On Tue, Jun 25, 2024 at 4:56 PM Jim Mattson <jmattson@xxxxxxxxxx> wrote:
>
> KVM does not support changing the APIC's base address. Prior to commit
> 3743c2f02517 ("KVM: x86: inhibit APICv/AVIC on changes to APIC ID or
> APIC base"), it emitted a rate-limited warning about this. Now, it's
> just silently broken.
>
> Use vcpu_unimpl() to complain about this unsupported operation. Even a
> rate-limited error message is better than complete silence.
>
> Fixes: 3743c2f02517 ("KVM: x86: inhibit APICv/AVIC on changes to APIC ID or APIC base")
> Signed-off-by: Jim Mattson <jmattson@xxxxxxxxxx>
> ---
> Changes in v2:
> * Changed format specifiers from "%#llx" to "%#x"
> * Cast apic->base_address to unsigned int for printing
>
> arch/x86/kvm/lapic.c | 3 +++
> 1 file changed, 3 insertions(+)
>
> diff --git a/arch/x86/kvm/lapic.c b/arch/x86/kvm/lapic.c
> index acd7d48100a1..43ac05d10b2e 100644
> --- a/arch/x86/kvm/lapic.c
> +++ b/arch/x86/kvm/lapic.c
> @@ -2583,6 +2583,9 @@ void kvm_lapic_set_base(struct kvm_vcpu *vcpu, u64 value)
>
> if ((value & MSR_IA32_APICBASE_ENABLE) &&
> apic->base_address != APIC_DEFAULT_PHYS_BASE) {
> + vcpu_unimpl(vcpu, "APIC base %#x is not %#x",
> + (unsigned int)apic->base_address,
> + APIC_DEFAULT_PHYS_BASE);
> kvm_set_apicv_inhibit(apic->vcpu->kvm,
> APICV_INHIBIT_REASON_APIC_BASE_MODIFIED);
> }
> --
> 2.45.2.741.gdbec12cfda-goog
Ping.
