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

arm64: cmpwait: Clear event register before arming exclusive monitor

2018-08-03T05:47:50+00:00

[ Upstream commit 1cfc63b5ae60fe7e01773f38132f98d8b13a99a0 ] When waiting for a cacheline to change state in cmpwait, we may immediately wake-up the first time around the outer loop if the event register was already set (for example, because of the event stream). Avoid these spurious wakeups by explicitly clearing the event register before loading the cacheline and setting the exclusive monitor. Signed-off-by: Will Deacon Signed-off-by: Catalin Marinas Signed-off-by: Sasha Levin Signed-off-by: Greg Kroah-Hartman

arm64: KVM: Add ARCH_WORKAROUND_2 discovery through ARCH_FEATURES_FUNC_ID

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

commit 5d81f7dc9bca4f4963092433e27b508cbe524a32 upstream. Now that all our infrastructure is in place, let's expose the availability of ARCH_WORKAROUND_2 to guests. We take this opportunity to tidy up a couple of SMCCC constants. Acked-by: Christoffer Dall Reviewed-by: Mark Rutland Signed-off-by: Marc Zyngier Signed-off-by: Catalin Marinas Signed-off-by: Greg Kroah-Hartman

arm64: KVM: Add ARCH_WORKAROUND_2 support for guests

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

commit 55e3748e8902ff641e334226bdcb432f9a5d78d3 upstream. In order to offer ARCH_WORKAROUND_2 support to guests, we need a bit of infrastructure. Let's add a flag indicating whether or not the guest uses SSBD mitigation. Depending on the state of this flag, allow KVM to disable ARCH_WORKAROUND_2 before entering the guest, and enable it when exiting it. Reviewed-by: Christoffer Dall Reviewed-by: Mark Rutland Signed-off-by: Marc Zyngier Signed-off-by: Catalin Marinas Signed-off-by: Greg Kroah-Hartman

arm64: KVM: Add HYP per-cpu accessors

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

commit 85478bab409171de501b719971fd25a3d5d639f9 upstream. As we're going to require to access per-cpu variables at EL2, let's craft the minimum set of accessors required to implement reading a per-cpu variable, relying on tpidr_el2 to contain the per-cpu offset. Reviewed-by: Christoffer Dall Reviewed-by: Mark Rutland 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: Add global mitigation state accessor

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

commit c32e1736ca03904c03de0e4459a673be194f56fd upstream. We're about to need the mitigation state in various parts of the kernel in order to do the right thing for userspace and guests. Let's expose an accessor that will let other subsystems know about the state. 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: neon: Fix function may_use_simd() return error status

2018-07-17T09:48:31+00:00

commit 2fd8eb4ad87104c54800ef3cea498c92eb15c78a upstream. It does not matter if the caller of may_use_simd() migrates to another cpu after the call, but it is still important that the kernel_neon_busy percpu instance that is read matches the cpu the task is running on at the time of the read. This means that raw_cpu_read() is not sufficient. kernel_neon_busy may appear true if the caller migrates during the execution of raw_cpu_read() and the next task to be scheduled in on the initial cpu calls kernel_neon_begin(). This patch replaces raw_cpu_read() with this_cpu_read() to protect against this race. Cc: Fixes: cb84d11e1625 ("arm64: neon: Remove support for nested or hardirq kernel-mode NEON") Acked-by: Ard Biesheuvel Reviewed-by: Dave Martin Reviewed-by: Mark Rutland Signed-off-by: Yandong Zhao Signed-off-by: Will Deacon Signed-off-by: Greg Kroah-Hartman