On 1/19/21 5:53 PM, Cornelia Huck wrote:
On Mon, 18 Jan 2021 14:17:39 +0100
Christian Borntraeger <borntraeger@xxxxxxxxxx> wrote:
From: Pierre Morel <pmorel@xxxxxxxxxxxxx>
When we receive intercept a DIAG_9C from the guest we verify
that the target real CPU associated with the virtual CPU
designated by the guest is running and if not we forward the
DIAG_9C to the target real CPU.
To avoid a diag9c storm we allow a maximal rate of diag9c forwarding.
The rate is calculated as a count per second defined as a
new parameter of the s390 kvm module: diag9c_forwarding_hz .
The default value is to not forward diag9c.
Signed-off-by: Pierre Morel <pmorel@xxxxxxxxxxxxx>
Signed-off-by: Christian Borntraeger <borntraeger@xxxxxxxxxx>
---
arch/s390/include/asm/kvm_host.h | 1 +
arch/s390/include/asm/smp.h | 1 +
arch/s390/kernel/smp.c | 1 +
arch/s390/kvm/diag.c | 31 ++++++++++++++++++++++++++++---
arch/s390/kvm/kvm-s390.c | 6 ++++++
arch/s390/kvm/kvm-s390.h | 8 ++++++++
6 files changed, 45 insertions(+), 3 deletions(-)
(...)
@@ -167,9 +180,21 @@ static int __diag_time_slice_end_directed(struct kvm_vcpu *vcpu)
if (!tcpu)
goto no_yield;
- /* target already running */
- if (READ_ONCE(tcpu->cpu) >= 0)
- goto no_yield;
+ /* target VCPU already running */
Maybe make this /* target guest VPCU already running */...
+ if (READ_ONCE(tcpu->cpu) >= 0) {
+ if (!diag9c_forwarding_hz || diag9c_forwarding_overrun())
+ goto no_yield;
+
+ /* target CPU already running */
...and this /* target host CPU already running */? I just read this
several times and was confused before I spotted the difference :)
I can only agree then :) .
...
--
Pierre Morel
IBM Lab Boeblingen
