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vfio: map contiguous areas in one go

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Currently, when we are creating DMA mappings for memory that's
either external or is backed by hugepages in IOVA as PA mode, we
assume that each page is necessarily discontiguous. This may not
actually be the case, especially for external memory, where the
user is able to create their own IOVA table and make it
contiguous. This is a problem because VFIO has a limited number
of DMA mappings, and it does not appear to concatenate them and
treats each mapping as separate, even when they cover adjacent
areas.

Fix this so that we always map contiguous memory in a single
chunk, as opposed to mapping each segment separately.

Signed-off-by: Anatoly Burakov <anatoly.burakov@intel.com>
Acked-by: Ray Kinsella <ray.kinsella@intel.com>
This commit is contained in:
Anatoly Burakov 2020-02-25 13:24:48 +00:00 committed by David Marchand
parent bcf789da73
commit d1c7c0cdf7
1 changed files with 51 additions and 8 deletions
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59
lib/librte_eal/linux/eal/eal_vfio.c
View File

@ -514,9 +514,11 @@ static void
vfio_mem_event_callback(enum rte_mem_event type, const void *addr, size_t len,
void *arg __rte_unused)
{
rte_iova_t iova_start, iova_expected;
struct rte_memseg_list *msl;
struct rte_memseg *ms;
size_t cur_len = 0;
uint64_t va_start;
msl = rte_mem_virt2memseg_list(addr);
@ -545,22 +547,63 @@ vfio_mem_event_callback(enum rte_mem_event type, const void *addr, size_t len,
#endif
/* memsegs are contiguous in memory */
ms = rte_mem_virt2memseg(addr, msl);
/*
* This memory is not guaranteed to be contiguous, but it still could
* be, or it could have some small contiguous chunks. Since the number
* of VFIO mappings is limited, and VFIO appears to not concatenate
* adjacent mappings, we have to do this ourselves.
*
* So, find contiguous chunks, then map them.
*/
va_start = ms->addr_64;
iova_start = iova_expected = ms->iova;
while (cur_len < len) {
bool new_contig_area = ms->iova != iova_expected;
bool last_seg = (len - cur_len) == ms->len;
bool skip_last = false;
/* only do mappings when current contiguous area ends */
if (new_contig_area) {
if (type == RTE_MEM_EVENT_ALLOC)
vfio_dma_mem_map(default_vfio_cfg, va_start,
iova_start,
iova_expected - iova_start, 1);
else
vfio_dma_mem_map(default_vfio_cfg, va_start,
iova_start,
iova_expected - iova_start, 0);
va_start = ms->addr_64;
iova_start = ms->iova;
}
/* some memory segments may have invalid IOVA */
if (ms->iova == RTE_BAD_IOVA) {
RTE_LOG(DEBUG, EAL, "Memory segment at %p has bad IOVA, skipping\n",
ms->addr);
goto next;
skip_last = true;
}
if (type == RTE_MEM_EVENT_ALLOC)
vfio_dma_mem_map(default_vfio_cfg, ms->addr_64,
ms->iova, ms->len, 1);
else
vfio_dma_mem_map(default_vfio_cfg, ms->addr_64,
ms->iova, ms->len, 0);
next:
iova_expected = ms->iova + ms->len;
cur_len += ms->len;
++ms;
/*
* don't count previous segment, and don't attempt to
* dereference a potentially invalid pointer.
*/
if (skip_last && !last_seg) {
iova_expected = iova_start = ms->iova;
va_start = ms->addr_64;
} else if (!skip_last && last_seg) {
/* this is the last segment and we're not skipping */
if (type == RTE_MEM_EVENT_ALLOC)
vfio_dma_mem_map(default_vfio_cfg, va_start,
iova_start,
iova_expected - iova_start, 1);
else
vfio_dma_mem_map(default_vfio_cfg, va_start,
iova_start,
iova_expected - iova_start, 0);
}
}
#ifdef RTE_ARCH_PPC_64
cur_len = 0;