linux-kernel - [PATCH AUTOSEL 4.18 019/126] cpupower: Fix coredump on VMWare

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Message-Id: <20181031230754.29029-19-sashal@kernel.org>
Date:   Wed, 31 Oct 2018 19:06:07 -0400
From:   Sasha Levin <sashal@...nel.org>
To:     stable@...r.kernel.org, linux-kernel@...r.kernel.org
Cc:     Prarit Bhargava <prarit@...hat.com>, Shuah Khan <shuah@...nel.org>,
        Stafford Horne <shorne@...il.com>,
        Sasha Levin <sashal@...nel.org>
Subject: [PATCH AUTOSEL 4.18 019/126] cpupower: Fix coredump on VMWare

From: Prarit Bhargava <prarit@...hat.com>

[ Upstream commit f69ffc5d3db8f1f03fd6d1df5930f9a1fbd787b6 ]

cpupower crashes on VMWare guests.  The guests have the AMD PStateDef MSR
(0xC0010064 + state number) set to zero.  As a result fid and did are zero
and the crash occurs because of a divide by zero (cof = fid/did).  This
can be prevented by checking the enable bit in the PStateDef MSR before
calculating cof.  By doing this the value of pstate[i] remains zero and
the value can be tested before displaying the active Pstates.

Check the enable bit in the PstateDef register for all supported families
and only print out enabled Pstates.

Signed-off-by: Prarit Bhargava <prarit@...hat.com>
Cc: Shuah Khan <shuah@...nel.org>
Cc: Stafford Horne <shorne@...il.com>
Signed-off-by: Shuah Khan (Samsung OSG) <shuah@...nel.org>
Signed-off-by: Sasha Levin <sashal@...nel.org>
---
 tools/power/cpupower/utils/cpufreq-info.c | 2 ++
 tools/power/cpupower/utils/helpers/amd.c  | 5 +++++
 2 files changed, 7 insertions(+)

diff --git a/tools/power/cpupower/utils/cpufreq-info.c b/tools/power/cpupower/utils/cpufreq-info.c
index df43cd45d810..ccd08dd00996 100644
--- a/tools/power/cpupower/utils/cpufreq-info.c
+++ b/tools/power/cpupower/utils/cpufreq-info.c
@@ -200,6 +200,8 @@ static int get_boost_mode(unsigned int cpu)
 		printf(_("    Boost States: %d\n"), b_states);
 		printf(_("    Total States: %d\n"), pstate_no);
 		for (i = 0; i < pstate_no; i++) {
+			if (!pstates[i])
+				continue;
 			if (i < b_states)
 				printf(_("    Pstate-Pb%d: %luMHz (boost state)"
 					 "\n"), i, pstates[i]);
diff --git a/tools/power/cpupower/utils/helpers/amd.c b/tools/power/cpupower/utils/helpers/amd.c
index bb41cdd0df6b..58d23997424d 100644
--- a/tools/power/cpupower/utils/helpers/amd.c
+++ b/tools/power/cpupower/utils/helpers/amd.c
@@ -119,6 +119,11 @@ int decode_pstates(unsigned int cpu, unsigned int cpu_family,
 		}
 		if (read_msr(cpu, MSR_AMD_PSTATE + i, &pstate.val))
 			return -1;
+		if ((cpu_family == 0x17) && (!pstate.fam17h_bits.en))
+			continue;
+		else if (!pstate.bits.en)
+			continue;
+
 		pstates[i] = get_cof(cpu_family, pstate);
 	}
 	*no = i;
-- 
2.17.1