Re: [PATCH v2 9/9] KVM: x86: remove exit_int_info warning in svm_handle_exit

From: Liam Merwick
Date: Mon Nov 21 2022 - 11:37:25 EST


On 09/11/2022 09:15, Maxim Levitsky wrote:
On Sun, 2022-11-06 at 15:53 +0000, Liam Merwick wrote:
On 03/11/2022 14:13, Maxim Levitsky wrote:
It is valid to receive external interrupt and have broken IDT entry,
which will lead to #GP with exit_int_into that will contain the index of
the IDT entry (e.g any value).

Other exceptions can happen as well, like #NP or #SS
(if stack switch fails).

Thus this warning can be user triggred and has very little value.

Cc: stable@xxxxxxxxxxxxxxx
Signed-off-by: Maxim Levitsky <mlevitsk@xxxxxxxxxx>
---
  arch/x86/kvm/svm/svm.c | 9 ---------
  1 file changed, 9 deletions(-)

diff --git a/arch/x86/kvm/svm/svm.c b/arch/x86/kvm/svm/svm.c
index e9cec1b692051c..36f651ce842174 100644
--- a/arch/x86/kvm/svm/svm.c
+++ b/arch/x86/kvm/svm/svm.c
@@ -3428,15 +3428,6 @@ static int svm_handle_exit(struct kvm_vcpu *vcpu, fastpath_t exit_fastpath)
                return 0;
        }
-       if (is_external_interrupt(svm->vmcb->control.exit_int_info) &&
-           exit_code != SVM_EXIT_EXCP_BASE + PF_VECTOR &&
-           exit_code != SVM_EXIT_NPF && exit_code != SVM_EXIT_TASK_SWITCH &&
-           exit_code != SVM_EXIT_INTR && exit_code != SVM_EXIT_NMI)
-               printk(KERN_ERR "%s: unexpected exit_int_info 0x%x "
-                      "exit_code 0x%x\n",
-                      __func__, svm->vmcb->control.exit_int_info,
-                      exit_code);
-
        if (exit_fastpath != EXIT_FASTPATH_NONE)
                return 1;

This was the only caller of is_external_interrupt() - should the
definition be removed also to avoid a 'defined but not used' warning?

I hate to say it but I have seen a warning about an unused function,
but I really didn't expect that to come from this patch.
I somehow thought that its some leftover in kvm/queue.

I'll remove the unused function in a next version.


Reviewed-by: Liam Merwick <liam.merwick@xxxxxxxxxx>