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Sai Praneeth 162ee5a8ab x86/mm: Fix bogus warning during EFI bootup, use boot_cpu_has() instead of this_cpu_has() in build_cr3_noflush() Linus reported the following boot warning: WARNING: CPU: 0 PID: 0 at arch/x86/include/asm/tlbflush.h:134 load_new_mm_cr3+0x114/0x170 [...] Call Trace: switch_mm_irqs_off+0x267/0x590 switch_mm+0xe/0x20 efi_switch_mm+0x3e/0x50 efi_enter_virtual_mode+0x43f/0x4da start_kernel+0x3bf/0x458 secondary_startup_64+0xa5/0xb0 ... after merging: `03781e4089`: x86/efi: Use efi_switch_mm() rather than manually twiddling with %cr3 When the platform supports PCID and if CONFIG_DEBUG_VM=y is enabled, build_cr3_noflush() (called via switch_mm()) does a sanity check to see if X86_FEATURE_PCID is set. Presently, build_cr3_noflush() uses "this_cpu_has(X86_FEATURE_PCID)" to perform the check but this_cpu_has() works only after SMP is initialized (i.e. per cpu cpu_info's should be populated) and this happens to be very late in the boot process (during rest_init()). As efi_runtime_services() are called during (early) kernel boot time and run time, modify build_cr3_noflush() to use boot_cpu_has() all the time. As suggested by Dave Hansen, this should be OK because all CPU's have same capabilities on x86. With this change the warning is fixed. ( Dave also suggested that we put a warning in this_cpu_has() if it's used early in the boot process. This is still work in progress as it affects MCE. ) Reported-by: Linus Torvalds <torvalds@linux-foundation.org> Signed-off-by: Sai Praneeth Prakhya <sai.praneeth.prakhya@intel.com> Cc: Andrew Morton <akpm@linux-foundation.org> Cc: Andy Lutomirski <luto@kernel.org> Cc: Ard Biesheuvel <ard.biesheuvel@linaro.org> Cc: Borislav Petkov <bp@alien8.de> Cc: Dave Hansen <dave.hansen@intel.com> Cc: Lee Chun-Yi <jlee@suse.com> Cc: Matt Fleming <matt@codeblueprint.co.uk> Cc: Michael S. Tsirkin <mst@redhat.com> Cc: Peter Zijlstra <a.p.zijlstra@chello.nl> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Ravi Shankar <ravi.v.shankar@intel.com> Cc: Ricardo Neri <ricardo.neri@intel.com> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Tony Luck <tony.luck@intel.com> Cc: linux-efi@vger.kernel.org Link: http://lkml.kernel.org/r/1522870459-7432-1-git-send-email-sai.praneeth.prakhya@intel.com Signed-off-by: Ingo Molnar <mingo@kernel.org>	2018-04-05 01:27:49 +02:00
..
asm	x86/mm: Fix bogus warning during EFI bootup, use boot_cpu_has() instead of this_cpu_has() in build_cr3_noflush()	2018-04-05 01:27:49 +02:00
uapi/asm	x86/MCE: Cleanup and complete struct mce fields definitions	2018-03-08 15:52:59 +01:00

Sai Praneeth 162ee5a8ab x86/mm: Fix bogus warning during EFI bootup, use boot_cpu_has() instead of this_cpu_has() in build_cr3_noflush()

Linus reported the following boot warning:

  WARNING: CPU: 0 PID: 0 at arch/x86/include/asm/tlbflush.h:134 load_new_mm_cr3+0x114/0x170
  [...]
  Call Trace:
  switch_mm_irqs_off+0x267/0x590
  switch_mm+0xe/0x20
  efi_switch_mm+0x3e/0x50
  efi_enter_virtual_mode+0x43f/0x4da
  start_kernel+0x3bf/0x458
  secondary_startup_64+0xa5/0xb0

... after merging:

  03781e4089: x86/efi: Use efi_switch_mm() rather than manually twiddling with %cr3

When the platform supports PCID and if CONFIG_DEBUG_VM=y is enabled,
build_cr3_noflush() (called via switch_mm()) does a sanity check to see
if X86_FEATURE_PCID is set.

Presently, build_cr3_noflush() uses "this_cpu_has(X86_FEATURE_PCID)" to
perform the check but this_cpu_has() works only after SMP is initialized
(i.e. per cpu cpu_info's should be populated) and this happens to be very
late in the boot process (during rest_init()).

As efi_runtime_services() are called during (early) kernel boot time
and run time, modify build_cr3_noflush() to use boot_cpu_has() all the
time. As suggested by Dave Hansen, this should be OK because all CPU's have
same capabilities on x86.

With this change the warning is fixed.

( Dave also suggested that we put a warning in this_cpu_has() if it's used
  early in the boot process. This is still work in progress as it affects
  MCE. )

Reported-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Sai Praneeth Prakhya <sai.praneeth.prakhya@intel.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Andy Lutomirski <luto@kernel.org>
Cc: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Dave Hansen <dave.hansen@intel.com>
Cc: Lee Chun-Yi <jlee@suse.com>
Cc: Matt Fleming <matt@codeblueprint.co.uk>
Cc: Michael S. Tsirkin <mst@redhat.com>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Ravi Shankar <ravi.v.shankar@intel.com>
Cc: Ricardo Neri <ricardo.neri@intel.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Tony Luck <tony.luck@intel.com>
Cc: linux-efi@vger.kernel.org
Link: http://lkml.kernel.org/r/1522870459-7432-1-git-send-email-sai.praneeth.prakhya@intel.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>

2018-04-05 01:27:49 +02:00

asm x86/mm: Fix bogus warning during EFI bootup, use boot_cpu_has() instead of this_cpu_has() in build_cr3_noflush() 2018-04-05 01:27:49 +02:00

uapi/asm x86/MCE: Cleanup and complete struct mce fields definitions 2018-03-08 15:52:59 +01:00