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[05/89] KVM: arm64: Extend comment in has_vhe()

Message ID 20220519134204.5379-6-will@kernel.org (mailing list archive)
State New, archived
Headers show
Series KVM: arm64: Base support for the pKVM hypervisor at EL2 | expand

Commit Message

Will Deacon May 19, 2022, 1:40 p.m. UTC
has_vhe() expands to a compile-time constant when evaluated from the VHE
or nVHE code, alternatively checking a static key when called from
elsewhere in the kernel. On face value, this looks like a case of
premature optimization, but in fact this allows symbol references on
VHE-specific code paths to be dropped from the nVHE object.

Expand the comment in has_vhe() to make this clearer, hopefully
discouraging anybody from simplifying the code.

Cc: David Brazdil <dbrazdil@google.com>
Acked-by: Mark Rutland <mark.rutland@arm.com>
Signed-off-by: Will Deacon <will@kernel.org>
 arch/arm64/include/asm/virt.h | 3 +++
 1 file changed, 3 insertions(+)
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diff --git a/arch/arm64/include/asm/virt.h b/arch/arm64/include/asm/virt.h
index 3c8af033a997..0e80db4327b6 100644
--- a/arch/arm64/include/asm/virt.h
+++ b/arch/arm64/include/asm/virt.h
@@ -113,6 +113,9 @@  static __always_inline bool has_vhe(void)
 	 * Code only run in VHE/NVHE hyp context can assume VHE is present or
 	 * absent. Otherwise fall back to caps.
+	 * This allows the compiler to discard VHE-specific code from the
+	 * nVHE object, reducing the number of external symbol references
+	 * needed to link.
 	if (is_vhe_hyp_code())
 		return true;