KVM: emulate: warn on invalid or uninitialized exception numbers

These were reported when running Jailhouse on AMD processors.

Initialize ctxt->exception.vector with an invalid exception number,
and warn if it remained invalid even though the emulator got
an X86EMUL_PROPAGATE_FAULT return code.

Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

diff --git a/arch/x86/kvm/emulate.c b/arch/x86/kvm/emulate.c
index 4fbf4b5..e5bf130 100644 (file)
--- a/arch/x86/kvm/emulate.c
+++ b/arch/x86/kvm/emulate.c
@@ -527,6 +527,7 @@ static unsigned long seg_base(struct x86_emulate_ctxt *ctxt, int seg)
 static int emulate_exception(struct x86_emulate_ctxt *ctxt, int vec,
                             u32 error, bool valid)
 {
+       WARN_ON(vec > 0x1f);
        ctxt->exception.vector = vec;
        ctxt->exception.error_code = error;
        ctxt->exception.error_code_valid = valid;
@@ -4827,8 +4828,10 @@ writeback:
        ctxt->eip = ctxt->_eip;
 
 done:
-       if (rc == X86EMUL_PROPAGATE_FAULT)
+       if (rc == X86EMUL_PROPAGATE_FAULT) {
+               WARN_ON(ctxt->exception.vector > 0x1f);
                ctxt->have_exception = true;
+       }
        if (rc == X86EMUL_INTERCEPTED)
                return EMULATION_INTERCEPTED;
 

diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
index 737b4bd..cd718c0 100644 (file)
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -5248,6 +5248,7 @@ int x86_emulate_instruction(struct kvm_vcpu *vcpu,
 
                ctxt->interruptibility = 0;
                ctxt->have_exception = false;
+               ctxt->exception.vector = -1;
                ctxt->perm_ok = false;
 
                ctxt->ud = emulation_type & EMULTYPE_TRAP_UD;