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KVM: arm64: Convert kvm_mpidr_index() to bitmap_gather()

PATCH Applied Marc Zyngier 2 participants 3 messages May 2, 2024 – May 3, 2024

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KVM arm64 KVM arm64
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Marc Zyngier

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PATCH 1/1 KVM: arm64: Convert kvm_mpidr_index() to bitmap_gather()

Linux 6.9 has introduced new bitmap manipulation helpers, with bitmap_gather() being of special interest, as it does exactly what kvm_mpidr_index() is already doing.

Make the latter a wrapper around the former.

Signed-off-by Marc Zyngier <[email protected]>
---
 arch/arm64/include/asm/kvm_host.h | 16 +++-------------
 1 file changed, 3 insertions(+), 13 deletions(-)
arch/arm64/include/asm/kvm_host.h +3 -13
index 23a117cb3e50..fe94e96dced8 100644
@@ -221,20 +221,10 @@ struct kvm_mpidr_data {
 
 static inline u16 kvm_mpidr_index(struct kvm_mpidr_data *data, u64 mpidr)
 {
-	unsigned long mask = data->mpidr_mask;
-	u64 aff = mpidr & MPIDR_HWID_BITMASK;
-	int nbits, bit, bit_idx = 0;
-	u16 index = 0;
+	unsigned long index = 0, mask = data->mpidr_mask;
+	unsigned long aff = mpidr & MPIDR_HWID_BITMASK;
 
-	/*
-	 * If this looks like RISC-V's BEXT or x86's PEXT
-	 * instructions, it isn't by accident.
-	 */
-	nbits = fls(mask);
-	for_each_set_bit(bit, &mask, nbits) {
-		index |= (aff & BIT(bit)) >> (bit - bit_idx);
-		bit_idx++;
-	}
+	bitmap_gather(&index, &aff, &mask, fls(mask));
 
 	return index;
 }
Signature · 1 line
2.39.2
Reviewed-by on v1 1/1
#1 lore raw
Quoted 3 lines · Marc Zyngier

Linux 6.9 has introduced new bitmap manipulation helpers, with bitmap_gather() being of special interest, as it does exactly what kvm_mpidr_index() is already doing.

Ooo, that's a handy one!

Quoted 3 lines

Make the latter a wrapper around the former.

Signed-off-by Marc Zyngier <[email protected]>
Reviewed-by Oliver Upton <[email protected]>
Signature · 2 lines
Thanks,
Oliver
author maintainer Applied
#2 lore raw
In reply to Marc Zyngier
Quoted 8 lines · Marc Zyngier

Linux 6.9 has introduced new bitmap manipulation helpers, with bitmap_gather() being of special interest, as it does exactly what kvm_mpidr_index() is already doing.

Make the latter a wrapper around the former.

[...]

Applied to next, thanks!

[1/1] KVM: arm64: Convert kvm_mpidr_index() to bitmap_gather()

      commit: 838d992b84486311e6039170d28b79a7a0633f06

Cheers,

	M.
Signature · 1 line
Without deviation from the norm, progress is not possible.