Commit ce0e3c40 authored by Alex Mastro's avatar Alex Mastro Committed by Alex Williamson
Browse files

vfio: selftests: add iova allocator 

Add struct iova_allocator, which gives tests a convenient way to generate
legally-accessible IOVAs to map. This allocator traverses the sorted
available IOVA ranges linearly, requires power-of-two size allocations,
and does not support freeing iova allocations. The assumption is that
tests are not IOVA space-bounded, and will not need to recycle IOVAs.

This is based on Alex Williamson's patch series for adding an IOVA
allocator [1].

[1] https://lore.kernel.org/all/20251108212954.26477-1-alex@shazbot.org/



Reviewed-by: default avatarDavid Matlack <dmatlack@google.com>
Tested-by: default avatarDavid Matlack <dmatlack@google.com>
Signed-off-by: default avatarAlex Mastro <amastro@fb.com>
Link: https://lore.kernel.org/r/20251111-iova-ranges-v3-3-7960244642c5@fb.com


Signed-off-by: default avatarAlex Williamson <alex@shazbot.org>
parent a77fa0b9

tools/testing/selftests/vfio/lib/include/vfio_util.h

+11 −0
Original line number Diff line number Diff line
@@ -188,6 +188,13 @@ struct vfio_pci_device { 
	struct vfio_pci_driver driver;

};



struct iova_allocator {

	struct iommu_iova_range *ranges;

	u32 nranges;

	u32 range_idx;

	u64 range_offset;

};



/*

 * Return the BDF string of the device that the test should use.

 *
@@ -212,6 +219,10 @@ void vfio_pci_device_reset(struct vfio_pci_device *device); 
struct iommu_iova_range *vfio_pci_iova_ranges(struct vfio_pci_device *device,

					      u32 *nranges);



struct iova_allocator *iova_allocator_init(struct vfio_pci_device *device);

void iova_allocator_cleanup(struct iova_allocator *allocator);

iova_t iova_allocator_alloc(struct iova_allocator *allocator, size_t size);



int __vfio_pci_dma_map(struct vfio_pci_device *device,

		       struct vfio_dma_region *region);

int __vfio_pci_dma_unmap(struct vfio_pci_device *device,

tools/testing/selftests/vfio/lib/vfio_pci_device.c

+73 −1
Original line number Diff line number Diff line
@@ -12,11 +12,12 @@ 
#include <sys/mman.h>



#include <uapi/linux/types.h>

#include <linux/iommufd.h>

#include <linux/limits.h>

#include <linux/mman.h>

#include <linux/overflow.h>

#include <linux/types.h>

#include <linux/vfio.h>

#include <linux/iommufd.h>



#include "../../../kselftest.h"

#include <vfio_util.h>
@@ -201,6 +202,77 @@ struct iommu_iova_range *vfio_pci_iova_ranges(struct vfio_pci_device *device, 
	return ranges;

}



struct iova_allocator *iova_allocator_init(struct vfio_pci_device *device)

{

	struct iova_allocator *allocator;

	struct iommu_iova_range *ranges;

	u32 nranges;



	ranges = vfio_pci_iova_ranges(device, &nranges);

	VFIO_ASSERT_NOT_NULL(ranges);



	allocator = malloc(sizeof(*allocator));

	VFIO_ASSERT_NOT_NULL(allocator);



	*allocator = (struct iova_allocator){

		.ranges = ranges,

		.nranges = nranges,

		.range_idx = 0,

		.range_offset = 0,

	};



	return allocator;

}



void iova_allocator_cleanup(struct iova_allocator *allocator)

{

	free(allocator->ranges);

	free(allocator);

}



iova_t iova_allocator_alloc(struct iova_allocator *allocator, size_t size)

{

	VFIO_ASSERT_GT(size, 0, "Invalid size arg, zero\n");

	VFIO_ASSERT_EQ(size & (size - 1), 0, "Invalid size arg, non-power-of-2\n");



	for (;;) {

		struct iommu_iova_range *range;

		iova_t iova, last;



		VFIO_ASSERT_LT(allocator->range_idx, allocator->nranges,

			       "IOVA allocator out of space\n");



		range = &allocator->ranges[allocator->range_idx];

		iova = range->start + allocator->range_offset;



		/* Check for sufficient space at the current offset */

		if (check_add_overflow(iova, size - 1, &last) ||

		    last > range->last)

			goto next_range;



		/* Align iova to size */

		iova = last & ~(size - 1);



		/* Check for sufficient space at the aligned iova */

		if (check_add_overflow(iova, size - 1, &last) ||

		    last > range->last)

			goto next_range;



		if (last == range->last) {

			allocator->range_idx++;

			allocator->range_offset = 0;

		} else {

			allocator->range_offset = last - range->start + 1;

		}



		return iova;



next_range:

		allocator->range_idx++;

		allocator->range_offset = 0;

	}

}



iova_t __to_iova(struct vfio_pci_device *device, void *vaddr)

{

	struct vfio_dma_region *region;