On Wed, Sep 21, 2022 at 2:39 PM David Matlack <dmatlack@xxxxxxxxxx> wrote: > > On Thu, Sep 15, 2022 at 12:04:44AM +0000, Vishal Annapurve wrote: > > Cache the vendor CPU type in a global variable so that multiple calls > > to is_intel_cpu() do not need to re-execute CPUID. > > > > Add cpu vendor check in kvm_hypercall() so that it executes correct > > vmcall/vmmcall instruction when running on Intel/AMD hosts. This avoids > > exit to KVM which anyway tries to patch the instruction according to > > the cpu type. > > Out of curiousity, why do we want to avoid this exit? Referring to the patch set posted for UPM selftests with non-confidential VMs [1], vmcall patching will not work for selftests executed with UPM feature enabled since guest memory can not be modified by KVM. So I tried to add a kvm_hypercall implementation that will execute the hypercall according to the cpu type. Hypercall updates in this series are done to ensure that such a change is done for all callers to allow consistency and avoid relying on KVM behavior to patch the vmmcall/vmcall instruction. [1] https://lore.kernel.org/lkml/20220819174659.2427983-5-vannapurve@xxxxxxxxxx/
