From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from galois.linutronix.de (Galois.linutronix.de [193.142.43.55]) (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 E94081EBFE0; Tue, 12 Aug 2025 18:22:25 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=193.142.43.55 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1755022947; cv=none; b=oqBeTwFVaXJTVUSk+oNEHF9IS4/Cp7snm9/lEPszOAJBdXkALGpSMRI6eeMZaetAlLRbR1San2qc3+nu4YpHWJ3Y/dtbHO/Dy0H+pvKgBKss4MWKQ++pz2aT+lxIoK9WL0zmy9Be2VIaCdUdXzom7Rwki8kSYsVZ+D52Rcj7uGQ= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1755022947; c=relaxed/simple; bh=p/3UD5jav3q32TaAM30o1fI04zVNZZyMfypSSa78HPM=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=mQOEJLMJRj5opximw7nMneyVybL31LvdICgl7nav0sVa+/AHQEDzxydqIoqqur6Xdbbcs7bgMxAOGrEWd9AxN3B0gsKovBtOBeKottBLbG2GAe/irdZY+iVWDRjL5Ky//TZLdymPx/1NVaOiPY667aH6NttKjpnX3aMVH05B7RI= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=linutronix.de; spf=pass smtp.mailfrom=linutronix.de; dkim=pass (2048-bit key) header.d=linutronix.de header.i=@linutronix.de header.b=W0PJU9Y0; dkim=permerror (0-bit key) header.d=linutronix.de header.i=@linutronix.de header.b=WvQmd9lb; arc=none smtp.client-ip=193.142.43.55 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=linutronix.de Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=linutronix.de Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=linutronix.de header.i=@linutronix.de header.b="W0PJU9Y0"; dkim=permerror (0-bit key) header.d=linutronix.de header.i=@linutronix.de header.b="WvQmd9lb" Date: Tue, 12 Aug 2025 20:22:09 +0200 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linutronix.de; s=2020; t=1755022943; 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=jxlU+znl/JTn8im/jrvMANP+QmBATT55GjJL6MNB2U0=; b=W0PJU9Y0mwFXzoNEYmmWJ9DEaVd18sk5xZhfL5P6+SPy/UiH96Z3lwfGfxX0XukryhTCCt BZqnOOBlkpLfNKaJgsY+2/RQYhMJlBV6VyncN5syQGvRjC50tBBIL7xXB5c8qNnPUF1nor DrzE/x1ETcN9nIlroHk2RBBiVJMRkWhgffdXx+WJSs46rdW8MCwnDTmHmitymuhHMXcy+S yclwkc14SY9Xnzf0hJ+tWOqgfn0Bo+xF6LA8rATGOK9vR+KCkMTPemRJKE+stAu/RslAHi eMtDvREiZqr/88kERqWShhUBJWbFgjK8zWbpl5yiYq5casOfpD1trpkH++Hx6A== DKIM-Signature: v=1; a=ed25519-sha256; c=relaxed/relaxed; d=linutronix.de; s=2020e; t=1755022943; 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=jxlU+znl/JTn8im/jrvMANP+QmBATT55GjJL6MNB2U0=; b=WvQmd9lbZTxISl3kvoyVzLH6spl7ILIfdAMDjJgeJRmHAqvHS2BR7rQ9CXzOO4ofU3Kwnh lXe4Kxy5BgpumeCg== From: Nam Cao To: Bjorn Helgaas Cc: Keith Busch , 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: <20250812182209.c31roKpC@linutronix.de> References: <20250812163015.GA194338@bhelgaas> Precedence: bulk X-Mailing-List: linux-kernel@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: <20250812163015.GA194338@bhelgaas> On Tue, Aug 12, 2025 at 11:30:15AM -0500, Bjorn Helgaas wrote: > On Tue, Aug 12, 2025 at 08:49:50AM -0600, Keith Busch wrote: > > 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. > > Thanks, Keith! I updated the commit log like this: > > 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]. > > However, the VMD device can't even tell the difference between a child > device using MSI and one using MSI-X. Per 185a383ada2e ("x86/PCI: Add > driver for Intel Volume Management Device (VMD)"), VMD does not support > INTx interrupts, but does support child devices using either MSI or MSI-X. > > Remove the sanity check to avoid the unnecessary WARN_ON reported by Ammar. Minor correction, it is not just an unnecessary WARN_ON, but child devices' drivers couldn't enable MSI at all. So perhaps something like "Remove the sanity check to allow child devices which only support MSI". Thank you both, Nam