Re: [PATCH v2 1/1] iommu/vt-d: Add Kconfig option to enable/disable scalable mode

[Lu Baolu]

Hi,

On 11/9/19 11:59 AM, Qian Cai wrote:
> > On Nov 8, 2019, at 10:40 PM, Lu Baolu <baolu.lu@xxxxxxxxxxxxxxx> wrote:
> >
> > This adds Kconfig option INTEL_IOMMU_SCALABLE_MODE_DEFAULT_ON
> > to make it easier for distributions to enable or disable the
> > Intel IOMMU scalable mode by default during kernel build.
> >
> > Signed-off-by: Lu Baolu <baolu.lu@xxxxxxxxxxxxxxx>
> > ---
> > drivers/iommu/Kconfig       | 9 +++++++++
> > drivers/iommu/intel-iommu.c | 7 ++++++-
> > 2 files changed, 15 insertions(+), 1 deletion(-)
> >
> > diff --git a/drivers/iommu/Kconfig b/drivers/iommu/Kconfig
> > index e3842eabcfdd..fbdf3fd291d9 100644
> > --- a/drivers/iommu/Kconfig
> > +++ b/drivers/iommu/Kconfig
> > @@ -242,6 +242,15 @@ config INTEL_IOMMU_FLOPPY_WA
> > 	  workaround will setup a 1:1 mapping for the first
> > 	  16MiB to make floppy (an ISA device) work.
> >
> > +config INTEL_IOMMU_SCALABLE_MODE_DEFAULT_ON
> > +	prompt "Enable Intel IOMMU scalable mode by default"
> > +	depends on INTEL_IOMMU
> > +	help
> > +	  Selecting this option will enable the scalable mode if
> > +	  hardware presents the capability. If this option is not
> > +	  selected, scalable mode support could also be enabled
> > +	  by passing intel_iommu=sm_on to the kernel.
>
>
> Maybe a sentence or two to describe what the scalable mode is in layman's
> terms could be useful, so developers donât need to search around for the
> Kconfig selection?

How about "pasid based multiple stages DMA translation"?

Best regards,
baolu

> > +
> > config IRQ_REMAP
> > 	bool "Support for Interrupt Remapping"
> > 	depends on X86_64 && X86_IO_APIC && PCI_MSI && ACPI
> > diff --git a/drivers/iommu/intel-iommu.c b/drivers/iommu/intel-iommu.c
> > index 6db6d969e31c..6051fe790c61 100644
> > --- a/drivers/iommu/intel-iommu.c
> > +++ b/drivers/iommu/intel-iommu.c
> > @@ -355,9 +355,14 @@ static phys_addr_t intel_iommu_iova_to_phys(struct iommu_domain *domain,
> > int dmar_disabled = 0;
> > #else
> > int dmar_disabled = 1;
> > -#endif /*CONFIG_INTEL_IOMMU_DEFAULT_ON*/
> > +#endif /* CONFIG_INTEL_IOMMU_DEFAULT_ON */
> >
> > +#ifdef INTEL_IOMMU_SCALABLE_MODE_DEFAULT_ON
> > +int intel_iommu_sm = 1;
> > +#else
> > int intel_iommu_sm;
> > +#endif /* INTEL_IOMMU_SCALABLE_MODE_DEFAULT_ON */
> > +
> > int intel_iommu_enabled = 0;
> > EXPORT_SYMBOL_GPL(intel_iommu_enabled);
> >
> > --
> > 2.17.1
> >
> > _______________________________________________
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> > iommu@xxxxxxxxxxxxxxxxxxxxxxxxxx
> > https://lists.linuxfoundation.org/mailman/listinfo/iommu