From: Russell Currey ruscur@russell.cc
[ Upstream commit 2efee6adb56159288bce9d1ab51fc9056d7007d4 ]
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 d02fa40d759f ("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: d02fa40d759f ("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 Signed-off-by: Sasha Levin sashal@kernel.org --- arch/powerpc/platforms/powernv/setup.c | 6 ++++++ 1 file changed, 6 insertions(+)
diff --git a/arch/powerpc/platforms/powernv/setup.c b/arch/powerpc/platforms/powernv/setup.c index 105d889abd51..378f7e5f18d2 100644 --- a/arch/powerpc/platforms/powernv/setup.c +++ b/arch/powerpc/platforms/powernv/setup.c @@ -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)