From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-2.3 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,USER_AGENT_SANE_1 autolearn=no autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 78C03C83004 for ; Wed, 29 Apr 2020 20:06:34 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 61B622076B for ; Wed, 29 Apr 2020 20:06:34 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726800AbgD2UGb (ORCPT ); Wed, 29 Apr 2020 16:06:31 -0400 Received: from mga18.intel.com ([134.134.136.126]:37019 "EHLO mga18.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726456AbgD2UGa (ORCPT ); Wed, 29 Apr 2020 16:06:30 -0400 IronPort-SDR: OqmVG6wuJxhpQbu6OPYgekd/oHCyHWVmDMqvwFDKln8Zn+sye7UbKRFnWS1qSI98GSJTiPgXoM aHI/PfKTRHlg== X-Amp-Result: SKIPPED(no attachment in message) X-Amp-File-Uploaded: False Received: from fmsmga005.fm.intel.com ([10.253.24.32]) by orsmga106.jf.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 29 Apr 2020 13:06:30 -0700 IronPort-SDR: m0hwcU/Pm2d+wtnIowylzWCVRuCjU8EwMkKdW30+nKlBoOHV3ncQiMMWzW2at5i/VsEZUZBqrr cmL1GXMTa68g== X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.73,333,1583222400"; d="scan'208";a="459315579" Received: from sjchrist-coffee.jf.intel.com (HELO linux.intel.com) ([10.54.74.202]) by fmsmga005.fm.intel.com with ESMTP; 29 Apr 2020 13:06:29 -0700 Date: Wed, 29 Apr 2020 13:06:29 -0700 From: Sean Christopherson To: Jim Mattson Cc: Paolo Bonzini , Vitaly Kuznetsov , Wanpeng Li , Joerg Roedel , kvm list , LKML , Oliver Upton , Peter Shier Subject: Re: [PATCH 09/13] KVM: nVMX: Prioritize SMI over nested IRQ/NMI Message-ID: <20200429200629.GH15992@linux.intel.com> References: <20200423022550.15113-1-sean.j.christopherson@intel.com> <20200423022550.15113-10-sean.j.christopherson@intel.com> <20200428225949.GP12735@linux.intel.com> <20200429145040.GA15992@linux.intel.com> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: <20200429145040.GA15992@linux.intel.com> User-Agent: Mutt/1.5.24 (2015-08-30) Sender: kvm-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: kvm@vger.kernel.org On Wed, Apr 29, 2020 at 07:50:40AM -0700, Sean Christopherson wrote: > On Tue, Apr 28, 2020 at 04:16:16PM -0700, Jim Mattson wrote: > > On Tue, Apr 28, 2020 at 3:59 PM Sean Christopherson > > wrote: > > > > > > On Tue, Apr 28, 2020 at 03:04:02PM -0700, Jim Mattson wrote: > > > > From the SDM, volume 3: > > > > > > > > • System-management interrupts (SMIs), INIT signals, and higher > > > > priority events take priority over MTF VM exits. > > > > > > > > I think this block needs to be moved up. > > > > > > Hrm. It definitely needs to be moved above the preemption timer, though I > > > can't find any public documentation about the preemption timer's priority. > > > Preemption timer is lower priority than MTF, ergo it's not in the same > > > class as SMI. > > > > > > Regarding SMI vs. MTF and #DB trap, to actually prioritize SMIs above MTF > > > and #DBs, we'd need to save/restore MTF and pending #DBs via SMRAM. I > > > think it makes sense to take the easy road and keep SMI after the traps, > > > with a comment to say it's technically wrong but not worth fixing. > > > > Pending debug exceptions should just go in the pending debug > > exceptions field. End of story and end of complications. I don't > > understand why kvm is so averse to using this field the way it was > > intended. > > Ah, it took my brain a bit to catch on. I assume you're suggesting calling > nested_vmx_updated_pending_dbg() so that the pending #DB naturally gets > propagated to/from vmcs12 on SMI/RSM? I think that should work. This works for L2, but not L1 :-( And L2 can't be fixed without first fixing L1 because inject_pending_event() also incorrectly prioritizes #DB over SMI. For L1, utilizing SMRAM to save/restore the pending #DB is likely the easiest solution as it avoids having to add new state for migration. I have everything coded up but it'll probably take a few weeks to test and get it sent out, need to focus on other stuff for a while.