[tip: x86/platform] x86/platform/uv: Update TSC sync state for UV5

[tip-bot2 for Mike Travis]

The following commit has been merged into the x86/platform branch of tip:

Commit-ID:     bb3ab81bdbd53f88f26ffabc9fb15bd8466486ec
Gitweb:        https://git.kernel.org/tip/bb3ab81bdbd53f88f26ffabc9fb15bd8466486ec
Author:        Mike Travis <mike.travis@xxxxxxx>
AuthorDate:    Wed, 06 Apr 2022 14:51:48 -05:00
Committer:     Borislav Petkov <bp@xxxxxxx>
CommitterDate: Thu, 07 Apr 2022 17:24:39 +02:00

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@xxxxxxx>
Signed-off-by: Steve Wahl <steve.wahl@xxxxxxx>
Signed-off-by: Borislav Petkov <bp@xxxxxxx>
Reviewed-by: Dimitri Sivanich <dimitri.sivanich@xxxxxxx>
Acked-by: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
Link: https://lore.kernel.org/r/20220406195149.228164-3-steve.wahl@xxxxxxx
---
 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 f5a48e6..a6e9c27 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;