Fail if the address of the allocated exception base doesn't fit into the
CP0_EBase register. This can happen on MIPS64 if CP0_EBase.WG isn't
implemented but RAM is available outside of the range of KSeg0.
Signed-off-by: James Hogan <james.hogan@xxxxxxxxxx>
Cc: Paolo Bonzini <pbonzini@xxxxxxxxxx>
Cc: "Radim Krčmář" <rkrcmar@xxxxxxxxxx>
Cc: Ralf Baechle <ralf@xxxxxxxxxxxxxx>
Cc: linux-mips@xxxxxxxxxxxxxx
Cc: kvm@xxxxxxxxxxxxxxx
---
arch/mips/kvm/mips.c | 12 ++++++++++++
1 file changed, 12 insertions(+)
diff --git a/arch/mips/kvm/mips.c b/arch/mips/kvm/mips.c
index 0d11d9595600..f01c9ce885f5 100644
--- a/arch/mips/kvm/mips.c
+++ b/arch/mips/kvm/mips.c
@@ -300,6 +300,18 @@ struct kvm_vcpu *kvm_arch_vcpu_create(struct kvm *kvm, unsigned int id)
kvm_debug("Allocated %d bytes for KVM Exception Handlers @ %p\n",
ALIGN(size, PAGE_SIZE), gebase);
+ /*
+ * Check new ebase actually fits in CP0_EBase. The lack of a write gate
+ * limits us to the low 512MB of physical address space. If the memory
+ * we allocate is out of range, just give up now.
+ */
+ if (!cpu_has_ebase_wg && virt_to_phys(gebase) >= 0x20000000) {
+ kvm_err("CP0_EBase.WG required for guest exception base %pK\n",
+ gebase);
+ err = -ENOMEM;
+ goto out_free_gebase;
+ }
+
/* Save new ebase */
vcpu->arch.guest_ebase = gebase;
--
2.4.10
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