x86/hvm: Crash domain rather than guest on unexpected PIO IO state

Under certain conditions, if an IO gets into an unexpected state,
hvmemul_do_io can return X86EMUL_UNHANDLEABLE.  Unfortunately,
handle_pio() does not expect this state, and calls BUG() if it sees
it, crashing the host.

Other HVM io-related code crashes the guest in this case.  This patch
makes handle_pio() do the same.

The crash was seen when executing crash_guest in dom0 to forcibly
crash the guest.

Signed-off-by: George Dunlap <george.dunlap@eu.citrix.com>

diff --git a/xen/arch/x86/hvm/io.c b/xen/arch/x86/hvm/io.c
index 274048d2278637d3d7a859be526a841c767c00fd..1c35d5743811a786f94b89e78b48ecedfe56b705 100644 (file)
--- a/xen/arch/x86/hvm/io.c
+++ b/xen/arch/x86/hvm/io.c
@@ -239,7 +239,9 @@ int handle_pio(uint16_t port, int size, int dir)
         curr->arch.hvm_vcpu.io_state = HVMIO_handle_pio_awaiting_completion;
         break;
     default:
-        BUG();
+        gdprintk(XENLOG_ERR, "Weird HVM ioemulation status %d.\n", rc);
+        domain_crash(curr->domain);
+        break;
     }
 
     return 1;