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iommu/amd: Add amd_iommu=force_enable option

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Add this option to enable the IOMMU on platforms like AMD Stoney,
where the kernel usually disables it because it may cause problems in
some scenarios.

Signed-off-by: Joerg Roedel <jroedel@suse.de>
Acked-by: Alex Deucher <alexander.deucher@amd.com>
Link: https://lore.kernel.org/r/20210603130203.29016-1-joro@8bytes.org
This commit is contained in:
Joerg Roedel 2021-06-03 15:02:03 +02:00
parent 4b21a503ad
commit b1e650db2c
2 changed files with 11 additions and 1 deletions
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3
Documentation/admin-guide/kernel-parameters.txt
View file

@ -301,6 +301,9 @@
allowed anymore to lift isolation
requirements as needed. This option
does not override iommu=pt
force_enable - Force enable the IOMMU on platforms known
to be buggy with IOMMU enabled. Use this
option with care.
amd_iommu_dump= [HW,X86-64]
Enable AMD IOMMU driver option to dump the ACPI table

9
drivers/iommu/amd/init.c
View file

@ -153,7 +153,8 @@ int amd_iommu_guest_ir = AMD_IOMMU_GUEST_IR_VAPIC;
static int amd_iommu_xt_mode = IRQ_REMAP_XAPIC_MODE;
static bool amd_iommu_detected;
static bool __initdata amd_iommu_disabled;
static bool amd_iommu_disabled __initdata;
static bool amd_iommu_force_enable __initdata;
static int amd_iommu_target_ivhd_type;
u16 amd_iommu_last_bdf; /* largest PCI device id we have
@ -2834,6 +2835,9 @@ static bool detect_ivrs(void)
acpi_put_table(ivrs_base);
if (amd_iommu_force_enable)
goto out;
/* Don't use IOMMU if there is Stoney Ridge graphics */
for (i = 0; i < 32; i++) {
u32 pci_id;
@ -2845,6 +2849,7 @@ static bool detect_ivrs(void)
}
}
out:
/* Make sure ACS will be enabled during PCI probe */
pci_request_acs();
@ -3100,6 +3105,8 @@ static int __init parse_amd_iommu_options(char *str)
for (; *str; ++str) {
if (strncmp(str, "fullflush", 9) == 0)
amd_iommu_unmap_flush = true;
if (strncmp(str, "force_enable", 12) == 0)
amd_iommu_force_enable = true;
if (strncmp(str, "off", 3) == 0)
amd_iommu_disabled = true;
if (strncmp(str, "force_isolation", 15) == 0)