From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (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 5B42417A586; Mon, 9 Sep 2024 17:55:03 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1725904503; cv=none; b=UmJPKz+CcDDlY+MVr00rwRYMrenEBaNxdohZZveZbuhr0NvO3UODQX8lUBqygP5P9EzHUHdINz1+utvTNlJAkurqZM98CvRXhFWK53ILMgAqiKxNBQg2qV609YB+jfdYZ9d4HVcn0ZNp3Ac6fVW+4XOYrH5z9vqRwTRo6fZjhMQ= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1725904503; c=relaxed/simple; bh=LX1XZG3Vbs1WbPGJLFhxXw5XknbqyrKQA+1PjI+vHjo=; h=Date:Message-ID:From:To:Cc:Subject:In-Reply-To:References: MIME-Version:Content-Type; b=miHhNGq/J8Vs5qlRoEWQ0PWmxRdXKtIM3vjRaFPeBB1HICr/GZeRF5XxZjwbbKT/0KYgxPMcKJYip9kQEo3j61yhq4lO/l4FYSRAsE1qMhVTRU3jEWibhYUEoNAuFXROsD7Z6Y78wA4mSX8uXzJGTJpbgXAioTDrJbID57Yiw3s= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=hnsANtkC; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="hnsANtkC" Received: by smtp.kernel.org (Postfix) with ESMTPSA id E2AEEC4CEC5; Mon, 9 Sep 2024 17:55:02 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1725904502; bh=LX1XZG3Vbs1WbPGJLFhxXw5XknbqyrKQA+1PjI+vHjo=; h=Date:From:To:Cc:Subject:In-Reply-To:References:From; b=hnsANtkCoNTDcUyxYk5nin8Rj5kLynFPVsCqXmaH8ael74UknqjaSqlQWt2vUCIRb M90cr+Oaekz+YibT2QxjhXJFQ2TUcCz8pZcKd5zmZQx0YQ3KoUPQRrgYylIjdRp1Er FjkGPFOYMDvuisG4QPPKnTs7gVKSvV1I50TTjyX55SmzhAXsW4ks/50KXVkiCoCBSv ADrQvVfK5z7Pm7p5C7SEW6ylwVyiUu/9KtA/cshHbCkojKCkTxCmqfS6Vcyk0vX0jw U+ZVTa1Ea88Nrf271a1crlgPmY+FSVFj4IVRpGGZHrLeCDh0fxPTDKB9w8nbuJrLwK IAN7o324ni+eg== 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 4.95) (envelope-from ) id 1snibN-00BDhz-06; Mon, 09 Sep 2024 18:55:01 +0100 Date: Mon, 09 Sep 2024 18:55:00 +0100 Message-ID: <861q1s90gb.wl-maz@kernel.org> From: Marc Zyngier To: Shameerali Kolothum Thodi Cc: Oliver Upton , "kvmarm@lists.linux.dev" , Sebastian Ott , James Morse , Suzuki K Poulose , yuzenghui , "kvm@vger.kernel.org" , Shaoqin Huang , Eric Auger , "Wangzhou (B)" Subject: Re: [PATCH v5 07/10] KVM: arm64: Treat CTR_EL0 as a VM feature ID register In-Reply-To: <8634m890on.wl-maz@kernel.org> References: <20240619174036.483943-1-oliver.upton@linux.dev> <20240619174036.483943-8-oliver.upton@linux.dev> <0db19a081d9e41f08b0043baeef16f16@huawei.com> <864j6o94fz.wl-maz@kernel.org> <8e361ab82d6c4adcb15890cd3cab48ee@huawei.com> <8634m890on.wl-maz@kernel.org> 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/29.4 (aarch64-unknown-linux-gnu) MULE/6.0 (HANACHIRUSATO) Precedence: bulk X-Mailing-List: kvm@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: shameerali.kolothum.thodi@huawei.com, oliver.upton@linux.dev, kvmarm@lists.linux.dev, sebott@redhat.com, james.morse@arm.com, suzuki.poulose@arm.com, yuzenghui@huawei.com, kvm@vger.kernel.org, shahuang@redhat.com, eric.auger@redhat.com, wangzhou1@hisilicon.com X-SA-Exim-Mail-From: maz@kernel.org X-SA-Exim-Scanned: No (on disco-boy.misterjones.org); SAEximRunCond expanded to false On Mon, 09 Sep 2024 18:50:00 +0100, Marc Zyngier wrote: > > > Ok. Just to clarify that " not necessarily any value lower than what's reported by > > hardware" means userspace can set PIPT if hardware supports VIPT? > > No, exactly the opposite. If the HW advertises VIPT, we can set s/can/can't/, dammit! > anything else. If the HW advertises PIPT, we can lie to the guest and > set VIPT. And if the HW advertises any of the two reserved values, it > can but in hell... ;-) M. -- Without deviation from the norm, progress is not possible.