kernel.git/arch/powerpc/platforms/pseries, branch linux-4.17.y

powerpc/64s: Add support for a store forwarding barrier at kernel entry/exit

2018-05-22T03:45:31Z

On some CPUs we can prevent a vulnerability related to store-to-load forwarding by preventing store forwarding between privilege domains, by inserting a barrier in kernel entry and exit paths. This is known to be the case on at least Power7, Power8 and Power9 powerpc CPUs. Barriers must be inserted generally before the first load after moving to a higher privilege, and after the last store before moving to a lower privilege, HV and PR privilege transitions must be protected. Barriers are added as patch sections, with all kernel/hypervisor entry points patched, and the exit points to lower privilge levels patched similarly to the RFI flush patching. Firmware advertisement is not implemented yet, so CPU flush types are hard coded. Thanks to Michal Suchánek for bug fixes and review. Signed-off-by: Nicholas Piggin Signed-off-by: Mauricio Faria de Oliveira Signed-off-by: Michael Neuling Signed-off-by: Michal Suchánek Signed-off-by: Michael Ellerman Signed-off-by: Linus Torvalds

powerpc/pseries: Restore default security feature flags on setup

2018-04-03T11:50:09Z

After migration the security feature flags might have changed (e.g., destination system with unpatched firmware), but some flags are not set/clear again in init_cpu_char_feature_flags() because it assumes the security flags to be the defaults. Additionally, if the H_GET_CPU_CHARACTERISTICS hypercall fails then init_cpu_char_feature_flags() does not run again, which potentially might leave the system in an insecure or sub-optimal configuration. So, just restore the security feature flags to the defaults assumed by init_cpu_char_feature_flags() so it can set/clear them correctly, and to ensure safe settings are in place in case the hypercall fail. Fixes: f636c14790ea ("powerpc/pseries: Set or clear security feature flags") Depends-on: 19887d6a28e2 ("powerpc: Move default security feature flags") Signed-off-by: Mauricio Faria de Oliveira Signed-off-by: Michael Ellerman

Merge branch 'topic/paca' into next

2018-03-30T22:09:36Z

Bring in yet another series that touches KVM code, and might need to be merged into the kvm-ppc branch to resolve conflicts. This required some changes in pnv_power9_force_smt4_catch/release() due to the paca array becomming an array of pointers.

powerpc/pseries: Fix clearing of security feature flags

2018-03-30T13:10:31Z

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 Fixes: f636c14790ea ("powerpc/pseries: Set or clear security feature flags") Signed-off-by: Mauricio Faria de Oliveira Signed-off-by: Michael Ellerman

powerpc/64s: Allocate LPPACAs individually

2018-03-30T12:34:24Z

We no longer allocate lppacas in an array, so this patch removes the 1kB static alignment for the structure, and enforces the PAPR alignment requirements at allocation time. We can not reduce the 1kB allocation size however, due to existing KVM hypervisors. Signed-off-by: Nicholas Piggin Signed-off-by: Michael Ellerman

powerpc/64: Use array of paca pointers and allocate pacas individually

2018-03-30T12:34:23Z

Change the paca array into an array of pointers to pacas. Allocate pacas individually. This allows flexibility in where the PACAs are allocated. Future work will allocate them node-local. Platforms that don't have address limits on PACAs would be able to defer PACA allocations until later in boot rather than allocate all possible ones up-front then freeing unused. This is slightly more overhead (one additional indirection) for cross CPU paca references, but those aren't too common. Signed-off-by: Nicholas Piggin Signed-off-by: Michael Ellerman

powerpc/lpar/debug: Initialize flags before printing debug message

2018-03-27T12:44:56Z

With enabled DEBUG, there is a compile error: "error: ‘flags’ is used uninitialized in this function". This moves pr_devel() little further where @flags are initialized. Signed-off-by: Alexey Kardashevskiy Signed-off-by: Michael Ellerman

powerpc/pseries: Use the security flags in pseries_setup_rfi_flush()

2018-03-27T12:44:54Z

Now that we have the security flags we can simplify the code in pseries_setup_rfi_flush() because the security flags have pessimistic defaults. Signed-off-by: Michael Ellerman

powerpc/pseries: Set or clear security feature flags

2018-03-27T12:44:52Z

Now that we have feature flags for security related things, set or clear them based on what we receive from the hypercall. Signed-off-by: Michael Ellerman

powerpc/rfi-flush: Call setup_rfi_flush() after LPM migration

2018-03-27T08:25:14Z

We might have migrated to a machine that uses a different flush type, or doesn't need flushing at all. Signed-off-by: Michael Ellerman Signed-off-by: Mauricio Faria de Oliveira Signed-off-by: Michael Ellerman