Re: [PATCH] arm64: Query per-VM capabilities when selecting vCPU features

On Tue, 14 Jul 2026 12:03:29 +0100, Fuad Tabba wrote:
> kvm_cpu__select_features() and kvm_cpu__configure_features() probe vCPU
> feature availability with kvm__supports_extension(), which issues
> KVM_CHECK_EXTENSION on the global /dev/kvm fd. That reports the host's
> raw capabilities, unaware of any per-VM restrictions.
> 
> Protected VMs support a subset of the host's features. The kernel
> reflects this on the VM fd (commit a3163dca4817 ("KVM: arm64: Use KVM
> extension checks for allowed protected VM capabilities")), while the
> global fd still advertises capabilities such as SVE that the VM cannot
> use. kvmtool then requests SVE in KVM_ARM_VCPU_INIT, which the kernel
> rejects.
> 
> [...]

Applied to kvmtool (master), thanks!

[1/1] arm64: Query per-VM capabilities when selecting vCPU features
      https://git.kernel.org/will/kvmtool/c/84464ba0246b

Cheers,
-- 
Will

https://fixes.arm64.dev
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