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 D37B928FD; Sun, 15 Dec 2024 09:22:56 +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=1734254576; cv=none; b=nkKjWACvsPb7aq94B05ox0zUzAeAMleT1+rklmE4n8+yhWi/AZCNrBTCu/hXy7BxgJHAlryRFBFZG+gV8gji3U8p4AJplH27AeVieQqr8O0kl1FIJY76A+zR0oy8Asspy1LQKchIi91twU2DT40Vh0nCi1uz+D6ImueLz634u7Y= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1734254576; c=relaxed/simple; bh=VA/fr2fanU2w8E9A58sNN9gLlEV2wRsSO8gXxlKoJjc=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=JtXgfRgag4rTG27QgpnMmjzx3vPIA1H2OG/ZWGHh9rx6reJpwRPMe9hSx8rPBosj4N6UwEupQAdUhyGV5DWbbd2CUBRvKhYEftN1dB7+uz7GYaqcUDFJE0rUJr90MEVs7bSqjumKBM2IiYeCQWqZTfRv6GsU1D7Ik4O1yIsv0GE= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=rhdoQNf8; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b="rhdoQNf8" Received: by smtp.kernel.org (Postfix) with ESMTPSA id CAB77C4CECE; Sun, 15 Dec 2024 09:22:55 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1734254576; bh=VA/fr2fanU2w8E9A58sNN9gLlEV2wRsSO8gXxlKoJjc=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=rhdoQNf8ZGsxq0OtLSI6TOY8eXGLpQiMg80mC9co5MB8vkpw0TO6RSdI2TXbLarRr 3puHKaN152VDKGxcAGKQHHoUv8YpKIcGE7RdDdhGElwIw2TV+oXx0ek8hpp+N495bn eMNvUw87z4AMK5lq0N6m/Vfd2qbHpnzNSDSI0ALQ= Date: Sun, 15 Dec 2024 10:22:53 +0100 From: Greg KH 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, maz@kernel.org, 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 Message-ID: <2024121528-refurbish-plausibly-31c7@gregkh> References: <20241212151406.1436382-1-joey.gouly@arm.com> 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: <20241212151406.1436382-1-joey.gouly@arm.com> On Thu, Dec 12, 2024 at 03:14:06PM +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/ > --- > > This fixes an issue seen when using KVM with a 6.6 host kernel, and > newer (6.13+) kernels in the guest. > > Tested with a stripped down version of set_id_regs from the original > patch series. What about 6.12.y? You can't just skip a stable tree, otherwise you will get a regression when you upgrade to 6.12.y, right? thanks, greg k-h