diff options
author | James Morse <james.morse@arm.com> | 2018-01-08 15:38:06 +0000 |
---|---|---|
committer | Catalin Marinas <catalin.marinas@arm.com> | 2018-01-13 10:44:33 +0000 |
commit | 6d99b68933fbcf51f84fcbba49246ce1209ec193 (patch) | |
tree | 894dd012b15f34f5c31f952fb52fc51485f24e9b /arch/arm64/kernel/cpufeature.c | |
parent | c97e166e54b662717d20ec2e36761758d2b6a7c2 (diff) |
arm64: alternatives: use tpidr_el2 on VHE hosts
Now that KVM uses tpidr_el2 in the same way as Linux's cpu_offset in
tpidr_el1, merge the two. This saves KVM from save/restoring tpidr_el1
on VHE hosts, and allows future code to blindly access per-cpu variables
without triggering world-switch.
Signed-off-by: James Morse <james.morse@arm.com>
Reviewed-by: Christoffer Dall <cdall@linaro.org>
Reviewed-by: Catalin Marinas <catalin.marinas@arm.com>
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
Diffstat (limited to 'arch/arm64/kernel/cpufeature.c')
-rw-r--r-- | arch/arm64/kernel/cpufeature.c | 17 |
1 files changed, 17 insertions, 0 deletions
diff --git a/arch/arm64/kernel/cpufeature.c b/arch/arm64/kernel/cpufeature.c index da6722db50b0..9ef84d0def9a 100644 --- a/arch/arm64/kernel/cpufeature.c +++ b/arch/arm64/kernel/cpufeature.c @@ -886,6 +886,22 @@ static int __init parse_kpti(char *str) __setup("kpti=", parse_kpti); #endif /* CONFIG_UNMAP_KERNEL_AT_EL0 */ +static int cpu_copy_el2regs(void *__unused) +{ + /* + * Copy register values that aren't redirected by hardware. + * + * Before code patching, we only set tpidr_el1, all CPUs need to copy + * this value to tpidr_el2 before we patch the code. Once we've done + * that, freshly-onlined CPUs will set tpidr_el2, so we don't need to + * do anything here. + */ + if (!alternatives_applied) + write_sysreg(read_sysreg(tpidr_el1), tpidr_el2); + + return 0; +} + static const struct arm64_cpu_capabilities arm64_features[] = { { .desc = "GIC system register CPU interface", @@ -955,6 +971,7 @@ static const struct arm64_cpu_capabilities arm64_features[] = { .capability = ARM64_HAS_VIRT_HOST_EXTN, .def_scope = SCOPE_SYSTEM, .matches = runs_at_el2, + .enable = cpu_copy_el2regs, }, { .desc = "32-bit EL0 Support", |