On 5/16/22 16:13, Pierre Morel wrote:
On 5/12/22 11:24, David Hildenbrand wrote:
On 06.05.22 11:24, Pierre Morel wrote:
We let the userland hypervisor know if the machine support the CPU
topology facility using a new KVM capability: KVM_CAP_S390_CPU_TOPOLOGY.
The PTF instruction will report a topology change if there is any change
with a previous STSI_15_1_2 SYSIB.
Changes inside a STSI_15_1_2 SYSIB occur if CPU bits are set or clear
inside the CPU Topology List Entry CPU mask field, which happens with
changes in CPU polarization, dedication, CPU types and adding or
removing CPUs in a socket.
The reporting to the guest is done using the Multiprocessor
Topology-Change-Report (MTCR) bit of the utility entry of the guest's
SCA which will be cleared during the interpretation of PTF.
To check if the topology has been modified we use a new field of the
arch vCPU to save the previous real CPU ID at the end of a schedule
and verify on next schedule that the CPU used is in the same socket.
We do not report polarization, CPU Type or dedication change.
STSI(15.1.x) gives information on the CPU configuration topology.
Let's accept the interception of STSI with the function code 15 and
let the userland part of the hypervisor handle it when userland
support the CPU Topology facility.
Signed-off-by: Pierre Morel <pmorel@xxxxxxxxxxxxx>
[...]
diff --git a/arch/s390/kvm/priv.c b/arch/s390/kvm/priv.c
index 0e8603acc105..d9e16b09c8bf 100644
--- a/arch/s390/kvm/priv.c
+++ b/arch/s390/kvm/priv.c
@@ -874,10 +874,12 @@ static int handle_stsi(struct kvm_vcpu *vcpu)
if (vcpu->arch.sie_block->gpsw.mask & PSW_MASK_PSTATE)
return kvm_s390_inject_program_int(vcpu, PGM_PRIVILEGED_OP);
- if (fc > 3) {
- kvm_s390_set_psw_cc(vcpu, 3);
- return 0;
- }
+ if (fc > 3 && fc != 15)
+ goto out_no_data;
+
+ /* fc 15 is provided with PTF/CPU topology support */
+ if (fc == 15 && !test_kvm_facility(vcpu->kvm, 11))
+ goto out_no_data;
Maybe shorter as
if (fc == 15 && !test_kvm_facility(vcpu->kvm, 11))
goto out_no_data;
else if (fc > 3)
goto out_no_data;
yes.
hum, sorry, but no.
when test_kvm_facility(11) is true then !test_kvm_facility(11) is false
and the first test fails
and the second succeed jumping to out_no_data for fc == 15
I can use what I proposed with a comment to make it better readable.
What about:
/* Bailout forbidden function codes */
if (fc > 3 && fc != 15)
goto out_no_data;
/* fc 15 is provided with PTF/CPU topology support */
if (fc == 15 && !test_kvm_facility(vcpu->kvm, 11))
goto out_no_data;
Apart from that, LGTM.
Thanks,
Pierre
--
Pierre Morel
IBM Lab Boeblingen
