[tip: x86/platform] x86/platform/uv: Update UV5 TSC checking

[tip-bot2 for Mike Travis]

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

Commit-ID:     6a7cf55e9f2b743695adac84375548aa18112327
Gitweb:        https://git.kernel.org/tip/6a7cf55e9f2b743695adac84375548aa18112327
Author:        Mike Travis <mike.travis@xxxxxxx>
AuthorDate:    Mon, 05 Oct 2020 15:39:27 -05:00
Committer:     Borislav Petkov <bp@xxxxxxx>
CommitterDate: Wed, 07 Oct 2020 09:09:04 +02:00

x86/platform/uv: Update UV5 TSC checking

Update check of BIOS TSC sync status to include both possible "invalid"
states provided by newer UV5 BIOS.

Signed-off-by: Mike Travis <mike.travis@xxxxxxx>
Signed-off-by: Borislav Petkov <bp@xxxxxxx>
Reviewed-by: Steve Wahl <steve.wahl@xxxxxxx>
Link: https://lkml.kernel.org/r/20201005203929.148656-12-mike.travis@xxxxxxx
---
 arch/x86/include/asm/uv/uv_hub.h   |  2 +-
 arch/x86/kernel/apic/x2apic_uv_x.c | 24 ++++++++++--------------
 2 files changed, 11 insertions(+), 15 deletions(-)

diff --git a/arch/x86/include/asm/uv/uv_hub.h b/arch/x86/include/asm/uv/uv_hub.h
index ecf5c93..07079b5 100644
--- a/arch/x86/include/asm/uv/uv_hub.h
+++ b/arch/x86/include/asm/uv/uv_hub.h
@@ -726,7 +726,7 @@ extern void uv_nmi_setup_hubless(void);
 #define UVH_TSC_SYNC_SHIFT_UV2K	16	/* UV2/3k have different bits */
 #define UVH_TSC_SYNC_MASK	3	/* 0011 */
 #define UVH_TSC_SYNC_VALID	3	/* 0011 */
-#define UVH_TSC_SYNC_INVALID	2	/* 0010 */
+#define UVH_TSC_SYNC_UNKNOWN	0	/* 0000 */
 
 /* BMC sets a bit this MMR non-zero before sending an NMI */
 #define UVH_NMI_MMR		UVH_BIOS_KERNEL_MMR
diff --git a/arch/x86/kernel/apic/x2apic_uv_x.c b/arch/x86/kernel/apic/x2apic_uv_x.c
index 9b44f45..9a83aa1 100644
--- a/arch/x86/kernel/apic/x2apic_uv_x.c
+++ b/arch/x86/kernel/apic/x2apic_uv_x.c
@@ -197,36 +197,32 @@ static void __init uv_tsc_check_sync(void)
 	int sync_state;
 	int mmr_shift;
 	char *state;
-	bool valid;
 
-	/* Accommodate different UV arch BIOSes */
+	/* Different returns from different UV BIOS versions */
 	mmr = uv_early_read_mmr(UVH_TSC_SYNC_MMR);
 	mmr_shift =
 		is_uv2_hub() ? UVH_TSC_SYNC_SHIFT_UV2K : UVH_TSC_SYNC_SHIFT;
 	sync_state = (mmr >> mmr_shift) & UVH_TSC_SYNC_MASK;
 
+	/* Check if TSC is valid for all sockets */
 	switch (sync_state) {
 	case UVH_TSC_SYNC_VALID:
 		state = "in sync";
-		valid = true;
+		mark_tsc_async_resets("UV BIOS");
 		break;
 
-	case UVH_TSC_SYNC_INVALID:
-		state = "unstable";
-		valid = false;
+	/* If BIOS state unknown, don't do anything */
+	case UVH_TSC_SYNC_UNKNOWN:
+		state = "unknown";
 		break;
+
+	/* Otherwise, BIOS indicates problem with TSC */
 	default:
-		state = "unknown: assuming valid";
-		valid = true;
+		state = "unstable";
+		mark_tsc_unstable("UV BIOS");
 		break;
 	}
 	pr_info("UV: TSC sync state from BIOS:0%d(%s)\n", sync_state, state);
-
-	/* Mark flag that says TSC != 0 is valid for socket 0 */
-	if (valid)
-		mark_tsc_async_resets("UV BIOS");
-	else
-		mark_tsc_unstable("UV BIOS");
 }
 
 /* Selector for (4|4A|5) structs */