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kvm tools: Fix 'kill -3' hangs

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Ingo Molnar reported that 'kill -3' didn't work on his machine:

  * Ingo Molnar <mingo@elte.hu> wrote:

  > This is really cumbersome to debug - is there some good way to get to the RIP
  > that the guest is hanging in? If kvm would print that out to the host console
  > (even if it's just the raw RIP initially) on a kill -3 that would help
  > enormously.

  Looks like the code should be doing that already - but the ioctl(KVM_GET_SREGS)
  hangs:

    [pid   748] ioctl(6, KVM_GET_SREGS

Avi Kivity pointed out that it's not safe to call KVM_GET_SREGS (or other vcpu
related ioctls) from other threads:

  > is it not OK to call KVM_GET_SREGS from other threads than the one
  > that's doing KVM_RUN?

  From Documentation/kvm/api.txt:

   - vcpu ioctls: These query and set attributes that control the operation
     of a single virtual cpu.

     Only run vcpu ioctls from the same thread that was used to create the
     vcpu.

Fix that up by using pthread_kill() to force the threads that are doing KVM_RUN
to do the register dumps.

Reported: Ingo Molnar <mingo@elte.hu>
Cc: Asias He <asias.hejun@gmail.com>
Cc: Avi Kivity <avi@redhat.com>
Cc: Cyrill Gorcunov <gorcunov@gmail.com>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: Prasad Joshi <prasadjoshi124@gmail.com>
Cc: Sasha Levin <levinsasha928@gmail.com>
Signed-off-by: Pekka Enberg <penberg@kernel.org>
This commit is contained in:
Pekka Enberg
2015-06-01 16:39:43 +01:00
committed by Will Deacon
parent 6a5e9cf4e6
commit 43119af7e7
1 changed files with 17 additions and 3 deletions
Download Patch File Download Diff File Expand all files Collapse all files
kvm-run.c
+17 -3
View File
@@ -127,6 +127,18 @@ static const struct option options[] = {
OPT_END()
};
static void handle_sigusr1(int sig)
{
struct kvm_cpu *cpu = current_kvm_cpu;
if (!cpu)
return;
kvm_cpu__show_registers(cpu);
kvm_cpu__show_code(cpu);
kvm_cpu__show_page_tables(cpu);
}
static void handle_sigquit(int sig)
{
int i;
@@ -134,9 +146,10 @@ static void handle_sigquit(int sig)
for (i = 0; i < nrcpus; i++) {
struct kvm_cpu *cpu = kvm_cpus[i];
kvm_cpu__show_registers(cpu);
kvm_cpu__show_code(cpu);
kvm_cpu__show_page_tables(cpu);
if (!cpu)
continue;
pthread_kill(cpu->thread, SIGUSR1);
}
serial8250__inject_sysrq(kvm);
@@ -332,6 +345,7 @@ int kvm_cmd_run(int argc, const char **argv, const char *prefix)
signal(SIGALRM, handle_sigalrm);
signal(SIGQUIT, handle_sigquit);
signal(SIGUSR1, handle_sigusr1);
while (argc != 0) {
argc = parse_options(argc, argv, options, run_usage,