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mpr, mps: Establish busdma boundaries for memory pools

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Most all of the memory used by the cards in the mpr(4) and mps(4)
drivers is required, according to the specs and Broadcom developers,
to be within a 4GB segment of memory.

This includes:

System Request Message Frames pool
Reply Free Queues pool
ReplyDescriptorPost Queues pool
Chain Segments pool
Sense Buffers pool
SystemReply message pool

We got a bug report from Dwight Engen, who ran into data corruption
in the BAE port of FreeBSD:

> We have a port of the FreeBSD mpr driver to our kernel and recently
> I found an issue under heavy load where a DMA may go to the wrong
> address. The test system is a Supermicro X10SRH-CLN4F with the
> onboard SAS3008 controller setup with 2 enterprise Micron SSDs in
> RAID 0 (striped). I have debugged the issue and narrowed down that
> the errant DMA is one that has a segment that crosses a 4GB
> physical boundary.  There are more details I can provide if you'd
> like, but with the attached patch in place I can no longer
> re-create the issue.

> I'm not sure if this is a known limit of the card (have not found a
> datasheet/programming docs for the chip) or our system is just
> doing something a bit different. Any helpful info or insight would
> be welcome.

> Anyway, just thought this might be helpful info if you want to
> apply a similar fix to FreeBSD. You can ignore/discard the commit
> message as it is my internal commit (blkio is our own tool we use
> to write/read every block of a device with CRC verification which
> is how I found the problem).

The commit message was:

> [PATCH 8/9] mpr: fix memory corrupting DMA when sg segment crosses
> 4GB boundary

> Test case was two SSD's in RAID 0 (stripe). The logical disk was
> then partitioned into two partitions. One partition had lots of
> filesystem I/O and the other was initially filled using blkio with
> CRCable data and then read back with blkio CRC verify in a loop.
> Eventually blkio would report a bad CRC block because the physical
> page being read-ahead into didn't contain the right data. If the
> physical address in the arq/segs was for example 0x500003000 the
> data would actually be DMAed to 0x400003000.

The original patch was against mpr(4) before busdma templates were
introduced, and only affected the buffer pool (sc->buffer_dmat) in
the mpr(4) driver. After some discussion with Dwight and the
LSI/Broadcom developers and looking through the driver, it looks
like most of the queues in the driver are ok, because they limit
the memory used to memory below 4GB. The buffer queue and the chain
frames seem to be the exceptions.

This is pretty much the same between the mpr(4) and mps(4) drivers.

So, apply a 4GB boundary limitation for the buffer and chain frame pools
in the mpr(4) and mps(4) drivers.

Reported by:	Dwight Engen <dwight.engen@gmail.com>
Reviewed by:	imp
Obtained from:	Dwight Engen <dwight.engen@gmail.com>
Differential Revision:	<https://reviews.freebsd.org/D43008>
This commit is contained in:
Kenneth D. Merry 2023-12-14 15:05:17 -05:00
parent 53fc8e1902
commit 264610a86e
2 changed files with 8 additions and 4 deletions
Show stats Download patch file Download diff file Expand all files Collapse all files

6
sys/dev/mpr/mpr.c
View file

@ -1500,7 +1500,8 @@ mpr_alloc_requests(struct mpr_softc *sc)
rsize = sc->chain_frame_size * sc->num_chains;
bus_dma_template_init(&t, sc->mpr_parent_dmat);
BUS_DMA_TEMPLATE_FILL(&t, BD_ALIGNMENT(16), BD_MAXSIZE(rsize),
BD_MAXSEGSIZE(rsize), BD_NSEGMENTS((howmany(rsize, PAGE_SIZE))));
BD_MAXSEGSIZE(rsize), BD_NSEGMENTS((howmany(rsize, PAGE_SIZE))),
BD_BOUNDARY(BUS_SPACE_MAXSIZE_32BIT+1));
if (bus_dma_template_tag(&t, &sc->chain_dmat)) {
mpr_dprint(sc, MPR_ERROR, "Cannot allocate chain DMA tag\n");
return (ENOMEM);
@ -1552,7 +1553,8 @@ mpr_alloc_requests(struct mpr_softc *sc)
BUS_DMA_TEMPLATE_FILL(&t, BD_MAXSIZE(BUS_SPACE_MAXSIZE_32BIT),
BD_NSEGMENTS(nsegs), BD_MAXSEGSIZE(BUS_SPACE_MAXSIZE_32BIT),
BD_FLAGS(BUS_DMA_ALLOCNOW), BD_LOCKFUNC(busdma_lock_mutex),
BD_LOCKFUNCARG(&sc->mpr_mtx));
BD_LOCKFUNCARG(&sc->mpr_mtx),
BD_BOUNDARY(BUS_SPACE_MAXSIZE_32BIT+1));
if (bus_dma_template_tag(&t, &sc->buffer_dmat)) {
mpr_dprint(sc, MPR_ERROR, "Cannot allocate buffer DMA tag\n");
return (ENOMEM);

6
sys/dev/mps/mps.c
View file

@ -1431,7 +1431,8 @@ mps_alloc_requests(struct mps_softc *sc)
rsize = sc->reqframesz * sc->num_chains;
bus_dma_template_clone(&t, sc->req_dmat);
BUS_DMA_TEMPLATE_FILL(&t, BD_MAXSIZE(rsize), BD_MAXSEGSIZE(rsize),
BD_NSEGMENTS(howmany(rsize, PAGE_SIZE)));
BD_NSEGMENTS(howmany(rsize, PAGE_SIZE)),
BD_BOUNDARY(BUS_SPACE_MAXSIZE_32BIT+1));
if (bus_dma_template_tag(&t, &sc->chain_dmat)) {
mps_dprint(sc, MPS_ERROR, "Cannot allocate chain DMA tag\n");
return (ENOMEM);
@ -1473,7 +1474,8 @@ mps_alloc_requests(struct mps_softc *sc)
BUS_DMA_TEMPLATE_FILL(&t, BD_MAXSIZE(BUS_SPACE_MAXSIZE_32BIT),
BD_NSEGMENTS(nsegs), BD_MAXSEGSIZE(BUS_SPACE_MAXSIZE_24BIT),
BD_FLAGS(BUS_DMA_ALLOCNOW), BD_LOCKFUNC(busdma_lock_mutex),
BD_LOCKFUNCARG(&sc->mps_mtx));
BD_LOCKFUNCARG(&sc->mps_mtx),
BD_BOUNDARY(BUS_SPACE_MAXSIZE_32BIT+1));
if (bus_dma_template_tag(&t, &sc->buffer_dmat)) {
mps_dprint(sc, MPS_ERROR, "Cannot allocate buffer DMA tag\n");
return (ENOMEM);