[PATCH]/[GIT PULL] stable/cpufreq.bugfixes for 3.0 for cpufreq fixes.

[PATCH]/[GIT PULL] stable/cpufreq.bugfixes for 3.0 for cpufreq fixes.

[Konrad Rzeszutek Wilk]

Hey Dave,

This is a follow up after the initial posting (http://www.gossamer-threads.com/lists/linux/kernel/1394515).

The first patch:
 [PATCH 1/3] [CPUFREQ]: Don't set stat->last_index to -1 if the pol->cur has incorrect value.

is exactly like the first posting, while the second (old) patch was split in two:

 [PATCH 2/3] [CPUFREQ] powernow-k8: Don't notify of successful transition if we failed (vid case).

and the pstate transition code was augmented a bit more:

 [PATCH 3/3] [CPUFREQ] powernow-k8: Don't try to transition if the pstate is incorrect

Also Borislav Acked and reviewed the patches.

Please either:

a). git pull git://git.kernel.org/pub/scm/linux/kernel/git/konrad/xen.git  stable/cpufreq.bugfixes

b) or git am this email thread.

I don't know which way you prefer. The patches have been rebased on top of v3.0-rc3 tag.

Thank you!

[PATCH 1/3] [CPUFREQ]: Don't set stat->last_index to -1 if the pol->cur has incorrect value.

[Konrad Rzeszutek Wilk]

If the driver submitted an non-existing pol>cur value (say it
used the default initialized value of zero), when the cpufreq
stats tries to setup its initial values it incorrectly sets
stat->last_index to -1 (or 0xfffff...). And cpufreq_stats_update
tries to update at that index location and fails.

This can be caused by:

stat->last_index = freq_table_get_index(stat, policy->cur);

not finding the appropiate frequency in the table (b/c the policy->cur
is wrong) and we end up crashing. The fix however is
concentrated in the 'cpufreq_stats_update' as the last_index
(and old_index) are updated there. Which means it can reset
the last_index to -1 again and on the next iteration cause a crash.

Without this patch, the following crash is observed:

powernow-k8: Found 1 AMD Athlon(tm) 64 Processor 3700+ (1 cpu cores) (version 2.20.00)
powernow-k8: fid 0x2 (1000 MHz), vid 0x12
powernow-k8: fid 0xa (1800 MHz), vid 0xa
powernow-k8: fid 0xc (2000 MHz), vid 0x8
powernow-k8: fid 0xe (2200 MHz), vid 0x8
Marking TSC unstable due to cpufreq changes
powernow-k8: fid trans failed, fid 0x2, curr 0x0
BUG: unable to handle kernel paging request at ffff880807e07b78
IP: [<ffffffff81479163>] cpufreq_stats_update+0x46/0x5b
.. snip..
Pid: 1, comm: swapper Not tainted 3.0.0-rc2 #45 MICRO-STAR INTERNATIONAL CO., LTD MS-7094/MS-7094
..snip..
Call Trace:
 [<ffffffff81479248>] cpufreq_stat_notifier_trans+0x48/0x7c
 [<ffffffff81095d68>] notifier_call_chain+0x32/0x5e
 [<ffffffff81095e6b>] __srcu_notifier_call_chain+0x47/0x63
 [<ffffffff81095e96>] srcu_notifier_call_chain+0xf/0x11
 [<ffffffff81477e7a>] cpufreq_notify_transition+0x111/0x134
 [<ffffffff8147b0d4>] powernowk8_target+0x53b/0x617
 [<ffffffff8147723a>] __cpufreq_driver_target+0x2e/0x30
 [<ffffffff8147a127>] cpufreq_governor_dbs+0x339/0x356
 [<ffffffff81477394>] __cpufreq_governor+0xa8/0xe9
 [<ffffffff81477525>] __cpufreq_set_policy+0x132/0x13e
 [<ffffffff8147848d>] cpufreq_add_dev_interface+0x272/0x28c

Reported-by: Tobias Diedrich <ranma+xen@tdiedrich.de>
Tested-by: Tobias Diedrich <ranma+xen@tdiedrich.de>
Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
---
 drivers/cpufreq/cpufreq_stats.c |    8 +++++---
 1 files changed, 5 insertions(+), 3 deletions(-)

diff --git a/drivers/cpufreq/cpufreq_stats.c b/drivers/cpufreq/cpufreq_stats.c
index b60a4c2..32ab381 100644
--- a/drivers/cpufreq/cpufreq_stats.c
+++ b/drivers/cpufreq/cpufreq_stats.c
@@ -298,11 +298,13 @@ static int cpufreq_stat_notifier_trans(struct notifier_block *nb,
 	old_index = stat->last_index;
 	new_index = freq_table_get_index(stat, freq->new);
 
-	cpufreq_stats_update(freq->cpu);
-	if (old_index == new_index)
+	/* We can't do stat->time_in_state[-1]= .. */
+	if (old_index == -1 || new_index == -1)
 		return 0;
 
-	if (old_index == -1 || new_index == -1)
+	cpufreq_stats_update(freq->cpu);
+
+	if (old_index == new_index)
 		return 0;
 
 	spin_lock(&cpufreq_stats_lock);
-- 
1.7.4.1

[PATCH 1/3] : Don't set stat->last_index to -1 if the pol->cur has incorrect value.

[Konrad Rzeszutek Wilk]

If the driver submitted an non-existing pol>cur value (say it
used the default initialized value of zero), when the cpufreq
stats tries to setup its initial values it incorrectly sets
stat->last_index to -1 (or 0xfffff...). And cpufreq_stats_update
tries to update at that index location and fails.

This can be caused by:

stat->last_index = freq_table_get_index(stat, policy->cur);

not finding the appropiate frequency in the table (b/c the policy->cur
is wrong) and we end up crashing. The fix however is
concentrated in the 'cpufreq_stats_update' as the last_index
(and old_index) are updated there. Which means it can reset
the last_index to -1 again and on the next iteration cause a crash.

Without this patch, the following crash is observed:

powernow-k8: Found 1 AMD Athlon(tm) 64 Processor 3700+ (1 cpu cores) (version 2.20.00)
powernow-k8: fid 0x2 (1000 MHz), vid 0x12
powernow-k8: fid 0xa (1800 MHz), vid 0xa
powernow-k8: fid 0xc (2000 MHz), vid 0x8
powernow-k8: fid 0xe (2200 MHz), vid 0x8
Marking TSC unstable due to cpufreq changes
powernow-k8: fid trans failed, fid 0x2, curr 0x0
BUG: unable to handle kernel paging request at ffff880807e07b78
IP: [<ffffffff81479163>] cpufreq_stats_update+0x46/0x5b
.. snip..
Pid: 1, comm: swapper Not tainted 3.0.0-rc2 #45 MICRO-STAR INTERNATIONAL CO., LTD MS-7094/MS-7094
..snip..
Call Trace:
 [<ffffffff81479248>] cpufreq_stat_notifier_trans+0x48/0x7c
 [<ffffffff81095d68>] notifier_call_chain+0x32/0x5e
 [<ffffffff81095e6b>] __srcu_notifier_call_chain+0x47/0x63
 [<ffffffff81095e96>] srcu_notifier_call_chain+0xf/0x11
 [<ffffffff81477e7a>] cpufreq_notify_transition+0x111/0x134
 [<ffffffff8147b0d4>] powernowk8_target+0x53b/0x617
 [<ffffffff8147723a>] __cpufreq_driver_target+0x2e/0x30
 [<ffffffff8147a127>] cpufreq_governor_dbs+0x339/0x356
 [<ffffffff81477394>] __cpufreq_governor+0xa8/0xe9
 [<ffffffff81477525>] __cpufreq_set_policy+0x132/0x13e
 [<ffffffff8147848d>] cpufreq_add_dev_interface+0x272/0x28c

Reported-by: Tobias Diedrich <ranma+xen@tdiedrich.de>
Tested-by: Tobias Diedrich <ranma+xen@tdiedrich.de>
Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
---
 drivers/cpufreq/cpufreq_stats.c |    8 +++++---
 1 files changed, 5 insertions(+), 3 deletions(-)

diff --git a/drivers/cpufreq/cpufreq_stats.c b/drivers/cpufreq/cpufreq_stats.c
index b60a4c2..32ab381 100644
--- a/drivers/cpufreq/cpufreq_stats.c
+++ b/drivers/cpufreq/cpufreq_stats.c
@@ -298,11 +298,13 @@ static int cpufreq_stat_notifier_trans(struct notifier_block *nb,
 	old_index = stat->last_index;
 	new_index = freq_table_get_index(stat, freq->new);
 
-	cpufreq_stats_update(freq->cpu);
-	if (old_index == new_index)
+	/* We can't do stat->time_in_state[-1]= .. */
+	if (old_index == -1 || new_index == -1)
 		return 0;
 
-	if (old_index == -1 || new_index == -1)
+	cpufreq_stats_update(freq->cpu);
+
+	if (old_index == new_index)
 		return 0;
 
 	spin_lock(&cpufreq_stats_lock);
-- 
1.7.4.1

[PATCH 2/3] [CPUFREQ] powernow-k8: Don't notify of successful transition if we failed (vid case).

[Konrad Rzeszutek Wilk]

Before this patch if we failed the vid transition would still try to
submit the "new" frequencies to cpufreq.
That is incorrect - also we could submit a non-existing frequency value
which would cause cpufreq to crash. The ultimate fix is in cpufreq
to deal with incorrect values, but this patch improves the error
recovery in the AMD powernowk8 driver.

The failure that was reported was as follows:

powernow-k8: Found 1 AMD Athlon(tm) 64 Processor 3700+ (1 cpu cores) (version 2.20.00)
powernow-k8: fid 0x2 (1000 MHz), vid 0x12
powernow-k8: fid 0xa (1800 MHz), vid 0xa
powernow-k8: fid 0xc (2000 MHz), vid 0x8
powernow-k8: fid 0xe (2200 MHz), vid 0x8
Marking TSC unstable due to cpufreq changes
powernow-k8: fid trans failed, fid 0x2, curr 0x0
BUG: unable to handle kernel paging request at ffff880807e07b78
IP: [<ffffffff81479163>] cpufreq_stats_update+0x46/0x5b
...

And transition fails and data->currfid ends up with 0. Since
the machine does not support 800Mhz value when the calculation is
done ('find_khz_freq_from_fid(data->currfid);') it reports the
new frequency as 800000 which is bogus. This patch fixes
the issue during target setting.

The patch however does not fix the issue in 'powernowk8_cpu_init'
where the pol->cur can also be set with the 800000 value:

          pol->cur = find_khz_freq_from_fid(data->currfid);
  dprintk("policy current frequency %d kHz\n", pol->cur);

  /* min/max the cpu is capable of */
  if (cpufreq_frequency_table_cpuinfo(pol, data->powernow_table)) {

The fix for that looks to update cpufreq_frequency_table_cpuinfo to
check pol->cur.... but that would cause an regression in how the
acpi-cpufreq driver works (it sets cpu->cur after calling
cpufreq_frequency_table_cpuinfo). Instead the fix will be to let
cpufreq gracefully handle bogus data (another patch).

Acked-by: Borislav Petkov <bp@alien8.de>
CC: andre.przywara@amd.com
CC: Mark.Langsdorf@amd.com
Reported-by: Tobias Diedrich <ranma+xen@tdiedrich.de>
Tested-by: Tobias Diedrich <ranma+xen@tdiedrich.de>
[v1: Rebased on v3.0-rc2, reduced patch to deal with vid case]
Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
---
 drivers/cpufreq/powernow-k8.c |    3 +++
 1 files changed, 3 insertions(+), 0 deletions(-)

diff --git a/drivers/cpufreq/powernow-k8.c b/drivers/cpufreq/powernow-k8.c
index 83479b6..287c56f 100644
--- a/drivers/cpufreq/powernow-k8.c
+++ b/drivers/cpufreq/powernow-k8.c
@@ -1079,6 +1079,9 @@ static int transition_frequency_fidvid(struct powernow_k8_data *data,
 	}
 
 	res = transition_fid_vid(data, fid, vid);
+	if (res)
+		return res;
+
 	freqs.new = find_khz_freq_from_fid(data->currfid);
 
 	for_each_cpu(i, data->available_cores) {
-- 
1.7.4.1

[PATCH 2/3] powernow-k8: Don't notify of successful transition if we failed (vid case).

[Konrad Rzeszutek Wilk]

Before this patch if we failed the vid transition would still try to
submit the "new" frequencies to cpufreq.
That is incorrect - also we could submit a non-existing frequency value
which would cause cpufreq to crash. The ultimate fix is in cpufreq
to deal with incorrect values, but this patch improves the error
recovery in the AMD powernowk8 driver.

The failure that was reported was as follows:

powernow-k8: Found 1 AMD Athlon(tm) 64 Processor 3700+ (1 cpu cores) (version 2.20.00)
powernow-k8: fid 0x2 (1000 MHz), vid 0x12
powernow-k8: fid 0xa (1800 MHz), vid 0xa
powernow-k8: fid 0xc (2000 MHz), vid 0x8
powernow-k8: fid 0xe (2200 MHz), vid 0x8
Marking TSC unstable due to cpufreq changes
powernow-k8: fid trans failed, fid 0x2, curr 0x0
BUG: unable to handle kernel paging request at ffff880807e07b78
IP: [<ffffffff81479163>] cpufreq_stats_update+0x46/0x5b
...

And transition fails and data->currfid ends up with 0. Since
the machine does not support 800Mhz value when the calculation is
done ('find_khz_freq_from_fid(data->currfid);') it reports the
new frequency as 800000 which is bogus. This patch fixes
the issue during target setting.

The patch however does not fix the issue in 'powernowk8_cpu_init'
where the pol->cur can also be set with the 800000 value:

          pol->cur = find_khz_freq_from_fid(data->currfid);
  dprintk("policy current frequency %d kHz\n", pol->cur);

  /* min/max the cpu is capable of */
  if (cpufreq_frequency_table_cpuinfo(pol, data->powernow_table)) {

The fix for that looks to update cpufreq_frequency_table_cpuinfo to
check pol->cur.... but that would cause an regression in how the
acpi-cpufreq driver works (it sets cpu->cur after calling
cpufreq_frequency_table_cpuinfo). Instead the fix will be to let
cpufreq gracefully handle bogus data (another patch).

Acked-by: Borislav Petkov <bp@alien8.de>
CC: andre.przywara@amd.com
CC: Mark.Langsdorf@amd.com
Reported-by: Tobias Diedrich <ranma+xen@tdiedrich.de>
Tested-by: Tobias Diedrich <ranma+xen@tdiedrich.de>
[v1: Rebased on v3.0-rc2, reduced patch to deal with vid case]
Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
---
 drivers/cpufreq/powernow-k8.c |    3 +++
 1 files changed, 3 insertions(+), 0 deletions(-)

diff --git a/drivers/cpufreq/powernow-k8.c b/drivers/cpufreq/powernow-k8.c
index 83479b6..287c56f 100644
--- a/drivers/cpufreq/powernow-k8.c
+++ b/drivers/cpufreq/powernow-k8.c
@@ -1079,6 +1079,9 @@ static int transition_frequency_fidvid(struct powernow_k8_data *data,
 	}
 
 	res = transition_fid_vid(data, fid, vid);
+	if (res)
+		return res;
+
 	freqs.new = find_khz_freq_from_fid(data->currfid);
 
 	for_each_cpu(i, data->available_cores) {
-- 
1.7.4.1

[PATCH 3/3] [CPUFREQ] powernow-k8: Don't try to transition if the pstate is incorrect

[Konrad Rzeszutek Wilk]

This patch augments the pstate transition code to error out
(instead of returning 0) when an incorrect pstate is provided.

Suggested-by: Borislav Petkov <bp@alien8.de>
CC: andre.przywara@amd.com
CC: Mark.Langsdorf@amd.com
Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
---
 drivers/cpufreq/powernow-k8.c |    3 ++-
 1 files changed, 2 insertions(+), 1 deletions(-)

diff --git a/drivers/cpufreq/powernow-k8.c b/drivers/cpufreq/powernow-k8.c
index 287c56f..bce576d 100644
--- a/drivers/cpufreq/powernow-k8.c
+++ b/drivers/cpufreq/powernow-k8.c
@@ -1104,7 +1104,8 @@ static int transition_frequency_pstate(struct powernow_k8_data *data,
 	/* get MSR index for hardware pstate transition */
 	pstate = index & HW_PSTATE_MASK;
 	if (pstate > data->max_hw_pstate)
-		return 0;
+		return -EINVAL;
+
 	freqs.old = find_khz_freq_from_pstate(data->powernow_table,
 			data->currpstate);
 	freqs.new = find_khz_freq_from_pstate(data->powernow_table, pstate);
-- 
1.7.4.1

[PATCH 3/3] powernow-k8: Don't try to transition if the pstate is incorrect

[Konrad Rzeszutek Wilk]

This patch augments the pstate transition code to error out
(instead of returning 0) when an incorrect pstate is provided.

Suggested-by: Borislav Petkov <bp@alien8.de>
CC: andre.przywara@amd.com
CC: Mark.Langsdorf@amd.com
Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
---
 drivers/cpufreq/powernow-k8.c |    3 ++-
 1 files changed, 2 insertions(+), 1 deletions(-)

diff --git a/drivers/cpufreq/powernow-k8.c b/drivers/cpufreq/powernow-k8.c
index 287c56f..bce576d 100644
--- a/drivers/cpufreq/powernow-k8.c
+++ b/drivers/cpufreq/powernow-k8.c
@@ -1104,7 +1104,8 @@ static int transition_frequency_pstate(struct powernow_k8_data *data,
 	/* get MSR index for hardware pstate transition */
 	pstate = index & HW_PSTATE_MASK;
 	if (pstate > data->max_hw_pstate)
-		return 0;
+		return -EINVAL;
+
 	freqs.old = find_khz_freq_from_pstate(data->powernow_table,
 			data->currpstate);
 	freqs.new = find_khz_freq_from_pstate(data->powernow_table, pstate);
-- 
1.7.4.1