UPSTREAM: KVM: arm64: GICv4.1: Give a chance to save VLPI state

Before GICv4.1, we don't have direct access to the VLPI state. So
we simply let it fail early when encountering any VLPI in saving.

But now we don't have to return -EACCES directly if on GICv4.1. Let’s
change the hard code and give a chance to save the VLPI state (and
preserve the UAPI).

Signed-off-by: Shenming Lu <lushenming@huawei.com>
Signed-off-by: Marc Zyngier <maz@kernel.org>
Link: https://lore.kernel.org/r/20210322060158.1584-7-lushenming@huawei.com
(cherry picked from commit 8082d50f48)
Signed-off-by: Will Deacon <willdeacon@google.com>
Bug: 190594147
Change-Id: I5f878c088b42772774d5189d32bf74814e932521

Documentation/virt/kvm/devices/arm-vgic-its.rst

@@ -80,7 +80,7 @@ KVM_DEV_ARM_VGIC_GRP_CTRL
     -EFAULT  Invalid guest ram access
     -EBUSY   One or more VCPUS are running
     -EACCES  The virtual ITS is backed by a physical GICv4 ITS, and the
-	     state is not available
+	     state is not available without GICv4.1
     =======  ==========================================================
 
 KVM_DEV_ARM_VGIC_GRP_ITS_REGS

arch/arm64/kvm/vgic/vgic-its.c

@@ -2218,10 +2218,10 @@ static int vgic_its_save_itt(struct vgic_its *its, struct its_device *device)
 		/*
 		 * If an LPI carries the HW bit, this means that this
 		 * interrupt is controlled by GICv4, and we do not
-		 * have direct access to that state. Let's simply fail
-		 * the save operation...
+		 * have direct access to that state without GICv4.1.
+		 * Let's simply fail the save operation...
 		 */
-		if (ite->irq->hw)
+		if (ite->irq->hw && !kvm_vgic_global_state.has_gicv4_1)
 			return -EACCES;
 
 		ret = vgic_its_save_ite(its, device, ite, gpa, ite_esz);