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| author | Arvind Sankar <nivedita@alum.mit.edu> | 2020-09-07 17:39:19 -0400 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2020-10-29 09:55:00 +0100 |
| commit | 87ab5f1415a7619983cc10fa099574512fdb9045 (patch) | |
| tree | 7f0ae79426341312806b931d32304b38e0a12770 /Documentation | |
| parent | dc0e1c91848e0615d73d4c22aa7b52d682cb8a9d (diff) | |
| download | linux-stable-87ab5f1415a7619983cc10fa099574512fdb9045.tar.gz linux-stable-87ab5f1415a7619983cc10fa099574512fdb9045.tar.bz2 linux-stable-87ab5f1415a7619983cc10fa099574512fdb9045.zip | |
x86/fpu: Allow multiple bits in clearcpuid= parameter
[ Upstream commit 0a4bb5e5507a585532cc413125b921c8546fc39f ]
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
Signed-off-by: Sasha Levin <sashal@kernel.org>
Diffstat (limited to 'Documentation')
| -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 30752db57587..fb129272240c 100644 --- a/Documentation/admin-guide/kernel-parameters.txt +++ b/Documentation/admin-guide/kernel-parameters.txt @@ -558,7 +558,7 @@ 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 |