linux/arch/arm64
Suzuki K Poulose 05abb595bb arm64: Delay enabling hardware DBM feature
We enable hardware DBM bit in a capable CPU, very early in the
boot via __cpu_setup. This doesn't give us a flexibility of
optionally disable the feature, as the clearing the bit
is a bit costly as the TLB can cache the settings. Instead,
we delay enabling the feature until the CPU is brought up
into the kernel. We use the feature capability mechanism
to handle it.

The hardware DBM is a non-conflicting feature. i.e, the kernel
can safely run with a mix of CPUs with some using the feature
and the others don't. So, it is safe for a late CPU to have
this capability and enable it, even if the active CPUs don't.

To get this handled properly by the infrastructure, we
unconditionally set the capability and only enable it
on CPUs which really have the feature. Also, we print the
feature detection from the "matches" call back to make sure
we don't mislead the user when none of the CPUs could use the
feature.

Cc: Catalin Marinas <catalin.marinas@arm.com>
Reviewed-by: Dave Martin <dave.martin@arm.com>
Signed-off-by: Suzuki K Poulose <suzuki.poulose@arm.com>
Signed-off-by: Will Deacon <will.deacon@arm.com>
2018-03-26 18:01:44 +01:00
..
boot ARM: SoC device tree updates for 4.16 2018-02-01 16:07:54 -08:00
configs ARM: SoC platform updates for 4.16 2018-02-01 16:17:40 -08:00
crypto crypto: arm64/sha512 - fix/improve new v8.2 Crypto Extensions code 2018-01-26 01:10:36 +11:00
include arm64: Delay enabling hardware DBM feature 2018-03-26 18:01:44 +01:00
kernel arm64: Delay enabling hardware DBM feature 2018-03-26 18:01:44 +01:00
kvm arm64: Add missing Falkor part number for branch predictor hardening 2018-02-12 11:28:45 +00:00
lib arm64: lse: Pass -fomit-frame-pointer to out-of-line ll/sc atomics 2018-03-06 18:52:32 +00:00
mm arm64: Delay enabling hardware DBM feature 2018-03-26 18:01:44 +01:00
net bpf, arm64: fix out of bounds access in tail call 2018-02-22 16:06:28 -08:00
xen arm64: mm: Add additional parameter to uaccess_ttbr0_disable 2018-01-17 13:57:49 +01:00
Kconfig arm64/sve: Document firmware support requirements in Kconfig 2018-03-26 12:29:35 +01:00
Kconfig.debug arm64: relocation testing module 2017-04-04 17:03:32 +01:00
Kconfig.platforms clk: meson-axg: add clock controller drivers 2017-12-14 10:19:37 +01:00
Makefile arm64/kernel: don't ban ADRP to work around Cortex-A53 erratum #843419 2018-03-09 13:21:53 +00:00