Re: [PATCH AUTOSEL 4.4 07/32] cpupower: Fix coredump on VMWare

Rafael David Tinoco
2018-11-12T10:29:35Z

On 10/31/18 9:11 PM, Sasha Levin wrote:
> From: Prarit Bhargava <prarit@redhat.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@redhat.com>
> Cc: Shuah Khan <shuah@kernel.org>
> Cc: Stafford Horne <shorne@gmail.com>
> Signed-off-by: Shuah Khan (Samsung OSG) <shuah@kernel.org>
> Signed-off-by: Sasha Levin <sashal@kernel.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 0e6764330241..f9b064ac8d94 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 6437ef39aeea..82adfb33d7a5 100644
> --- a/tools/power/cpupower/utils/helpers/amd.c
> +++ b/tools/power/cpupower/utils/helpers/amd.c
> @@ -103,6 +103,11 @@ 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;
>

Sasha,

This commit is causing:

$ make V=1 -C tools/power/cpupower all

gcc -fPIC -DVERSION=\"4.4.163.99.g0d9e7b\" -DPACKAGE=\"cpupower\"
-DPACKAGE_BUGREPORT=\"linux-pm@vger.kernel.org\" -D_GNU_SOURCE -pipe
-DNLS -Wall -Wchar-subscripts -Wpointer-arith -Wsign-compare
-Wno-pointer-sign -Wdeclaration-after-statement -Wshadow -O1 -g -DDEBUG
-I./lib -I ./utils -o utils/helpers/amd.o -c utils/helpers/amd.c
utils/helpers/amd.c: In function ‘decode_pstates’:
utils/helpers/amd.c:106:39: error: ‘union msr_pstate’ has no member
named ‘fam17h_bits’
if ((cpu_family == 0x17) && (!pstate.fam17h_bits.en))

I think it should be dropped from v4.4 and v4.9 RCs, since this is a fix
for a CPU that isn't supported for those 2.

Thanks
--
Rafael D. Tinoco
Linaro Kernel Validation