From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-alma10-1.taild15c8.ts.net [100.103.45.18]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 9B355233943; Fri, 7 Aug 2026 08:20:50 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=100.103.45.18 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1786090851; cv=none; b=uM7p3Wm/58AIYhb6e43VFXrqfvGp22m+OX/+ESNCCO3BCnmKh8KPS3bP+B1cEMxdU8fBOWCH1Yrg9Wosvg6f88vsIhrKT2qkqbUoXBJ8bk60iJysFborhLk1zBpawMpqGIJBMMeBkq2ejppx1xae0Scuj2PSJqvXVdPtVDBGaeU= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1786090851; c=relaxed/simple; bh=dhUNmDI6VbmprVcGqgptGxWcoEJ2fWnzq6u0LSONKz0=; h=Date:Message-ID:From:To:Cc:Subject:In-Reply-To:References: MIME-Version:Content-Type; b=oAyAzUMrn+gF58a5P80mCxVDkK7I5YuGKgMebm1+k688nzSPLtflIKbxSo/98lZRIkhTSjjDc4pde4Tm2u/yIYHfciBg6DbSvzI6+VabhGwr3cvrlDFWmk+B+c5XL8W0yxAqwG74D1UkXk48KHdnXVP3dEYW5EJpxl/Bs79vWNc= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=DFA3/3G0; arc=none smtp.client-ip=100.103.45.18 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="DFA3/3G0" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 7F9E41F000E9; Fri, 7 Aug 2026 08:20:50 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1786090850; bh=Gd0DBh2Yz9bW2/wF4XYjseP/PmyhrTgYWP2JAKOk8ek=; h=Date:From:To:Cc:Subject:In-Reply-To:References; b=DFA3/3G0/2+0d2k9Fts0ddQl3TyfXps4evW+FUzvjgybg7WpUL1s1nkyHo/oEn7WE LhN+5ghiRPo5oaDZ4mhtDnzBDbE9QkY4ilp5H2mwTLeN5iVlcLIe+HpvGLvzE9ZqsZ qRzpx4CNMLP7kYV91KGRLI+nmP8+5STgn42k3leoMn0PRTKp2LGsIe332xB35HnqzR m0UbKaQ37MpSgbpO1RpXMxVazkkrX3s3YCbCCpngzvdBQpvAkYVc/MrozYdJ8fPfYj 81fWw61bwg7epzRY7LZTR+kqRoUJaPIxcILsdzAVnDATBtV3KU5vGEoJjwfGTt5n/K e5TTaRUJrgn8w== Received: from sofa.misterjones.org ([185.219.108.64] helo=goblin-girl.misterjones.org) by disco-boy.misterjones.org with esmtpsa (TLS1.3) tls TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384 (Exim 4.98.2) (envelope-from ) id 1wsFou-0000000DGX0-0sIR; Fri, 07 Aug 2026 08:20:48 +0000 Date: Fri, 07 Aug 2026 09:20:47 +0100 Message-ID: <8633wqbau8.wl-maz@kernel.org> From: Marc Zyngier To: Sean Christopherson Cc: Oliver Upton , Paolo Bonzini , Joey Gouly , Steffen Eiden , Suzuki K Poulose , Zenghui Yu , linux-arm-kernel@lists.infradead.org, kvmarm@lists.linux.dev, kvm@vger.kernel.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH] KVM: Never clear KVM_REQ_VM_DEAD from a vCPU's requests In-Reply-To: <20260806214618.82180-1-seanjc@google.com> References: <20260806214618.82180-1-seanjc@google.com> User-Agent: Wanderlust/2.15.9 (Almost Unreal) SEMI-EPG/1.14.7 (Harue) FLIM-LB/1.14.9 (=?UTF-8?B?R29qxY0=?=) APEL-LB/10.8 EasyPG/1.0.0 Emacs/30.1 (aarch64-unknown-linux-gnu) MULE/6.0 (HANACHIRUSATO) Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 (generated by SEMI-EPG 1.14.7 - "Harue") Content-Type: text/plain; charset=US-ASCII X-SA-Exim-Connect-IP: 185.219.108.64 X-SA-Exim-Rcpt-To: seanjc@google.com, oupton@kernel.org, pbonzini@redhat.com, joey.gouly@arm.com, seiden@linux.ibm.com, suzuki.poulose@arm.com, yuzenghui@huawei.com, linux-arm-kernel@lists.infradead.org, kvmarm@lists.linux.dev, kvm@vger.kernel.org, linux-kernel@vger.kernel.org X-SA-Exim-Mail-From: maz@kernel.org X-SA-Exim-Scanned: No (on disco-boy.misterjones.org); SAEximRunCond expanded to false On Thu, 06 Aug 2026 22:46:18 +0100, Sean Christopherson wrote: > > Use kvm_test_request() instead of kvm_check_request() when querying > KVM_REQ_VM_DEAD, i.e. don't clear KVM_REQ_VM_DEAD, as the entire purpose > of KVM_REQ_VM_DEAD is to prevent the vCPU from enterring the guest ever > again, even if userspace insists on redoing KVM_RUN. > > Ensuring KVM_REQ_VM_DEAD is never cleared will allow relaxing KVM's rule > that ioctls can't be invoked on dead VMs, to only disallow ioctls if the > VM is bugged, i.e. if KVM hit a KVM_BUG_ON(). > > Opportunistically add compile-time assertions to guard against clearing > KVM_REQ_VM_DEAD through the standard APIs. > > Signed-off-by: Sean Christopherson Acked-by: Marc Zyngier M. -- Without deviation from the norm, progress is not possible.