diff options
| author | Marc Zyngier <maz@kernel.org> | 2023-11-09 15:47:49 +0000 |
|---|---|---|
| committer | Marc Zyngier <maz@kernel.org> | 2023-12-19 09:50:18 +0000 |
| commit | 2bfc654b89c4dd1c372bb2cbba6b5a0eb578d214 (patch) | |
| tree | 486ae0eb72ae9bd0bc68b0b08ef7503f519d13ec /arch/arm64/kernel | |
| parent | 2cc14f52aeb78ce3f29677c2de1f06c0e91471ab (diff) | |
arm64: cpufeatures: Restrict NV support to FEAT_NV2
To anyone who has played with FEAT_NV, it is obvious that the level
of performance is rather low due to the trap amplification that it
imposes on the host hypervisor. FEAT_NV2 solves a number of the
problems that FEAT_NV had.
It also turns out that all the existing hardware that has FEAT_NV
also has FEAT_NV2. Finally, it is now allowed by the architecture
to build FEAT_NV2 *only* (as denoted by ID_AA64MMFR4_EL1.NV_frac),
which effectively seals the fate of FEAT_NV.
Restrict the NV support to NV2, and be done with it. Nobody will
cry over the old crap. NV_frac will eventually be supported once
the intrastructure is ready.
Reviewed-by: Oliver Upton <oliver.upton@linux.dev>
Signed-off-by: Marc Zyngier <maz@kernel.org>
Diffstat (limited to 'arch/arm64/kernel')
| -rw-r--r-- | arch/arm64/kernel/cpufeature.c | 2 |
1 files changed, 1 insertions, 1 deletions
diff --git a/arch/arm64/kernel/cpufeature.c b/arch/arm64/kernel/cpufeature.c index 646591c67e7a..1329e974d187 100644 --- a/arch/arm64/kernel/cpufeature.c +++ b/arch/arm64/kernel/cpufeature.c @@ -2339,7 +2339,7 @@ static const struct arm64_cpu_capabilities arm64_features[] = { .capability = ARM64_HAS_NESTED_VIRT, .type = ARM64_CPUCAP_SYSTEM_FEATURE, .matches = has_nested_virt_support, - ARM64_CPUID_FIELDS(ID_AA64MMFR2_EL1, NV, IMP) + ARM64_CPUID_FIELDS(ID_AA64MMFR2_EL1, NV, NV2) }, { .capability = ARM64_HAS_32BIT_EL0_DO_NOT_USE, |