Re: [PATCH] powerpc/pseries: Fix update of LPAR security flavor after LPM

[Michael Ellerman]

On Thu, 5 Aug 2021 17:23:08 +0200, Laurent Dufour wrote:
> After LPM, when migrating from a system with security mitigation enabled to
> a system with mitigation disabled, the security flavor exposed in /proc is
> not correctly set back to 0.
> 
> Do not assume the value of the security flavor is set to 0 when entering
> init_cpu_char_feature_flags(), so when called after a LPM, the value is set
> correctly even if the mitigation are not turned off.
> 
> [...]

Applied to powerpc/fixes.

[1/1] powerpc/pseries: Fix update of LPAR security flavor after LPM
  https://git.kernel.org/powerpc/c/c18956e6e0b95f78dad2773ecc8c61a9e41f6405

cheers

[PATCH] powerpc/pseries: Fix update of LPAR security flavor after LPM

[Laurent Dufour]

After LPM, when migrating from a system with security mitigation enabled to
a system with mitigation disabled, the security flavor exposed in /proc is
not correctly set back to 0.

Do not assume the value of the security flavor is set to 0 when entering
init_cpu_char_feature_flags(), so when called after a LPM, the value is set
correctly even if the mitigation are not turned off.

Fixes: 6ce56e1ac380 ("powerpc/pseries: export LPAR security flavor in
lparcfg")

Cc: sta...@vger.kernel.org # 5.13.x
Signed-off-by: Laurent Dufour 
---
 arch/powerpc/platforms/pseries/setup.c | 5 +++--
 1 file changed, 3 insertions(+), 2 deletions(-)

diff --git a/arch/powerpc/platforms/pseries/setup.c 
b/arch/powerpc/platforms/pseries/setup.c
index 6b0886668465..0dfaa6ab44cc 100644
--- a/arch/powerpc/platforms/pseries/setup.c
+++ b/arch/powerpc/platforms/pseries/setup.c
@@ -539,9 +539,10 @@ static void init_cpu_char_feature_flags(struct 
h_cpu_char_result *result)
 * H_CPU_BEHAV_FAVOUR_SECURITY_H could be set only if
 * H_CPU_BEHAV_FAVOUR_SECURITY is.
 */
-   if (!(result->behaviour & H_CPU_BEHAV_FAVOUR_SECURITY))
+   if (!(result->behaviour & H_CPU_BEHAV_FAVOUR_SECURITY)) {
security_ftr_clear(SEC_FTR_FAVOUR_SECURITY);
-   else if (result->behaviour & H_CPU_BEHAV_FAVOUR_SECURITY_H)
+   pseries_security_flavor = 0;
+   } else if (result->behaviour & H_CPU_BEHAV_FAVOUR_SECURITY_H)
pseries_security_flavor = 1;
else
pseries_security_flavor = 2;
-- 
2.32.0