linux-kernel - [PATCH v4 11/13] x86/platform/uv: Update UV5 TSC Checking

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Date:   Mon,  5 Oct 2020 15:39:27 -0500
From:   Mike Travis <mike.travis@....com>
To:     Thomas Gleixner <tglx@...utronix.de>,
        Ingo Molnar <mingo@...hat.com>, Borislav Petkov <bp@...en8.de>,
        x86@...nel.org, Steve Wahl <steve.wahl@....com>,
        Dave Hansen <dave.hansen@...ux.intel.com>,
        Andy Lutomirski <luto@...nel.org>,
        Peter Zijlstra <peterz@...radead.org>,
        Dimitri Sivanich <dimitri.sivanich@....com>,
        Arnd Bergmann <arnd@...db.de>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>
Cc:     Mike Travis <mike.travis@....com>,
        "H. Peter Anvin" <hpa@...or.com>,
        Russ Anderson <russ.anderson@....com>,
        Darren Hart <dvhart@...radead.org>,
        Andy Shevchenko <andy@...radead.org>,
        Alexandre Chartre <alexandre.chartre@...cle.com>,
        Jian Cai <caij2003@...il.com>,
        Vitaly Kuznetsov <vkuznets@...hat.com>,
        linux-kernel@...r.kernel.org, platform-driver-x86@...r.kernel.org
Subject: [PATCH v4 11/13] 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@....com>
Reviewed-by: Steve Wahl <steve.wahl@....com>
---
 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 ecf5c93e7ae8..07079b59824d 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 c7f5c1a55552..9ab4ac4d3ec0 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 */
-- 
2.21.0