On Thu, 11 Mar 2021 12:26:38 +0000,
Shenming Lu <lushenming@xxxxxxxxxx> wrote:
>
> On 2021/3/11 16:57, Marc Zyngier wrote:
> > On Wed, 27 Jan 2021 12:13:34 +0000,
> > Shenming Lu <lushenming@xxxxxxxxxx> wrote:
> >>
> >> With GICv4.1 and the vPE unmapped, which indicates the invalidation
> >> of any VPT caches associated with the vPE, we can get the VLPI state
> >> by peeking at the VPT. So we add a function for this.
> >>
> >> Signed-off-by: Shenming Lu <lushenming@xxxxxxxxxx>
> >> ---
> >> arch/arm64/kvm/vgic/vgic-v4.c | 19 +++++++++++++++++++
> >> arch/arm64/kvm/vgic/vgic.h | 1 +
> >> 2 files changed, 20 insertions(+)
> >>
> >> diff --git a/arch/arm64/kvm/vgic/vgic-v4.c b/arch/arm64/kvm/vgic/vgic-v4.c
> >> index 66508b03094f..ac029ba3d337 100644
> >> --- a/arch/arm64/kvm/vgic/vgic-v4.c
> >> +++ b/arch/arm64/kvm/vgic/vgic-v4.c
> >> @@ -203,6 +203,25 @@ void vgic_v4_configure_vsgis(struct kvm *kvm)
> >> kvm_arm_resume_guest(kvm);
> >> }
> >>
> >> +/*
> >> + * Must be called with GICv4.1 and the vPE unmapped, which
> >> + * indicates the invalidation of any VPT caches associated
> >> + * with the vPE, thus we can get the VLPI state by peeking
> >> + * at the VPT.
> >> + */
> >> +void vgic_v4_get_vlpi_state(struct vgic_irq *irq, bool *val)
> >> +{
> >> + struct its_vpe *vpe = &irq->target_vcpu->arch.vgic_cpu.vgic_v3.its_vpe;
> >> + int mask = BIT(irq->intid % BITS_PER_BYTE);
> >> + void *va;
> >> + u8 *ptr;
> >> +
> >> + va = page_address(vpe->vpt_page);
> >> + ptr = va + irq->intid / BITS_PER_BYTE;
> >> +
> >> + *val = !!(*ptr & mask);
> >
> > What guarantees that you can actually read anything valid? Yes, the
> > VPT caches are clean. But that doesn't make them coherent with CPU
> > caches.
> >
> > You need some level of cache maintenance here.
>
> Yeah, and you have come up with some codes for this in v2:
>
> diff --git a/drivers/irqchip/irq-gic-v3-its.c
> b/drivers/irqchip/irq-gic-v3-its.c
> index 7db602434ac5..2dbef127ca15 100644
> --- a/drivers/irqchip/irq-gic-v3-its.c
> +++ b/drivers/irqchip/irq-gic-v3-its.c
> @@ -4552,6 +4552,10 @@ static void its_vpe_irq_domain_deactivate(struct
> irq_domain *domain,
>
> its_send_vmapp(its, vpe, false);
> }
> +
> + if (find_4_1_its() && !atomic_read(vpe->vmapp_count))
> + gic_flush_dcache_to_poc(page_address(vpe->vpt_page),
> + LPI_PENDBASE_SZ);
> }
>
> static const struct irq_domain_ops its_vpe_domain_ops = {
>
> Could I add it to this series? :-)
Yes, please.
M.
--
Without deviation from the norm, progress is not possible.
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