linux.git/arch/x86/kernel/cpu, branch v4.19

x86/intel_rdt: Fix out-of-bounds memory access in CBM tests

2018-10-09T06:02:15+00:00

While the DOC at the beginning of lib/bitmap.c explicitly states that
"The number of valid bits in a given bitmap does _not_ need to be an
exact multiple of BITS_PER_LONG.", some of the bitmap operations do
indeed access BITS_PER_LONG portions of the provided bitmap no matter
the size of the provided bitmap. For example, if bitmap_intersects()
is provided with an 8 bit bitmap the operation will access
BITS_PER_LONG bits from the provided bitmap. While the operation
ensures that these extra bits do not affect the result, the memory
is still accessed.

The capacity bitmasks (CBMs) are typically stored in u32 since they
can never exceed 32 bits. A few instances exist where a bitmap_*
operation is performed on a CBM by simply pointing the bitmap operation
to the stored u32 value.

The consequence of this pattern is that some bitmap_* operations will
access out-of-bounds memory when interacting with the provided CBM. This
is confirmed with a KASAN test that reports:

 BUG: KASAN: stack-out-of-bounds in __bitmap_intersects+0xa2/0x100

and

 BUG: KASAN: stack-out-of-bounds in __bitmap_weight+0x58/0x90

Fix this by moving any CBM provided to a bitmap operation needing
BITS_PER_LONG to an 'unsigned long' variable.

[ tglx: Changed related function arguments to unsigned long and got rid
	of the _cbm extra step ]

Fixes: 72d505056604 ("x86/intel_rdt: Add utilities to test pseudo-locked region possibility")
Fixes: 49f7b4efa110 ("x86/intel_rdt: Enable setting of exclusive mode")
Fixes: d9b48c86eb38 ("x86/intel_rdt: Display resource groups' allocations' size in bytes")
Fixes: 95f0b77efa57 ("x86/intel_rdt: Initialize new resource group with sane defaults")
Signed-off-by: Reinette Chatre 
Signed-off-by: Thomas Gleixner 
Cc: fenghua.yu@intel.com
Cc: tony.luck@intel.com
Cc: gavin.hindman@intel.com
Cc: jithu.joseph@intel.com
Cc: dave.hansen@intel.com
Cc: hpa@zytor.com
Link: https://lkml.kernel.org/r/69a428613a53f10e80594679ac726246020ff94f.1538686926.git.reinette.chatre@intel.com
Signed-off-by: Ingo Molnar

x86/cpu/amd: Remove unnecessary parentheses

2018-10-03T06:27:47+00:00

Clang warns when multiple pairs of parentheses are used for a single
conditional statement.

arch/x86/kernel/cpu/amd.c:925:14: warning: equality comparison with
extraneous parentheses [-Wparentheses-equality]
        if ((c->x86 == 6)) {
             ~~~~~~~^~~~
arch/x86/kernel/cpu/amd.c:925:14: note: remove extraneous parentheses
around the comparison to silence this warning
        if ((c->x86 == 6)) {
            ~       ^   ~
arch/x86/kernel/cpu/amd.c:925:14: note: use '=' to turn this equality
comparison into an assignment
        if ((c->x86 == 6)) {
                    ^~
                    =
1 warning generated.

Signed-off-by: Nathan Chancellor 
Cc: Borislav Petkov 
Cc: Linus Torvalds 
Cc: Peter Zijlstra 
Cc: Thomas Gleixner 
Link: http://lkml.kernel.org/r/20181002224511.14929-1-natechancellor@gmail.com
Link: https://github.com/ClangBuiltLinux/linux/issues/187
Signed-off-by: Ingo Molnar

x86/intel_rdt: Fix incorrect loop end condition

2018-09-18T21:38:07+00:00

In order to determine a sane default cache allocation for a new CAT/CDP
resource group, all resource groups are checked to determine which cache
portions are available to share. At this time all possible CLOSIDs
that can be supported by the resource is checked. This is problematic
if the resource supports more CLOSIDs than another CAT/CDP resource. In
this case, the number of CLOSIDs that could be allocated are fewer than
the number of CLOSIDs that can be supported by the resource.

Limit the check of closids to that what is supported by the system based
on the minimum across all resources.

Fixes: 95f0b77ef ("x86/intel_rdt: Initialize new resource group with sane defaults")
Signed-off-by: Reinette Chatre 
Signed-off-by: Fenghua Yu 
Signed-off-by: Thomas Gleixner 
Cc: "H Peter Anvin" 
Cc: "Tony Luck" 
Cc: "Xiaochen Shen" 
Cc: "Chen Yu" 
Link: https://lkml.kernel.org/r/1537048707-76280-10-git-send-email-fenghua.yu@intel.com

x86/intel_rdt: Fix exclusive mode handling of MBA resource

2018-09-18T21:38:07+00:00

It is possible for a resource group to consist out of MBA as well as
CAT/CDP resources. The "exclusive" resource mode only applies to the
CAT/CDP resources since MBA allocations cannot be specified to overlap
or not. When a user requests a resource group to become "exclusive" then it
can only be successful if there are CAT/CDP resources in the group
and none of their CBMs associated with the group's CLOSID overlaps with
any other resource group.

Fix the "exclusive" mode setting by failing if there isn't any CAT/CDP
resource in the group and ensuring that the CBM checking is only done on
CAT/CDP resources.

Fixes: 49f7b4efa ("x86/intel_rdt: Enable setting of exclusive mode")
Signed-off-by: Reinette Chatre 
Signed-off-by: Fenghua Yu 
Signed-off-by: Thomas Gleixner 
Cc: "H Peter Anvin" 
Cc: "Tony Luck" 
Cc: "Xiaochen Shen" 
Cc: "Chen Yu" 
Link: https://lkml.kernel.org/r/1537048707-76280-9-git-send-email-fenghua.yu@intel.com

x86/intel_rdt: Fix incorrect loop end condition

2018-09-18T21:38:06+00:00

A loop is used to check if a CAT resource's CBM of one CLOSID
overlaps with the CBM of another CLOSID of the same resource. The loop
is run over all CLOSIDs supported by the resource.

The problem with running the loop over all CLOSIDs supported by the
resource is that its number of supported CLOSIDs may be more than the
number of supported CLOSIDs on the system, which is the minimum number of
CLOSIDs supported across all resources.

Fix the loop to only consider the number of system supported CLOSIDs,
not all that are supported by the resource.

Fixes: 49f7b4efa ("x86/intel_rdt: Enable setting of exclusive mode")
Signed-off-by: Reinette Chatre 
Signed-off-by: Fenghua Yu 
Signed-off-by: Thomas Gleixner 
Cc: "H Peter Anvin" 
Cc: "Tony Luck" 
Cc: "Xiaochen Shen" 
Cc: "Chen Yu" 
Link: https://lkml.kernel.org/r/1537048707-76280-8-git-send-email-fenghua.yu@intel.com

x86/intel_rdt: Do not allow pseudo-locking of MBA resource

2018-09-18T21:38:06+00:00

A system supporting pseudo-locking may have MBA as well as CAT
resources of which only the CAT resources could support cache
pseudo-locking. When the schemata to be pseudo-locked is provided it
should be checked that that schemata does not attempt to pseudo-lock a
MBA resource.

Fixes: e0bdfe8e3 ("x86/intel_rdt: Support creation/removal of pseudo-locked region")
Signed-off-by: Reinette Chatre 
Signed-off-by: Fenghua Yu 
Signed-off-by: Thomas Gleixner 
Cc: "H Peter Anvin" 
Cc: "Tony Luck" 
Cc: "Xiaochen Shen" 
Cc: "Chen Yu" 
Link: https://lkml.kernel.org/r/1537048707-76280-7-git-send-email-fenghua.yu@intel.com

x86/intel_rdt: Fix unchecked MSR access

2018-09-18T21:38:06+00:00

When a new resource group is created, it is initialized with sane
defaults that currently assume the resource being initialized is a CAT
resource. This code path is also followed by a MBA resource that is not
allocated the same as a CAT resource and as a result we encounter the
following unchecked MSR access error:

unchecked MSR access error: WRMSR to 0xd51 (tried to write 0x0000
000000000064) at rIP: 0xffffffffae059994 (native_write_msr+0x4/0x20)
Call Trace:
mba_wrmsr+0x41/0x80
update_domains+0x125/0x130
rdtgroup_mkdir+0x270/0x500

Fix the above by ensuring the initial allocation is only attempted on a
CAT resource.

Fixes: 95f0b77ef ("x86/intel_rdt: Initialize new resource group with sane defaults")
Signed-off-by: Reinette Chatre 
Signed-off-by: Fenghua Yu 
Signed-off-by: Thomas Gleixner 
Cc: "H Peter Anvin" 
Cc: "Tony Luck" 
Cc: "Xiaochen Shen" 
Cc: "Chen Yu" 
Link: https://lkml.kernel.org/r/1537048707-76280-6-git-send-email-fenghua.yu@intel.com

x86/intel_rdt: Fix invalid mode warning when multiple resources are managed

2018-09-18T21:38:05+00:00

When multiple resources are managed by RDT, the number of CLOSIDs used
is the minimum of the CLOSIDs supported by each resource. In the function
rdt_bit_usage_show(), the annotated bitmask is created to depict how the
CAT supporting caches are being used. During this annotated bitmask
creation, each resource group is queried for its mode that is used as a
label in the annotated bitmask.

The maximum number of resource groups is currently assumed to be the
number of CLOSIDs supported by the resource for which the information is
being displayed. This is incorrect since the number of active CLOSIDs is
the minimum across all resources.

If information for a cache instance with more CLOSIDs than another is
being generated we thus encounter a warning like:

invalid mode for closid 8
WARNING: CPU: 88 PID: 1791 at [SNIP]/arch/x86/kernel/cpu/intel_rdt_rdtgroup.c
:827 rdt_bit_usage_show+0x221/0x2b0

Fix this by ensuring that only the number of supported CLOSIDs are
considered.

Fixes: e651901187ab8 ("x86/intel_rdt: Introduce "bit_usage" to display cache allocations details")
Signed-off-by: Reinette Chatre 
Signed-off-by: Fenghua Yu 
Signed-off-by: Thomas Gleixner 
Cc: "H Peter Anvin" 
Cc: "Tony Luck" 
Cc: "Xiaochen Shen" 
Cc: "Chen Yu" 
Link: https://lkml.kernel.org/r/1537048707-76280-5-git-send-email-fenghua.yu@intel.com

x86/intel_rdt: Global closid helper to support future fixes

2018-09-18T21:38:05+00:00

The number of CLOSIDs supported by a system is the minimum number of
CLOSIDs supported by any of its resources. Care should be taken when
iterating over the CLOSIDs of a resource since it may be that the number
of CLOSIDs supported on the system is less than the number of CLOSIDs
supported by the resource.

Introduce a helper function that can be used to query the number of
CLOSIDs that is supported by all resources, irrespective of how many
CLOSIDs are supported by a particular resource.

Signed-off-by: Reinette Chatre 
Signed-off-by: Fenghua Yu 
Signed-off-by: Thomas Gleixner 
Cc: "H Peter Anvin" 
Cc: "Tony Luck" 
Cc: "Xiaochen Shen" 
Cc: "Chen Yu" 
Link: https://lkml.kernel.org/r/1537048707-76280-4-git-send-email-fenghua.yu@intel.com

x86/intel_rdt: Fix size reporting of MBA resource

2018-09-18T21:38:05+00:00

Chen Yu reported a divide-by-zero error when accessing the 'size'
resctrl file when a MBA resource is enabled.

divide error: 0000 [#1] SMP PTI
CPU: 93 PID: 1929 Comm: cat Not tainted 4.19.0-rc2-debug-rdt+ #25
RIP: 0010:rdtgroup_cbm_to_size+0x7e/0xa0
Call Trace:
rdtgroup_size_show+0x11a/0x1d0
seq_read+0xd8/0x3b0

Quoting Chen Yu's report: This is because for MB resource, the
r->cache.cbm_len is zero, thus calculating size in rdtgroup_cbm_to_size()
will trigger the exception.

Fix this issue in the 'size' file by getting correct memory bandwidth value
which is in MBps when MBA software controller is enabled or in percentage
when MBA software controller is disabled.

Fixes: d9b48c86eb38 ("x86/intel_rdt: Display resource groups' allocations in bytes")
Reported-by: Chen Yu 
Signed-off-by: Reinette Chatre 
Signed-off-by: Fenghua Yu 
Signed-off-by: Thomas Gleixner 
Tested-by: Chen Yu 
Cc: "H Peter Anvin" 
Cc: "Tony Luck" 
Cc: "Xiaochen Shen" 
Link: https://lkml.kernel.org/r/20180904174614.26682-1-yu.c.chen@intel.com
Link: https://lkml.kernel.org/r/1537048707-76280-3-git-send-email-fenghua.yu@intel.com