x86/resctrl: Allow arch to allocate memory needed in resctrl_arch_rmid_read()

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Depending on the number of monitors available, Arm's MPAM may need to
allocate a monitor prior to reading the counter value. Allocating a
contended resource may involve sleeping.

__check_limbo() and mon_event_count() each make multiple calls to
resctrl_arch_rmid_read(), to avoid extra work on contended systems,
the allocation should be valid for multiple invocations of
resctrl_arch_rmid_read().

The memory or hardware allocated is not specific to a domain.

Add arch hooks for this allocation, which need calling before
resctrl_arch_rmid_read(). The allocated monitor is passed to
resctrl_arch_rmid_read(), then freed again afterwards. The helper
can be called on any CPU, and can sleep.

Signed-off-by: James Morse <james.morse@arm.com>
Signed-off-by: Borislav Petkov (AMD) <bp@alien8.de>
Reviewed-by: Shaopeng Tan <tan.shaopeng@fujitsu.com>
Reviewed-by: Reinette Chatre <reinette.chatre@intel.com>
Reviewed-by: Babu Moger <babu.moger@amd.com>
Tested-by: Shaopeng Tan <tan.shaopeng@fujitsu.com>
Tested-by: Peter Newman <peternewman@google.com>
Tested-by: Babu Moger <babu.moger@amd.com>
Tested-by: Carl Worth <carl@os.amperecomputing.com> # arm64
Link: https://lore.kernel.org/r/20240213184438.16675-16-james.morse@arm.com
Signed-off-by: Borislav Petkov (AMD) <bp@alien8.de>

...

This commit is contained in:

James Morse 2024-02-13 18:44:29 +00:00 • committed by Borislav Petkov (AMD)

parent 6fde1424f2

commit e557999f80

5 changed files with 55 additions and 4 deletions

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11

arch/x86/include/asm/resctrl.h

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7

arch/x86/kernel/cpu/resctrl/ctrlmondata.c

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1

arch/x86/kernel/cpu/resctrl/internal.h

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35

arch/x86/kernel/cpu/resctrl/monitor.c

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5

include/linux/resctrl.h

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