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From:   Greg Kroah-Hartman <gregkh@linuxfoundation.org>
To:     linux-kernel@vger.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
        stable@vger.kernel.org, Mike Travis <mike.travis@hpe.com>,
        Steve Wahl <steve.wahl@hpe.com>, Borislav Petkov <bp@suse.de>,
        Dimitri Sivanich <dimitri.sivanich@hpe.com>,
        Thomas Gleixner <tglx@linutronix.de>,
        Sasha Levin <sashal@kernel.org>
Subject: [PATCH 5.15 054/667] x86/platform/uv: Update TSC sync state for UV5
Date:   Tue,  7 Jun 2022 18:55:19 +0200
Message-Id: <20220607164936.431769189@linuxfoundation.org>
In-Reply-To: <20220607164934.766888869@linuxfoundation.org>
References: <20220607164934.766888869@linuxfoundation.org>
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From: Mike Travis <mike.travis@hpe.com>

[ Upstream commit bb3ab81bdbd53f88f26ffabc9fb15bd8466486ec ]

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
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
 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;
-- 
2.35.1