On Thu, Sep 8, 2022 at 3:54 PM David Matlack dmatlack@google.com wrote:
Please use "KVM: selftest: ..." for the shortlog.
Ack.
On Sat, Sep 03, 2022 at 01:28:47AM +0000, Vishal Annapurve wrote:
Modify following APIs for x86 implementation:
- kvm_arch_main : Query the cpu vendor and cache the value in advance.
- kvm_arch_post_vm_load: Populate cpu type in the guest memory so that guest doesn't need to execute cpuid instruction again.
This commit message only describes a subset of the changes in this commit, and does not provide any context on why the changes are being made (other than a clue about avoiding CPUID).
I also think this could be split up into 2 separate commits.
Ack, will add more details to the commit log. Though since is_amd_cpu/is_intel_cpu is used by both selftest VMM and selftest guest logic, I would prefer to not split this change into two. For now, I will upload the series with this change being a single patch. We can discuss again if this split is really needed.
Regards, Vishal
I would suggest first patch changes is_{intel,amd}_cpu() to return a cached result. e.g.
KVM: selftests: Precompute the result for is_{intel,amd}_cpu()
Cache the vendor CPU type in a global variable so that multiple calls to is_intel_cpu() do not need to re-execute CPUID. This will be useful in a follow-up commit to check if running on AMD or Intel from within a selftest guest where executing CPUID requires a VM-exit.
Then add support for AMD to kvm_hypercall():
KVM: selftests: Add AMD support to kvm_hypercall()
Add support for AMD hypercalls to kvm_hypercall() so that it can be used in selftests running on Intel or AMD hosts. This will be used in a follow up commit to ...
As part of this change, sync the global variable is_cpu_amd into the guest so the guest can determine which hypercall instruction to use without needing to re-execute CPUID for every hypercall.