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 D5479D111A8 for ; Thu, 27 Nov 2025 16:38:44 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=bombadil.20210309; h=Sender:List-Subscribe:List-Help :List-Post:List-Archive:List-Unsubscribe:List-Id:Content-Type:MIME-Version: References:In-Reply-To:Subject:Cc:To:From:Message-ID:Date:Reply-To: Content-Transfer-Encoding:Content-ID:Content-Description:Resent-Date: Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID:List-Owner; bh=tauP3GTawUIh8aTHZFObzzUqlu/yiM1llIITrrDJ0kw=; b=1VG+t4SJIQACMPoRmRWDhKGHl6 q9XIxr7IXgLpZt0Wi6y8HB49gypplFd8DOPfV3IFOBY7qs8YgPhMHEoZynR5ZGxTJUBwDNM6e796H rk6cGaMqvLVrj1TMcStjI+rC8VPyLuX5AA06/C2kEZWSjtD6ebTkzNtPx+CkCRF22akAIRgvWczlK vGIpmh/HQiEgxTO8pBeMir2vpmSnmtwwuS1x+YzvDWnBcwUVKNkqTEs0j7Aai639rW/WE2tvjJfzr YPe/Pc27jyderh4sO2RJIqEk1SNvcsYXu1RVJ+TFQqCm5UE6fI02YfECcz2vFtIKJmV0mIIvjKuWx bVND6upQ==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.98.2 #2 (Red Hat Linux)) id 1vOf0y-0000000GwIT-0HOL; Thu, 27 Nov 2025 16:38:40 +0000 Received: from tor.source.kernel.org ([172.105.4.254]) by bombadil.infradead.org with esmtps (Exim 4.98.2 #2 (Red Hat Linux)) id 1vOf0w-0000000GwIC-1eoL for linux-arm-kernel@lists.infradead.org; Thu, 27 Nov 2025 16:38:38 +0000 Received: from smtp.kernel.org (transwarp.subspace.kernel.org [100.75.92.58]) by tor.source.kernel.org (Postfix) with ESMTP id CAA9760242; Thu, 27 Nov 2025 16:38:37 +0000 (UTC) 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) 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 X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org 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.