[PATCH] x86/hvm: Improve error information in handle_pio()

[Andrew Cooper <andrew.cooper3@xxxxxxxxxx>]

domain_crash() should always have a message which emitted even in release
builds, so something more useful than this is presented.

  (XEN) domain_crash called from io.c:171
  (XEN) domain_crash called from io.c:171
  (XEN) domain_crash called from io.c:171
  ...

Signed-off-by: Andrew Cooper <andrew.cooper3@xxxxxxxxxx>
---
CC: Jan Beulich <JBeulich@xxxxxxxx>
CC: Wei Liu <wl@xxxxxxx>
CC: Roger Pau Monné <roger.pau@xxxxxxxxxx>
CC: Paul Durrant <paul.durrant@xxxxxxxxxx>
CC: Marek Marczykowski-Górecki <marmarek@xxxxxxxxxxxxxxxxxxxxxx>

Part of a bug reported by Marek.  Something else is wonky in the IO emulation
state, and preventing us from yielding to the scheduler so the domain can
progress with being shut down.
---
 xen/arch/x86/hvm/io.c | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/xen/arch/x86/hvm/io.c b/xen/arch/x86/hvm/io.c
index a5b0a23f06..4e468bfb6b 100644
--- a/xen/arch/x86/hvm/io.c
+++ b/xen/arch/x86/hvm/io.c
@@ -167,7 +167,9 @@ bool handle_pio(uint16_t port, unsigned int size, int dir)
         break;
 
     default:
-        gdprintk(XENLOG_ERR, "Weird HVM ioemulation status %d.\n", rc);
+        gprintk(XENLOG_ERR, "Unexpected PIO status %d, port %#x %s 0x%0*lx\n",
+                rc, port, dir == IOREQ_WRITE ? "write" : "read",
+                size * 2, data & ((1ul << (size * 8)) - 1));
         domain_crash(curr->domain);
         return false;
     }
-- 
2.11.0