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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>
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@ -2339,7 +2339,7 @@ static const struct arm64_cpu_capabilities arm64_features[] = {
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.capability = ARM64_HAS_NESTED_VIRT,
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.type = ARM64_CPUCAP_SYSTEM_FEATURE,
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.matches = has_nested_virt_support,
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ARM64_CPUID_FIELDS(ID_AA64MMFR2_EL1, NV, IMP)
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ARM64_CPUID_FIELDS(ID_AA64MMFR2_EL1, NV, NV2)
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},
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{
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.capability = ARM64_HAS_32BIT_EL0_DO_NOT_USE,
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