From mboxrd@z Thu Jan 1 00:00:00 1970 Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.remote-ip=95.215.58.131 ARC-Seal: i=1; d=subspace.kernel.org; s=arc20261015; a=rsa-sha256; cv=none; t=1793813139; b=fwtrZOFbduOapXz9OvUt/O3QGMiY35FHWuJ7KDEMIGcrYhy8Dh+EPDx4FpRhA3Rdhwax bhWDH07iaZ5HW0ohVls9G5aqSR86KoM/1gfCN1jd2gSBad+tatDK1GAfkaXpEMJuRRBdz FpHVpR9Z/Fodx+CJclkryiuloNvGBRlxIqkj6LPOJoJ42Y41w0MHg7CydQ6CvV5wXb3sk gRsluG5jNxbic1kggjSCkta3zI7OjF0URx0GiAXiQ2vSEKqUinYrpW3KaryiL1G5xWlet /sDxyAZcggXzQGCGjgSQ44gI+ezv/IpZbOBe2k4qoxpcjjwNc2sc73YBZI5PKzRKkPw== ARC-Message-Signature: i=1; d=subspace.kernel.org; s=arc20261015; a=rsa-sha256; c=relaxed/relaxed; t=1793813139; h=DMARC-Filter:X-Envelope-To:DKIM-Signature:X-Envelope-To:Received: X-Mizu-Trace-ID:X-Migadu-Flow:From:To:Cc:Subject:Date:Message-ID: X-Mailer:In-Reply-To:References:MIME-Version: Content-Transfer-Encoding; bh=Xenqm7tT8aY2/8jh0immIrLobh1PPDktvJtMt0frxlE=; b=mAaeUbrRcGe8/Q0yfVB8mMXcFq5DfGoVk8ucbXeGxUCfnqoYro6R4AHI16sUpJ8AHzZN 2ZpCjuy746lApiwEEZlvw6ZrfSyjkaywiw/P/OFcVEnBwu5S/MzeOAvLQINJ2sAEsibYH GA5BgwOJ3MRKx2KPYAv9INcGieGpQg8FRcMMog2EIy6rsE1eOwnYpAYB9WrS2pzoRZQzL HhZj/QRru8z+jj0KOD/g91olBGL8PZoOjWq3EWcE9L1uEmnRoWju3TD0Uxe5lIgRL0meg FGv/pBekL6YV8ndLRCJxJWz5PmYnQHfQUCUsF9yU+m0OKipe4gjAMSf3rkxuwsUJYfQ== ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dmarc=pass header.from=linux.dev; spf=pass smtp.mailfrom=linux.dev; dkim=pass header.d=linux.dev header.i=@linux.dev header.a=rsa-sha256 header.s=key1 header.b=uXUSWSDc; arc=none smtp.remote-ip=95.215.58.131 Received: from mta1.migadu.com (out-131.mta1.migadu.com [95.215.58.131]) (using TLSv1.3 with cipher TLS_AES_128_GCM_SHA256 (128/128 bits) key-exchange X25519 server-signature ECDSA (prime256v1) server-digest SHA256) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 9129C606A32D for ; Wed, 4 Nov 2026 17:25:37 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.4.2 smtp.subspace.kernel.org 9129C606A32D 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, unprotected) header.d=linux.dev header.i=@linux.dev header.a=rsa-sha256 header.s=key1 header.b=uXUSWSDc X-Envelope-To: linux-cxl@vger.kernel.org DKIM-Signature: a=rsa-sha256; bh=Xenqm7tT8aY2/8jh0immIrLobh1PPDktvJtMt0frxlE=; c=simple/simple; d=linux.dev; h=from:to:subject:date:message-id:mime-version:content-type; s=key1; t=1793813135; v=1; x=1794417935; b=uXUSWSDcK92X6GLIz+Jw8/CmM3fFrx5BxuYT63jVUmVZj9utLsJTCcBH7flqI+0vR1vD23BT htRa9gx2spS4Fn7iSpkFmg43hYbGFXMwkrPA2XwSe8yKjbYrdn1gydgu3TgKCzpUjrBmOjEOxGi SKdeRJqN7hQ7b6rVBHjjoTv8= X-Envelope-To: linux-cxl@vger.kernel.org Received: by smtp.migadu.com with ESMTPS id 3b99aa60dbfaf8f0; Wed, 04 Nov 2026 17:25:35 +0000 X-Mizu-Trace-ID: 3b99aa60dbfaf8f0 X-Migadu-Flow: FLOW_OUT From: Junjie Cao To: shrihari.s@samsung.com Cc: jic23@kernel.org, linux-cxl@vger.kernel.org, linux-pci@vger.kernel.org, qemu-devel@nongnu.org, anisa.su887@gmail.com, mst@redhat.com, marcel.apfelbaum@gmail.com, arun.george@samsung.com, cpgs@samsung.com, dave@stgolabs.net, dongjoo.seo1@samsung.com, gost.dev@samsung.com, s.neeraj@samsung.com, vikash.k5@samsung.com, anisa.su@samsung.com, junjie.cao@linux.dev Subject: Re: [PATCH qemu v1 3/8] hw/cxl: Wire UIO capability into HDM decoder and DVSEC registers Date: Wed, 4 Nov 2026 11:25:24 -0600 Message-ID: <20261104172527.2172366-1-junjie.cao@linux.dev> X-Mailer: git-send-email 2.43.0 In-Reply-To: <1384010761.101793792283622.JavaMail.epsvc@epcpadp2new> References: <20261104115242.2035807-1-shrihari.s@samsung.com> <1384010761.101793792283622.JavaMail.epsvc@epcpadp2new> X-Mailing-List: linux-cxl@vger.kernel.org List-Id: List-Post: List-Help: List-Subscribe: List-Unsubscribe: List-Owner: Precedence: list MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Hi Shrihari, The switch/HB write mask opens UIG and UIW, but leaves ISP read-only. CXL 3.2 section 8.2.4.20.7 makes ISP writable on a UIO-capable switch or Host Bridge too. With two UIO-enabled host bridges in a two-way CFMWS (4 KiB granularity), the switch below the second HB advertises UIO, but writing decoder 0 Control with UIO=1, UIG=4, UIW=1 (two ways), ISP=1 reads back 0x00144000 rather than 0x01144000. Software cannot configure the second position in the interleave set. Could R_CXL_HDM_DECODER0_CTRL_ISP_MASK be included alongside UIG and UIW in that switch/HB branch? It may also be worth diagnosing a partially configured host bridge: with x-uio=on and two RPs, one without SVC/flit, the HB reads 0x22382 but that RP reads 0x312. The HB UIO bit is defined to cover all its root ports (8.2.4.20.1). A warning would make this inconsistent setup easier to spot. Many thanks, Junjie