kernel/arch/powerpc/platforms/pseries/setup.c, branch linux-4.16.y

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

2018-05-25T14:46:06Z

commit a048a07d7f4535baa4cbad6bc024f175317ab938 upstream. 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 Signed-off-by: Greg Kroah-Hartman

powerpc/pseries: Fix clearing of security feature flags

2018-05-25T14:46:06Z

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

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

2018-05-25T14:46:05Z

commit 2e4a16161fcd324b1f9bf6cb6856529f7eaf0689 upstream. 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 Signed-off-by: Greg Kroah-Hartman

powerpc/pseries: Set or clear security feature flags

2018-05-25T14:46:05Z

commit f636c14790ead6cc22cf62279b1f8d7e11a67116 upstream. 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 Signed-off-by: Greg Kroah-Hartman

powerpc/rfi-flush: Always enable fallback flush on pseries

2018-05-25T14:46:04Z

commit 84749a58b6e382f109abf1e734bc4dd43c2c25bb upstream. This ensures the fallback flush area is always allocated on pseries, so in case a LPAR is migrated from a patched to an unpatched system, it is possible to enable the fallback flush in the target system. Signed-off-by: Michael Ellerman Signed-off-by: Mauricio Faria de Oliveira Signed-off-by: Michael Ellerman Signed-off-by: Greg Kroah-Hartman

powerpc/pseries: Support firmware disable of RFI flush

2018-02-23T05:55:40Z

Some versions of firmware will have a setting that can be configured to disable the RFI flush, add support for it. Fixes: 8989d56878a7 ("powerpc/pseries: Query hypervisor for RFI flush settings") Signed-off-by: Michael Ellerman

powerpc/pseries: Add Initialization of VF Bars

2018-01-27T09:02:53Z

When enabling SR-IOV in pseries platform, the VF bar properties for a PF are reported on the device node in the device tree. This patch adds the IOV Bar resources to Linux structures from the device tree for later use when configuring SR-IOV by PF driver. Signed-off-by: Bryant G. Ly Signed-off-by: Juan J. Alvarez Acked-by: Russell Currey Signed-off-by: Michael Ellerman

powerpc/pseries, ps3: panic flush kernel messages before halting system

2018-01-22T00:44:24Z

Platforms with a panic handler that halts the system can have problems getting kernel messages out, because the panic notifiers are called before kernel/panic.c does its flushing of printk buffers an console etc. This was attempted to be solved with commit a3b2cb30f252 ("powerpc: Do not call ppc_md.panic in fadump panic notifier"), but that wasn't the right approach and caused other problems, and was reverted by commit ab9dbf771ff9. Instead, the powernv shutdown paths have already had a similar problem, fixed by taking the message flushing sequence from kernel/panic.c. That's a little bit ugly, but while we have the code duplicated, it will work for this case as well. So have ppc panic handlers do the same flushing before they terminate. Without this patch, a qemu pseries_le_defconfig guest stops silently when issued the nmi command when xmon is off and no crash dumpers enabled. Afterwards, an oops is printed by each CPU as expected. Fixes: ab9dbf771ff9 ("Revert "powerpc: Do not call ppc_md.panic in fadump panic notifier"") Signed-off-by: Nicholas Piggin Reviewed-by: David Gibson Signed-off-by: Michael Ellerman

Merge branch 'fixes' into next

2018-01-21T12:21:14Z

Merge our fixes branch from the 4.15 cycle. Unusually the fixes branch saw some significant features merged, notably the RFI flush patches, so we want the code in next to be tested against that, to avoid any surprises when the two are merged. There's also some other work on the panic handling that was reverted in fixes and we now want to do properly in next, which would conflict. And we also fix a few other minor merge conflicts.

powerpc/pseries: Query hypervisor for RFI flush settings

2018-01-10T10:27:15Z

A new hypervisor call is available which tells the guest settings related to the RFI flush. Use it to query the appropriate flush instruction(s), and whether the flush is required. Signed-off-by: Michael Neuling Signed-off-by: Michael Ellerman