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([2001:b07:6468:f312:a0c0:5d2e:1d35:17bb]) by smtp.gmail.com with ESMTPSA id a6sm7362518wrn.38.2020.06.04.06.29.26 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Thu, 04 Jun 2020 06:29:27 -0700 (PDT) Subject: Re: [patch V9 00/39] x86/entry: Rework leftovers (was part V) To: Peter Zijlstra , Andrew Cooper Cc: Thomas Gleixner , LKML , Andy Lutomirski , X86 ML , "Paul E. McKenney" , Alexandre Chartre , Frederic Weisbecker , Sean Christopherson , Masami Hiramatsu , Petr Mladek , Steven Rostedt , Joel Fernandes , Boris Ostrovsky , Juergen Gross , Brian Gerst , Mathieu Desnoyers , Josh Poimboeuf , Will Deacon , Tom Lendacky , Wei Liu , Michael Kelley , Jason Chen CJ , Zhao Yakui , "H. Peter Anvin" References: <20200521200513.656533920@linutronix.de> <5e68aa83-feac-2aa7-10ee-aebebc60c83e@citrix.com> <20200522211706.GZ2483@worktop.programming.kicks-ass.net> <83474edd-195f-f10b-9fe9-8ee168344e29@citrix.com> <20200604132537.GA3976@hirez.programming.kicks-ass.net> From: Paolo Bonzini Message-ID: Date: Thu, 4 Jun 2020 15:29:26 +0200 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:68.0) Gecko/20100101 Thunderbird/68.6.0 MIME-Version: 1.0 In-Reply-To: <20200604132537.GA3976@hirez.programming.kicks-ass.net> Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 04/06/20 15:25, Peter Zijlstra wrote: > It being enabled through IA32_DEBUGCTL instead of through DR7 means that > the current code doesn't disable it and this then means we can have > nested #DB again. /me bangs head on door > Who sodding throught this was a good idea ?! What happened to #AC that > SLD currently uses? It was per-core and (presumably) considered unfixable? Paolo