From mboxrd@z Thu Jan 1 00:00:00 1970 From: Anthony Liguori Subject: Re: [PATCH] Print a user-friendly message on failed vmentry Date: Thu, 20 May 2010 09:46:49 -0500 Message-ID: <4BF54B59.9040509@codemonkey.ws> References: <1274303782-21497-1-git-send-email-m.gamal005@gmail.com> <4BF54915.7070201@redhat.com> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Cc: Mohammed Gamal , avi@redhat.com, mtosatti@redhat.com, kvm@vger.kernel.org To: Chris Lalancette Return-path: Received: from mail-gx0-f227.google.com ([209.85.217.227]:61726 "EHLO mail-gx0-f227.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751961Ab0ETOqy (ORCPT ); Thu, 20 May 2010 10:46:54 -0400 Received: by gxk27 with SMTP id 27so5250033gxk.1 for ; Thu, 20 May 2010 07:46:53 -0700 (PDT) In-Reply-To: <4BF54915.7070201@redhat.com> Sender: kvm-owner@vger.kernel.org List-ID: On 05/20/2010 09:37 AM, Chris Lalancette wrote: > On 05/19/2010 05:16 PM, Mohammed Gamal wrote: > >> This patch address bug report in https://bugs.launchpad.net/qemu/+bug/530077. >> >> Failed vmentries were handled with handle_unhandled() which prints a rather >> unfriendly message to the user. This patch separates handling vmentry failures >> from unknown exit reasons and prints a friendly message to the user. >> >> Signed-off-by: Mohammed Gamal >> --- >> qemu-kvm.c | 16 +++++++++++++++- >> 1 files changed, 15 insertions(+), 1 deletions(-) >> >> diff --git a/qemu-kvm.c b/qemu-kvm.c >> index 35a4c8a..deb4df8 100644 >> --- a/qemu-kvm.c >> +++ b/qemu-kvm.c >> @@ -106,6 +106,20 @@ static int handle_unhandled(uint64_t reason) >> return -EINVAL; >> } >> >> +static int handle_failed_vmentry(uint64_t reason) >> +{ >> + fprintf(stderr, "kvm: vm entry failed with error 0x%" PRIx64 "\n\n", reason); >> + fprintf(stderr, "If you're runnning a guest on an Intel machine, it can be\n"); >> + fprintf(stderr, "most-likely due to the guest going into an invalid state\n"); >> + fprintf(stderr, "for Intel VT. For example, the guest maybe running in big\n"); >> + fprintf(stderr, "real mode which is not supported by Intel VT.\n\n"); >> + fprintf(stderr, "You may want to try enabling real mode emulation in KVM.\n"); >> + fprintf(stderr, "To Enable it, you may run the following commands as root:\n"); >> + fprintf(stderr, "# rmmod kvm_intel\n"); >> + fprintf(stderr, "# rmmod kvm\n"); >> + fprintf(stderr, "# modprobe kvm_intel emulate_invalid_guest_state=1\n"); >> + return -EINVAL; >> +} >> > The thing is, there are other valid reasons for vmentry failure. A while ago I tracked > down a bug in the Linux kernel that was causing us to vmenter with invalid segments; > this message would have been very misleading in that case. I think you'd have to do > more complete analysis of the vmentry failure code to be more certain about the reason > for failure. > We should probably only display this message if reason == 0x80000021. It may be worth looking at the cpu_state to verify that we're trying to enter 16-bit mode too. Then the message can be much more definitive too. Regards, Anthony Liguori