GitHub-Mirror/Star64_linux
2
0
Fork 0
mirror of https://github.com/Fishwaldo/Star64_linux.git synced 2025-07-23 07:12:09 +00:00
Code Issues Projects Releases Packages Wiki Activity Actions

[S390] s390-kvm: leave sie context on work. Removes preemption requirement

Browse source 
From: Martin Schwidefsky <schwidefsky@de.ibm.com>

This patch fixes a bug with cpu bound guest on kvm-s390. Sometimes it
was impossible to deliver a signal to a spinning guest. We used
preemption as a circumvention. The preemption notifiers called
vcpu_load, which checked for pending signals and triggered a host
intercept. But even with preemption, a sigkill was not delivered
immediately.

This patch changes the low level host interrupt handler to check for the
SIE  instruction, if TIF_WORK is set. In that case we change the
instruction pointer of the return PSW to rerun the vcpu_run loop. The kvm
code sees an intercept reason 0 if that happens. This patch adds accounting
for these types of intercept as well.

The advantages:
- works with and without preemption
- signals are delivered immediately
- much better host latencies without preemption

Acked-by: Carsten Otte <cotte@de.ibm.com>
Signed-off-by: Christian Borntraeger <borntraeger@de.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
This commit is contained in:
Christian Borntraeger 2008-05-07 09:22:53 +02:00 • committed by Martin Schwidefsky
parent 2688905e6a
commit 0eaeafa10f
5 changed files with 34 additions and 6 deletions
Download patch file Download diff file Expand all files Collapse all files

3
arch/s390/kvm/intercept.c
View file

@ -105,6 +105,9 @@ static intercept_handler_t instruction_handlers[256] = {
static int handle_noop(struct kvm_vcpu *vcpu)
{
switch (vcpu->arch.sie_block->icptcode) {
case 0x0:
vcpu->stat.exit_null++;
break;
case 0x10:
vcpu->stat.exit_external_request++;
break;