[PATCH 0/2] VERW based clean-up

Daniel Sneddon posted 2 patches 3 weeks, 6 days ago
arch/x86/include/asm/processor.h |   2 +-
arch/x86/kernel/cpu/bugs.c       | 206 +++++++++++++------------------
2 files changed, 90 insertions(+), 118 deletions(-)
[PATCH 0/2] VERW based clean-up
Posted by Daniel Sneddon 3 weeks, 6 days ago
There are several mitigations that use the VERW instruction to clean
up internal CPU buffers.  Currently, each of these mitigations is
treated independently, but if VERW is needed for one of the
mitigations, it's on for all of them. This can lead to some confusion
if a user tries to disable one of the mitigations, but it is left
enabled for one of the others. The user needs to disable all 4 VERW-
based mitigations. Warn the user when one or more VERW mitigations are
disabled but not all of them. While we're messing with VERW
mitigations, might as well simplify them and remove the need to call
each of them twice.

V2:
Dropped the new knob previously introduced in the first patch (Borislav)
Add warning if not all 4 mitigations states match (Borislav)
Removed extra comment (Josh)
Code clean-up (Josh)


Daniel Sneddon (2):
  x86/bugs: Check VERW mitigations for consistency
  x86/bugs: Clean-up verw mitigations

 arch/x86/include/asm/processor.h |   2 +-
 arch/x86/kernel/cpu/bugs.c       | 206 +++++++++++++------------------
 2 files changed, 90 insertions(+), 118 deletions(-)

-- 
2.25.1
Re: [PATCH 0/2] VERW based clean-up
Posted by Daniel Sneddon 3 weeks, 6 days ago
Of course it isn't until after I hit send to realize I missed the "-v2" flag
when I generated these patches! Sorry for the confusion!

On 10/28/24 16:50, Daniel Sneddon wrote:
> There are several mitigations that use the VERW instruction to clean
> up internal CPU buffers.  Currently, each of these mitigations is
> treated independently, but if VERW is needed for one of the
> mitigations, it's on for all of them. This can lead to some confusion
> if a user tries to disable one of the mitigations, but it is left
> enabled for one of the others. The user needs to disable all 4 VERW-
> based mitigations. Warn the user when one or more VERW mitigations are
> disabled but not all of them. While we're messing with VERW
> mitigations, might as well simplify them and remove the need to call
> each of them twice.
> 
> V2:
> Dropped the new knob previously introduced in the first patch (Borislav)
> Add warning if not all 4 mitigations states match (Borislav)
> Removed extra comment (Josh)
> Code clean-up (Josh)
> 
> 
> Daniel Sneddon (2):
>   x86/bugs: Check VERW mitigations for consistency
>   x86/bugs: Clean-up verw mitigations
> 
>  arch/x86/include/asm/processor.h |   2 +-
>  arch/x86/kernel/cpu/bugs.c       | 206 +++++++++++++------------------
>  2 files changed, 90 insertions(+), 118 deletions(-)
>