From mboxrd@z Thu Jan 1 00:00:00 1970 From: Sean Christopherson Date: Wed, 10 Jul 2024 08:51:51 -0700 Subject: [PATCH v3 0/3] KVM: Set vcpu->preempted/ready iff scheduled out while running In-Reply-To: References: <20240503181734.1467938-1-dmatlack@google.com> <171874683295.1901599.10170158200177384059.b4-ty@google.com> Message-ID: List-Id: To: kvm-riscv@lists.infradead.org MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit On Mon, Jul 01, 2024, David Matlack wrote: > On Tue, Jun 18, 2024 at 2:41?PM Sean Christopherson wrote: > > > > On Fri, 03 May 2024 11:17:31 -0700, David Matlack wrote: > > > This series changes KVM to mark a vCPU as preempted/ready if-and-only-if > > > it's scheduled out while running. i.e. Do not mark a vCPU > > > preempted/ready if it's scheduled out during a non-KVM_RUN ioctl() or > > > when userspace is doing KVM_RUN with immediate_exit=true. > > > > > > This is a logical extension of commit 54aa83c90198 ("KVM: x86: do not > > > set st->preempted when going back to user space"), which stopped > > > marking a vCPU as preempted when returning to userspace. But if userspace > > > invokes a KVM vCPU ioctl() that gets preempted, the vCPU will be marked > > > preempted/ready. This is arguably incorrect behavior since the vCPU was > > > not actually preempted while the guest was running, it was preempted > > > while doing something on behalf of userspace. > > > > > > [...] > > > > Applied to kvm-x86 generic, with minor changelog tweaks (me thinks you've been > > away from upstream too long ;-) ). Thanks! > > Thanks for the cleanups. Looks like you replaced "[Tt]his commit" > throughout. Anything else (so I can avoid the same mistakes in the > future)? I don't think so? The "This commit" stuff is the only thing that I remember, so any other tweaks can't be that important :-) From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mail-pl1-f202.google.com (mail-pl1-f202.google.com [209.85.214.202]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 6027819247B for ; Wed, 10 Jul 2024 15:51:53 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=209.85.214.202 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1720626714; cv=none; b=cjUhe9gTrgK600aflZE9xhpyxf1n350qqHhGtRYUybc38GGLfo6AJDktSrreB9EOS+uBFemuxk+DKZe2uKjjUm/RXEtQoIvCv5ulUEz8x+xUZ/lNkj26id40lvVs+hb2r/otcZPwONOlfB3aXXPnNng4gSxQ9//LCwDNSnnaHws= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1720626714; c=relaxed/simple; bh=Yd7wN4MEwb/4Ych5ZfYI8ZDswiwmmeax1EQOB34ZhJk=; h=Date:In-Reply-To:Mime-Version:References:Message-ID:Subject:From: To:Cc:Content-Type; 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charset="utf-8" Content-Transfer-Encoding: quoted-printable On Mon, Jul 01, 2024, David Matlack wrote: > On Tue, Jun 18, 2024 at 2:41=E2=80=AFPM Sean Christopherson wrote: > > > > On Fri, 03 May 2024 11:17:31 -0700, David Matlack wrote: > > > This series changes KVM to mark a vCPU as preempted/ready if-and-only= -if > > > it's scheduled out while running. i.e. Do not mark a vCPU > > > preempted/ready if it's scheduled out during a non-KVM_RUN ioctl() or > > > when userspace is doing KVM_RUN with immediate_exit=3Dtrue. > > > > > > This is a logical extension of commit 54aa83c90198 ("KVM: x86: do not > > > set st->preempted when going back to user space"), which stopped > > > marking a vCPU as preempted when returning to userspace. But if users= pace > > > invokes a KVM vCPU ioctl() that gets preempted, the vCPU will be mark= ed > > > preempted/ready. This is arguably incorrect behavior since the vCPU w= as > > > not actually preempted while the guest was running, it was preempted > > > while doing something on behalf of userspace. > > > > > > [...] > > > > Applied to kvm-x86 generic, with minor changelog tweaks (me thinks you'= ve been > > away from upstream too long ;-) ). Thanks! >=20 > Thanks for the cleanups. Looks like you replaced "[Tt]his commit" > throughout. Anything else (so I can avoid the same mistakes in the > future)? I don't think so? The "This commit" stuff is the only thing that I remembe= r, so any other tweaks can't be that important :-) 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 bombadil.infradead.org (bombadil.infradead.org [198.137.202.133]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id 99477C3DA41 for ; Wed, 10 Jul 2024 15:52:16 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=bombadil.20210309; h=Sender: Content-Transfer-Encoding:Content-Type:List-Subscribe:List-Help:List-Post: List-Archive:List-Unsubscribe:List-Id:Cc:To:From:Subject:Message-ID: References:Mime-Version:In-Reply-To:Date:Reply-To:Content-ID: Content-Description:Resent-Date:Resent-From:Resent-Sender:Resent-To:Resent-Cc :Resent-Message-ID:List-Owner; bh=KkWER4FqHswXMFPtKIBpYLxYup/Vxu5A4n5UUbc8Qig=; 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Wed, 10 Jul 2024 08:51:52 -0700 (PDT) Date: Wed, 10 Jul 2024 08:51:51 -0700 In-Reply-To: Mime-Version: 1.0 References: <20240503181734.1467938-1-dmatlack@google.com> <171874683295.1901599.10170158200177384059.b4-ty@google.com> Message-ID: Subject: Re: [PATCH v3 0/3] KVM: Set vcpu->preempted/ready iff scheduled out while running From: Sean Christopherson To: David Matlack Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: quoted-printable X-BeenThere: linuxppc-dev@lists.ozlabs.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Linux on PowerPC Developers Mail List List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: kvm@vger.kernel.org, David Hildenbrand , Paul Walmsley , linux-riscv@lists.infradead.org, Claudio Imbrenda , Janosch Frank , Marc Zyngier , Huacai Chen , Zenghui Yu , Palmer Dabbelt , Christian Borntraeger , Albert Ou , Suzuki K Poulose , Nicholas Piggin , Bibo Mao , loongarch@lists.linux.dev, Atish Patra , kvmarm@lists.linux.dev, linux-arm-kernel@lists.infradead.org, linux-mips@vger.kernel.org, Oliver Upton , James Morse , kvm-riscv@lists.infradead.org, Anup Patel , Paolo Bonzini , Tianrui Zhao , linuxppc-dev@lists.ozlabs.org Errors-To: linuxppc-dev-bounces+linuxppc-dev=archiver.kernel.org@lists.ozlabs.org Sender: "Linuxppc-dev" On Mon, Jul 01, 2024, David Matlack wrote: > On Tue, Jun 18, 2024 at 2:41=E2=80=AFPM Sean Christopherson wrote: > > > > On Fri, 03 May 2024 11:17:31 -0700, David Matlack wrote: > > > This series changes KVM to mark a vCPU as preempted/ready if-and-only= -if > > > it's scheduled out while running. i.e. Do not mark a vCPU > > > preempted/ready if it's scheduled out during a non-KVM_RUN ioctl() or > > > when userspace is doing KVM_RUN with immediate_exit=3Dtrue. > > > > > > This is a logical extension of commit 54aa83c90198 ("KVM: x86: do not > > > set st->preempted when going back to user space"), which stopped > > > marking a vCPU as preempted when returning to userspace. But if users= pace > > > invokes a KVM vCPU ioctl() that gets preempted, the vCPU will be mark= ed > > > preempted/ready. This is arguably incorrect behavior since the vCPU w= as > > > not actually preempted while the guest was running, it was preempted > > > while doing something on behalf of userspace. > > > > > > [...] > > > > Applied to kvm-x86 generic, with minor changelog tweaks (me thinks you'= ve been > > away from upstream too long ;-) ). Thanks! >=20 > Thanks for the cleanups. Looks like you replaced "[Tt]his commit" > throughout. Anything else (so I can avoid the same mistakes in the > future)? I don't think so? The "This commit" stuff is the only thing that I remembe= r, so any other tweaks can't be that important :-)