From mboxrd@z Thu Jan 1 00:00:00 1970 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=citrix.com header.i=@citrix.com header.b="l1M0w1Aw" Received: from mail-wr1-x42b.google.com (mail-wr1-x42b.google.com [IPv6:2a00:1450:4864:20::42b]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id C069DB0 for ; Wed, 13 Dec 2023 04:12:11 -0800 (PST) Received: by mail-wr1-x42b.google.com with SMTP id ffacd0b85a97d-3331752d2b9so4518197f8f.3 for ; Wed, 13 Dec 2023 04:12:11 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=citrix.com; s=google; t=1702469530; x=1703074330; darn=vger.kernel.org; h=in-reply-to:content-transfer-encoding:content-disposition :mime-version:references:message-id:subject:cc:to:from:date:from:to :cc:subject:date:message-id:reply-to; bh=1+N4toHCJ10eN7beh/9j8TkfnPseGcXj+HseAP1tdBY=; b=l1M0w1Aw5OhVxpzkfqCNOdZdayqytpT4jHHl44iOBHtj0sow0Jed5aGOhUYpSdoU1b mdbLND4MaPnkbcxMVhepl6AdmC9Q69gbaaHu2++VG8gtb6A8XB83cpNWPwvNPmjtUFKo 6Y0fPC7UMLgkDsWXiJTX4ghVIvehEISGdm4+w= X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1702469530; x=1703074330; h=in-reply-to:content-transfer-encoding:content-disposition :mime-version:references:message-id:subject:cc:to:from:date :x-gm-message-state:from:to:cc:subject:date:message-id:reply-to; bh=1+N4toHCJ10eN7beh/9j8TkfnPseGcXj+HseAP1tdBY=; b=p8FCP0IBL2a+MUVmRA8FsFmTTrXfDXaSNx6XukbuwZlU2z9B+Em0PVFKgSpw3iqywD ypekmF2M2i3FUBl+31efade4LI/DGRIB9XRQ7rNx6MqlsQzQPIRjwne/1WIoPbJ4xt7h PJhr28ONXumkPIqR/SDRmi8sanz9EIZpgQKPvrKM6VH2HDUlJ8dcjpLyY7sNjUjNk9Ly YMbMGUbp9aEd0G0emX/yFIhK0iHHxdeI5nwj6kz3bDytyUXhjBYOiGAGNgKWkZLRd33m 93aVnnyVRGxMQJRWf8Bz1rFf1C8Ur4RFK2PZ6ox0Yvs8n8f8ETVaryBOknTiuNV/Kypg RMYQ== X-Gm-Message-State: AOJu0YwHNDCmOBTtXZyoNTHtv47HYoa+wVWOEcQ9u8VYJE5VjS+TeZAR cnmx2/W7ZurLMHYFxUHH4gcF0Q== X-Google-Smtp-Source: AGHT+IEXQImdxtidsySE8Dvo4Qp275qPuasc4MbJLcUoaLv3rryHkHfFfLlFqk21Zhh1xtU9nWcpFQ== X-Received: by 2002:adf:fd08:0:b0:333:43a2:2caf with SMTP id e8-20020adffd08000000b0033343a22cafmr4973429wrr.14.1702469530209; Wed, 13 Dec 2023 04:12:10 -0800 (PST) Received: from localhost ([213.195.127.70]) by smtp.gmail.com with ESMTPSA id k2-20020a5d6282000000b003363432c0ffsm3429132wru.113.2023.12.13.04.12.09 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 13 Dec 2023 04:12:09 -0800 (PST) Date: Wed, 13 Dec 2023 13:12:09 +0100 From: Roger Pau =?utf-8?B?TW9ubsOp?= To: "Chen, Jiqian" Cc: "Rafael J . Wysocki" , Len Brown , Bjorn Helgaas , "linux-kernel@vger.kernel.org" , "linux-pci@vger.kernel.org" , "linux-acpi@vger.kernel.org" , "xen-devel@lists.xenproject.org" , "Deucher, Alexander" , "Koenig, Christian" , "Huang, Ray" Subject: Re: [RFC KERNEL PATCH v3 3/3] PCI/sysfs: Add gsi sysfs for pci_dev Message-ID: References: <20231210161519.1550860-1-Jiqian.Chen@amd.com> <20231210161519.1550860-4-Jiqian.Chen@amd.com> Precedence: bulk X-Mailing-List: linux-acpi@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: On Wed, Dec 13, 2023 at 03:31:21AM +0000, Chen, Jiqian wrote: > On 2023/12/12 17:18, Roger Pau Monné wrote: > > On Tue, Dec 12, 2023 at 06:34:27AM +0000, Chen, Jiqian wrote: > >> > >> On 2023/12/12 01:57, Roger Pau Monné wrote: > >>> On Mon, Dec 11, 2023 at 12:15:19AM +0800, Jiqian Chen wrote: > >>>> There is a need for some scenarios to use gsi sysfs. > >>>> For example, when xen passthrough a device to dumU, it will > >>>> use gsi to map pirq, but currently userspace can't get gsi > >>>> number. > >>>> So, add gsi sysfs for that and for other potential scenarios. > >>>> > >>>> Co-developed-by: Huang Rui > >>>> Signed-off-by: Jiqian Chen > >>>> --- > >>>> drivers/acpi/pci_irq.c | 1 + > >>>> drivers/pci/pci-sysfs.c | 11 +++++++++++ > >>>> include/linux/pci.h | 2 ++ > >>>> 3 files changed, 14 insertions(+) > >>>> > >>>> diff --git a/drivers/acpi/pci_irq.c b/drivers/acpi/pci_irq.c > >>>> index 630fe0a34bc6..739a58755df2 100644 > >>>> --- a/drivers/acpi/pci_irq.c > >>>> +++ b/drivers/acpi/pci_irq.c > >>>> @@ -449,6 +449,7 @@ int acpi_pci_irq_enable(struct pci_dev *dev) > >>>> kfree(entry); > >>>> return 0; > >>>> } > >>>> + dev->gsi = gsi; > >>> > >>> It would be better if the gsi if fetched without requiring calling > >>> acpi_pci_irq_enable(), as the gsi doesn't require the interrupt to be > >>> enabled. The gsi is known at boot time and won't change for the > >>> lifetime of the device. > >> Do you have any suggest places to do this? > > > > I'm not an expert on this, but drivers/pci/pci-sysfs.c would seem like > > a better place, together with the rest of the resources. > I'm not familiar with this too. But it seems pci-sysfs.c only creates sysfs node and supports the read/write method without initializing the values. > If want to initialize the value of gsi here. An approach to initialize it is to call acpi_pci_irq_lookup to get gsi number when the first time it is read? Hm, maybe, I don't really have much experience with sysfs, so don't know how nodes are usually initialized. > > > > Maybe my understanding is incorrect, but given the suggested placement > > in acpi_pci_irq_enable() I think the device would need to bind the > > interrupt in order for the gsi node to appear on sysfs? > No, gsi sysfs has existed there, in acpi_pci_irq_enable is to initialize the value of gsi. > > > > > Would the current approach work if the device is assigned to pciback > > on the kernel command line, and thus never owned by any driver in > > dom0? > If assigned to pciback, I think pciback will enable the device, and then acpi_pci_irq_enable will be called, and then the gsi will be initialized. So, current can work. This needs checking to be sure, I'm certainly not that familiar. You would need to at least test that it works properly when the device is hidden using xen-pciback.hide=(SBDF) in the Linux kernel command line. Thanks, Roger.