From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from out-179.mta0.migadu.com (out-179.mta0.migadu.com [91.218.175.179]) (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 3A94C175D5D for ; Fri, 7 Feb 2025 18:10:16 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=91.218.175.179 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1738951818; cv=none; b=nOLh0PGVQVgNPR1tnIVfEIwrMYI1ESrT72eH+/itJbyZ6ci5O8EaBMqcaid+fM9DFuUlKR2brpwoANONw9oUJjEPCYwrSPHfCeOkKa5ATE+Cv64qsvrAUcU76/18KyG9P/eMcJPaahi+BXoM/89a5jZJDXwGP6/cx3e140Qrgxc= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1738951818; c=relaxed/simple; bh=+G+YBZTgA9QIbY2A+UZYK3QXLmcb1dpBWlg/zQMm6Zc=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=cV68rPz3o8Ehi8ojIJ3dWEqaXFZ71OTNKxxWszgHvWQxUBNPASKE7o48PEGVE25h7reMo8jwIEcvUMCYYQ/edmCeN9reeodhiQh39dBkNm6xsfw4Wj7BD8L6FmmjqP8gfHevJUwO+9Q7y2CqfBt4Qah/GYvOh1qjbQOr1wa37uM= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=linux.dev; spf=pass smtp.mailfrom=linux.dev; dkim=pass (1024-bit key) header.d=linux.dev header.i=@linux.dev header.b=DBeVwjXj; arc=none smtp.client-ip=91.218.175.179 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=linux.dev Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=linux.dev Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linux.dev header.i=@linux.dev header.b="DBeVwjXj" Date: Fri, 7 Feb 2025 10:09:58 -0800 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linux.dev; s=key1; t=1738951803; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: in-reply-to:in-reply-to:references:references; bh=ZolRaIlCgaZRdZ2y7P6BoM5Dq+0ObR3jHsmtYgVaSNI=; b=DBeVwjXjnPTYpQs6Lq9Mvygma9/LdKK5EEukS36yscCrnbkZZcopW5h0QH0FR9304mEJVg Xlr/eeKMf+3R0mb40Kic+82+T0Sp+HGlGTQFnlHe2KBXWxMaPSOoRxAfoJk472uVfK3Kh2 TQvD3khEOYtwiOiOb/dYlH+PWd6e21k= X-Report-Abuse: Please report any abuse attempt to abuse@migadu.com and include these headers. From: Oliver Upton To: Marc Zyngier Cc: Eric Auger , Ganapatrao Kulkarni , kvmarm , linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org, christoffer.dall@arm.com, suzuki.poulose@arm.com, will@kernel.org, catalin.marinas@arm.com, coltonlewis@google.com, joey.gouly@arm.com, yuzenghui@huawei.com, darren@os.amperecomputing.com, vishnu@os.amperecomputing.com Subject: Re: [PATCH] KVM: arm64: nv: Set ISTATUS for emulated timers, If timer expired Message-ID: References: <86y10osr19.wl-maz@kernel.org> <4d443db1-85b1-4071-acd5-3187deb9cb17@redhat.com> <2f6b2cb1-3d32-480a-9801-9b993ae74e2d@os.amperecomputing.com> <152d262e-641d-4bb1-9656-a13e049d62c4@redhat.com> <86h661wje4.wl-maz@kernel.org> <4a9fbdd9-ad23-44bc-8ba5-399f08068db4@redhat.com> <86cygpwfy0.wl-maz@kernel.org> <86frkptzr6.wl-maz@kernel.org> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <86frkptzr6.wl-maz@kernel.org> X-Migadu-Flow: FLOW_OUT Hey, On Fri, Feb 07, 2025 at 05:45:33PM +0000, Marc Zyngier wrote: > I found at least one issue that could fail the migration. Before the > VM starts running, we limit the feature set to the subset we actually > support with NV. > > By doing this, we also change the value of IDreg fields that are not > writable, because they describe features that we don't support. > Obviously, that fails on restore. > > I need to have a think... We spoke about this a while ago (and I forgot til now), but I was wondering if we could use vCPU feature flags to describe NV, including the selection between FEAT_E2H0 and FEAT_VHE. I think this might match userspace expectations a bit more closely where the state of the ID registers after init gives the actual feature set supported by the VM. -- Thanks, Oliver