From: Fan Du fan.du@intel.com
commit 28e5e44aa3f4e0e0370864ed008fb5e2d85f4dc8 upstream.
tl;dr:
Several SGX users reported seeing the following message on NUMA systems:
sgx: [Firmware Bug]: Unable to map EPC section to online node. Fallback to the NUMA node 0.
This turned out to be the memblock code mistakenly throwing away SGX memory.
=== Full Changelog ===
The 'max_pfn' variable represents the highest known RAM address. It can be used, for instance, to quickly determine for which physical addresses there is mem_map[] space allocated. The numa_meminfo code makes an effort to throw out ("trim") all memory blocks which are above 'max_pfn'.
SGX memory is not considered RAM (it is marked as "Reserved" in the e820) and is not taken into account by max_pfn. Despite this, SGX memory areas have NUMA affinity and are enumerated in the ACPI SRAT table. The existing SGX code uses the numa_meminfo mechanism to look up the NUMA affinity for its memory areas.
In cases where SGX memory was above max_pfn (usually just the one EPC section in the last highest NUMA node), the numa_memblock is truncated at 'max_pfn', which is below the SGX memory. When the SGX code tries to look up the affinity of this memory, it fails and produces an error message:
sgx: [Firmware Bug]: Unable to map EPC section to online node. Fallback to the NUMA node 0.
and assigns the memory to NUMA node 0.
Instead of silently truncating the memory block at 'max_pfn' and dropping the SGX memory, add the truncated portion to 'numa_reserved_meminfo'. This allows the SGX code to later determine the NUMA affinity of its 'Reserved' area.
Before, numa_meminfo looked like this (from 'crash'):
blk = { start = 0x0, end = 0x2080000000, nid = 0x0 } { start = 0x2080000000, end = 0x4000000000, nid = 0x1 }
numa_reserved_meminfo is empty.
With this, numa_meminfo looks like this:
blk = { start = 0x0, end = 0x2080000000, nid = 0x0 } { start = 0x2080000000, end = 0x4000000000, nid = 0x1 }
and numa_reserved_meminfo has an entry for node 1's SGX memory:
blk = { start = 0x4000000000, end = 0x4080000000, nid = 0x1 }
[ daveh: completely rewrote/reworked changelog ]
Fixes: 5d30f92e7631 ("x86/NUMA: Provide a range-to-target_node lookup facility") Reported-by: Reinette Chatre reinette.chatre@intel.com Signed-off-by: Fan Du fan.du@intel.com Signed-off-by: Dave Hansen dave.hansen@intel.com Signed-off-by: Borislav Petkov bp@suse.de Reviewed-by: Jarkko Sakkinen jarkko@kernel.org Reviewed-by: Dan Williams dan.j.williams@intel.com Reviewed-by: Dave Hansen dave.hansen@intel.com Cc: stable@vger.kernel.org Link: https://lkml.kernel.org/r/20210617194657.0A99CB22@viggo.jf.intel.com Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- arch/x86/mm/numa.c | 8 +++++++- 1 file changed, 7 insertions(+), 1 deletion(-)
--- a/arch/x86/mm/numa.c +++ b/arch/x86/mm/numa.c @@ -254,7 +254,13 @@ int __init numa_cleanup_meminfo(struct n
/* make sure all non-reserved blocks are inside the limits */ bi->start = max(bi->start, low); - bi->end = min(bi->end, high); + + /* preserve info for non-RAM areas above 'max_pfn': */ + if (bi->end > high) { + numa_add_memblk_to(bi->nid, high, bi->end, + &numa_reserved_meminfo); + bi->end = high; + }
/* and there's no empty block */ if (bi->start >= bi->end)