linux-kernel - PCI: Disable not requested resource types in pci_enable

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Date:   Thu, 28 May 2020 20:47:12 +0200
From:   Heiner Kallweit <hkallweit1@...il.com>
To:     Bjorn Helgaas <bhelgaas@...gle.com>
Cc:     "linux-pci@...r.kernel.org" <linux-pci@...r.kernel.org>,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>
Subject: PCI: Disable not requested resource types in pci_enable_resources

Currently, if both resource types are enabled before the call, the mask
value doesn't matter. Means as of today I wouldn't be able to e.g.
disable PCI_COMMAND_IO. At least my interpretation is that mask defines
which resource types are enabled after the call. Therefore change the
behavior to disable not requested resource types.

At least on my x86 devices this change doesn't have side effects.

Signed-off-by: Heiner Kallweit <hkallweit1@...il.com>
---
 drivers/pci/setup-res.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/drivers/pci/setup-res.c b/drivers/pci/setup-res.c
index d21fa04fa..6ef458c10 100644
--- a/drivers/pci/setup-res.c
+++ b/drivers/pci/setup-res.c
@@ -459,8 +459,8 @@ int pci_enable_resources(struct pci_dev *dev, int mask)
 	int i;
 	struct resource *r;
 
-	pci_read_config_word(dev, PCI_COMMAND, &cmd);
-	old_cmd = cmd;
+	pci_read_config_word(dev, PCI_COMMAND, &old_cmd);
+	cmd = old_cmd & ~(PCI_COMMAND_IO | PCI_COMMAND_MEMORY);
 
 	for (i = 0; i < PCI_NUM_RESOURCES; i++) {
 		if (!(mask & (1 << i)))
-- 
2.26.2