nestedsvm: Remove bogus debug message from nestedsvm_check_intercepts

Changeset ef3e8db806 ("x86/hvm: Corrections and improvements to
unhandled vmexit logging") introduced a printk to the default path of
the switch statement in nestedsvm_check_intercepts(), complaining of
an unknown exit reason.

Unfortunately, the "core" switch statement which is meant to handle
all vmexit reasons is in nsvm_vmcb_guest_intercepts_exitcode(); the
switch statement in nestedsvm_check_intercepts() is only meant to
superimpose on top of that some special-casing for how to interaction
between L1 and L0 vmexits.

Remove the printk, and add a comment to prevent future confusion.

Fixes: ef3e8db806 ("x86/hvm: Corrections and improvements to unhandled vmexit logging")

Signed-off-by: George Dunlap <george.dunlap@cloud.com>
Reviewed-by: Jan Beulich <jbeulich@suse.com>

xen/arch/x86/hvm/svm/nestedsvm.c

@@ -1294,6 +1294,10 @@ nestedsvm_check_intercepts(struct vcpu *v, struct cpu_user_regs *regs,
     ASSERT(vcpu_nestedhvm(v).nv_vmexit_pending == 0);
     is_intercepted = nsvm_vmcb_guest_intercepts_exitcode(v, regs, exitcode);
 
+    /* 
+     * Handle specific interactions between things the guest and host
+     * may both want to intercept
+     */
     switch ( exitcode )
     {
     case VMEXIT_INVALID:
@@ -1349,8 +1353,6 @@ nestedsvm_check_intercepts(struct vcpu *v, struct cpu_user_regs *regs,
         /* Always let the guest handle VMMCALL/VMCALL */
         return NESTEDHVM_VMEXIT_INJECT;
     default:
-        gprintk(XENLOG_ERR, "Unexpected nested vmexit: reason %#"PRIx64"\n",
-                exitcode);
         break;
     }