[Xen-devel] [PATCH v2 for-4.9] x86/hvm: Corrections and improvements to unhandled vmexit logging

[Andrew Cooper <andrew.cooper3@xxxxxxxxxx>]

 * Use gprintk rather than gdprintk.  These logging messages shouldn't
   disappear in release builds, as they usually happen immediately before a
   domain crash.  Raise them from WARNING to ERR.
 * Format the vmexit reason in the same base as is used in the vendor
   manuals (decimal for Intel, hex for AMD), and consistently use 0x for hex
   numbers.
 * Consistently use "Unexpected vmexit" terminology.

In particular, this corrects the information printed for nested VT-x, and
actually prints information for nested SVM.

Signed-off-by: Andrew Cooper <andrew.cooper3@xxxxxxxxxx>
Reviewed-by: Boris Ostrovsky <boris.ostrovsky@xxxxxxxxxx>
Reviewed-by: Jan Beulich <jbeulich@xxxxxxxx>
Reviewed-by: Kevin Tian <kevin.tian@xxxxxxxxx>
Release-acked-by: Julien Grall <julien.grall@xxxxxxx>
---
v2:
 * Use consistent terminology
 * Remove redundant casts

For the nested virt side of things, it is insecure to ever hit the default
case, as it causes unknown exits to be handled in the context of being L1,
even when it originated from L2.  I considered putting using domain_crash(),
but that isn't very helpful, and nested virt is still strictly expermiental.
---
 xen/arch/x86/hvm/svm/nestedsvm.c | 2 ++
 xen/arch/x86/hvm/svm/svm.c       | 7 +++----
 xen/arch/x86/hvm/vmx/vmx.c       | 2 +-
 xen/arch/x86/hvm/vmx/vvmx.c      | 4 ++--
 4 files changed, 8 insertions(+), 7 deletions(-)

diff --git a/xen/arch/x86/hvm/svm/nestedsvm.c b/xen/arch/x86/hvm/svm/nestedsvm.c
index d4fc81f..f46e346 100644
--- a/xen/arch/x86/hvm/svm/nestedsvm.c
+++ b/xen/arch/x86/hvm/svm/nestedsvm.c
@@ -1406,6 +1406,8 @@ 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;
     }
 
diff --git a/xen/arch/x86/hvm/svm/svm.c b/xen/arch/x86/hvm/svm/svm.c
index 07e9718..178adc5 100644
--- a/xen/arch/x86/hvm/svm/svm.c
+++ b/xen/arch/x86/hvm/svm/svm.c
@@ -2833,10 +2833,9 @@ void svm_vmexit_handler(struct cpu_user_regs *regs)
 
     default:
     unexpected_exit_type:
-        gdprintk(XENLOG_ERR, "unexpected VMEXIT: exit reason = %#"PRIx64", "
-                 "exitinfo1 = %#"PRIx64", exitinfo2 = %#"PRIx64"\n",
-                 exit_reason, 
-                 (u64)vmcb->exitinfo1, (u64)vmcb->exitinfo2);
+        gprintk(XENLOG_ERR, "Unexpected vmexit: reason %#"PRIx64", "
+                "exitinfo1 %#"PRIx64", exitinfo2 %#"PRIx64"\n",
+                exit_reason, vmcb->exitinfo1, vmcb->exitinfo2);
         svm_crash_or_fault(v);
         break;
     }
diff --git a/xen/arch/x86/hvm/vmx/vmx.c b/xen/arch/x86/hvm/vmx/vmx.c
index f8d3c17..c8ef18a 100644
--- a/xen/arch/x86/hvm/vmx/vmx.c
+++ b/xen/arch/x86/hvm/vmx/vmx.c
@@ -4106,7 +4106,7 @@ void vmx_vmexit_handler(struct cpu_user_regs *regs)
     /* fall through */
     default:
     exit_and_crash:
-        gdprintk(XENLOG_WARNING, "Bad vmexit (reason %#lx)\n", exit_reason);
+        gprintk(XENLOG_ERR, "Unexpected vmexit: reason %lu\n", exit_reason);
 
         if ( vmx_get_cpl() )
             hvm_inject_hw_exception(TRAP_invalid_op,
diff --git a/xen/arch/x86/hvm/vmx/vvmx.c b/xen/arch/x86/hvm/vmx/vvmx.c
index 936feb6..3560fae 100644
--- a/xen/arch/x86/hvm/vmx/vvmx.c
+++ b/xen/arch/x86/hvm/vmx/vvmx.c
@@ -2550,8 +2550,8 @@ int nvmx_n2_vmexit_handler(struct cpu_user_regs *regs,
             nvcpu->nv_vmexit_pending = 1;
         break;
     default:
-        gdprintk(XENLOG_WARNING, "Unknown nested vmexit reason %x.\n",
-                 exit_reason);
+        gprintk(XENLOG_ERR, "Unexpected nested vmexit: reason %u\n",
+                exit_reason);
     }
 
     return ( nvcpu->nv_vmexit_pending == 1 );
-- 
2.1.4


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