From nobody Tue Feb 10 01:30:52 2026 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 801F713D2B8; Thu, 4 Jul 2024 17:28:48 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1720114128; cv=none; b=cA/LcXYKvws7NNvrkpl2Amn56T4zTm4eex9ryg7brTZTrxmbbGq4dP2TRyhxNwcI3zNH1fFyqtyPOyMwa+Vk66cZflE/tA0ccd1NDFwGlYsN680lnxL4lijA3B+49sHdQIqUl2uvIN8jjKdCyi+KBZ37g2WRna5DNv60Z6l+Uzw= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1720114128; c=relaxed/simple; bh=qYUCz/GnFjAVns0VEq9hJ3jJLihZ2D7gvH2hjVtPvmE=; h=From:Date:Subject:MIME-Version:Content-Type:Message-Id:References: In-Reply-To:To:Cc; b=UZ1AqmhpZZ6SfFk1RB1279F9KsFb3MTipucahzOBmGZAcBdkWAglxXqNWIKIvIQhUJyCRdeOcbQwq1Z9krNbVyyWkKhD0ZLnyxyB+lWP94nQEWWEN0Uzx/Ypwfw5ZomNhHwmtm/kPRjSRKc9UnRN4rrq0FTjTAFhsmkmqLNIpAY= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=HrFhL8ow; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="HrFhL8ow" Received: by smtp.kernel.org (Postfix) with ESMTPSA id DC483C3277B; Thu, 4 Jul 2024 17:28:45 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1720114128; bh=qYUCz/GnFjAVns0VEq9hJ3jJLihZ2D7gvH2hjVtPvmE=; h=From:Date:Subject:References:In-Reply-To:To:Cc:From; b=HrFhL8ow/k7gBBjT+WBHhdu1OjFM4fEi1FE5VOYblB+u5q2HhldLB+ryIbPjVj3/W 5wA+led0bsdiLSc+wBRKJ9xCimdnZlrkq/G78VE4tGL93MxMaduyz/1qm6m1pLywNW k6k1XeEJe7hkItRDQBKirmOTLkO4d9MfARvinY1A5Vfz8PWwI1hrAQFRzKnfWEvT81 R9kEhUiWhLLiiH325CNLYgAtQQb+Dn9osN2MT1f/7OwrqgMMqhBylNoE8ASEVOKKRb 4n7t5LSReJirKR5Y/nkNHxkvBSH/W6yBBdr8fRyEvVGT//+9Uc/1YYtnIRfMWloJnP rDaqWHcnPC91A== From: Mark Brown Date: Thu, 04 Jul 2024 18:28:17 +0100 Subject: [PATCH v4 2/4] arm64/fpsimd: Discover maximum vector length implemented by any CPU Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: quoted-printable Message-Id: <20240704-kvm-arm64-fix-pkvm-sve-vl-v4-2-b6898ab23dc4@kernel.org> References: <20240704-kvm-arm64-fix-pkvm-sve-vl-v4-0-b6898ab23dc4@kernel.org> In-Reply-To: <20240704-kvm-arm64-fix-pkvm-sve-vl-v4-0-b6898ab23dc4@kernel.org> To: Catalin Marinas , Will Deacon , Marc Zyngier , Oliver Upton , James Morse , Suzuki K Poulose , Fuad Tabba Cc: linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org, kvmarm@lists.linux.dev, Mark Brown X-Mailer: b4 0.14-dev-d4707 X-Developer-Signature: v=1; a=openpgp-sha256; l=4205; i=broonie@kernel.org; h=from:subject:message-id; bh=qYUCz/GnFjAVns0VEq9hJ3jJLihZ2D7gvH2hjVtPvmE=; b=owEBbQGS/pANAwAKASTWi3JdVIfQAcsmYgBmhtvGwTqR0Qpu0QyOIQAR3ZrqTal/2x8TbIx+X5rI KKrfOgyJATMEAAEKAB0WIQSt5miqZ1cYtZ/in+ok1otyXVSH0AUCZobbxgAKCRAk1otyXVSH0G1CB/ 0bgImdVDSPC86pbzqA6/g+5XP7ZhZ1dNI59aVX9jSvOgJzbZoTdKC5sqLeX6P8sQ8t7RF0LXg/ODcR nDPI1LtcjYZW3/fnsNdeFMvK8CEvayZy5wSiRtWxz7NIFA6EA52MkhgsPzEWoEZe8zZ6daMbd+FOQO ORuKi/dskT1qKPGcQuLP1fKFd4mhe4ftDnTqVuq9XRGu2HBQrcIsK6Hf47r/Iix9n1zl4Zwerjp1PO CvBSkKbYVQglNoz8By8uaLHLzJNOD6HIr/jOqIb9PNW08dR3o6rof2k2S5o9BH+VOJdOf1QB/60/DQ eFmPMmJsSMPLWnnFa2V3FhsmLgmIW3 X-Developer-Key: i=broonie@kernel.org; a=openpgp; fpr=3F2568AAC26998F9E813A1C5C3F436CA30F5D8EB When discovering the vector lengths for SVE and SME we do not currently record the maximum VL supported on any individual CPU. This is expected to be the same for all CPUs but the architecture allows asymmetry, if we do encounter an asymmetric system then some CPUs may support VLs higher than the maximum Linux will use. Since the pKVM hypervisor needs to support saving and restoring anything the host can physically set it needs to know the maximum value any CPU could have, add support for enumerating it and validation for late CPUs. Acked-by: Catalin Marinas Signed-off-by: Mark Brown --- arch/arm64/include/asm/fpsimd.h | 13 +++++++++++++ arch/arm64/kernel/fpsimd.c | 26 +++++++++++++++++++++++++- 2 files changed, 38 insertions(+), 1 deletion(-) diff --git a/arch/arm64/include/asm/fpsimd.h b/arch/arm64/include/asm/fpsim= d.h index 51c21265b4fa..cd19713c9deb 100644 --- a/arch/arm64/include/asm/fpsimd.h +++ b/arch/arm64/include/asm/fpsimd.h @@ -188,6 +188,9 @@ struct vl_info { int max_vl; int max_virtualisable_vl; =20 + /* Maximum vector length observed on any CPU */ + int max_cpu_vl; + /* * Set of available vector lengths, * where length vq encoded as bit __vq_to_bit(vq): @@ -278,6 +281,11 @@ static inline int vec_max_virtualisable_vl(enum vec_ty= pe type) return vl_info[type].max_virtualisable_vl; } =20 +static inline int vec_max_cpu_vl(enum vec_type type) +{ + return vl_info[type].max_cpu_vl; +} + static inline int sve_max_vl(void) { return vec_max_vl(ARM64_VEC_SVE); @@ -288,6 +296,11 @@ static inline int sve_max_virtualisable_vl(void) return vec_max_virtualisable_vl(ARM64_VEC_SVE); } =20 +static inline int sve_max_cpu_vl(void) +{ + return vec_max_cpu_vl(ARM64_VEC_SVE); +} + /* Ensure vq >=3D SVE_VQ_MIN && vq <=3D SVE_VQ_MAX before calling this fun= ction */ static inline bool vq_available(enum vec_type type, unsigned int vq) { diff --git a/arch/arm64/kernel/fpsimd.c b/arch/arm64/kernel/fpsimd.c index 22542fb81812..83984cb3f21a 100644 --- a/arch/arm64/kernel/fpsimd.c +++ b/arch/arm64/kernel/fpsimd.c @@ -129,6 +129,7 @@ __ro_after_init struct vl_info vl_info[ARM64_VEC_MAX] = =3D { .min_vl =3D SVE_VL_MIN, .max_vl =3D SVE_VL_MIN, .max_virtualisable_vl =3D SVE_VL_MIN, + .max_cpu_vl =3D SVE_VL_MIN, }, #endif #ifdef CONFIG_ARM64_SME @@ -1041,8 +1042,13 @@ static void vec_probe_vqs(struct vl_info *info, void __init vec_init_vq_map(enum vec_type type) { struct vl_info *info =3D &vl_info[type]; + unsigned long b; + vec_probe_vqs(info, info->vq_map); bitmap_copy(info->vq_partial_map, info->vq_map, SVE_VQ_MAX); + + b =3D find_first_bit(info->vq_map, SVE_VQ_MAX); + info->max_cpu_vl =3D __bit_to_vl(b); } =20 /* @@ -1054,11 +1060,16 @@ void vec_update_vq_map(enum vec_type type) { struct vl_info *info =3D &vl_info[type]; DECLARE_BITMAP(tmp_map, SVE_VQ_MAX); + unsigned long b; =20 vec_probe_vqs(info, tmp_map); bitmap_and(info->vq_map, info->vq_map, tmp_map, SVE_VQ_MAX); bitmap_or(info->vq_partial_map, info->vq_partial_map, tmp_map, SVE_VQ_MAX); + + b =3D find_first_bit(tmp_map, SVE_VQ_MAX); + if (__bit_to_vl(b) > info->max_cpu_vl) + info->max_cpu_vl =3D __bit_to_vl(b); } =20 /* @@ -1069,10 +1080,23 @@ int vec_verify_vq_map(enum vec_type type) { struct vl_info *info =3D &vl_info[type]; DECLARE_BITMAP(tmp_map, SVE_VQ_MAX); - unsigned long b; + unsigned long b, max_vl; =20 vec_probe_vqs(info, tmp_map); =20 + /* + * Currently the maximum VL is only used for pKVM which + * doesn't allow late CPUs but we don't expect asymmetry and + * if we encounter any then future users will need handling so + * warn if we see anything. + */ + max_vl =3D __bit_to_vl(find_first_bit(tmp_map, SVE_VQ_MAX)); + if (max_vl > info->max_cpu_vl) { + pr_warn("%s: cpu%d: increases maximum VL to %lu\n", + info->name, smp_processor_id(), max_vl); + info->max_cpu_vl =3D max_vl; + } + bitmap_complement(tmp_map, tmp_map, SVE_VQ_MAX); if (bitmap_intersects(tmp_map, info->vq_map, SVE_VQ_MAX)) { pr_warn("%s: cpu%d: Required vector length(s) missing\n", --=20 2.39.2