This is a note to let you know that I've just added the patch titled
powerpc/powernv: Get STF barrier requirements from device-tree
to the 5.18-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
powerpc-powernv-get-stf-barrier-requirements-from-de.patch
and it can be found in the queue-5.18 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
commit cecb2072e7e16aaa91b1efb1f8546b00b3302430
Author: Russell Currey <ruscur@xxxxxxxxxx>
Date: Mon Apr 4 20:15:36 2022 +1000
powerpc/powernv: Get STF barrier requirements from device-tree
[ Upstream commit d2a3c131981d4498571908df95c3c9393a00adf5 ]
The device-tree property no-need-store-drain-on-priv-state-switch is
equivalent to H_CPU_BEHAV_NO_STF_BARRIER from the
H_CPU_GET_CHARACTERISTICS hcall on pseries.
Since commit 84ed26fd00c5 ("powerpc/security: Add a security feature for
STF barrier") powernv systems with this device-tree property have been
enabling the STF barrier when they have no need for it. This patch
fixes this by clearing the STF barrier feature on those systems.
Fixes: 84ed26fd00c5 ("powerpc/security: Add a security feature for STF barrier")
Reported-by: Joel Stanley <joel@xxxxxxxxx>
Signed-off-by: Russell Currey <ruscur@xxxxxxxxxx>
Signed-off-by: Michael Ellerman <mpe@xxxxxxxxxxxxxx>
Link: https://lore.kernel.org/r/20220404101536.104794-2-ruscur@xxxxxxxxxx
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
diff --git a/arch/powerpc/platforms/powernv/setup.c b/arch/powerpc/platforms/powernv/setup.c
index 378f7e5f18d2..824c3ad7a0fa 100644
--- a/arch/powerpc/platforms/powernv/setup.c
+++ b/arch/powerpc/platforms/powernv/setup.c
@@ -102,6 +102,9 @@ static void __init init_fw_feat_flags(struct device_node *np)
if (fw_feature_is("enabled", "no-need-l1d-flush-kernel-on-user-access", np))
security_ftr_clear(SEC_FTR_L1D_FLUSH_UACCESS);
+
+ if (fw_feature_is("enabled", "no-need-store-drain-on-priv-state-switch", np))
+ security_ftr_clear(SEC_FTR_STF_BARRIER);
}
static void __init pnv_setup_security_mitigations(void)
