) {
dbprint(VMI_DEBUG_KVM, "--Removing PAUSE_VCPU event from the buffer\n");
ev = kvm->pause_events_list[vcpu];
kvm->pause_events_list[vcpu] = NULL;
break;
}
}

// if no pause event is waiting in the list, pop next one
if (!ev) {
if (VMI_FAILURE == kvm_get_next_event(kvm, &ev, 1000)) {
errprint("Failed to get next KVMi event\n");
}
if (!ev) {
// no new events
// report error
// wait until the pause event for the current vcpu is received
while (!kvm->pause_events_list[vcpu]) {
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dbprint(VMI_DEBUG_KVM, "--Waiting to receive PAUSE_VCPU event for vcpu %u\n", vcpu);
if (kvm_process_events_with_timeout(vmi, 100) == VMI_FAILURE) {
return VMI_FAILURE;
}
}

dbprint(VMI_DEBUG_KVM, "--Removing PAUSE_VCPU event from the buffer\n");
ev = kvm->pause_events_list[vcpu];
kvm->pause_events_list[vcpu] = NULL;

// handle event
ev_id = ev->event.common.event;
switch (ev_id) {
case KVMI_EVENT_PAUSE_VCPU:
dbprint(VMI_DEBUG_KVM, "--Received VCPU pause event\n");
kvm->expected_pause_count--;
if (reply_continue(kvm, ev) == VMI_FAILURE) {
errprint("%s: Fail to send continue reply", __func__);
free(ev);
return VMI_FAILURE;
}
free(ev);
break;
default:
errprint("%s: Unexpected event %u\n", __func__, ev_id);
free(ev);
return VMI_FAILURE;
dbprint(VMI_DEBUG_KVM, "--Sending continue reply\n");
if (reply_continue(kvm, ev) == VMI_FAILURE) {
errprint("%s: Failed to send continue reply\n", __func__);
free(ev);
return VMI_FAILURE;
}
free(ev);
}

kvm->paused = false;

return VMI_SUCCESS;
}
20 changes: 12 additions & 8 deletions libvmi/driver/kvm/kvm_events.c
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Expand Up @@ -821,7 +821,7 @@ kvm_events_destroy(
dbprint(VMI_DEBUG_KVM, "--Destroying KVM driver events\n");
// pause VM
dbprint(VMI_DEBUG_KVM, "--Ensure VM is paused\n");
if (VMI_FAILURE == vmi_pause_vm(vmi))
if (VMI_FAILURE == kvm_pause_vm(vmi))
errprint("--Failed to pause VM while destroying events\n");

reg_event_t regevent = { .in_access = VMI_REGACCESS_N };
Expand Down Expand Up @@ -878,13 +878,13 @@ kvm_events_destroy(
// clean event queue
if (kvm_are_events_pending(vmi)) {
dbprint(VMI_DEBUG_KVM, "--Cleanup event queue\n");
if (VMI_FAILURE == vmi_events_listen(vmi, 0))
if (VMI_FAILURE == kvm_events_listen(vmi, 0))
errprint("--Failed to clean event queue\n");
}

// resume VM
dbprint(VMI_DEBUG_KVM, "--Resume VM\n");
if (VMI_FAILURE == vmi_resume_vm(vmi))
if (VMI_FAILURE == kvm_resume_vm(vmi))
errprint("--Failed to resume VM while destroying events\n");
}

Expand Down Expand Up @@ -952,8 +952,8 @@ process_pending_events(vmi_instance_t vmi)
return VMI_SUCCESS;
}

static status_t
process_events_with_timeout(vmi_instance_t vmi, uint32_t timeout)
status_t
kvm_process_events_with_timeout(vmi_instance_t vmi, uint32_t timeout)
{
kvm_instance_t *kvm = kvm_get_instance(vmi);
struct kvmi_dom_event *event = NULL;
Expand Down Expand Up @@ -992,7 +992,7 @@ kvm_events_listen(

GSList *loop;

if (process_events_with_timeout(vmi, timeout) == VMI_FAILURE) {
if (kvm_process_events_with_timeout(vmi, timeout) == VMI_FAILURE) {
return VMI_FAILURE;
}

Expand All @@ -1004,7 +1004,9 @@ kvm_events_listen(
* are pending we can remove/swap the events.
*/
if (vmi->swap_events || (vmi->clear_events && g_hash_table_size(vmi->clear_events))) {
vmi_pause_vm(vmi);
if (kvm_pause_vm(vmi) == VMI_FAILURE) {
return VMI_FAILURE;
}
if (process_pending_events(vmi) == VMI_FAILURE) {
return VMI_FAILURE;
}
Expand All @@ -1023,7 +1025,9 @@ kvm_events_listen(

g_hash_table_foreach_remove(vmi->clear_events, clear_events_full, vmi);

vmi_resume_vm(vmi);
if (kvm_resume_vm(vmi) == VMI_FAILURE) {
return VMI_FAILURE;
}
}

return VMI_SUCCESS;
Expand Down
5 changes: 5 additions & 0 deletions libvmi/driver/kvm/kvm_events.h
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Expand Up @@ -38,6 +38,11 @@ kvm_events_init(
void
kvm_events_destroy(vmi_instance_t vmi);

status_t
kvm_process_events_with_timeout(
vmi_instance_t vmi,
uint32_t timeout);

status_t
kvm_events_listen(
vmi_instance_t vmi,
Expand Down
4 changes: 2 additions & 2 deletions libvmi/driver/kvm/kvm_private.h
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Expand Up @@ -56,8 +56,8 @@ typedef struct kvm_instance {
libkvmi_wrapper_t libkvmi;
pthread_mutex_t kvm_connect_mutex;
pthread_cond_t kvm_start_cond;
unsigned int expected_pause_count;
// store KVMI_EVENT_PAUSE_VCPU events poped by vmi_events_listen(vmi, 0)
bool paused;
// store KVMI_EVENT_PAUSE_VCPU events popped by vmi_events_listen(vmi, 0)
// to be used by vmi_resume_vm()
struct kvmi_dom_event** pause_events_list;
// dispatcher to handle VM events in each process_xxx functions
Expand Down