黄乐 <huangle1@xxxxxx> writes:
> In vcpu_load_eoi_exitmap(), currently the eoi_exit_bitmap[4] array is
> initialized only when Hyper-V context is available, in other path it is
> just passed to kvm_x86_ops.load_eoi_exitmap() directly from on the stack,
> which would cause unexpected interrupt delivery/handling issues, e.g. an
> *old* linux kernel that relies on PIT to do clock calibration on KVM might
> randomly fail to boot.
>
> Fix it by passing ioapic_handled_vectors to load_eoi_exitmap() when Hyper-V
> context is not available.
>
> Signed-off-by: Huang Le <huangle1@xxxxxx>
Fixes: f2bc14b69c38 ("KVM: x86: hyper-v: Prepare to meet unallocated Hyper-V context")
Cc: stable@xxxxxxxxxxxxxxx
> ---
> diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
> index dc7eb5fddfd3..0699832504c9 100644
> --- a/arch/x86/kvm/x86.c
> +++ b/arch/x86/kvm/x86.c
> @@ -9547,11 +9547,14 @@ static void vcpu_load_eoi_exitmap(struct kvm_vcpu *vcpu)
> if (!kvm_apic_hw_enabled(vcpu->arch.apic))
> return;
>
> - if (to_hv_vcpu(vcpu))
> - bitmap_or((ulong *)eoi_exit_bitmap,
> - vcpu->arch.ioapic_handled_vectors,
> - to_hv_synic(vcpu)->vec_bitmap, 256);
> + if (!to_hv_vcpu(vcpu)) {
> + static_call(kvm_x86_load_eoi_exitmap)(
> + vcpu, (u64 *)vcpu->arch.ioapic_handled_vectors);
> + return;
> + }
>
> + bitmap_or((ulong *)eoi_exit_bitmap, vcpu->arch.ioapic_handled_vectors,
> + to_hv_synic(vcpu)->vec_bitmap, 256);
> static_call(kvm_x86_load_eoi_exitmap)(vcpu, eoi_exit_bitmap);
> }
>
Reviewed-by: Vitaly Kuznetsov <vkuznets@xxxxxxxxxx>
My personal preference, however, would be to keep 'if
(to_hv_vcpu(vcpu))' check and not invert it, i.e.:
if (to_hv_vcpu(vcpu)) {
bitmap_or((ulong *)eoi_exit_bitmap,
vcpu->arch.ioapic_handled_vectors,
to_hv_synic(vcpu)->vec_bitmap, 256);
static_call(...)(vcpu, eoi_exit_bitmap)
return;
}
static_call(...)(vcpu, (u64 *)vcpu->arch.ioapic_handled_vectors);
to slightly reduce the code churn but it doesn't matter much.
Thanks!
--
Vitaly
