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 2C431274FC6; Tue, 12 Aug 2025 14:49:52 +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=1755010193; cv=none; b=KPcI4jSbxmrM8GjVKHwhBAle/L+LOY5wHU/ZmH7RO7xh2AvV5iOFq7bRD0eu2e8bNDFE8eN8cvDSsrW2pN0ennAzgsW0lJLFuG5TFBY8qvp9CAIsulNzj2VdYqOV+wYD6VG67Gh8UOtXhwQtByO/BL7xAoc3feML7ZXCBsVIg5s= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1755010193; c=relaxed/simple; bh=UKuqCyEgLnvgIIRxsYh7oEJjRyl6V42MwADrM0/ZGog=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=Mu4x2cXjxH+7jDKDBc0yBxXyn0putEtaM9zReinVzhzTzhe1E4NvCNZ9IIbn9CqymKr79kTw0GIgQ3IDvWT2dGh2paFhGSHZJHlhAYAb0H6oFxi8oBr/S3D90nArXy82ddiSIJtRqDZH2RdDHOdx8Kqo2UuQEcB9QVjgeZAT2z8= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=L0cMKc2p; 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="L0cMKc2p" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 1281CC4CEF0; Tue, 12 Aug 2025 14:49:52 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1755010192; bh=UKuqCyEgLnvgIIRxsYh7oEJjRyl6V42MwADrM0/ZGog=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=L0cMKc2pTp3gYSKV+88F7qXc4YXgTAND6YV2DBzb3DPFWfAlu4jWKyYAIFsOnvdtJ XRMKfd7xkuTPQNpKsKJAiz8d2L1q+ZFBVCPVzo3iIIMpb9P9lbynXheFeGWagw/sFm M4dQteqxjKHuzc/Xl6XjtwBaews2MfS03CIPL8FTGM1ITXYfYy0BroZ9VhHp2/BhGb nleug69klUzOUsvvcbvmtnBhRSA0kjf+QxUIsY8TCTEYCHKRpQFCYd6dP4AJcraXlq kt1UesaL8nxpKCHIhZMZQZ8KRqlG7ktcRo4ootcOlTkKD+C0dvrkla+hxItFIN3dKq aJTCUKqtvwxQA== Date: Tue, 12 Aug 2025 08:49:50 -0600 From: Keith Busch To: Nam Cao Cc: Bjorn Helgaas , Nirmal Patel , Jonathan Derrick , Lorenzo Pieralisi , Krzysztof =?iso-8859-1?Q?Wilczy=B4nski?= , Manivannan Sadhasivam , Rob Herring , Bjorn Helgaas , Thomas Gleixner , linux-pci@vger.kernel.org, linux-kernel@vger.kernel.org, Ammar Faizi Subject: Re: [PATCH] PCI: vmd: Remove MSI-X check on child devices Message-ID: References: <20250811053935.4049211-1-namcao@linutronix.de> <20250811224659.GA168102@bhelgaas> <20250812062715.X9TWWWh-@linutronix.de> Precedence: bulk X-Mailing-List: linux-pci@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20250812062715.X9TWWWh-@linutronix.de> On Tue, Aug 12, 2025 at 08:27:15AM +0200, Nam Cao wrote: > On Mon, Aug 11, 2025 at 05:46:59PM -0500, Bjorn Helgaas wrote: > > On Mon, Aug 11, 2025 at 07:39:35AM +0200, Nam Cao wrote: > > > Commit d7d8ab87e3e7 ("PCI: vmd: Switch to msi_create_parent_irq_domain()") > > > added a WARN_ON sanity check that child devices support MSI-X, because VMD > > > document says [1]: > > > > > > "Intel VMD only supports MSIx Interrupts from child devices and > > > therefore the BIOS must enable PCIe Hot Plug and MSIx interrups [sic]." > > > > Can VMD tell the difference between an incoming MSI MWr transaction > > and an MSI-X MWr? > > > > I wonder if "MSIx" was meant to mean "VMD only supports MSI or MSI-X > > interrupts, not INTx interrupts, from child devices"? > > I don't know, sorry. I am hoping that the VMD maintainers can help us here. The doc you linked is riddled with errors. The original vmd commit message is more accurate: VMD domains support child devices with MSI and MSI-x interrupts. The VMD device can't even tell the difference which one the device is using. It just manipulates messages sent to the usual APIC address 0xfeeXXXXX.