This is the only vCPU command handled by the receiving thread.
It increments a pause request counter and kicks the vCPU out of guest.
Signed-off-by: Adalbert Lazăr <alazar@xxxxxxxxxxxxxxx>
---
Documentation/virt/kvm/kvmi.rst | 64 ++++++++++++++++++-
include/linux/kvmi_host.h | 2 +
include/uapi/linux/kvmi.h | 11 +++-
.../testing/selftests/kvm/x86_64/kvmi_test.c | 31 +++++++++
virt/kvm/introspection/kvmi.c | 63 ++++++++++++++++--
virt/kvm/introspection/kvmi_int.h | 1 +
virt/kvm/introspection/kvmi_msg.c | 44 +++++++++++++
7 files changed, 210 insertions(+), 6 deletions(-)
diff --git a/Documentation/virt/kvm/kvmi.rst b/Documentation/virt/kvm/kvmi.rst
index 16438e863003..642e2f10adfd 100644
--- a/Documentation/virt/kvm/kvmi.rst
+++ b/Documentation/virt/kvm/kvmi.rst
@@ -478,12 +478,51 @@ Returns the TSC frequency (in HZ) for the specified vCPU if available
* -KVM_EINVAL - the selected vCPU is invalid
* -KVM_EAGAIN - the selected vCPU can't be introspected yet
+9. KVMI_VCPU_PAUSE
+------------------
+
+:Architecture: all
+:Versions: >= 1
+:Parameters:
+
+::
+
+ struct kvmi_vcpu_hdr;
+ struct kvmi_vcpu_pause {
+ __u8 wait;
+ __u8 padding1;
+ __u16 padding2;
+ __u32 padding3;
+ };
+
+:Returns:
+
+::
+
+ struct kvmi_error_code;
+
+Kicks the vCPU out of guest.
+
+If `wait` is 1, the command will wait for vCPU to acknowledge the IPI.
+
+The vCPU will handle the pending commands/events and send the
+*KVMI_EVENT_PAUSE_VCPU* event (one for every successful *KVMI_VCPU_PAUSE*
+command) before returning to guest.
+
+:Errors:
+
+* -KVM_EINVAL - the padding is not zero
+* -KVM_EINVAL - the selected vCPU is invalid
+* -KVM_EAGAIN - the selected vCPU can't be introspected yet
+* -KVM_EBUSY - the selected vCPU has too many queued *KVMI_EVENT_PAUSE_VCPU* events
+* -KVM_EPERM - the *KVMI_EVENT_PAUSE_VCPU* event is disallowed
+
Events
======
All introspection events (VM or vCPU related) are sent
using the *KVMI_EVENT* message id. No event will be sent unless
-it is explicitly enabled.
+it is explicitly enabled or requested (eg. *KVMI_EVENT_PAUSE_VCPU*).
The *KVMI_EVENT_UNHOOK* event doesn't have a reply and share the kvmi_event
structure, for consistency with the vCPU events.
@@ -542,3 +581,26 @@ the guest (see **Unhooking**) and the introspection has been enabled
for this event (see **KVMI_VM_CONTROL_EVENTS**). The introspection tool
has a chance to unhook and close the KVMI channel (signaling that the
operation can proceed).
+
+2. KVMI_EVENT_PAUSE_VCPU
+------------------------
+
+:Architectures: all
+:Versions: >= 1
+:Actions: CONTINUE, CRASH
+:Parameters:
+
+::
+
+ struct kvmi_event;
+
+:Returns:
+
+::
+
+ struct kvmi_vcpu_hdr;
+ struct kvmi_event_reply;
+
+This event is sent in response to a *KVMI_VCPU_PAUSE* command.
+Because it has a low priority, it will be sent after any other vCPU
+introspection event and when no vCPU introspection command is queued.
diff --git a/include/linux/kvmi_host.h b/include/linux/kvmi_host.h
index 6a0fb481b192..988927c29bf5 100644
--- a/include/linux/kvmi_host.h
+++ b/include/linux/kvmi_host.h
@@ -23,6 +23,8 @@ struct kvm_vcpu_introspection {
struct list_head job_list;
spinlock_t job_lock;
+
+ atomic_t pause_requests;
};
struct kvm_introspection {
diff --git a/include/uapi/linux/kvmi.h b/include/uapi/linux/kvmi.h
index 4cdaad656de4..38954a5297da 100644
--- a/include/uapi/linux/kvmi.h
+++ b/include/uapi/linux/kvmi.h
@@ -26,12 +26,14 @@ enum {
KVMI_VM_WRITE_PHYSICAL = 8,
KVMI_VCPU_GET_INFO = 9,
+ KVMI_VCPU_PAUSE = 10,
KVMI_NUM_MESSAGES
};
enum {
- KVMI_EVENT_UNHOOK = 0,
+ KVMI_EVENT_UNHOOK = 0,
+ KVMI_EVENT_PAUSE_VCPU = 1,
KVMI_NUM_EVENTS
};
@@ -108,6 +110,13 @@ struct kvmi_vcpu_hdr {
__u32 padding2;
};
+struct kvmi_vcpu_pause {
+ __u8 wait;
+ __u8 padding1;
+ __u16 padding2;
+ __u32 padding3;
+};
+
struct kvmi_event {
__u16 size;
__u16 vcpu;
diff --git a/tools/testing/selftests/kvm/x86_64/kvmi_test.c b/tools/testing/selftests/kvm/x86_64/kvmi_test.c
index c765b1e5707d..bc84d478ff6b 100644
--- a/tools/testing/selftests/kvm/x86_64/kvmi_test.c
+++ b/tools/testing/selftests/kvm/x86_64/kvmi_test.c
@@ -655,6 +655,36 @@ static void test_cmd_get_vcpu_info(struct kvm_vm *vm)
DEBUG("tsc_speed: %llu HZ\n", rpl.tsc_speed);
}
+static int cmd_pause_vcpu(struct kvm_vm *vm)
+{
+ struct {
+ struct kvmi_msg_hdr hdr;
+ struct kvmi_vcpu_hdr vcpu_hdr;
+ struct kvmi_vcpu_pause cmd;
+ } req = {};
+ __u16 vcpu_index = 0;
+
+ req.vcpu_hdr.vcpu = vcpu_index;
+
+ return do_command(KVMI_VCPU_PAUSE, &req.hdr, sizeof(req),
+ NULL, 0);
+}
+
+static void pause_vcpu(struct kvm_vm *vm)
+{
+ int r;
+
+ r = cmd_pause_vcpu(vm);
+ TEST_ASSERT(r == 0,
+ "KVMI_VCPU_PAUSE failed, error %d(%s)\n",
+ -r, kvm_strerror(-r));
+}
+
+static void test_pause(struct kvm_vm *vm)
+{
+ pause_vcpu(vm);
+}
+
static void test_introspection(struct kvm_vm *vm)
{
srandom(time(0));
@@ -670,6 +700,7 @@ static void test_introspection(struct kvm_vm *vm)
test_cmd_vm_control_events();
test_memory_access(vm);
test_cmd_get_vcpu_info(vm);
+ test_pause(vm);
unhook_introspection(vm);
}
diff --git a/virt/kvm/introspection/kvmi.c b/virt/kvm/introspection/kvmi.c
index 65a77b8d2616..c4da264ad5a6 100644
--- a/virt/kvm/introspection/kvmi.c
+++ b/virt/kvm/introspection/kvmi.c
@@ -11,6 +11,8 @@
#define KVMI_MSG_SIZE_ALLOC (sizeof(struct kvmi_msg_hdr) + KVMI_MSG_SIZE)
+#define MAX_PAUSE_REQUESTS 1001
+
static DECLARE_BITMAP(Kvmi_always_allowed_commands, KVMI_NUM_COMMANDS);
DECLARE_BITMAP(Kvmi_known_events, KVMI_NUM_EVENTS);
DECLARE_BITMAP(Kvmi_known_vm_events, KVMI_NUM_EVENTS);
@@ -69,6 +71,7 @@ static void setup_known_events(void)
set_bit(KVMI_EVENT_UNHOOK, Kvmi_known_vm_events);
bitmap_zero(Kvmi_known_vcpu_events, KVMI_NUM_EVENTS);
+ set_bit(KVMI_EVENT_PAUSE_VCPU, Kvmi_known_vcpu_events);
bitmap_or(Kvmi_known_events, Kvmi_known_vm_events,
Kvmi_known_vcpu_events, KVMI_NUM_EVENTS);
@@ -87,10 +90,14 @@ void kvmi_uninit(void)
kvmi_cache_destroy();
}
-static void kvmi_make_request(struct kvm_vcpu *vcpu)
+static void kvmi_make_request(struct kvm_vcpu *vcpu, bool wait)
{
kvm_make_request(KVM_REQ_INTROSPECTION, vcpu);
- kvm_vcpu_kick(vcpu);
+
+ if (wait)
+ kvm_vcpu_kick_and_wait(vcpu);
+ else
+ kvm_vcpu_kick(vcpu);
}
static int __kvmi_add_job(struct kvm_vcpu *vcpu,
@@ -125,7 +132,7 @@ int kvmi_add_job(struct kvm_vcpu *vcpu,
err = __kvmi_add_job(vcpu, fct, ctx, free_fct);
if (!err)
- kvmi_make_request(vcpu);
+ kvmi_make_request(vcpu, false);
return err;
}
@@ -304,6 +311,22 @@ static int __kvmi_hook(struct kvm *kvm,
return 0;
}
+static void kvmi_job_release_vcpu(struct kvm_vcpu *vcpu, void *ctx)
+{
+ struct kvm_vcpu_introspection *vcpui = VCPUI(vcpu);
+
+ atomic_set(&vcpui->pause_requests, 0);
+}
+
+static void kvmi_release_vcpus(struct kvm *kvm)
+{
+ struct kvm_vcpu *vcpu;
+ int i;
+
+ kvm_for_each_vcpu(i, vcpu, kvm)
+ kvmi_add_job(vcpu, kvmi_job_release_vcpu, NULL, NULL);
+}
+
static int kvmi_recv_thread(void *arg)
{
struct kvm_introspection *kvmi = arg;
@@ -317,6 +340,8 @@ static int kvmi_recv_thread(void *arg)
*/
kvmi_sock_shutdown(kvmi);
+ kvmi_release_vcpus(kvmi->kvm);
+
kvmi_put(kvmi->kvm);
return 0;
}
@@ -681,15 +706,45 @@ void kvmi_run_jobs(struct kvm_vcpu *vcpu)
}
}
+static void kvmi_vcpu_pause_event(struct kvm_vcpu *vcpu)
+{
+ struct kvm_vcpu_introspection *vcpui = VCPUI(vcpu);
+
+ atomic_dec(&vcpui->pause_requests);
+ /* to be implemented */
+}
+
void kvmi_handle_requests(struct kvm_vcpu *vcpu)
{
+ struct kvm_vcpu_introspection *vcpui = VCPUI(vcpu);
struct kvm_introspection *kvmi;
kvmi = kvmi_get(vcpu->kvm);
if (!kvmi)
return;
- kvmi_run_jobs(vcpu);
+ for (;;) {
+ kvmi_run_jobs(vcpu);
+
+ if (atomic_read(&vcpui->pause_requests))
+ kvmi_vcpu_pause_event(vcpu);
+ else
+ break;
+ }
kvmi_put(vcpu->kvm);
}
+
+int kvmi_cmd_vcpu_pause(struct kvm_vcpu *vcpu, bool wait)
+{
+ struct kvm_vcpu_introspection *vcpui = VCPUI(vcpu);
+
+ if (atomic_read(&vcpui->pause_requests) > MAX_PAUSE_REQUESTS)
+ return -KVM_EBUSY;
+
+ atomic_inc(&vcpui->pause_requests);
+
+ kvmi_make_request(vcpu, wait);
+
+ return 0;
+}
diff --git a/virt/kvm/introspection/kvmi_int.h b/virt/kvm/introspection/kvmi_int.h
index 4a71e33d46ef..bd968e837a54 100644
--- a/virt/kvm/introspection/kvmi_int.h
+++ b/virt/kvm/introspection/kvmi_int.h
@@ -44,6 +44,7 @@ int kvmi_cmd_read_physical(struct kvm *kvm, u64 gpa, size_t size,
const struct kvmi_msg_hdr *ctx);
int kvmi_cmd_write_physical(struct kvm *kvm, u64 gpa, size_t size,
const void *buf);
+int kvmi_cmd_vcpu_pause(struct kvm_vcpu *vcpu, bool wait);
/* arch */
int kvmi_arch_cmd_vcpu_get_info(struct kvm_vcpu *vcpu,
diff --git a/virt/kvm/introspection/kvmi_msg.c b/virt/kvm/introspection/kvmi_msg.c
index 62dc50060a1e..772ba1d7d9df 100644
--- a/virt/kvm/introspection/kvmi_msg.c
+++ b/virt/kvm/introspection/kvmi_msg.c
@@ -28,6 +28,7 @@ static const char *const msg_IDs[] = {
[KVMI_VM_READ_PHYSICAL] = "KVMI_VM_READ_PHYSICAL",
[KVMI_VM_WRITE_PHYSICAL] = "KVMI_VM_WRITE_PHYSICAL",
[KVMI_VCPU_GET_INFO] = "KVMI_VCPU_GET_INFO",
+ [KVMI_VCPU_PAUSE] = "KVMI_VCPU_PAUSE",
};
static const char *id2str(u16 id)
@@ -298,6 +299,48 @@ static int handle_write_physical(struct kvm_introspection *kvmi,
return kvmi_msg_vm_reply(kvmi, msg, ec, NULL, 0);
}
+/*
+ * This vCPU command is handled from the receiving thread instead of
+ * the vCPU thread, to make it easier for userspace to implement a 'pause VM'
+ * command by sending a 'pause vCPU' command (with wait=1) for every vCPU.
+ * By handling the command here, the userspace can consider that the VM
+ * is stopped (no vCPU runs guest code) once it receives the reply
+ * for the last 'pause vCPU' command.
+ */
+static int handle_pause_vcpu(struct kvm_introspection *kvmi,
+ const struct kvmi_msg_hdr *msg,
+ const void *_req)
+{
+ const struct kvmi_vcpu_pause *req = _req;
+ const struct kvmi_vcpu_hdr *cmd;
+ struct kvm_vcpu *vcpu = NULL;
+ int err;
+
+ cmd = (const struct kvmi_vcpu_hdr *) (msg + 1);
+
+ if (invalid_vcpu_hdr(cmd) || req->wait > 0) {
+ err = -KVM_EINVAL;
+ goto reply;
+ }
+
+ if (req->padding1 || req->padding2 || req->padding3) {
+ err = -KVM_EINVAL;
+ goto reply;
+ }
+
+ if (!is_event_allowed(kvmi, KVMI_EVENT_PAUSE_VCPU)) {
+ err = -KVM_EPERM;
+ goto reply;
+ }
+
+ err = kvmi_get_vcpu(kvmi, cmd->vcpu, &vcpu);
+ if (!err)
+ err = kvmi_cmd_vcpu_pause(vcpu, req->wait == 1);
+
+reply:
+ return kvmi_msg_vm_reply(kvmi, msg, err, NULL, 0);
+}
+
/*
* These commands are executed by the receiving thread/worker.
*/
@@ -310,6 +353,7 @@ static int(*const msg_vm[])(struct kvm_introspection *,
[KVMI_VM_GET_INFO] = handle_get_info,
[KVMI_VM_READ_PHYSICAL] = handle_read_physical,
[KVMI_VM_WRITE_PHYSICAL] = handle_write_physical,
+ [KVMI_VCPU_PAUSE] = handle_pause_vcpu,
};
static bool is_vm_command(u16 id)
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