This is probably a candidate to backport to 4.1.x at some point.
On Tue, 2011-06-14 at 14:54 +0100, George Dunlap wrote:
> 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
> 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;
> - BUG();
> + gdprintk(XENLOG_ERR, "Weird HVM ioemulation status %d.\n", rc);
> + domain_crash(curr->domain);
> + break;
> return 1;
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