kvm: arm64: vgic: fix hyp panic with 64k pages on juno platform

commit 63afbe7a0ac184ef8485dac4914e87b211b5bfaa upstream.

If the physical address of GICV isn't page-aligned, then we end up
creating a stage-2 mapping of the page containing it, which causes us to
map neighbouring memory locations directly into the guest.

As an example, consider a platform with GICV at physical 0x2c02f000
running a 64k-page host kernel. If qemu maps this into the guest at
0x80010000, then guest physical addresses 0x80010000 - 0x8001efff will
map host physical region 0x2c020000 - 0x2c02efff. Accesses to these
physical regions may cause UNPREDICTABLE behaviour, for example, on the
Juno platform this will cause an SError exception to EL3, which brings
down the entire physical CPU resulting in RCU stalls / HYP panics / host
crashing / wasted weeks of debugging.

SBSA recommends that systems alias the 4k GICV across the bounding 64k
region, in which case GICV physical could be described as 0x2c020000 in
the above scenario.

This patch fixes the problem by failing the vgic probe if the physical
base address or the size of GICV aren't page-aligned. Note that this
generated a warning in dmesg about freeing enabled IRQs, so I had to
move the IRQ enabling later in the probe.

Cc: Christoffer Dall <christoffer.dall@linaro.org>
Cc: Marc Zyngier <marc.zyngier@arm.com>
Cc: Gleb Natapov <gleb@kernel.org>
Cc: Paolo Bonzini <pbonzini@redhat.com>
Cc: Joel Schopp <joel.schopp@amd.com>
Cc: Don Dutile <ddutile@redhat.com>
Acked-by: Peter Maydell <peter.maydell@linaro.org>
Acked-by: Joel Schopp <joel.schopp@amd.com>
Acked-by: Marc Zyngier <marc.zyngier@arm.com>
Signed-off-by: Will Deacon <will.deacon@arm.com>
Signed-off-by: Christoffer Dall <christoffer.dall@linaro.org>
Cc: Shannon Zhao <shannon.zhao@linaro.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/virt/kvm/arm/vgic.c b/virt/kvm/arm/vgic.c
index 4dc45e27f10b0101328dc5b4c0d60ddf21a9e038..4eec2d43610988abc444c87fb84d00c5973c99c6 100644 (file)
--- a/virt/kvm/arm/vgic.c
+++ b/virt/kvm/arm/vgic.c
@@ -1526,17 +1526,33 @@ int kvm_vgic_hyp_init(void)
                goto out_unmap;
        }
 
-       kvm_info("%s@%llx IRQ%d\n", vgic_node->name,
-                vctrl_res.start, vgic_maint_irq);
-       on_each_cpu(vgic_init_maintenance_interrupt, NULL, 1);
-
        if (of_address_to_resource(vgic_node, 3, &vcpu_res)) {
                kvm_err("Cannot obtain VCPU resource\n");
                ret = -ENXIO;
                goto out_unmap;
        }
+
+       if (!PAGE_ALIGNED(vcpu_res.start)) {
+               kvm_err("GICV physical address 0x%llx not page aligned\n",
+                       (unsigned long long)vcpu_res.start);
+               ret = -ENXIO;
+               goto out_unmap;
+       }
+
+       if (!PAGE_ALIGNED(resource_size(&vcpu_res))) {
+               kvm_err("GICV size 0x%llx not a multiple of page size 0x%lx\n",
+                       (unsigned long long)resource_size(&vcpu_res),
+                       PAGE_SIZE);
+               ret = -ENXIO;
+               goto out_unmap;
+       }
+
        vgic_vcpu_base = vcpu_res.start;
 
+       kvm_info("%s@%llx IRQ%d\n", vgic_node->name,
+                vctrl_res.start, vgic_maint_irq);
+       on_each_cpu(vgic_init_maintenance_interrupt, NULL, 1);
+
        goto out;
 
 out_unmap: