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[PATCH 4.8 019/140] cpufreq: intel_pstate: Fix unsafe HWP MSR access

From Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Newsgroups linux.kernel
Subject [PATCH 4.8 019/140] cpufreq: intel_pstate: Fix unsafe HWP MSR access
Date 2016-10-26 15:40 +0200
Message-ID <swwAV-4k7-1@gated-at.bofh.it> (permalink)
References <swvvb-3zX-3@gated-at.bofh.it>
Organization linux.* mail to news gateway

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

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

From: Srinivas Pandruvada <srinivas.pandruvada@linux.intel.com>

commit f9f4872df6e1801572949f8a370c886122d4b6da upstream.

This is a requirement that MSR MSR_PM_ENABLE must be set to 0x01 before
reading MSR_HWP_CAPABILITIES on a given CPU. If cpufreq init() is
scheduled on a CPU which is not same as policy->cpu or migrates to a
different CPU before calling msr read for MSR_HWP_CAPABILITIES, it
is possible that MSR_PM_ENABLE was not to set to 0x01 on that CPU.
This will cause GP fault. So like other places in this path
rdmsrl_on_cpu should be used instead of rdmsrl.

Moreover the scope of MSR_HWP_CAPABILITIES is on per thread basis, so it
should be read from the same CPU, for which MSR MSR_HWP_REQUEST is
getting set.

dmesg dump or warning:

[   22.014488] WARNING: CPU: 139 PID: 1 at arch/x86/mm/extable.c:50 ex_handler_rdmsr_unsafe+0x68/0x70
[   22.014492] unchecked MSR access error: RDMSR from 0x771
[   22.014493] Modules linked in:
[   22.014507] CPU: 139 PID: 1 Comm: swapper/0 Not tainted 4.7.5+ #1
...
...
[   22.014516] Call Trace:
[   22.014542]  [<ffffffff813d7dd1>] dump_stack+0x63/0x82
[   22.014558]  [<ffffffff8107bc8b>] __warn+0xcb/0xf0
[   22.014561]  [<ffffffff8107bcff>] warn_slowpath_fmt+0x4f/0x60
[   22.014563]  [<ffffffff810676f8>] ex_handler_rdmsr_unsafe+0x68/0x70
[   22.014564]  [<ffffffff810677d9>] fixup_exception+0x39/0x50
[   22.014604]  [<ffffffff8102e400>] do_general_protection+0x80/0x150
[   22.014610]  [<ffffffff817f9ec8>] general_protection+0x28/0x30
[   22.014635]  [<ffffffff81687940>] ? get_target_pstate_use_performance+0xb0/0xb0
[   22.014642]  [<ffffffff810600c7>] ? native_read_msr+0x7/0x40
[   22.014657]  [<ffffffff81688123>] intel_pstate_hwp_set+0x23/0x130
[   22.014660]  [<ffffffff81688406>] intel_pstate_set_policy+0x1b6/0x340
[   22.014662]  [<ffffffff816829bb>] cpufreq_set_policy+0xeb/0x2c0
[   22.014664]  [<ffffffff81682f39>] cpufreq_init_policy+0x79/0xe0
[   22.014666]  [<ffffffff81682cb0>] ? cpufreq_update_policy+0x120/0x120
[   22.014669]  [<ffffffff816833a6>] cpufreq_online+0x406/0x820
[   22.014671]  [<ffffffff8168381f>] cpufreq_add_dev+0x5f/0x90
[   22.014717]  [<ffffffff81530ac8>] subsys_interface_register+0xb8/0x100
[   22.014719]  [<ffffffff816821bc>] cpufreq_register_driver+0x14c/0x210
[   22.014749]  [<ffffffff81fe1d90>] intel_pstate_init+0x39d/0x4d5
[   22.014751]  [<ffffffff81fe13f2>] ? cpufreq_gov_dbs_init+0x12/0x12

Signed-off-by: Srinivas Pandruvada <srinivas.pandruvada@linux.intel.com>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
 drivers/cpufreq/intel_pstate.c |   10 +++++-----
 1 file changed, 5 insertions(+), 5 deletions(-)

--- a/drivers/cpufreq/intel_pstate.c
+++ b/drivers/cpufreq/intel_pstate.c
@@ -556,12 +556,12 @@ static void intel_pstate_hwp_set(const s
 	int min, hw_min, max, hw_max, cpu, range, adj_range;
 	u64 value, cap;
 
-	rdmsrl(MSR_HWP_CAPABILITIES, cap);
-	hw_min = HWP_LOWEST_PERF(cap);
-	hw_max = HWP_HIGHEST_PERF(cap);
-	range = hw_max - hw_min;
-
 	for_each_cpu(cpu, cpumask) {
+		rdmsrl_on_cpu(cpu, MSR_HWP_CAPABILITIES, &cap);
+		hw_min = HWP_LOWEST_PERF(cap);
+		hw_max = HWP_HIGHEST_PERF(cap);
+		range = hw_max - hw_min;
+
 		rdmsrl_on_cpu(cpu, MSR_HWP_REQUEST, &value);
 		adj_range = limits->min_perf_pct * range / 100;
 		min = hw_min + adj_range;

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[PATCH 4.8 000/140] 4.8.5-stable review Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2016-10-26 15:30 +0200
  [PATCH 4.8 058/140] zfcp: fix payload trace length for SAN request&response Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2016-10-26 15:30 +0200
  [PATCH 4.8 043/140] powerpc/mm: Update FORCE_MAX_ZONEORDER range to allow hugetlb w/4K Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2016-10-26 15:30 +0200
  [PATCH 4.8 065/140] [media] mb86a20s: fix demod settings Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2016-10-26 15:30 +0200
  [PATCH 4.8 076/140] NFSD: fix corruption in notifier registration Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2016-10-26 15:30 +0200
  [PATCH 4.8 009/140] ath10k: fix copy engine 5 destination ring stuck Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2016-10-26 15:30 +0200
  [PATCH 4.8 044/140] powerpc/64: Fix incorrect return value from __copy_tofrom_user Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2016-10-26 15:30 +0200
  [PATCH 4.8 042/140] powerpc/powernv: Use CPU-endian PEST in pnv_pci_dump_p7ioc_diag_data() Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2016-10-26 15:30 +0200
  [PATCH 4.8 045/140] powerpc/pseries: Fix stack corruption in htpe code Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2016-10-26 15:30 +0200
  [PATCH 4.8 064/140] [media] mb86a20s: fix the locking logic Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2016-10-26 15:30 +0200
  [PATCH 4.8 007/140] spi: spidev_test: Fix buffer overflow in unescape() Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2016-10-26 15:30 +0200
  [PATCH 4.8 073/140] Input: elantech - force needed quirks on Fujitsu H760 Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2016-10-26 15:30 +0200
  [PATCH 4.8 050/140] zfcp: fix fc_host port_type with NPIV Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2016-10-26 15:30 +0200
  [PATCH 4.8 049/140] ubi: Deal with interrupted erasures in WL Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2016-10-26 15:30 +0200
  [PATCH 4.8 040/140] powerpc/eeh: Null check uses of eeh_pe_bus_get Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2016-10-26 15:30 +0200
  [PATCH 4.8 052/140] zfcp: close window with unblocked rport during rport gone Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2016-10-26 15:30 +0200
  [PATCH 4.8 038/140] powerpc/vdso64: Use double word compare on pointers Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2016-10-26 15:30 +0200
  [PATCH 4.8 047/140] IB/srp: Fix infinite loop when FMR sg[0].offset != 0 Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2016-10-26 15:30 +0200
  [PATCH 4.8 060/140] scsi: zfcp: spin_lock_irqsave() is not nestable Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2016-10-26 15:30 +0200
  [PATCH 4.8 071/140] MIPS: ptrace: Fix regs_return_value for kernel context Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2016-10-26 15:30 +0200
  [PATCH 4.8 054/140] zfcp: restore: Dont use 0 to indicate invalid LUN in rec trace Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2016-10-26 15:30 +0200
  [PATCH 4.8 019/140] cpufreq: intel_pstate: Fix unsafe HWP MSR access Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2016-10-26 15:40 +0200
  [PATCH 4.8 023/140] parisc: Fix kernel memory layout regarding position of __gp Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2016-10-26 15:40 +0200
  [PATCH 4.8 018/140] cpufreq: skip invalid entries when searching the frequency Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2016-10-26 15:40 +0200
  [PATCH 4.8 015/140] platform: dont return 0 from platform_get_irq[_byname]() on error Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2016-10-26 15:40 +0200
  [PATCH 4.8 036/140] dm crypt: fix crash on exit Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2016-10-26 15:40 +0200
  [PATCH 4.8 022/140] parisc: Fix self-detected CPU stall warnings on Mako machines Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2016-10-26 15:40 +0200
  [PATCH 4.8 025/140] pstore/ramoops: fixup driver removal Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2016-10-26 15:40 +0200
  [PATCH 4.8 021/140] parisc: Increase KERNEL_INITIAL_SIZE for 32-bit SMP kernels Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2016-10-26 15:40 +0200
  [PATCH 4.8 030/140] perf intel-pt: Fix estimated timestamps for cycle-accurate mode Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2016-10-26 15:40 +0200
  [PATCH 4.8 034/140] dm rq: take request_queue lock while clearing QUEUE_FLAG_STOPPED Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2016-10-26 15:40 +0200
  [PATCH 4.8 017/140] cpufreq: conservative: Fix next frequency selection Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2016-10-26 15:40 +0200
  [PATCH 4.8 005/140] clk: imx6: initialize GPU clocks Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2016-10-26 15:40 +0200
  [PATCH 4.8 028/140] pstore/ram: Use memcpy_fromio() to save old buffer Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2016-10-26 15:40 +0200
  [PATCH 4.8 031/140] perf intel-pt: Fix MTC timestamp calculation for large MTC periods Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2016-10-26 15:40 +0200
  [PATCH 4.8 033/140] dm: return correct error code in dm_resume()s retry loop Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2016-10-26 15:40 +0200
  Re: [PATCH 4.8 000/140] 4.8.5-stable review Shuah Khan <shuah.kh@samsung.com> - 2016-10-26 20:50 +0200
  Re: [PATCH 4.8 000/140] 4.8.5-stable review Guenter Roeck <linux@roeck-us.net> - 2016-10-26 23:50 +0200

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