linux-kernel - [PATCH v7 1/4] arm64/fpsimd: Introduce __bit_to

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Message-Id: <20241001-kvm-arm64-fix-pkvm-sve-vl-v7-1-7b0171a36695@kernel.org>
Date: Tue, 01 Oct 2024 12:29:06 +0100
From: Mark Brown <broonie@...nel.org>
To: Catalin Marinas <catalin.marinas@....com>, 
 Will Deacon <will@...nel.org>, Marc Zyngier <maz@...nel.org>, 
 Oliver Upton <oliver.upton@...ux.dev>, James Morse <james.morse@....com>, 
 Suzuki K Poulose <suzuki.poulose@....com>, Fuad Tabba <tabba@...gle.com>
Cc: linux-arm-kernel@...ts.infradead.org, linux-kernel@...r.kernel.org, 
 kvmarm@...ts.linux.dev, Mark Brown <broonie@...nel.org>
Subject: [PATCH v7 1/4] arm64/fpsimd: Introduce __bit_to_vl() helper

In all cases where we use the existing __bit_to_vq() helper we immediately
convert the result into a VL. Provide and use __bit_to_vl() doing this
directly.

Acked-by: Catalin Marinas <catalin.marinas@....com>
Signed-off-by: Mark Brown <broonie@...nel.org>
---
 arch/arm64/include/asm/fpsimd.h |  4 ++++
 arch/arm64/kernel/fpsimd.c      | 12 ++++++------
 2 files changed, 10 insertions(+), 6 deletions(-)

diff --git a/arch/arm64/include/asm/fpsimd.h b/arch/arm64/include/asm/fpsimd.h
index f2a84efc3618..3c30da35c285 100644
--- a/arch/arm64/include/asm/fpsimd.h
+++ b/arch/arm64/include/asm/fpsimd.h
@@ -170,6 +170,10 @@ static inline unsigned int __bit_to_vq(unsigned int bit)
 	return SVE_VQ_MAX - bit;
 }
 
+static inline unsigned int __bit_to_vl(unsigned int bit)
+{
+	return sve_vl_from_vq(__bit_to_vq(bit));
+}
 
 struct vl_info {
 	enum vec_type type;
diff --git a/arch/arm64/kernel/fpsimd.c b/arch/arm64/kernel/fpsimd.c
index 77006df20a75..8a080dbd8988 100644
--- a/arch/arm64/kernel/fpsimd.c
+++ b/arch/arm64/kernel/fpsimd.c
@@ -530,7 +530,7 @@ static unsigned int find_supported_vector_length(enum vec_type type,
 
 	bit = find_next_bit(info->vq_map, SVE_VQ_MAX,
 			    __vq_to_bit(sve_vq_from_vl(vl)));
-	return sve_vl_from_vq(__bit_to_vq(bit));
+	return __bit_to_vl(bit);
 }
 
 #if defined(CONFIG_ARM64_SVE) && defined(CONFIG_SYSCTL)
@@ -1103,7 +1103,7 @@ int vec_verify_vq_map(enum vec_type type)
 	 * Mismatches above sve_max_virtualisable_vl are fine, since
 	 * no guest is allowed to configure ZCR_EL2.LEN to exceed this:
 	 */
-	if (sve_vl_from_vq(__bit_to_vq(b)) <= info->max_virtualisable_vl) {
+	if (__bit_to_vl(b) <= info->max_virtualisable_vl) {
 		pr_warn("%s: cpu%d: Unsupported vector length(s) present\n",
 			info->name, smp_processor_id());
 		return -EINVAL;
@@ -1169,7 +1169,7 @@ void __init sve_setup(void)
 		set_bit(__vq_to_bit(SVE_VQ_MIN), info->vq_map);
 
 	max_bit = find_first_bit(info->vq_map, SVE_VQ_MAX);
-	info->max_vl = sve_vl_from_vq(__bit_to_vq(max_bit));
+	info->max_vl = __bit_to_vl(max_bit);
 
 	/*
 	 * For the default VL, pick the maximum supported value <= 64.
@@ -1188,7 +1188,7 @@ void __init sve_setup(void)
 		/* No virtualisable VLs?  This is architecturally forbidden. */
 		info->max_virtualisable_vl = SVE_VQ_MIN;
 	else /* b + 1 < SVE_VQ_MAX */
-		info->max_virtualisable_vl = sve_vl_from_vq(__bit_to_vq(b + 1));
+		info->max_virtualisable_vl = __bit_to_vl(b + 1);
 
 	if (info->max_virtualisable_vl > info->max_vl)
 		info->max_virtualisable_vl = info->max_vl;
@@ -1305,10 +1305,10 @@ void __init sme_setup(void)
 	WARN_ON(bitmap_empty(info->vq_map, SVE_VQ_MAX));
 
 	min_bit = find_last_bit(info->vq_map, SVE_VQ_MAX);
-	info->min_vl = sve_vl_from_vq(__bit_to_vq(min_bit));
+	info->min_vl = __bit_to_vl(min_bit);
 
 	max_bit = find_first_bit(info->vq_map, SVE_VQ_MAX);
-	info->max_vl = sve_vl_from_vq(__bit_to_vq(max_bit));
+	info->max_vl = __bit_to_vl(max_bit);
 
 	WARN_ON(info->min_vl > info->max_vl);
 

-- 
2.39.2