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[198.145.29.99]) by mx.google.com with ESMTPS id k193si16941568pge.306.2019.05.13.11.13.48 for (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Mon, 13 May 2019 11:13:48 -0700 (PDT) Received-SPF: pass (google.com: domain of luto@kernel.org designates 198.145.29.99 as permitted sender) client-ip=198.145.29.99; Authentication-Results: mx.google.com; dkim=pass header.i=@kernel.org header.s=default header.b=Kr4h++I2; spf=pass (google.com: domain of luto@kernel.org designates 198.145.29.99 as permitted sender) smtp.mailfrom=luto@kernel.org; dmarc=pass (p=NONE sp=NONE dis=NONE) header.from=kernel.org Received: from mail-wm1-f50.google.com (mail-wm1-f50.google.com [209.85.128.50]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id AE0AE21019 for ; Mon, 13 May 2019 18:13:47 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1557771227; bh=xJ43iv8JIVJV06BJOR4VuJn38wWKCPs7W85gx3/vesQ=; h=References:In-Reply-To:From:Date:Subject:To:Cc:From; b=Kr4h++I20RzmmFkfWraxMrcWykCiUWMo5cD7jMZUl9TScjEnTaCNGSOpZQ712x9Es JiAUEzbZ2+437fzGeZMnpa+NXORIleALchDX+pLifwNBmHbDzh9hXNyOOpZK+nIkqf JVQfKpUHOI+nklMyMK7NzcpfAx5+BRYIXL99WiV8= Received: by mail-wm1-f50.google.com with SMTP id f2so286329wmj.3 for ; Mon, 13 May 2019 11:13:47 -0700 (PDT) X-Received: by 2002:a1c:486:: with SMTP id 128mr15655411wme.83.1557771226305; Mon, 13 May 2019 11:13:46 -0700 (PDT) MIME-Version: 1.0 References: <1557758315-12667-1-git-send-email-alexandre.chartre@oracle.com> <1557758315-12667-7-git-send-email-alexandre.chartre@oracle.com> <64c49aa6-e7f2-4400-9254-d280585b4067@oracle.com> In-Reply-To: <64c49aa6-e7f2-4400-9254-d280585b4067@oracle.com> From: Andy Lutomirski Date: Mon, 13 May 2019 11:13:34 -0700 X-Gmail-Original-Message-ID: Message-ID: Subject: Re: [RFC KVM 06/27] KVM: x86: Exit KVM isolation on IRQ entry To: Alexandre Chartre Cc: Andy Lutomirski , Paolo Bonzini , Radim Krcmar , Thomas Gleixner , Ingo Molnar , Borislav Petkov , "H. Peter Anvin" , Dave Hansen , Peter Zijlstra , kvm list , X86 ML , Linux-MM , LKML , Konrad Rzeszutek Wilk , jan.setjeeilers@oracle.com, Liran Alon , Jonathan Adams Content-Type: text/plain; charset="UTF-8" X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: On Mon, May 13, 2019 at 9:28 AM Alexandre Chartre wrote: > > > > On 5/13/19 5:51 PM, Andy Lutomirski wrote: > > On Mon, May 13, 2019 at 7:39 AM Alexandre Chartre > > wrote: > >> > >> From: Liran Alon > >> > >> Next commits will change most of KVM #VMExit handlers to run > >> in KVM isolated address space. Any interrupt handler raised > >> during execution in KVM address space needs to switch back > >> to host address space. > >> > >> This patch makes sure that IRQ handlers will run in full > >> host address space instead of KVM isolated address space. > > > > IMO this needs to be somewhere a lot more central. What about NMI and > > MCE? Or async page faults? Or any other entry? > > > > Actually, I am not sure this is effectively useful because the IRQ > handler is probably faulting before it tries to exit isolation, so > the isolation exit will be done by the kvm page fault handler. I need > to check that. > The whole idea of having #PF exit with a different CR3 than was loaded on entry seems questionable to me. I'd be a lot more comfortable with the whole idea if a page fault due to accessing the wrong data was an OOPS and the code instead just did the right thing directly. --Andy