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powerpc/powernv: Get L1D flush requirements from device-tree 

The device-tree properties no-need-l1d-flush-msr-pr-1-to-0 and
no-need-l1d-flush-kernel-on-user-access are the equivalents of
H_CPU_BEHAV_NO_L1D_FLUSH_ENTRY and H_CPU_BEHAV_NO_L1D_FLUSH_UACCESS
from the H_GET_CPU_CHARACTERISTICS hcall on pseries respectively.

In commit d02fa40d75 ("powerpc/powernv: Remove POWER9 PVR version
check for entry and uaccess flushes") the condition for disabling the
L1D flush on kernel entry and user access was changed from any non-P9
CPU to only checking P7 and P8.  Without the appropriate device-tree
checks for newer processors on powernv, these flushes are unnecessarily
enabled on those systems.  This patch corrects this.

Fixes: d02fa40d75 ("powerpc/powernv: Remove POWER9 PVR version check for entry and uaccess flushes")
Reported-by: Joel Stanley <joel@jms.id.au>
Signed-off-by: Russell Currey <ruscur@russell.cc>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20220404101536.104794-1-ruscur@russell.cc
This commit is contained in:
Russell Currey 2022-04-04 20:15:35 +10:00 committed by Michael Ellerman
parent 294299b3d3
commit 2efee6adb5
1 changed files with 6 additions and 0 deletions
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6
arch/powerpc/platforms/powernv/setup.c
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@ -96,6 +96,12 @@ static void __init init_fw_feat_flags(struct device_node *np)
if (fw_feature_is("disabled", "needs-spec-barrier-for-bound-checks", np))
security_ftr_clear(SEC_FTR_BNDS_CHK_SPEC_BAR);
if (fw_feature_is("enabled", "no-need-l1d-flush-msr-pr-1-to-0", np))
security_ftr_clear(SEC_FTR_L1D_FLUSH_ENTRY);
if (fw_feature_is("enabled", "no-need-l1d-flush-kernel-on-user-access", np))
security_ftr_clear(SEC_FTR_L1D_FLUSH_UACCESS);
}
static void __init pnv_setup_security_mitigations(void)