x2APIC has no registers for DFR and ICR (see Intel SDM 10.12.1.2 "x2APIC
Register Address Space"). KVM needs to cause #GP on such accesses.

Fix it.

Signed-off-by: Nadav Amit <na...@cs.technion.ac.il>
---
 arch/x86/kvm/lapic.c | 6 ++++++
 1 file changed, 6 insertions(+)

diff --git a/arch/x86/kvm/lapic.c b/arch/x86/kvm/lapic.c
index e0e5642..7611b75 100644
--- a/arch/x86/kvm/lapic.c
+++ b/arch/x86/kvm/lapic.c
@@ -1897,6 +1897,12 @@ int kvm_x2apic_msr_read(struct kvm_vcpu *vcpu, u32 msr, 
u64 *data)
        if (!irqchip_in_kernel(vcpu->kvm) || !apic_x2apic_mode(apic))
                return 1;
 
+       if (reg == APIC_DFR || reg == APIC_ICR2) {
+               apic_debug("KVM_APIC_READ: read x2apic reserved register %x\n",
+                          reg);
+               return 1;
+       }
+
        if (apic_reg_read(apic, reg, 4, &low))
                return 1;
        if (msr == 0x830)
-- 
1.9.1

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