Re: [PATCH 2/2] vfio: hugepage support for vfio_iommu_type1
+ * Turns out AMD IOMMU has a page table bug where it won't map large pages
+ * to a region that previously mapped smaller pages. This should be fixed
+ * soon, so this is just a temporary workaround to break mappings down into
+ * PAGE_SIZE. Better to map smaller pages than nothing.
+ */
+static int map_try_harder(struct vfio_iommu *iommu, dma_addr_t iova,
+ unsigned long pfn, long npage, int prot)
+{
+ long i;
+ int ret;
+
+ for (i = 0; i npage; i++, pfn++, iova += PAGE_SIZE) {
+ ret = iommu_map(iommu-domain, iova,
+ (phys_addr_t)pfn PAGE_SHIFT,
+ PAGE_SIZE, prot);
+ if (ret)
+ break;
+ }
+
+ for (; i npage i 0; i--, iova -= PAGE_SIZE)
+ iommu_unmap(iommu-domain, iova, PAGE_SIZE);
+
return ret;
}
This looks to belong to a vfio-quirk file (a something else) that deals with
various IOMMU's quirks.
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Re: [PATCH 0/2] vfio: type1 iommu hugepage support
On Fri, May 24, 2013 at 11:24:26AM -0600, Alex Williamson wrote: This series let's the vfio type1 iommu backend take advantage of iommu large page support. See patch 2/2 for the details. This has been tested on both amd_iommu and intel_iommu, but only my AMD system has large page support. I'd appreciate any testing and feedback on other systems, particularly vt-d systems supporting large pages. Mapping efficiency should be improved a bit without iommu hugepages, but I hope that it's much more noticeable with huge pages, especially for very large QEMU guests. I took a very very quick look - and I am wondering if there should also be a flag to turn it on/off in ther kernel in such case? Especially in the field if a user finds out that their particular IOMMU chipset might be doing something funky with large-pages ? This change includes a clarification to the mapping expectations for users of the type1 iommu, but is compatible with known users and works with existing QEMU userspace supporting vfio. Thanks, Alex --- Alex Williamson (2): vfio: Convert type1 iommu to use rbtree vfio: hugepage support for vfio_iommu_type1 drivers/vfio/vfio_iommu_type1.c | 607 --- include/uapi/linux/vfio.h |8 - 2 files changed, 387 insertions(+), 228 deletions(-) ___ iommu mailing list iommu@lists.linux-foundation.org https://lists.linuxfoundation.org/mailman/listinfo/iommu ___ iommu mailing list iommu@lists.linux-foundation.org https://lists.linuxfoundation.org/mailman/listinfo/iommu
Re: [PATCH 0/2] vfio: type1 iommu hugepage support
On Sat, 2013-05-25 at 07:21 -0400, Konrad Rzeszutek Wilk wrote: On Fri, May 24, 2013 at 11:24:26AM -0600, Alex Williamson wrote: This series let's the vfio type1 iommu backend take advantage of iommu large page support. See patch 2/2 for the details. This has been tested on both amd_iommu and intel_iommu, but only my AMD system has large page support. I'd appreciate any testing and feedback on other systems, particularly vt-d systems supporting large pages. Mapping efficiency should be improved a bit without iommu hugepages, but I hope that it's much more noticeable with huge pages, especially for very large QEMU guests. I took a very very quick look - and I am wondering if there should also be a flag to turn it on/off in ther kernel in such case? Especially in the field if a user finds out that their particular IOMMU chipset might be doing something funky with large-pages ? Yeah, that's probably a reasonable feature. intel-iommu has a boot option to disable superpages, but we could make it more consistent at the vfio level if we have a switch there. It could provided interesting performance and debugging info. I'll add a module option to do this. Thanks, Alex This change includes a clarification to the mapping expectations for users of the type1 iommu, but is compatible with known users and works with existing QEMU userspace supporting vfio. Thanks, Alex --- Alex Williamson (2): vfio: Convert type1 iommu to use rbtree vfio: hugepage support for vfio_iommu_type1 drivers/vfio/vfio_iommu_type1.c | 607 --- include/uapi/linux/vfio.h |8 - 2 files changed, 387 insertions(+), 228 deletions(-) ___ iommu mailing list iommu@lists.linux-foundation.org https://lists.linuxfoundation.org/mailman/listinfo/iommu ___ iommu mailing list iommu@lists.linux-foundation.org https://lists.linuxfoundation.org/mailman/listinfo/iommu
