This is a note to let you know that I've just added the patch titled
powerpc/pseries: Fix clearing of security feature flags
to the 4.16-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-pseries-fix-clearing-of-security-feature-flags.patch
and it can be found in the queue-4.16 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <sta...@vger.kernel.org> know about it.
>From foo@baz Wed May 23 19:18:22 CEST 2018
From: Michael Ellerman <m...@ellerman.id.au>
Date: Wed, 23 May 2018 00:41:23 +1000
Subject: powerpc/pseries: Fix clearing of security feature flags
To: g...@kroah.com
Cc: sta...@vger.kernel.org, t...@linutronix.de, linuxppc-...@ozlabs.org
Message-ID: <20180522144125.10345-13-...@ellerman.id.au>
From: Mauricio Faria de Oliveira <mauri...@linux.vnet.ibm.com>
commit 0f9bdfe3c77091e8704d2e510eb7c2c2c6cde524 upstream.
The H_CPU_BEHAV_* flags should be checked for in the 'behaviour' field
of 'struct h_cpu_char_result' -- 'character' is for H_CPU_CHAR_*
flags.
Found by playing around with QEMU's implementation of the hypercall:
H_CPU_CHAR=0xf000000000000000
H_CPU_BEHAV=0x0000000000000000
This clears H_CPU_BEHAV_FAVOUR_SECURITY and H_CPU_BEHAV_L1D_FLUSH_PR
so pseries_setup_rfi_flush() disables 'rfi_flush'; and it also
clears H_CPU_CHAR_L1D_THREAD_PRIV flag. So there is no RFI flush
mitigation at all for cpu_show_meltdown() to report; but currently
it does:
Original kernel:
# cat /sys/devices/system/cpu/vulnerabilities/meltdown
Mitigation: RFI Flush
Patched kernel:
# cat /sys/devices/system/cpu/vulnerabilities/meltdown
Not affected
H_CPU_CHAR=0x0000000000000000
H_CPU_BEHAV=0xf000000000000000
This sets H_CPU_BEHAV_BNDS_CHK_SPEC_BAR so cpu_show_spectre_v1() should
report vulnerable; but currently it doesn't:
Original kernel:
# cat /sys/devices/system/cpu/vulnerabilities/spectre_v1
Not affected
Patched kernel:
# cat /sys/devices/system/cpu/vulnerabilities/spectre_v1
Vulnerable
Brown-paper-bag-by: Michael Ellerman <m...@ellerman.id.au>
Fixes: f636c14790ea ("powerpc/pseries: Set or clear security feature flags")
Signed-off-by: Mauricio Faria de Oliveira <mauri...@linux.vnet.ibm.com>
Signed-off-by: Michael Ellerman <m...@ellerman.id.au>
Signed-off-by: Greg Kroah-Hartman <gre...@linuxfoundation.org>
---
arch/powerpc/platforms/pseries/setup.c | 6 +++---
1 file changed, 3 insertions(+), 3 deletions(-)
--- a/arch/powerpc/platforms/pseries/setup.c
+++ b/arch/powerpc/platforms/pseries/setup.c
@@ -484,13 +484,13 @@ static void init_cpu_char_feature_flags(
* The features below are enabled by default, so we instead look to see
* if firmware has *disabled* them, and clear them if so.
*/
- if (!(result->character & H_CPU_BEHAV_FAVOUR_SECURITY))
+ if (!(result->behaviour & H_CPU_BEHAV_FAVOUR_SECURITY))
security_ftr_clear(SEC_FTR_FAVOUR_SECURITY);
- if (!(result->character & H_CPU_BEHAV_L1D_FLUSH_PR))
+ if (!(result->behaviour & H_CPU_BEHAV_L1D_FLUSH_PR))
security_ftr_clear(SEC_FTR_L1D_FLUSH_PR);
- if (!(result->character & H_CPU_BEHAV_BNDS_CHK_SPEC_BAR))
+ if (!(result->behaviour & H_CPU_BEHAV_BNDS_CHK_SPEC_BAR))
security_ftr_clear(SEC_FTR_BNDS_CHK_SPEC_BAR);
}
Patches currently in stable-queue which might be from m...@ellerman.id.au are
queue-4.16/powerpc-pseries-fix-clearing-of-security-feature-flags.patch
queue-4.16/powerpc-powernv-set-or-clear-security-feature-flags.patch
queue-4.16/powerpc-64s-move-cpu_show_meltdown.patch
queue-4.16/powerpc-pseries-set-or-clear-security-feature-flags.patch
queue-4.16/powerpc-move-default-security-feature-flags.patch
queue-4.16/powerpc-powernv-use-the-security-flags-in-pnv_setup_rfi_flush.patch
queue-4.16/powerpc-add-security-feature-flags-for-spectre-meltdown.patch
queue-4.16/powerpc-pseries-use-the-security-flags-in-pseries_setup_rfi_flush.patch
queue-4.16/powerpc-64s-enhance-the-information-in-cpu_show_meltdown.patch
queue-4.16/powerpc-rfi-flush-always-enable-fallback-flush-on-pseries.patch
queue-4.16/powerpc-pseries-add-new-h_get_cpu_characteristics-flags.patch
queue-4.16/powerpc-64s-add-support-for-a-store-forwarding-barrier-at-kernel-entry-exit.patch
queue-4.16/powerpc-64s-wire-up-cpu_show_spectre_v1.patch
queue-4.16/powerpc-64s-wire-up-cpu_show_spectre_v2.patch
