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 2AC27212554; Fri, 13 Feb 2026 10:40:09 +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=1770979210; cv=none; b=Eabg9Gk4XXudLOn+h50v8NQDkockKJghu2fjJErp5d4Ez5UOUYXE688Ub+aGp4XY/Qk5tImVPOqadFF0jT4jTXI5doz40z0uUX89ioXOiWNHrCtNV668bGa1If9TedQDyGEHzlXVFebM2XY2nk9JObSHzks3aiJOnplG6RweX3U= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1770979210; c=relaxed/simple; bh=Xqz6za0FavxiZ7fDMciG090joG/GKFc1LpHoJfcba0w=; h=Date:Message-ID:From:To:Cc:Subject:In-Reply-To:References: MIME-Version:Content-Type; b=vCctzmvGx+q7dryDHaOHw1AKup99umsbLZ5F7a8NfEyZvtqYh4e3HXBUuaYp0zUpHBTiTBKBLtVmSDzttAD9bAsSLmohYZG92Fy4eCm6l+h1wTDs0yFBDEMH7U4FsLyN+BiRtKhoolgUj0Xku0+If7UdLE2IpG6ipkl8I5jGK+A= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=IpjTBKin; 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="IpjTBKin" Received: by smtp.kernel.org (Postfix) with ESMTPSA id AA286C116C6; Fri, 13 Feb 2026 10:40:09 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1770979209; bh=Xqz6za0FavxiZ7fDMciG090joG/GKFc1LpHoJfcba0w=; h=Date:From:To:Cc:Subject:In-Reply-To:References:From; b=IpjTBKin7B81H+bwSfU+aUQh7ariYE9q67Gk6wzrek0HB0CLhpMF9utWlVFmsSg5a p+bKzkpCNCbcFFCmTJugmHeb3Gl1kKdW+sX0NiI19crR9kSoOCSN4pB/PRjEv8JWT0 VEHYv3P882F97T0x78MSbCN4EjDymneEqWOW/Zx9/Sk0YU3qrH2aR9oRDW5lDiEdAn u1eeI6LO8Rtit1nX6T+lURFD2tJziUCldf1gs/GHFkGvRQsNOMRH7xp0UZf2pvZa6B qbbkDP03/zTHFBnCwK/Q8Ecatv9beYxm9kbFC1G3Fgm6LbZmZMP/krH6Lob9TVDWBT xMijghpMH5Fgw== 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 1vqqal-0000000Ar8t-1BHt; Fri, 13 Feb 2026 10:40:07 +0000 Date: Fri, 13 Feb 2026 10:40:06 +0000 Message-ID: <86fr75apvd.wl-maz@kernel.org> From: Marc Zyngier To: Fuad Tabba Cc: kvm@vger.kernel.org, kvmarm@lists.linux.dev, linux-arm-kernel@lists.infradead.org, oliver.upton@linux.dev, joey.gouly@arm.com, suzuki.poulose@arm.com, yuzenghui@huawei.com, catalin.marinas@arm.com, will@kernel.org, stable@vger.kernel.org Subject: Re: [PATCH v1 1/3] KVM: arm64: Hide S1POE from guests when not supported by the host In-Reply-To: References: <20260212090252.158689-1-tabba@google.com> <20260212090252.158689-2-tabba@google.com> <86jywib98e.wl-maz@kernel.org> <86ikc2asa8.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/30.1 (aarch64-unknown-linux-gnu) MULE/6.0 (HANACHIRUSATO) Precedence: bulk X-Mailing-List: stable@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: tabba@google.com, kvm@vger.kernel.org, kvmarm@lists.linux.dev, linux-arm-kernel@lists.infradead.org, oliver.upton@linux.dev, joey.gouly@arm.com, suzuki.poulose@arm.com, yuzenghui@huawei.com, catalin.marinas@arm.com, will@kernel.org, stable@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, 12 Feb 2026 18:53:05 +0000, Fuad Tabba wrote: > Ouch! Yeah, no easy solutions here. For now, as a fix to be able to > backport, would you like me to respin this without the change to > kvm_has_s1poe(), or with that change as a separate patch? I'll remove the hunk myself when applying the series, no need to resend (unless I find another issue in the rest of the series, but it looks good so far). FWIW, I have an alternative set of hacks at [1], which appear to work, but we need to collectively convince ourselves that this is the correct thing to do (i.e. the required traps are always set, irrespective of the configuration). This affects PAuth, SVE, MTE and S1POE. SME and GCS are not supported in KVM, and BTI has no additional state, so these shouldn't be affected. Thanks, M. [1] https://git.kernel.org/pub/scm/linux/kernel/git/maz/arm-platforms.git/log/?h=arm64/ftr_config -- Without deviation from the norm, progress is not possible.