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PCI: Add "pci=noats" boot parameter

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Adds a "pci=noats" boot parameter.  When supplied, all ATS related
functions fail immediately and the IOMMU is configured to not use
device-IOTLB.

Any function that checks for ATS capabilities directly against the devices
should also check this flag.  Currently, such functions exist only in IOMMU
drivers, and they are covered by this patch.

The motivation behind this patch is the existence of malicious devices.
Lots of research has been done about how to use the IOMMU as protection
from such devices.  When ATS is supported, any I/O device can access any
physical address by faking device-IOTLB entries.  Adding the ability to
ignore these entries lets sysadmins enhance system security.

Signed-off-by: Gil Kupfer <gilkup@cs.technion.ac.il>
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>
Acked-by: Joerg Roedel <jroedel@suse.de>
This commit is contained in:
Gil Kupfer
2018-05-10 17:56:02 -05:00
committed by Bjorn Helgaas
parent f154a718e6
commit cef74409ea
6 changed files with 28 additions and 4 deletions
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11
drivers/pci/pci.c
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@@ -112,6 +112,14 @@ unsigned int pcibios_max_latency = 255;
/* If set, the PCIe ARI capability will not be used. */
static bool pcie_ari_disabled;
/* If set, the PCIe ATS capability will not be used. */
static bool pcie_ats_disabled;
bool pci_ats_disabled(void)
{
return pcie_ats_disabled;
}
/* Disable bridge_d3 for all PCIe ports */
static bool pci_bridge_d3_disable;
/* Force bridge_d3 for all PCIe ports */
@@ -5793,6 +5801,9 @@ static int __init pci_setup(char *str)
if (*str && (str = pcibios_setup(str)) && *str) {
if (!strcmp(str, "nomsi")) {
pci_no_msi();
} else if (!strncmp(str, "noats", 5)) {
pr_info("PCIe: ATS is disabled\n");
pcie_ats_disabled = true;
} else if (!strcmp(str, "noaer")) {
pci_no_aer();
} else if (!strncmp(str, "realloc=", 8)) {