diff options
| author | Mauricio Faria de Oliveira <mauricfo@linux.vnet.ibm.com> | 2018-06-02 21:09:04 +1000 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2018-06-06 16:44:37 +0200 |
| commit | 9e337dcf2edc095971751bf55293f8a92d5e55e3 (patch) | |
| tree | 193ee41219f4462d9b429294036e3ecc55a39b4c | |
| parent | 1dc0f1f17539c3931c9e3613ce59aa37d3747c94 (diff) | |
powerpc/pseries: Fix clearing of security feature flags
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 <mpe@ellerman.id.au>
Fixes: f636c14790ea ("powerpc/pseries: Set or clear security feature flags")
Signed-off-by: Mauricio Faria de Oliveira <mauricfo@linux.vnet.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
| -rw-r--r-- | arch/powerpc/platforms/pseries/setup.c | 6 |
1 files changed, 3 insertions, 3 deletions
diff --git a/arch/powerpc/platforms/pseries/setup.c b/arch/powerpc/platforms/pseries/setup.c index 28d7cd2001cc..8d9f591e7950 100644 --- a/arch/powerpc/platforms/pseries/setup.c +++ b/arch/powerpc/platforms/pseries/setup.c @@ -475,13 +475,13 @@ static void init_cpu_char_feature_flags(struct h_cpu_char_result *result) * 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); } |