[Xen-devel] [PATCH] 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.

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>
---
CC: Jan Beulich <JBeulich@xxxxxxxx>
CC: Jun Nakajima <jun.nakajima@xxxxxxxxx>
CC: Kevin Tian <kevin.tian@xxxxxxxxx>
CC: Boris Ostrovsky <boris.ostrovsky@xxxxxxxxxx>
CC: Suravee Suthikulpanit <suravee.suthikulpanit@xxxxxxx>
CC: Julien Grall <julien.grall@xxxxxxx>

Request for this to be in 4.9, for the purposes of these log messages
remaining present in release builds.  The nested versions are less important,
but modified here for consistency.

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..097a4d8 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, "Unhandled 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..68bdcdd 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, "Bad vmexit: reason %#"PRIx64", "
+                "exitinfo1 %#"PRIx64", exitinfo2 %#"PRIx64"\n",
+                exit_reason, (u64)vmcb->exitinfo1, (u64)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..98d3f08 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, "Bad vmexit: reason %ld\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..560babb 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, "Unhandled nested vmexit: reason %u\n",
+                exit_reason);
     }
 
     return ( nvcpu->nv_vmexit_pending == 1 );
-- 
2.1.4


_______________________________________________
Xen-devel mailing list
Xen-devel@xxxxxxxxxxxxx
https://lists.xen.org/xen-devel