From 1584b89c921acefe88881f08d836d80f00600a84 Mon Sep 17 00:00:00 2001 From: Andi Kleen Date: Wed, 11 Jan 2006 22:43:42 +0100 Subject: [PATCH] [PATCH] x86_64: Validate SLIT table A lot of Opteron BIOS just pass 10 in all SLIT entries (10 is the normalized unit). This is actually worse than the default heuristic because it leads to pci_distance not knowing the difference between local and remote nodes anymore. This messes up some NUMA heuristics in generic code. In this case it's better to fall back to the default heuristic which just does nodea == nodeb ? 10 : 20. This patch does some basic sanity checking on the SLIT and only accepts the SLIT when it passes. Invariants enforced are: - Node to itself shall be 10 - Any other distance shouldn't be 10 - Distances smaller than 10 are illegal Signed-off-by: Andi Kleen Signed-off-by: Linus Torvalds --- arch/x86_64/mm/srat.c | 27 +++++++++++++++++++++++++++ 1 file changed, 27 insertions(+) diff --git a/arch/x86_64/mm/srat.c b/arch/x86_64/mm/srat.c index 33340bd1e328..9f69d28652f8 100644 --- a/arch/x86_64/mm/srat.c +++ b/arch/x86_64/mm/srat.c @@ -91,9 +91,36 @@ static __init inline int srat_disabled(void) return numa_off || acpi_numa < 0; } +/* + * A lot of BIOS fill in 10 (= no distance) everywhere. This messes + * up the NUMA heuristics which wants the local node to have a smaller + * distance than the others. + * Do some quick checks here and only use the SLIT if it passes. + */ +static __init int slit_valid(struct acpi_table_slit *slit) +{ + int i, j; + int d = slit->localities; + for (i = 0; i < d; i++) { + for (j = 0; j < d; j++) { + u8 val = slit->entry[d*i + j]; + if (i == j) { + if (val != 10) + return 0; + } else if (val <= 10) + return 0; + } + } + return 1; +} + /* Callback for SLIT parsing */ void __init acpi_numa_slit_init(struct acpi_table_slit *slit) { + if (!slit_valid(slit)) { + printk(KERN_INFO "ACPI: SLIT table looks invalid. Not used.\n"); + return; + } acpi_slit = slit; } -- 2.30.2