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 1A2681FFC44; Mon, 16 Dec 2024 08:52:07 +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=1734339128; cv=none; b=diU6wJvYqG+oM+2r39T1VzKEN3MuiFozs5Dhi+VaGBsteX4HqCcyNgcMUSt1YDW+0WaafEWA0W09Ki0k2dmqZwQ65kC02LdxP8lGG6HPEP5sHBY0erJTobsFq2o8JxspN1QDW4PkV3du2tDAA4gFb2T/nN0No3WNhZjDeRbgfD8= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1734339128; c=relaxed/simple; bh=gs8goDXstShtLE5/00djVnwCrZT3j32AWHB5T4dafHw=; h=Date:Message-ID:From:To:Cc:Subject:In-Reply-To:References: MIME-Version:Content-Type; b=qKUM7CJxfTSGxEfu4jGDtPvDHBBgCzxMCdoCyTFIzqHkKbakYkCmOTVJxKZEJVUxZGcRHO6ONAXHtCUXA/0p8UW/2taywGWEUeRrya8A1mRvseQgQpZlTw40D/e+k8vaeihqLhXwxkoMWT61QCs3XPNLVlotv7mjjHyYjE8KTVA= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=sJvDvFsa; 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="sJvDvFsa" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 9C61DC4CED3; Mon, 16 Dec 2024 08:52:07 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1734339127; bh=gs8goDXstShtLE5/00djVnwCrZT3j32AWHB5T4dafHw=; h=Date:From:To:Cc:Subject:In-Reply-To:References:From; b=sJvDvFsa933M12L8z+R4lazlDeiMs4UtDXOn0WqNRRBAbC+8GphlQaAoN7xajLvFt t2/m3hUqTR+Mu/Upg/Wnklr7ARLghcz1q/2TDtMFkloRcBnNkuO1HQdVhYri7NhfJT p6uTExjlBm63voZi8dj0FJy5bdczf/xMOZbQ7/FDRRbl+jjSW19xEKnROes8x/+lI6 4kDiW4WXXLM9gPV7K578dXKQzD1rjx0qbD3i8ZQP5gpVnXi32g1HIlP9zONzuDY2qV vnXiE34zKI+Ugkh437jG3ikY1Il8+rFP2kBZzd9iiz+7EdEYKOCald7Xqarly4lHTl /3ch0HGR/P3uQ== 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 1tN6ph-0046M6-Ar; Mon, 16 Dec 2024 08:52:05 +0000 Date: Mon, 16 Dec 2024 08:52:04 +0000 Message-ID: <868qsgrowb.wl-maz@kernel.org> From: Marc Zyngier To: Joey Gouly Cc: stable@vger.kernel.org, linux-arm-kernel@lists.infradead.org, kvmarm@lists.linux.dev, gshan@redhat.com, james.morse@arm.com, oliver.upton@linux.dev, shameerali.kolothum.thodi@huawei.com, vt@altlinux.org, Suzuki K Poulose , Zenghui Yu , Jing Zhang , Catalin Marinas , Will Deacon Subject: Re: [PATCH 6.6 v1] KVM: arm64: Disable MPAM visibility by default and ignore VMM writes In-Reply-To: <20241212151406.1436382-1-joey.gouly@arm.com> References: <20241212151406.1436382-1-joey.gouly@arm.com> 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: kvmarm@lists.linux.dev 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: joey.gouly@arm.com, stable@vger.kernel.org, linux-arm-kernel@lists.infradead.org, kvmarm@lists.linux.dev, gshan@redhat.com, james.morse@arm.com, oliver.upton@linux.dev, shameerali.kolothum.thodi@huawei.com, vt@altlinux.org, suzuki.poulose@arm.com, yuzenghui@huawei.com, jingzhangos@google.com, catalin.marinas@arm.com, will@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 Dec 2024 15:14:06 +0000, Joey Gouly wrote: > > From: James Morse > > commit 6685f5d572c22e1003e7c0d089afe1c64340ab1f upstream. > > commit 011e5f5bf529f ("arm64/cpufeature: Add remaining feature bits in > ID_AA64PFR0 register") exposed the MPAM field of AA64PFR0_EL1 to guests, > but didn't add trap handling. A previous patch supplied the missing trap > handling. > > Existing VMs that have the MPAM field of ID_AA64PFR0_EL1 set need to > be migratable, but there is little point enabling the MPAM CPU > interface on new VMs until there is something a guest can do with it. > > Clear the MPAM field from the guest's ID_AA64PFR0_EL1 and on hardware > that supports MPAM, politely ignore the VMMs attempts to set this bit. > > Guests exposed to this bug have the sanitised value of the MPAM field, > so only the correct value needs to be ignored. This means the field > can continue to be used to block migration to incompatible hardware > (between MPAM=1 and MPAM=5), and the VMM can't rely on the field > being ignored. > > Signed-off-by: James Morse > Co-developed-by: Joey Gouly > Signed-off-by: Joey Gouly > Reviewed-by: Gavin Shan > Tested-by: Shameer Kolothum > Reviewed-by: Marc Zyngier > Link: https://lore.kernel.org/r/20241030160317.2528209-7-joey.gouly@arm.com > Signed-off-by: Oliver Upton > [ joey: fixed up merge conflict, no ID_FILTERED macro in 6.6 ] > Signed-off-by: Joey Gouly > Cc: stable@vger.kernel.org # 6.6.x > Cc: Vitaly Chikunov > Link: https://lore.kernel.org/linux-arm-kernel/20241202045830.e4yy3nkvxtzaybxk@altlinux.org/ Acked-by: Marc Zyngier M. -- Without deviation from the norm, progress is not possible.