linux-kernel - [PATCH 4.7 036/186] intel_pstate: Fix MSR_CONFIG_TDP_x addressing in core_get_max

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Message-Id: <20160818135933.724217323@linuxfoundation.org>
Date:	Thu, 18 Aug 2016 15:57:33 +0200
From:	Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:	linux-kernel@...r.kernel.org
Cc:	Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
	stable@...r.kernel.org, Jan Kiszka <jan.kiszka@...mens.com>,
	Srinivas Pandruvada <srinivas.pandruvada@...ux.intel.com>,
	"Rafael J. Wysocki" <rafael.j.wysocki@...el.com>
Subject: [PATCH 4.7 036/186] intel_pstate: Fix MSR_CONFIG_TDP_x addressing in core_get_max_pstate()

4.7-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Jan Kiszka <jan.kiszka@...mens.com>

commit 5fc8f707a2aa40c767c3a338738b9b6fcd151ac1 upstream.

If MSR_CONFIG_TDP_CONTROL is locked, we currently try to address some
MSR 0x80000648 or so. Mask out the relevant level bits 0 and 1.

Found while running over the Jailhouse hypervisor which became upset
about this strange MSR index.

Signed-off-by: Jan Kiszka <jan.kiszka@...mens.com>
Acked-by: Srinivas Pandruvada <srinivas.pandruvada@...ux.intel.com>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@...el.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>

---
 drivers/cpufreq/intel_pstate.c |    2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

--- a/drivers/cpufreq/intel_pstate.c
+++ b/drivers/cpufreq/intel_pstate.c
@@ -944,7 +944,7 @@ static int core_get_max_pstate(void)
 			if (err)
 				goto skip_tar;

-			tdp_msr = MSR_CONFIG_TDP_NOMINAL + tdp_ctrl;
+			tdp_msr = MSR_CONFIG_TDP_NOMINAL + (tdp_ctrl & 0x3);
 			err = rdmsrl_safe(tdp_msr, &tdp_ratio);
 			if (err)
 				goto skip_tar;