x86/platform/UV: Fix 2 socket config problem

A UV4 chassis with only 2 sockets configured can unexpectedly
target the wrong UV hub.  Fix the problem by limiting the minimum
size of a partition to 4 sockets even if only 2 are configured.

Signed-off-by: Mike Travis <travis@sgi.com>
Reviewed-by: Russ Anderson <rja@hpe.com>
Acked-by: Dimitri Sivanich <sivanich@hpe.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: http://lkml.kernel.org/r/20170113152111.313888353@asylum.americas.sgi.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>

diff --git a/arch/x86/kernel/apic/x2apic_uv_x.c b/arch/x86/kernel/apic/x2apic_uv_x.c
index 43930787cab9689b6ff2f3a487309d7ff71a78e7..97ea712fc72f3eeb2997dcc0baf80a77f3bb346d 100644 (file)
--- a/arch/x86/kernel/apic/x2apic_uv_x.c
+++ b/arch/x86/kernel/apic/x2apic_uv_x.c
@@ -56,6 +56,7 @@ static struct {
        unsigned int socketid_shift;    /* aka pnode_shift for UV1/2/3 */
        unsigned int pnode_mask;
        unsigned int gpa_shift;
+       unsigned int gnode_shift;
 } uv_cpuid;
 
 int uv_min_hub_revision_id;
@@ -133,6 +134,7 @@ static int __init early_get_pnodeid(void)
                break;
        case UV4_HUB_PART_NUMBER:
                uv_min_hub_revision_id += UV4_HUB_REVISION_BASE - 1;
+               uv_cpuid.gnode_shift = 2; /* min partition is 4 sockets */
                break;
        }
 
@@ -1074,8 +1076,10 @@ void __init uv_init_hub_info(struct uv_hub_info_s *hub_info)
                (1UL << uv_cpuid.gpa_shift) - 1;
 
        node_id.v = uv_read_local_mmr(UVH_NODE_ID);
+       uv_cpuid.gnode_shift = max_t(unsigned int,
+                                       uv_cpuid.gnode_shift, mn.n_val);
        hub_info->gnode_extra =
-               (node_id.s.node_id & ~((1 << mn.n_val) - 1)) >> 1;
+               (node_id.s.node_id & ~((1 << uv_cpuid.gnode_shift) - 1)) >> 1;
 
        hub_info->gnode_upper =
                ((unsigned long)hub_info->gnode_extra << mn.m_val);