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 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 8F450C433F5 for ; Thu, 30 Sep 2021 18:08:38 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 65B2060D42 for ; Thu, 30 Sep 2021 18:08:38 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1353132AbhI3SKU (ORCPT ); Thu, 30 Sep 2021 14:10:20 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:59760 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1353043AbhI3SKT (ORCPT ); Thu, 30 Sep 2021 14:10:19 -0400 Received: from mail-pj1-x1031.google.com (mail-pj1-x1031.google.com [IPv6:2607:f8b0:4864:20::1031]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 15055C06176A for ; Thu, 30 Sep 2021 11:08:37 -0700 (PDT) Received: by mail-pj1-x1031.google.com with SMTP id v19so4779360pjh.2 for ; Thu, 30 Sep 2021 11:08:37 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20210112; h=date:from:to:cc:subject:message-id:references:mime-version :content-disposition:in-reply-to; bh=EoZfu8bpen5KFMUVG6jLqzqied/lYe6mK0ma9Cef8Os=; b=bXQfSxmBXOfT4WF1wCJ2uHhAn2c04X0SQKHS2xapCL9/Uhsl4XxrYsrnsseZhnbA60 b3qEkUcxB21kqfR4mXgiff7CBu78x9TTEzl0jDrljzdTFi35bN/2k1dmNFkQpcTLFTtN C2Ky2PMllbuODghV5eIb0Yxe1DYKlq4jSZtLsriuQVzE7BwnOUkmePZH1dGOpGKmhIye UxrQ77bpWdbAQDK/csIhkwjanA6B3nYpkd89EVa9Gwi3gvs1YvJFs+XoYLjw/9MMVkmm kCxoN1yVCaXXDLrTwAI4w+eoV5ZCrwXGMd+XNb100w15ojbpdx+k+/6m6X+PqPdIz+jO DG4Q== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=x-gm-message-state:date:from:to:cc:subject:message-id:references :mime-version:content-disposition:in-reply-to; bh=EoZfu8bpen5KFMUVG6jLqzqied/lYe6mK0ma9Cef8Os=; b=BdVNK5cW3UdYaikGCpfYVHjXd5iWK2ci0dfqfVSaVu0R7jokxng+xwwVaH0zHXCJNE vlqYycUuh3lDVW57kHc/5mj7WQCi6TXgwOmMnw1SXMZIHdZ56g4x1suoLaPIlw8yNyE5 Z3xv3kV5cKzSKGIq5UVrIir/hc5fhvMVkb/uTj/WXMFr+KKv87Cw1wHbXL13xNr+SGEC 1GD/2gPr8oxlnzPOP+PL3etcwUVt9alK4ySugD8t6wGXDeXapqpqouCYwEr0x4Zssmsl lS86rxr9Qlp25WCndEn/yVdU0gt670k75PmVPBs+Phn9ySh0Zugb/OIaD0xjzfvZ5SjB qJoA== X-Gm-Message-State: AOAM532ULDjy1pk9zICU8BfF1o2Mt9oNikwNK39GqHI11370INXafd+U cDw8hEs2wJaCE7KO5l1/Ew0ZrQ== X-Google-Smtp-Source: ABdhPJyofT3EyCRTUH4uH/kvj1uCfmupdajOzWbRL4wny0VfkHxLMQqDTXmIdg75I/pNah8kDYB0sQ== X-Received: by 2002:a17:90b:38d0:: with SMTP id nn16mr3499466pjb.112.1633025316319; Thu, 30 Sep 2021 11:08:36 -0700 (PDT) Received: from google.com (157.214.185.35.bc.googleusercontent.com. [35.185.214.157]) by smtp.gmail.com with ESMTPSA id d22sm3668968pgi.73.2021.09.30.11.08.35 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Thu, 30 Sep 2021 11:08:35 -0700 (PDT) Date: Thu, 30 Sep 2021 18:08:32 +0000 From: Sean Christopherson To: Oliver Upton Cc: Marc Zyngier , kvm@vger.kernel.org, Peter Shier , kvmarm@lists.cs.columbia.edu Subject: Re: [PATCH v2 05/11] KVM: arm64: Defer WFI emulation as a requested event Message-ID: References: <20210923191610.3814698-1-oupton@google.com> <20210923191610.3814698-6-oupton@google.com> <878rzetk0o.wl-maz@kernel.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: Precedence: bulk List-ID: X-Mailing-List: kvm@vger.kernel.org On Thu, Sep 30, 2021, Oliver Upton wrote: > On Thu, Sep 30, 2021 at 10:09 AM Sean Christopherson wrote: > > Unlike PSCI power-off, WFI isn't cross-vCPU, thus there's no hard requirement > > for using a request. And KVM_REQ_SLEEP also has an additional guard in that it > > doesn't enter rcuwait if power_off (or pause) was cleared after the request was > > made, e.g. if userspace stuffed vCPU state and set the vCPU RUNNABLE. > > Yeah, I don't think the punt is necessary for anything but the case > where userspace sets the MP state to request WFI behavior. A helper > method amongst all WFI cases is sufficient, and using the deferral for > everything is a change in behavior. Is there an actual use case for letting userspace request WFI behavior?