From: Mike Travis <mike.travis@xxxxxxx>
The UV5 platform synchronizes the TSCs among all chassis, and will not
proceed to OS boot without achieving synchronization. Previous UV
platforms provided a register indicating successful synchronization.
This is no longer available on UV5. On this platform TSC_ADJUST
should not be reset by the kernel.
Signed-off-by: Mike Travis <mike.travis@xxxxxxx>
Signed-off-by: Steve Wahl <steve.wahl@xxxxxxx>
Reviewed-by: Dimitri Sivanich <dimitri.sivanich@xxxxxxx>
---
v2: Update patch description to be more explanatory.
v4: Update patch description to provide better context
Removed a pr_debug() and an unrelated whitespace change
---
arch/x86/kernel/apic/x2apic_uv_x.c | 8 +++++++-
1 file changed, 7 insertions(+), 1 deletion(-)
diff --git a/arch/x86/kernel/apic/x2apic_uv_x.c b/arch/x86/kernel/apic/x2apic_uv_x.c
index f5a48e66e4f5..a6e9c2794ef5 100644
--- a/arch/x86/kernel/apic/x2apic_uv_x.c
+++ b/arch/x86/kernel/apic/x2apic_uv_x.c
@@ -199,7 +199,13 @@ static void __init uv_tsc_check_sync(void)
int mmr_shift;
char *state;
- /* Different returns from different UV BIOS versions */
+ /* UV5 guarantees synced TSCs; do not zero TSC_ADJUST */
+ if (!is_uv(UV2|UV3|UV4)) {
+ mark_tsc_async_resets("UV5+");
+ return;
+ }
+
+ /* UV2,3,4, UV BIOS TSC sync state available */
mmr = uv_early_read_mmr(UVH_TSC_SYNC_MMR);
mmr_shift =
is_uv2_hub() ? UVH_TSC_SYNC_SHIFT_UV2K : UVH_TSC_SYNC_SHIFT;
--
2.26.2
