Problems on AMD laptops
kerneloops.org shows tons of oopses on amd, see http://www.kerneloops.org/oops.php?number=79008. I suspect this has to do with resuming a laptop while a guest is running. Can anyone confirm or deny?
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error compiling committee.c: too many arguments to function
Quoted 4 lines · Avi Kivity
kerneloops.org shows tons of oopses on amd, see
http://www.kerneloops.org/oops.php?number=79008. I suspect this has to do with resuming a laptop while a guest is running. Can anyone confirm or deny?
I havn't verified this yet but it may have to do with dirty caches that are not written back to memory in suspend-to-ram and are thus lost. The resume code-path looks otherwise sane to me. The only thing I can imagine is that a bit in the cpu_hardware_enabled cpumask is wrong after resume.
Btw. it is guaranteed that with cpu-hotplug the cpu isn't already executing processes when the CPU_ONLINE event call chain is called? At least the CPU is marked online and active at that point in time.
Joerg
Quoted 10 lines · Joerg Roedel
Quoted 5 lines · Avi Kivity
kerneloops.org shows tons of oopses on amd, see
http://www.kerneloops.org/oops.php?number=79008. I suspect this has to do with resuming a laptop while a guest is running. Can anyone confirm or deny?I havn't verified this yet but it may have to do with dirty caches that are not written back to memory in suspend-to-ram and are thus lost.
Wouldn't that kill resume generally, not just kvm on amd?
Quoted 5 lines
The
resume code-path looks otherwise sane to me. The only thing I can imagine is that a bit in thecpu_hardware_enabledcpumask is wrong after resume.
I saw some of these oopses on cpu 0, which had better be plugged in.
Quoted 4 lines
Btw. it is guaranteed that with cpu-hotplug the cpu isn't already executing processes when the
CPU_ONLINEevent call chain is called? At least the CPU is marked online and active at that point in time.
Yes:
static struct notifier_block kvm_cpu_notifier = {
.notifier_call = kvm_cpu_hotplug, .priority = 20, /* must be > scheduler priority */
};
One thing I think is missing is a call to svm_cpu_init() on real hotplug.
Signature · 1 line
error compiling committee.c: too many arguments to function
Quoted 9 lines · Avi Kivity
Quoted 8 lines · Joerg Roedel
Quoted 5 lines · Avi Kivity
kerneloops.org shows tons of oopses on amd, see
http://www.kerneloops.org/oops.php?number=79008. I suspect this has to do with resuming a laptop while a guest is running. Can anyone confirm or deny?
Quoted 4 lines
Quoted 2 lines
I havn't verified this yet but it may have to do with dirty caches that are not written back to memory in suspend-to-ram and are thus lost.
Wouldn't that kill resume generally, not just kvm on amd?
Its a race condition which may be more likely on one hardware than on another. I remember similar bugs fixed by Mark in the past.
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The
resume code-path looks otherwise sane to me. The only thing I can imagine is that a bit in thecpu_hardware_enabledcpumask is wrong after resume.I saw some of these oopses on cpu 0, which had better be plugged in.
Yeah, but if this bit is set to 0 on suspend and this change does not make it from cache to main memory it can still be 1 on resume. And virtualization hardware will not be re-enabled then.
Anyway, this was only a guess from me. I think we should reproduce this oops and find out what is really going on.
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Btw. it is guaranteed that with cpu-hotplug the cpu isn't already executing processes when the
CPU_ONLINEevent call chain is called? At least the CPU is marked online and active at that point in time.Yes:
static struct
notifier_blockkvm_cpu_notifier= {
.notifier_call =kvm_cpu_hotplug, .priority = 20, /* must be > scheduler priority */
};
Ok.
Quoted 1 line
One thing I think is missing is a call to
svm_cpu_init()on real hotplug.
Yes, true. There is no svm_data allocated for cpus not online on module load.
Joerg