From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from out-177.mta0.migadu.com (out-177.mta0.migadu.com [91.218.175.177]) (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 2B04920297C for ; Fri, 12 Sep 2025 21:48:32 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=91.218.175.177 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1757713714; cv=none; b=UjCkLL8KerS1Bvr546Lk34MzLN0Jm3hqO4520wVHHWxiSM/bayoXGlSJe1oi9ScZ1yhatlaZi7rh1ebRV+QYrw3+t+M+opqycq6PxqJMawDTqB3D/kmisQowqAXJt3edcWWI91rRbuWUW6ezL5/Uz8Yl/ECUy2hptvUnckzVBFs= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1757713714; c=relaxed/simple; bh=cqyUoph485fZREJjS7zJCLofAmjNjCMNsbUrCTIetVw=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=c/ELm9SJS01HyEoMkhWCfprrHMOildRwd+1ss0trZuCp36mqlf9TF++gWx4SkVyNeEj7YW7qny8rwWukA0ALYFRWwfF5Ab3AExVj8m3HGn/tnDCERaQ2K51AdnOhb+QCA9a0Tbf4XeT+jm/c5OWZBFijpIRSBXqSnt8HDQl5f1c= 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=OsPxm6iU; arc=none smtp.client-ip=91.218.175.177 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="OsPxm6iU" Date: Fri, 12 Sep 2025 14:48:23 -0700 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linux.dev; s=key1; t=1757713710; 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=miOiqM9PJywRP2ijiFmsLcJxHKl4Qa+wDhHbmBUP2eQ=; b=OsPxm6iU6Pwzs1p1SeMcYRzrfnqf0pCfLvHp0Lx1s/dXAsG5dN2MCFEIJ1/FH8ZSUXSkni kGFuj7uoLPnjAtUlZyaKkEIPxcrM58kOUyzUY0D1n5ObaNujYQXL7ezPpBkKuFrvQVVkpb NBU6PouDFEir6uAXHhy11xAjYC9mf6g= X-Report-Abuse: Please report any abuse attempt to abuse@migadu.com and include these headers. From: Oliver Upton To: Marc Zyngier Cc: kvmarm@lists.linux.dev, Joey Gouly , Suzuki K Poulose , Zenghui Yu , Jinqian Yang Subject: Re: [PATCH 00/11] KVM: arm64: nv: Align feature limitations with current state of support Message-ID: References: <20250912212258.407350-1-oliver.upton@linux.dev> <87ecsbz6s6.wl-maz@kernel.org> Precedence: bulk X-Mailing-List: kvmarm@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <87ecsbz6s6.wl-maz@kernel.org> X-Migadu-Flow: FLOW_OUT On Fri, Sep 12, 2025 at 10:43:05PM +0100, Marc Zyngier wrote: > > In so doing, I found a bug relating to FEAT_DoubleLock where we > > accidentally claim support where we shouldn't as the 0 value implies > > the feature is implemented. > > Meh. Don't you love negative features? Just about as fun as negative polarity traps. > > I've made each relaxation into its own patch to capture the rationale in > > the changelog but I'm also fine squashing these based on the affected > > register. Features that limit our MMU implementation are deliberately > > left masked, e.g. FEAT_ETS* and FEAT_nTLBPA place constraints on the > > behavior of our nested MMU. Although the latter is highly unlikely to > > matter. > > Well, unlikely to matter for S2. For S1, this is a different story. Indeed -- just my general impression is that we shouldn't constrain ourselves in terms of future MMU / TLB behavior at this point. > > Applies to 6.17-rc4. **NOTE** this depends on Jinqian's series to make > > ID_AA64MMFR1_EL1.TWED writable [*], that should be applied before this > > series. > > Thanks for that. I'll have a look shortly. I'll also have a look at the series, need to revisit an open Q from the last spin. Thanks, Oliver