[xen staging] x86/hvm: add defensive statements in unreachable program points

[patchbot@xxxxxxx]

commit 643c2b6bc7df1971559855de854a80aee3b878e6
Author:     Federico Serafini <federico.serafini@xxxxxxxxxxx>
AuthorDate: Wed Jul 31 13:09:58 2024 +0200
Commit:     Jan Beulich <jbeulich@xxxxxxxx>
CommitDate: Wed Jul 31 13:09:58 2024 +0200

    x86/hvm: add defensive statements in unreachable program points
    
    As a defensive measure, make sure to signal an error to the caller
    if an unreachable program point is reached.
    
    Signed-off-by: Federico Serafini <federico.serafini@xxxxxxxxxxx>
    Reviewed-by: Jan Beulich <jbeulich@xxxxxxxx>
---
 xen/arch/x86/hvm/emulate.c  | 1 +
 xen/arch/x86/hvm/hvm.c      | 4 ++++
 xen/arch/x86/hvm/vmx/vmcs.c | 2 ++
 3 files changed, 7 insertions(+)

diff --git a/xen/arch/x86/hvm/emulate.c b/xen/arch/x86/hvm/emulate.c
index 135aa6fc22..b6ca5cb9d1 100644
--- a/xen/arch/x86/hvm/emulate.c
+++ b/xen/arch/x86/hvm/emulate.c
@@ -2673,6 +2673,7 @@ static int _hvm_emulate_one(struct hvm_emulate_ctxt 
*hvmemul_ctxt,
 
     default:
         ASSERT_UNREACHABLE();
+        return X86EMUL_UNHANDLEABLE;
     }
 
     if ( hvmemul_ctxt->ctxt.retire.singlestep )
diff --git a/xen/arch/x86/hvm/hvm.c b/xen/arch/x86/hvm/hvm.c
index 1d32f473a4..d7f195ba9a 100644
--- a/xen/arch/x86/hvm/hvm.c
+++ b/xen/arch/x86/hvm/hvm.c
@@ -4919,6 +4919,8 @@ static int do_altp2m_op(
 
     default:
         ASSERT_UNREACHABLE();
+        rc = -EOPNOTSUPP;
+        break;
     }
 
  out:
@@ -5020,6 +5022,8 @@ static int compat_altp2m_op(
 
     default:
         ASSERT_UNREACHABLE();
+        rc = -EOPNOTSUPP;
+        break;
     }
 
     return rc;
diff --git a/xen/arch/x86/hvm/vmx/vmcs.c b/xen/arch/x86/hvm/vmx/vmcs.c
index 9b6dc51f36..5787110a56 100644
--- a/xen/arch/x86/hvm/vmx/vmcs.c
+++ b/xen/arch/x86/hvm/vmx/vmcs.c
@@ -1446,6 +1446,7 @@ struct vmx_msr_entry *vmx_find_msr(const struct vcpu *v, 
uint32_t msr,
 
     default:
         ASSERT_UNREACHABLE();
+        break;
     }
 
     if ( !start )
@@ -1598,6 +1599,7 @@ int vmx_del_msr(struct vcpu *v, uint32_t msr, enum 
vmx_msr_list_type type)
 
     default:
         ASSERT_UNREACHABLE();
+        return -EINVAL;
     }
 
     if ( !start )
--
generated by git-patchbot for /home/xen/git/xen.git#staging