Nitesh Narayan Lal <nitesh@xxxxxxxxxx> writes:
> Previously all fields of structure kvm_lapic_irq were not initialized
> before it was passed to kvm_bitmap_or_dest_vcpus(). Which will cause
> an issue when any of those fields are used for processing a request.
> For example not initializing the msi_redir_hint field before passing
> to the kvm_bitmap_or_dest_vcpus(), may lead to a misbehavior of
> kvm_apic_map_get_dest_lapic(). This will specifically happen when the
> kvm_lowest_prio_delivery() returns TRUE due to a non-zero garbage
> value of msi_redir_hint, which should not happen as the request belongs
> to APIC fixed delivery mode and we do not want to deliver the
> interrupt only to the lowest priority candidate.
>
> This patch initializes all the fields of kvm_lapic_irq based on the
> values of ioapic redirect_entry object before passing it on to
> kvm_bitmap_or_dest_vcpus().
>
> Fixes: 7ee30bc132c6("KVM: x86: deliver KVM IOAPIC scan request to target vCPUs")
> Signed-off-by: Nitesh Narayan Lal <nitesh@xxxxxxxxxx>
> ---
> arch/x86/kvm/ioapic.c | 7 +++++--
> 1 file changed, 5 insertions(+), 2 deletions(-)
>
> diff --git a/arch/x86/kvm/ioapic.c b/arch/x86/kvm/ioapic.c
> index 7668fed..3a8467d 100644
> --- a/arch/x86/kvm/ioapic.c
> +++ b/arch/x86/kvm/ioapic.c
> @@ -378,12 +378,15 @@ static void ioapic_write_indirect(struct kvm_ioapic *ioapic, u32 val)
> if (e->fields.delivery_mode == APIC_DM_FIXED) {
> struct kvm_lapic_irq irq;
>
> - irq.shorthand = APIC_DEST_NOSHORT;
> irq.vector = e->fields.vector;
> irq.delivery_mode = e->fields.delivery_mode << 8;
> - irq.dest_id = e->fields.dest_id;
> irq.dest_mode =
> kvm_lapic_irq_dest_mode(!!e->fields.dest_mode);
> + irq.level = 1;
'level' is bool in struct kvm_lapic_irq but other than that, is there a
reason we set it to 'true' here? I understand that any particular
setting is likely better than random and it should actually not be used
without setting it first but still?
> + irq.trig_mode = e->fields.trig_mode;
> + irq.shorthand = APIC_DEST_NOSHORT;
> + irq.dest_id = e->fields.dest_id;
> + irq.msi_redir_hint = false;
> bitmap_zero(&vcpu_bitmap, 16);
> kvm_bitmap_or_dest_vcpus(ioapic->kvm, &irq,
> &vcpu_bitmap);
--
Vitaly
