Received-SPF: pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 23.128.96.18 as permitted sender) client-ip=23.128.96.18;
Date:   Thu, 14 May 2020 16:16:16 +0200
From:   Borislav Petkov <bp@alien8.de>
To:     Andy Lutomirski <luto@kernel.org>
Cc:     Thomas Gleixner <tglx@linutronix.de>,
        LKML <linux-kernel@vger.kernel.org>, X86 ML <x86@kernel.org>,
        "Paul E. McKenney" <paulmck@kernel.org>,
        Alexandre Chartre <alexandre.chartre@oracle.com>,
        Frederic Weisbecker <frederic@kernel.org>,
        Paolo Bonzini <pbonzini@redhat.com>,
        Sean Christopherson <sean.j.christopherson@intel.com>,
        Masami Hiramatsu <mhiramat@kernel.org>,
        Petr Mladek <pmladek@suse.com>,
        Steven Rostedt <rostedt@goodmis.org>,
        Joel Fernandes <joel@joelfernandes.org>,
        Boris Ostrovsky <boris.ostrovsky@oracle.com>,
        Juergen Gross <jgross@suse.com>,
        Brian Gerst <brgerst@gmail.com>,
        Mathieu Desnoyers <mathieu.desnoyers@efficios.com>,
        Josh Poimboeuf <jpoimboe@redhat.com>,
        Will Deacon <will@kernel.org>,
        "Peter Zijlstra (Intel)" <peterz@infradead.org>
Subject: Re: [patch V4 part 1 29/36] x86/mce: Send #MC singal from task work
Message-ID: <20200514141616.GC9266@zn.tnic>
References: <20200505131602.633487962@linutronix.de>
 <20200505134100.957390899@linutronix.de>
 <CALCETrX=Obqn2ms5EYs7HPxTE_UgnVkmt-HoAoGzB4BajuMwLA@mail.gmail.com>
MIME-Version: 1.0
Content-Type: text/plain; charset=utf-8
Content-Disposition: inline
In-Reply-To: <CALCETrX=Obqn2ms5EYs7HPxTE_UgnVkmt-HoAoGzB4BajuMwLA@mail.gmail.com>
User-Agent: Mutt/1.10.1 (2018-07-13)
Sender: linux-kernel-owner@vger.kernel.org
Precedence: bulk

On Thu, May 07, 2020 at 11:02:09AM -0700, Andy Lutomirski wrote:
> IOW, if we want to recover from CPL0 #MC, we will need a different mechanism.

Recovering from CPL0 #MC is mostly doomed to failure. Except this mcsafe
crap with the exception handling:

                /*
                 * Handle an MCE which has happened in kernel space but from
                 * which the kernel can recover: ex_has_fault_handler() has
                 * already verified that the rIP at which the error happened is
                 * a rIP from which the kernel can recover (by jumping to
                 * recovery code specified in _ASM_EXTABLE_FAULT()) and the
                 * corresponding exception handler which would do that is the
                 * proper one.
                 */
                if (m.kflags & MCE_IN_KERNEL_RECOV) {
                        if (!fixup_exception(regs, X86_TRAP_MC, error_code, 0))
                                mce_panic("Failed kernel mode recovery", &m, msg);


Other than that, we iz done.

-- 
Regards/Gruss,
    Boris.

https://people.kernel.org/tglx/notes-about-netiquette