Patch "KVM: arm64: vgic: Read HW interrupt pending state from the HW" has been added to the 5.16-stable tree

[Sasha Levin <sashal@xxxxxxxxxx>]

This is a note to let you know that I've just added the patch titled

    KVM: arm64: vgic: Read HW interrupt pending state from the HW

to the 5.16-stable tree which can be found at:
    http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary

The filename of the patch is:
     kvm-arm64-vgic-read-hw-interrupt-pending-state-from-.patch
and it can be found in the queue-5.16 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.



commit b75e323ff88c3e835d47e365bba06ec286e3014d
Author: Marc Zyngier <maz@xxxxxxxxxx>
Date:   Thu Feb 3 09:24:45 2022 +0000

    KVM: arm64: vgic: Read HW interrupt pending state from the HW
    
    [ Upstream commit 5bfa685e62e9ba93c303a9a8db646c7228b9b570 ]
    
    It appears that a read access to GIC[DR]_I[CS]PENDRn doesn't always
    result in the pending interrupts being accurately reported if they are
    mapped to a HW interrupt. This is particularily visible when acking
    the timer interrupt and reading the GICR_ISPENDR1 register immediately
    after, for example (the interrupt appears as not-pending while it really
    is...).
    
    This is because a HW interrupt has its 'active and pending state' kept
    in the *physical* distributor, and not in the virtual one, as mandated
    by the spec (this is what allows the direct deactivation). The virtual
    distributor only caries the pending and active *states* (note the
    plural, as these are two independent and non-overlapping states).
    
    Fix it by reading the HW state back, either from the timer itself or
    from the distributor if necessary.
    
    Reported-by: Ricardo Koller <ricarkol@xxxxxxxxxx>
    Tested-by: Ricardo Koller <ricarkol@xxxxxxxxxx>
    Reviewed-by: Ricardo Koller <ricarkol@xxxxxxxxxx>
    Signed-off-by: Marc Zyngier <maz@xxxxxxxxxx>
    Link: https://lore.kernel.org/r/20220208123726.3604198-1-maz@xxxxxxxxxx
    Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>

diff --git a/arch/arm64/kvm/vgic/vgic-mmio.c b/arch/arm64/kvm/vgic/vgic-mmio.c
index 48c6067fc5ecb..f972992682746 100644
--- a/arch/arm64/kvm/vgic/vgic-mmio.c
+++ b/arch/arm64/kvm/vgic/vgic-mmio.c
@@ -248,6 +248,8 @@ unsigned long vgic_mmio_read_pending(struct kvm_vcpu *vcpu,
 						    IRQCHIP_STATE_PENDING,
 						    &val);
 			WARN_RATELIMIT(err, "IRQ %d", irq->host_irq);
+		} else if (vgic_irq_is_mapped_level(irq)) {
+			val = vgic_get_phys_line_level(irq);
 		} else {
 			val = irq_is_pending(irq);
 		}