Hi Oliver,
On 3/25/22 3:35 PM, Oliver Upton wrote:
On Fri, Mar 25, 2022 at 02:59:52PM +0800, Gavin Shan wrote:
The PSCI implementation is a great example of how KVM has grown its
implementation in line with a specification, all the while preserving
backwards compatibility.
The only information feed by VMM is the exposed events. The events
can't be registered from guest kernel, and raised from host to guest
kernel until it's exposed by VMM.
I would suggest assuming that all SDEI events are exposed by default in
KVM. We will not require a VMM change to enable events individually.
Ok, it was exactly what I did in v4, but the event is exposed
by VMM in v5. In v6, it will be staticly defined again :)
Besides, the exposed events will
be defined staticly in host/KVM as we discussed on PATCH[02/22]. We
also discussed to eliminate those ioctl commands. So I think we needn't
to add KVM_SDEI_CMD_SET_VERSION. Further more, the version is only a
concern to host itself if the migration can be done through the
firmware pseudo system registers since the migration compatibility
is the only concern to VMM (QEMU).
This all needs to work just like the KVM_REG_ARM_PSCI_VERSION version,
I'd recommend taking a look at how we handle that register in KVM.
Ok. I will do necessary investigation :)
Yes, Currently, 0.1/0.2/1.0 versions are supported by PSCI. 0.1 is
picked until VMM asks for 0.2 and 1.0 explicitly. However, it seems
QEMU isn't using 1.0 PSCI yet and maybe more patch is needed to enable
it.
As far as how it interacts with KVM, QEMU looks fine. The name of the
KVM_ARM_VCPU_PSCI_0_2 bit is quite frustrating. It actually implies that
KVM will enable it highest supported PSCI version. If the feature bit is
cleared then you only get PSCIv0.1
However, the DT node that QEMU sets up looks a bit crusty. The
properties for conveying PSCI function IDs were only ever necessary for
PSCIv0.1. The only property of interest any more is 'method', to convey
the SMCCC conduit instruction.
Ok, Thanks again for the further information about PSCI implementation.
I will go through the code when I have free cycyles :)
Thanks,
Gavin
_______________________________________________
kvmarm mailing list
kvmarm@xxxxxxxxxxxxxxxxxxxxx
https://lists.cs.columbia.edu/mailman/listinfo/kvmarm
