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It is not uncommon for BIOSes to report wrong RMRR entries in DMAR

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table.  Among them, some (old AMI ?) BIOSes report entries with range
like (bf7ec000, bf7ebfff).  Attempts to ignore the bogus entries
result in faults, so the range must be covered somehow.

Provide a workaround by identity mapping the 32 pages after the bogus
entry start, which seems to be enough for the reported BIOS.

Reported and tested by:	Jason Harmening <jason.harmening@gmail.com>
Sponsored by:	The FreeBSD Foundation
MFC after:	1 week
This commit is contained in:
kib 2014-03-18 16:20:33 +00:00
parent f53199b05b
commit f8f145010f
1 changed files with 9 additions and 0 deletions
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9
sys/x86/iommu/intel_ctx.c
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@ -182,6 +182,15 @@ ctx_init_rmrr(struct dmar_ctx *ctx, device_t dev)
end = entry->end;
entry->start = trunc_page(start);
entry->end = round_page(end);
if (entry->start == entry->end) {
/* Workaround for some AMI (?) BIOSes */
if (bootverbose) {
device_printf(dev, "BIOS bug: dmar%d RMRR "
"region (%jx, %jx) corrected\n",
ctx->dmar->unit, start, end);
}
entry->end += DMAR_PAGE_SIZE * 0x20;
}
size = OFF_TO_IDX(entry->end - entry->start);
ma = malloc(sizeof(vm_page_t) * size, M_TEMP, M_WAITOK);
for (i = 0; i < size; i++) {