BMC/Intel-BMC/linux.git/arch/arm64/kernel, branch dev-4.17

arm64: KVM: Handle guest's ARCH_WORKAROUND_2 requests

2018-07-22T13:16:08+00:00

commit b4f18c063a13dfb33e3a63fe1844823e19c2265e upstream. In order to forward the guest's ARCH_WORKAROUND_2 calls to EL3, add a small(-ish) sequence to handle it at EL2. Special care must be taken to track the state of the guest itself by updating the workaround flags. We also rely on patching to enable calls into the firmware. Note that since we need to execute branches, this always executes after the Spectre-v2 mitigation has been applied. Reviewed-by: Mark Rutland Signed-off-by: Marc Zyngier Signed-off-by: Catalin Marinas Signed-off-by: Greg Kroah-Hartman

arm64: ssbd: Add prctl interface for per-thread mitigation

2018-07-22T13:16:08+00:00

commit 9cdc0108baa8ef87c76ed834619886a46bd70cbe upstream. If running on a system that performs dynamic SSBD mitigation, allow userspace to request the mitigation for itself. This is implemented as a prctl call, allowing the mitigation to be enabled or disabled at will for this particular thread. Acked-by: Will Deacon Signed-off-by: Marc Zyngier Signed-off-by: Catalin Marinas Signed-off-by: Greg Kroah-Hartman

arm64: ssbd: Introduce thread flag to control userspace mitigation

2018-07-22T13:16:08+00:00

commit 9dd9614f5476687abbff8d4b12cd08ae70d7c2ad upstream. In order to allow userspace to be mitigated on demand, let's introduce a new thread flag that prevents the mitigation from being turned off when exiting to userspace, and doesn't turn it on on entry into the kernel (with the assumption that the mitigation is always enabled in the kernel itself). This will be used by a prctl interface introduced in a later patch. Reviewed-by: Mark Rutland Acked-by: Will Deacon Signed-off-by: Marc Zyngier Signed-off-by: Catalin Marinas Signed-off-by: Greg Kroah-Hartman

arm64: ssbd: Restore mitigation status on CPU resume

2018-07-22T13:16:08+00:00

commit 647d0519b53f440a55df163de21c52a8205431cc upstream. On a system where firmware can dynamically change the state of the mitigation, the CPU will always come up with the mitigation enabled, including when coming back from suspend. If the user has requested "no mitigation" via a command line option, let's enforce it by calling into the firmware again to disable it. Similarily, for a resume from hibernate, the mitigation could have been disabled by the boot kernel. Let's ensure that it is set back on in that case. Acked-by: Will Deacon Reviewed-by: Mark Rutland Signed-off-by: Marc Zyngier Signed-off-by: Catalin Marinas Signed-off-by: Greg Kroah-Hartman

arm64: ssbd: Skip apply_ssbd if not using dynamic mitigation

2018-07-22T13:16:08+00:00

commit 986372c4367f46b34a3c0f6918d7fb95cbdf39d6 upstream. In order to avoid checking arm64_ssbd_callback_required on each kernel entry/exit even if no mitigation is required, let's add yet another alternative that by default jumps over the mitigation, and that gets nop'ed out if we're doing dynamic mitigation. Think of it as a poor man's static key... Reviewed-by: Julien Grall Reviewed-by: Mark Rutland Acked-by: Will Deacon Signed-off-by: Marc Zyngier Signed-off-by: Catalin Marinas Signed-off-by: Greg Kroah-Hartman

arm64: Add 'ssbd' command-line option

2018-07-22T13:16:07+00:00

commit a43ae4dfe56a01f5b98ba0cb2f784b6a43bafcc6 upstream. On a system where the firmware implements ARCH_WORKAROUND_2, it may be useful to either permanently enable or disable the workaround for cases where the user decides that they'd rather not get a trap overhead, and keep the mitigation permanently on or off instead of switching it on exception entry/exit. In any case, default to the mitigation being enabled. Reviewed-by: Julien Grall Reviewed-by: Mark Rutland Acked-by: Will Deacon Signed-off-by: Marc Zyngier Signed-off-by: Catalin Marinas Signed-off-by: Greg Kroah-Hartman

arm64: Add ARCH_WORKAROUND_2 probing

2018-07-22T13:16:07+00:00

commit a725e3dda1813ed306734823ac4c65ca04e38500 upstream. As for Spectre variant-2, we rely on SMCCC 1.1 to provide the discovery mechanism for detecting the SSBD mitigation. A new capability is also allocated for that purpose, and a config option. Reviewed-by: Julien Grall Reviewed-by: Mark Rutland Acked-by: Will Deacon Reviewed-by: Suzuki K Poulose Signed-off-by: Marc Zyngier Signed-off-by: Catalin Marinas Signed-off-by: Greg Kroah-Hartman

arm64: Add per-cpu infrastructure to call ARCH_WORKAROUND_2

2018-07-22T13:16:07+00:00

commit 5cf9ce6e5ea50f805c6188c04ed0daaec7b6887d upstream. In a heterogeneous system, we can end up with both affected and unaffected CPUs. Let's check their status before calling into the firmware. Reviewed-by: Julien Grall Reviewed-by: Mark Rutland Acked-by: Will Deacon Signed-off-by: Marc Zyngier Signed-off-by: Catalin Marinas Signed-off-by: Greg Kroah-Hartman

arm64: Call ARCH_WORKAROUND_2 on transitions between EL0 and EL1

2018-07-22T13:16:07+00:00

commit 8e2906245f1e3b0d027169d9f2e55ce0548cb96e upstream. In order for the kernel to protect itself, let's call the SSBD mitigation implemented by the higher exception level (either hypervisor or firmware) on each transition between userspace and kernel. We must take the PSCI conduit into account in order to target the right exception level, hence the introduction of a runtime patching callback. Reviewed-by: Mark Rutland Reviewed-by: Julien Grall Acked-by: Will Deacon Signed-off-by: Marc Zyngier Signed-off-by: Catalin Marinas Signed-off-by: Greg Kroah-Hartman

arm64: kpti: Use early_param for kpti= command-line option

2018-07-03T09:26:53+00:00

commit b5b7dd647f2d21b93f734ce890671cd908e69b0a upstream. We inspect __kpti_forced early on as part of the cpufeature enable callback which remaps the swapper page table using non-global entries. Ensure that __kpti_forced has been updated to reflect the kpti= command-line option before we start using it. Fixes: ea1e3de85e94 ("arm64: entry: Add fake CPU feature for unmapping the kernel at EL0") Cc: # 4.16.x- Reported-by: Wei Xu Tested-by: Sudeep Holla Tested-by: Wei Xu Signed-off-by: Will Deacon Signed-off-by: Catalin Marinas Signed-off-by: Greg Kroah-Hartman