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[Qemu-devel] Re: [PATCH] Resend: x86: Reboot CPU on triple fault
From: |
Jan Kiszka |
Subject: |
[Qemu-devel] Re: [PATCH] Resend: x86: Reboot CPU on triple fault |
Date: |
Mon, 12 Jan 2009 13:14:35 +0100 |
User-agent: |
Mozilla/5.0 (X11; U; Linux i686 (x86_64); de; rv:1.8.1.12) Gecko/20080226 SUSE/2.0.0.12-1.1 Thunderbird/2.0.0.12 Mnenhy/0.7.5.666 |
address@hidden wrote:
> This is a (slightly adjusted for 2009-01-04 SVN) resend of Jan Kiszka's
> Reboot CPU on triple fault patch (see patch file for the exact reference)
>
> It seems like a consensus was reached on how to deal with tripple faults,
> but noone commited the last version (8) of the patch anyways.
>
> Just for the record -- 386BSD relies on this behavior to reset the CPU --
> it unmaps the whole address space in order to trigger a tripple fault.
>
Good that you picked this up! It is still on my to-do list to get this
in, but with medium prio. However, let's try to push it a bit.
> This is a slightly adjusted (for 2009-01-04 SVN) "reset on tripple fault
> patch"
>
> Originally from:
>
> Subject: [Qemu-devel] Re: [PATCH] x86: Reboot CPU on triple fault - Version 8
> Message-ID: <address@hidden>
> Date: Tue, 27 May 2008 18:17:18 +0200
> From: Jan Kiszka <address@hidden>
Note that I posted an enhanced version on 2008-09-02, also covering
reset logging for non-x86 archs. Please use that one.
...
> Index: target-i386/op_helper.c
> ===================================================================
> --- target-i386/op_helper.c (revision 6159)
> +++ target-i386/op_helper.c (working copy)
> @@ -1244,6 +1244,9 @@
> }
> }
>
> +/* This should come from sysemu.h - if we could include it here... */
> +void qemu_system_reset_request(void);
> +
> /*
> * Check nested exceptions and change to double or triple fault if
> * needed. It should only be called, if this is not an interrupt.
> @@ -1261,9 +1264,19 @@
> fprintf(logfile, "check_exception old: 0x%x new 0x%x\n",
> env->old_exception, intno);
>
> - if (env->old_exception == EXCP08_DBLE)
> - cpu_abort(env, "triple fault");
> +#if !defined(CONFIG_USER_ONLY)
> + if (env->old_exception == EXCP08_DBLE) {
> + if (env->intercept)
> + helper_vmexit(SVM_EXIT_SHUTDOWN, 0);
>
> + if (loglevel & CPU_LOG_RESET)
> + fprintf(logfile, "Triple fault\n");
> +
> + qemu_system_reset_request();
> + return EXCP_HLT;
> + }
> +#endif
> +
> if ((first_contributory && second_contributory)
> || (env->old_exception == EXCP0E_PAGE &&
> (second_contributory || (intno == EXCP0E_PAGE)))) {
I meanwhile think that SVM hook should rather look like this
helper_svm_check_intercept_param(SVM_EXIT_SHUTDOWN, 0);
in order to properly check if shutdown events are actually intercepted.
Alexander, am I right?
Jan
--
Siemens AG, Corporate Technology, CT SE 26
Corporate Competence Center Embedded Linux