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 E633D2D94B2; Thu, 27 Nov 2025 16:38:37 +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=1764261518; cv=none; b=Mn6OaNmesv58OgA0icYP9hovXAXeEi8/yBPhfq97pj/I/NSsXWS1dYU2kvMfoh6QIDJlm0gzfS16BnP6UTSOvv+f62YVPvn7g7HbFg+muxs5kfH6ca3G+bJsr36mAk4nYwuQac89nyg3T/cfmAnJKTDO8YB1GbROXDa5mfG9RUw= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1764261518; c=relaxed/simple; bh=KbmAovPW7NQWTvYbrFMMlfWlRV/+WdW1rESMqn+8NHs=; h=Date:Message-ID:From:To:Cc:Subject:In-Reply-To:References: MIME-Version:Content-Type; b=TtKiorqB51WtZiXvliYqlShSVXDCScys8iAIzf5cTCLA150YaJBjCSBnuBQVUOZDkF2ysIB0RKpIZ9/pSVE1G9vx4ySSMHc6Agln7Zsc4+yUHoQ29eXhLXcg4wHXZhP0MJK/SWsC2vZXILdY0kXcGtlYg3y8BXZYPwI35lKUizk= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=WsAiDcPO; 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="WsAiDcPO" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 75181C4CEF8; Thu, 27 Nov 2025 16:38:37 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1764261517; bh=KbmAovPW7NQWTvYbrFMMlfWlRV/+WdW1rESMqn+8NHs=; h=Date:From:To:Cc:Subject:In-Reply-To:References:From; b=WsAiDcPOO4FIOb14VhhEGIB50XdJvbCLmbPd35/OPwREufanSEr51f1qjWCpKKqNT 47JLTP6HCvTw9QHmDm6o1CSdAoHMijlB4tIgKxy3XqBp8fUsTdTWnxP4lYzJeN64W+ q64zShkrBuqBFuKfPmXMCPAZlGlK3EtSzh5LOZWxeITg+eZMJwv0FMW6cl82N/WnL6 EjMHl7LhYTq1EpNJbZ4zHt9w+C4WCgJgXhk0057Nqd9wzRUfipnqvCsTnHkb7hwlbK l4I7qymtKdrq3rAZt4JG/B8Tg66DcHCTblo3aaL2U99KpIJJvpPI351Oj9vCt7XtYC YErMvBDsBZF+g== 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 1vOf0t-00000008qxk-1IgN; Thu, 27 Nov 2025 16:38:35 +0000 Date: Thu, 27 Nov 2025 16:38:34 +0000 Message-ID: <86y0nrph11.wl-maz@kernel.org> From: Marc Zyngier To: kvmarm@lists.linux.dev, kvm@vger.kernel.org, linux-arm-kernel@lists.infradead.org Cc: Joey Gouly , Suzuki K Poulose , Oliver Upton , Zenghui Yu , Ben Horgan Subject: Re: [PATCH v2 0/5] KVM: arm64: Add support for FEAT_IDST In-Reply-To: <20251126155951.1146317-1-maz@kernel.org> References: <20251126155951.1146317-1-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/30.1 (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: kvmarm@lists.linux.dev, kvm@vger.kernel.org, linux-arm-kernel@lists.infradead.org, joey.gouly@arm.com, suzuki.poulose@arm.com, oupton@kernel.org, yuzenghui@huawei.com, ben.horgan@arm.com X-SA-Exim-Mail-From: maz@kernel.org X-SA-Exim-Scanned: No (on disco-boy.misterjones.org); SAEximRunCond expanded to false On Wed, 26 Nov 2025 15:59:46 +0000, Marc Zyngier wrote: > > FEAT_IDST appeared in ARMv8.4, and allows ID registers to be trapped > if they are not implemented. This only concerns 3 registers (GMID_EL1, > CCSIDR2_EL1 and SMIDR_EL1), which are part of features that may not be > exposed to the guest even if present on the host. > > For these registers, the HW should report them with EC=0x18, even if > the feature isn't implemented. > > Add support for this feature by handling these registers in a specific > way and implementing GMID_EL1 support in the process. A very basic > selftest checks that these registers behave as expected. Except that said selftest indicates that pKVM doesn't do the right thing and requires similar rework. I now have some patches to address it, and will repost the series sometime next week. M. -- Without deviation from the norm, progress is not possible.