[Xen-devel] [PATCH] xen: Crash domain rather than guest on unexpected PIO IO state

[George Dunlap <george.dunlap@xxxxxxxxxxxxx>]

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@xxxxxxxxxxxxx>

diff -r 782bc7b2661a -r f93006ca6d02 xen/arch/x86/hvm/io.c
--- a/xen/arch/x86/hvm/io.c     Fri Jun 10 13:51:39 2011 +0100
+++ b/xen/arch/x86/hvm/io.c     Tue Jun 14 14:53:27 2011 +0100
@@ -239,7 +239,9 @@ int handle_pio(uint16_t port, int size, 
         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;

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