[AMD Public Use] > -----Original Message----- > From: Joerg Roedel <[email protected]> > Sent: Thursday, April 22, 2021 9:07 AM > To: [email protected] > Cc: Joerg Roedel <[email protected]>; Will Deacon <[email protected]>; > Deucher, Alexander <[email protected]>; > [email protected]; [email protected]; linux- > [email protected]; Joerg Roedel <[email protected]> > Subject: [PATCH] iommu/amd: Add amd_iommu=force_enable option > > 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]>
Acked-by: Alex Deucher <[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
