From: Joerg Roedel <[email protected]> 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 <[email protected]> --- Documentation/admin-guide/kernel-parameters.txt | 3 +++ drivers/iommu/amd/init.c | 7 +++++++ 2 files changed, 10 insertions(+) diff --git a/Documentation/admin-guide/kernel-parameters.txt b/Documentation/admin-guide/kernel-parameters.txt index 04545725f187..c9573f726707 100644 --- a/Documentation/admin-guide/kernel-parameters.txt +++ b/Documentation/admin-guide/kernel-parameters.txt @@ -303,6 +303,9 @@ 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 diff --git a/drivers/iommu/amd/init.c b/drivers/iommu/amd/init.c index 321f5906e6ed..3e2295d3b3e2 100644 --- a/drivers/iommu/amd/init.c +++ b/drivers/iommu/amd/init.c @@ -155,6 +155,7 @@ static int amd_iommu_xt_mode = IRQ_REMAP_XAPIC_MODE; static bool amd_iommu_detected; static bool __initdata amd_iommu_disabled; +static bool __initdata amd_iommu_force_enable; static int amd_iommu_target_ivhd_type; u16 amd_iommu_last_bdf; /* largest PCI device id we have @@ -2882,6 +2883,9 @@ 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; @@ -2893,6 +2897,7 @@ static bool detect_ivrs(void) } } +out: /* Make sure ACS will be enabled during PCI probe */ pci_request_acs(); @@ -3148,6 +3153,8 @@ 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) -- 2.31.1 _______________________________________________ iommu mailing list [email protected] https://lists.linuxfoundation.org/mailman/listinfo/iommu
