[PATCH][RFC] PCI: Add "pci=blacklist_dev=" parameter to blacklist specific devices

From: Chen Yu <yu.c.chen@intel.com>
To: linux-pci@vger.kernel.org
Cc: Jonathan Corbet <corbet@lwn.net>,
	Bjorn Helgaas <bhelgaas@google.com>,
	linux-doc@vger.kernel.org, linux-kernel@vger.kernel.org,
	Len Brown <lenb@kernel.org>,
	"Rafael J. Wysocki" <rjw@rjwysocki.net>,
	Chen Yu <yu.c.chen@intel.com>
Subject: [PATCH][RFC] PCI: Add "pci=blacklist_dev=" parameter to blacklist specific devices
Date: Fri, 24 Jan 2020 22:42:48 +0800	[thread overview]
Message-ID: <20200124144248.11719-1-yu.c.chen@intel.com> (raw)

It was found that on some platforms the bogus pci device might bring
troubles to the system. For example, on a MacBookPro the system could
not be power off or suspended due to internal pci resource confliction
between bogus pci device and [io 0x1804]. Another case is that, once
resumed from hibernation on a VM, the pci config space of a pci device
is corrupt.

To narrow down and benefit future debugging for such kind of issues,
introduce the command line blacklist_dev=<vendor:device_id>> to blacklist
such pci devices thus they will not be scanned thus not visible after
bootup. For example,

 pci.blacklist_dev=8086:293e

forbid the audio device to be exposed to the OS.

Signed-off-by: Chen Yu <yu.c.chen@intel.com>
---
 Documentation/admin-guide/kernel-parameters.txt |  6 ++++++
 drivers/pci/pci.c                               | 17 +++++++++++++++++
 drivers/pci/pci.h                               |  1 +
 drivers/pci/probe.c                             |  3 +++
 4 files changed, 27 insertions(+)

diff --git a/Documentation/admin-guide/kernel-parameters.txt b/Documentation/admin-guide/kernel-parameters.txt
index ade4e6ec23e0..cd4a47e236aa 100644
--- a/Documentation/admin-guide/kernel-parameters.txt
+++ b/Documentation/admin-guide/kernel-parameters.txt
@@ -3583,6 +3583,12 @@
 				may put more devices in an IOMMU group.
 		force_floating	[S390] Force usage of floating interrupts.
 		nomio		[S390] Do not use MIO instructions.
+		blacklist_dev=<vendor:device_id>[; ...]
+				Specify one or more PCI devices (in the format
+				specified above) separated by semicolons.
+				Each device specified will not be scanned thus
+				will be invisible after boot up. This can be
+				used for debugging purpose.
 
 	pcie_aspm=	[PCIE] Forcibly enable or disable PCIe Active State Power
 			Management.
diff --git a/drivers/pci/pci.c b/drivers/pci/pci.c
index e87196cc1a7f..0e3626a401f4 100644
--- a/drivers/pci/pci.c
+++ b/drivers/pci/pci.c
@@ -6393,6 +6393,19 @@ void __weak pci_fixup_cardbus(struct pci_bus *bus)
 }
 EXPORT_SYMBOL(pci_fixup_cardbus);
 
+static const char *pci_blacklist_devs_param;
+
+bool pci_is_blacklist_dev(unsigned short vendor, unsigned short device)
+{
+	char search[10];
+
+	if (!pci_blacklist_devs_param)
+		return false;
+	sprintf(search, "%x:%x", vendor, device);
+
+	return strstr(pci_blacklist_devs_param, search) ? true : false;
+}
+
 static int __init pci_setup(char *str)
 {
 	while (str) {
@@ -6451,6 +6464,8 @@ static int __init pci_setup(char *str)
 				pci_add_flags(PCI_SCAN_ALL_PCIE_DEVS);
 			} else if (!strncmp(str, "disable_acs_redir=", 18)) {
 				disable_acs_redir_param = str + 18;
+			} else if (!strncmp(str, "blacklist_dev=", 14)) {
+				pci_blacklist_devs_param = str + 14;
 			} else {
 				pr_err("PCI: Unknown option `%s'\n", str);
 			}
@@ -6476,6 +6491,8 @@ static int __init pci_realloc_setup_params(void)
 					   GFP_KERNEL);
 	disable_acs_redir_param = kstrdup(disable_acs_redir_param, GFP_KERNEL);
 
+	pci_blacklist_devs_param = kstrdup(pci_blacklist_devs_param, GFP_KERNEL);
+
 	return 0;
 }
 pure_initcall(pci_realloc_setup_params);
diff --git a/drivers/pci/pci.h b/drivers/pci/pci.h
index a0a53bd05a0b..01b8ab2da065 100644
--- a/drivers/pci/pci.h
+++ b/drivers/pci/pci.h
@@ -669,4 +669,5 @@ static inline int pci_acpi_program_hp_params(struct pci_dev *dev)
 extern const struct attribute_group aspm_ctrl_attr_group;
 #endif
 
+bool pci_is_blacklist_dev(unsigned short vendor, unsigned short device);
 #endif /* DRIVERS_PCI_H */
diff --git a/drivers/pci/probe.c b/drivers/pci/probe.c
index 512cb4312ddd..812ef901ecea 100644
--- a/drivers/pci/probe.c
+++ b/drivers/pci/probe.c
@@ -2271,6 +2271,9 @@ static struct pci_dev *pci_scan_device(struct pci_bus *bus, int devfn)
 	if (!pci_bus_read_dev_vendor_id(bus, devfn, &l, 60*1000))
 		return NULL;
 
+	if (pci_is_blacklist_dev(l & 0xffff, (l >> 16) & 0xffff))
+		return NULL;
+
 	dev = pci_alloc_dev(bus);
 	if (!dev)
 		return NULL;
-- 
2.17.1

