Re: [PATCH] KVM: nVMX: Dynamically compute max VMCS index for vmcs12

From: Paolo Bonzini
Date: Mon Jun 21 2021 - 12:44:26 EST


On 18/06/21 23:46, Sean Christopherson wrote:
Calculate the max VMCS index for vmcs12 by walking the array to find the
actual max index. Hardcoding the index is prone to bitrot, and the
calculation is only done on KVM bringup (albeit on every CPU, but there
aren't _that_ many null entries in the array).

Fixes: 3c0f99366e34 ("KVM: nVMX: Add a TSC multiplier field in VMCS12")
Signed-off-by: Sean Christopherson <seanjc@xxxxxxxxxx>
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Note, the vmx test in kvm-unit-tests will still fail using stock QEMU,
as QEMU also hardcodes and overwrites the MSR. The test passes if I
hack KVM to ignore userspace (it was easier than rebuilding QEMU).

Queued, thanks. Without having checked the kvm-unit-tests sources very thoroughly, this might be a configuration issue in kvm-unit-tests; in theory "-cpu host" (unlike "-cpu host,migratable=no") should not enable TSC scaling.

Paolo