Messages in this thread | | | Date | Wed, 12 May 2021 12:18:08 +0200 | From | Jean-Philippe Brucker <> | Subject | Re: [PATCH v4 1/2] iommu/sva: Tighten SVA bind API with explicit flags |
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On Mon, May 10, 2021 at 06:25:07AM -0700, Jacob Pan wrote: > The void* drvdata parameter isn't really used in iommu_sva_bind_device() > API, the current IDXD code "borrows" the drvdata for a VT-d private flag > for supervisor SVA usage. > > Supervisor/Privileged mode request is a generic feature. It should be > promoted from the VT-d vendor driver to the generic code. > > This patch replaces void* drvdata with a unsigned int flags parameter > and adjusts callers accordingly. > > Link: https://lore.kernel.org/linux-iommu/YFhiMLR35WWMW%2FHu@myrica/ > Suggested-by: Jean-Philippe Brucker <jean-philippe@linaro.org> > Signed-off-by: Jacob Pan <jacob.jun.pan@linux.intel.com>
Thanks for cleaning this up. Whether Vt-d's supervisor mode will need rework or not, this is still good to have. One nit below if you resend
Reviewed-by: Jean-Philippe Brucker <jean-philippe@linaro.org>
[...] > diff --git a/include/linux/iommu.h b/include/linux/iommu.h > index 32d448050bf7..fcc9d36b4b01 100644 > --- a/include/linux/iommu.h > +++ b/include/linux/iommu.h > @@ -152,6 +152,19 @@ enum iommu_dev_features { > > #define IOMMU_PASID_INVALID (-1U) > > +/* > + * The IOMMU_SVA_BIND_SUPERVISOR flag requests a PASID which can be used only > + * for access to kernel addresses. No IOTLB flushes are automatically done > + * for kernel mappings; it is valid only for access to the kernel's static > + * 1:1 mapping of physical memory — not to vmalloc or even module mappings. > + * A future API addition may permit the use of such ranges, by means of an > + * explicit IOTLB flush call (akin to the DMA API's unmap method). > + * > + * It is unlikely that we will ever hook into flush_tlb_kernel_range() to > + * do such IOTLB flushes automatically.
I would add that this is platform specific and not all IOMMU drivers support the feature.
Thanks, Jean
> + */ > +#define IOMMU_SVA_BIND_SUPERVISOR BIT(0) > + > #ifdef CONFIG_IOMMU_API
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