On 15/03/23 1:27 pm, Greg KH wrote:
On Tue, Mar 14, 2023 at 04:11:59AM -0700, Rhythm Mahajan wrote:
The commit: 3f235279828c ("x86/cpu: Restore AMD's DE_CFG MSR after resume")
renamed the MSR_F10H_DECFG_LFENCE_SERIALIZE macro to
MSR_AMD64_DE_CFG_LFENCE_SERIALIZE.
The fix changed MSR_F10H_DECFG_LFENCE_SERIALIZE to
MSR_AMD64_DE_CFG_LFENCE_SERIALIZE_BIT in the init_amd() function,
but should have used MSR_AMD64_DE_CFG_LFENCE_SERIALIZE.
This causes a discrepancy in the LFENCE serialization
check in the init_amd() function.
This causes a ~16% sysbench memory regression, when running:
sysbench --test=memory run
Fixes: 3f235279828c2a8aff3164fef08d58f7af2d64fc("x86/cpu: Restore AMD's DE_CFG MSR after resume
")
Odd line-wrapping :(
And please use the proper way to reference SHA1 as documented in the
kernel documentation.
Thanks, I will send a v2 for this.
And why is this only needed in 4.14.y? What about Linus's tree and all
of the other stable trees?
The regression was introduced after the backport of 2632daebafd0
("x86/cpu: Restore AMD's DE_CFG MSR after resume") for 4.14.y and 4.9.y.
Mainline and other stable don't have this regression.
The fix is only needed for 4.14.y and 4.9.y.
Please get this fixed in Linus's tree first and then we can take a
backport.
Mainline doesn't require this fix.
thanks,
greg k-h
Thanks,
Rhythm
