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| author | Arvind Sankar <nivedita@alum.mit.edu> | 2020-09-07 23:39:19 +0200 |
|---|---|---|
| committer | Borislav Petkov <bp@suse.de> | 2020-09-10 18:32:05 +0200 |
| commit | 0a4bb5e5507a585532cc413125b921c8546fc39f (patch) | |
| tree | 3784e5e88c7033f16b2208549a738ebf4a39f8cd /Documentation/admin-guide/kernel-parameters.txt | |
| parent | Linux 5.9-rc4 (diff) | |
| download | linux-0a4bb5e5507a585532cc413125b921c8546fc39f.tar.xz linux-0a4bb5e5507a585532cc413125b921c8546fc39f.zip | |
x86/fpu: Allow multiple bits in clearcpuid= parameter
Commit
0c2a3913d6f5 ("x86/fpu: Parse clearcpuid= as early XSAVE argument")
changed clearcpuid parsing from __setup() to cmdline_find_option().
While the __setup() function would have been called for each clearcpuid=
parameter on the command line, cmdline_find_option() will only return
the last one, so the change effectively made it impossible to disable
more than one bit.
Allow a comma-separated list of bit numbers as the argument for
clearcpuid to allow multiple bits to be disabled again. Log the bits
being disabled for informational purposes.
Also fix the check on the return value of cmdline_find_option(). It
returns -1 when the option is not found, so testing as a boolean is
incorrect.
Fixes: 0c2a3913d6f5 ("x86/fpu: Parse clearcpuid= as early XSAVE argument")
Signed-off-by: Arvind Sankar <nivedita@alum.mit.edu>
Signed-off-by: Borislav Petkov <bp@suse.de>
Link: https://lkml.kernel.org/r/20200907213919.2423441-1-nivedita@alum.mit.edu
Diffstat (limited to 'Documentation/admin-guide/kernel-parameters.txt')
| -rw-r--r-- | Documentation/admin-guide/kernel-parameters.txt | 2 |
1 files changed, 1 insertions, 1 deletions
diff --git a/Documentation/admin-guide/kernel-parameters.txt b/Documentation/admin-guide/kernel-parameters.txt index a1068742a6df..ffe864390c5a 100644 --- a/Documentation/admin-guide/kernel-parameters.txt +++ b/Documentation/admin-guide/kernel-parameters.txt @@ -577,7 +577,7 @@ loops can be debugged more effectively on production systems. - clearcpuid=BITNUM [X86] + clearcpuid=BITNUM[,BITNUM...] [X86] Disable CPUID feature X for the kernel. See arch/x86/include/asm/cpufeatures.h for the valid bit numbers. Note the Linux specific bits are not necessarily |