Commit 562ad58b authored by Huacai Chen's avatar Huacai Chen Committed by Hongchen Zhang
Browse files

PCI: loongson: Don't access non-existent devices 

mainline inclusion
from mainline-v6.0-rc1
commit 2410e330
category: feature
bugzilla: https://gitee.com/openeuler/kernel/issues/I5OHOB
CVE: NA

--------------------------------

On LS2K/LS7A, config reads to some non-existent devices don't return
0xffffffff (they are hidden devices for debug, and accessing the config
space may cause machine hang). This is a hardware flaw but we can only
avoid it by software now.

Link: https://lore.kernel.org/r/20220714124216.1489304-5-chenhuacai@loongson.cn


Signed-off-by: default avatarHuacai Chen <chenhuacai@loongson.cn>
Signed-off-by: default avatarBjorn Helgaas <bhelgaas@google.com>
parent b9fe609e

drivers/pci/controller/pci-loongson.c

+23 −6
Original line number Diff line number Diff line
@@ -26,6 +26,7 @@ 
#define FLAG_CFG0	BIT(0)

#define FLAG_CFG1	BIT(1)

#define FLAG_DEV_FIX	BIT(2)

#define FLAG_DEV_HIDDEN	BIT(3)



struct loongson_pci_data {

	u32 flags;
@@ -138,18 +139,34 @@ static void __iomem *cfg1_map(struct loongson_pci *priv, struct pci_bus *bus, 
	return priv->cfg1_base + addroff;

}



static bool pdev_may_exist(struct pci_bus *bus, unsigned int device,

			   unsigned int function)

{

	return !(pci_is_root_bus(bus) &&

		(device >= 9 && device <= 20) && (function > 0));

}



static void __iomem *pci_loongson_map_bus(struct pci_bus *bus,

					  unsigned int devfn, int where)

{

	unsigned int device = PCI_SLOT(devfn);

	unsigned int function = PCI_FUNC(devfn);

	struct loongson_pci *priv = pci_bus_to_loongson_pci(bus);



	/*

	 * Do not read more than one device on the bus other than

	 * the host bus.

	 */

	if (priv->data->flags & FLAG_DEV_FIX &&

			!pci_is_root_bus(bus) && PCI_SLOT(devfn) > 0)

	if ((priv->data->flags & FLAG_DEV_FIX) && bus->self) {

		if (!pci_is_root_bus(bus) && (device > 0))

			return NULL;

	}



	/* Don't access non-existent devices */

	if (priv->data->flags & FLAG_DEV_HIDDEN) {

		if (!pdev_may_exist(bus, device, function))

			return NULL;

	}



	/* CFG0 can only access standard space */

	if (where < PCI_CFG_SPACE_SIZE && priv->cfg0_base)
@@ -197,12 +214,12 @@ static struct pci_ops loongson_pci_ops32 = { 
};



static const struct loongson_pci_data ls2k_pci_data = {

	.flags = FLAG_CFG1 | FLAG_DEV_FIX,

	.flags = FLAG_CFG1 | FLAG_DEV_FIX | FLAG_DEV_HIDDEN,

	.ops = &loongson_pci_ops,

};



static const struct loongson_pci_data ls7a_pci_data = {

	.flags = FLAG_CFG1 | FLAG_DEV_FIX,

	.flags = FLAG_CFG1 | FLAG_DEV_FIX | FLAG_DEV_HIDDEN,

	.ops = &loongson_pci_ops,

};
@@ -297,7 +314,7 @@ static int loongson_pci_ecam_init(struct pci_config_window *cfg) 
		return -ENOMEM;



	cfg->priv = priv;

	data->flags = FLAG_CFG1;

	data->flags = FLAG_CFG1 | FLAG_DEV_HIDDEN;

	priv->data = data;

	priv->cfg1_base = cfg->win - (cfg->busr.start << 16);