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Commit bd94e7ae authored Oct 27, 2017 by Marc Zyngier Committed by Christoffer Dall Nov 10, 2017

KVM: arm/arm64: GICv4: Prevent a VM using GICv4 from being saved



The GICv4 architecture doesn't make it easy for save/restore to
work, as it doesn't give any guarantee that the pending state
is written into the pending table.

So let's not take any chance, and let's return an error if
we encounter any LPI that has the HW bit set. In order for
userspace to distinguish this error from other failure modes,
use -EACCES as an error code.

Reviewed-by: Eric Auger <eric.auger@redhat.com>
Signed-off-by: Marc Zyngier <marc.zyngier@arm.com>
Signed-off-by: Christoffer Dall <christoffer.dall@linaro.org>

parent 374be35e

Documentation/virtual/kvm/devices/arm-vgic-its.txt

+2 −0

Original line number	Diff line number	Diff line
		@@ -64,6 +64,8 @@ Groups:
		-EINVAL: Inconsistent restored data
		-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

		KVM_DEV_ARM_VGIC_GRP_ITS_REGS
		Attributes:

virt/kvm/arm/vgic/vgic-its.c

+9 −0

Original line number	Diff line number	Diff line
		@@ -1995,6 +1995,15 @@ static int vgic_its_save_itt(struct vgic_its its, struct its_device device)
		list_for_each_entry(ite, &device->itt_head, ite_list) {
		gpa_t gpa = base + ite->event_id * ite_esz;

		/*
		* 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...
		*/
		if (ite->irq->hw)
		return -EACCES;

		ret = vgic_its_save_ite(its, device, ite, gpa, ite_esz);
		if (ret)
		return ret;