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powerpc/pseries: Fix clearing of security feature flags
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: f636c14790
("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>
This commit is contained in:
parent
95dff480bb
commit
0f9bdfe3c7
@ -484,13 +484,13 @@ static void init_cpu_char_feature_flags(struct h_cpu_char_result *result)
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* The features below are enabled by default, so we instead look to see
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* if firmware has *disabled* them, and clear them if so.
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*/
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if (!(result->character & H_CPU_BEHAV_FAVOUR_SECURITY))
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if (!(result->behaviour & H_CPU_BEHAV_FAVOUR_SECURITY))
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security_ftr_clear(SEC_FTR_FAVOUR_SECURITY);
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if (!(result->character & H_CPU_BEHAV_L1D_FLUSH_PR))
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if (!(result->behaviour & H_CPU_BEHAV_L1D_FLUSH_PR))
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security_ftr_clear(SEC_FTR_L1D_FLUSH_PR);
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if (!(result->character & H_CPU_BEHAV_BNDS_CHK_SPEC_BAR))
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if (!(result->behaviour & H_CPU_BEHAV_BNDS_CHK_SPEC_BAR))
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security_ftr_clear(SEC_FTR_BNDS_CHK_SPEC_BAR);
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}
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