x86/platform/uv: Update TSC sync state for UV5

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@hpe.com>
Signed-off-by: Steve Wahl <steve.wahl@hpe.com>
Signed-off-by: Borislav Petkov <bp@suse.de>
Reviewed-by: Dimitri Sivanich <dimitri.sivanich@hpe.com>
Acked-by: Thomas Gleixner <tglx@linutronix.de>
Link: https://lore.kernel.org/r/20220406195149.228164-3-steve.wahl@hpe.com

diff --git a/arch/x86/kernel/apic/x2apic_uv_x.c b/arch/x86/kernel/apic/x2apic_uv_x.c
index f5a48e66e4f5462f83c4a76e89554377372964c6..a6e9c2794ef5607b82b0db0d59a34556c0012277 100644 (file)
--- 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;