Commit 66f8ca55 authored Oct 29, 2019 by Zenghui Yu Committed by Greg Kroah-Hartman Dec 13, 2019

KVM: arm/arm64: vgic: Don't rely on the wrong pending table



commit ca185b260951d3b55108c0b95e188682d8a507b7 upstream.

It's possible that two LPIs locate in the same "byte_offset" but target
two different vcpus, where their pending status are indicated by two
different pending tables.  In such a scenario, using last_byte_offset
optimization will lead KVM relying on the wrong pending table entry.
Let us use last_ptr instead, which can be treated as a byte index into
a pending table and also, can be vcpu specific.

Fixes: 28077125 ("KVM: arm64: vgic-v3: KVM_DEV_ARM_VGIC_SAVE_PENDING_TABLES")
Cc: stable@vger.kernel.org
Signed-off-by: Zenghui Yu <yuzenghui@huawei.com>
Signed-off-by: Marc Zyngier <maz@kernel.org>
Acked-by: Eric Auger <eric.auger@redhat.com>
Link: https://lore.kernel.org/r/20191029071919.177-4-yuzenghui@huawei.com


Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

parent e8d9825d

virt/kvm/arm/vgic/vgic-v3.c

+3 −3

Original line number	Diff line number	Diff line
		@@ -375,8 +375,8 @@ int vgic_v3_lpi_sync_pending_status(struct kvm kvm, struct vgic_irq irq)
		int vgic_v3_save_pending_tables(struct kvm *kvm)
		{
		struct vgic_dist *dist = &kvm->arch.vgic;
		int last_byte_offset = -1;
		struct vgic_irq *irq;
		gpa_t last_ptr = ~(gpa_t)0;
		int ret;
		u8 val;

		@@ -396,11 +396,11 @@ int vgic_v3_save_pending_tables(struct kvm *kvm)
		bit_nr = irq->intid % BITS_PER_BYTE;
		ptr = pendbase + byte_offset;

		if (byte_offset != last_byte_offset) {
		if (ptr != last_ptr) {
		ret = kvm_read_guest_lock(kvm, ptr, &val, 1);
		if (ret)
		return ret;
		last_byte_offset = byte_offset;
		last_ptr = ptr;
		}

		stored = val & (1U << bit_nr);