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Diffstat (limited to 'hw/vfio/spapr.c')
-rw-r--r--hw/vfio/spapr.c49
1 files changed, 36 insertions, 13 deletions
diff --git a/hw/vfio/spapr.c b/hw/vfio/spapr.c
index becf71a3fc..57fe758e54 100644
--- a/hw/vfio/spapr.c
+++ b/hw/vfio/spapr.c
@@ -143,19 +143,19 @@ int vfio_spapr_create_window(VFIOContainer *container,
MemoryRegionSection *section,
hwaddr *pgsize)
{
- int ret;
+ int ret = 0;
IOMMUMemoryRegion *iommu_mr = IOMMU_MEMORY_REGION(section->mr);
uint64_t pagesize = memory_region_iommu_get_min_page_size(iommu_mr);
- unsigned entries, pages;
+ unsigned entries, bits_total, bits_per_level, max_levels;
struct vfio_iommu_spapr_tce_create create = { .argsz = sizeof(create) };
- long systempagesize = qemu_getrampagesize();
+ long rampagesize = qemu_getrampagesize();
/*
* The host might not support the guest supported IOMMU page size,
* so we will use smaller physical IOMMU pages to back them.
*/
- if (pagesize > systempagesize) {
- pagesize = systempagesize;
+ if (pagesize > rampagesize) {
+ pagesize = rampagesize;
}
pagesize = 1ULL << (63 - clz64(container->pgsizes &
(pagesize | (pagesize - 1))));
@@ -176,16 +176,38 @@ int vfio_spapr_create_window(VFIOContainer *container,
create.window_size = int128_get64(section->size);
create.page_shift = ctz64(pagesize);
/*
- * SPAPR host supports multilevel TCE tables, there is some
- * heuristic to decide how many levels we want for our table:
- * 0..64 = 1; 65..4096 = 2; 4097..262144 = 3; 262145.. = 4
+ * SPAPR host supports multilevel TCE tables. We try to guess optimal
+ * levels number and if this fails (for example due to the host memory
+ * fragmentation), we increase levels. The DMA address structure is:
+ * rrrrrrrr rxxxxxxx xxxxxxxx xxxxxxxx xxxxxxxx xxxxxxxx xxxxxxxx iiiiiiii
+ * where:
+ * r = reserved (bits >= 55 are reserved in the existing hardware)
+ * i = IOMMU page offset (64K in this example)
+ * x = bits to index a TCE which can be split to equal chunks to index
+ * within the level.
+ * The aim is to split "x" to smaller possible number of levels.
*/
entries = create.window_size >> create.page_shift;
- pages = MAX((entries * sizeof(uint64_t)) / getpagesize(), 1);
- pages = MAX(pow2ceil(pages), 1); /* Round up */
- create.levels = ctz64(pages) / 6 + 1;
-
- ret = ioctl(container->fd, VFIO_IOMMU_SPAPR_TCE_CREATE, &create);
+ /* bits_total is number of "x" needed */
+ bits_total = ctz64(entries * sizeof(uint64_t));
+ /*
+ * bits_per_level is a safe guess of how much we can allocate per level:
+ * 8 is the current minimum for CONFIG_FORCE_MAX_ZONEORDER and MAX_ORDER
+ * is usually bigger than that.
+ * Below we look at getpagesize() as TCEs are allocated from system pages.
+ */
+ bits_per_level = ctz64(getpagesize()) + 8;
+ create.levels = bits_total / bits_per_level;
+ if (bits_total % bits_per_level) {
+ ++create.levels;
+ }
+ max_levels = (64 - create.page_shift) / ctz64(getpagesize());
+ for ( ; create.levels <= max_levels; ++create.levels) {
+ ret = ioctl(container->fd, VFIO_IOMMU_SPAPR_TCE_CREATE, &create);
+ if (!ret) {
+ break;
+ }
+ }
if (ret) {
error_report("Failed to create a window, ret = %d (%m)", ret);
return -errno;
@@ -200,6 +222,7 @@ int vfio_spapr_create_window(VFIOContainer *container,
return -EINVAL;
}
trace_vfio_spapr_create_window(create.page_shift,
+ create.levels,
create.window_size,
create.start_addr);
*pgsize = pagesize;