From nobody Fri Dec 19 00:36:18 2025 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 49148245016; Tue, 8 Apr 2025 18:22:26 +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=1744136546; cv=none; b=J9d28TxKxP+WCvv58u6SNQiAbNLAKcKXWtPa6bd6GaitW9fywKgKZNe3Cnb9+cIneKBFxcr0TB4a8706yER/hmLkCPmXD/14d+EhneqYXr6UvQQPRF9wK5VuV/4khySoX6aLGHCrwku8wEEY1RFAjgMjmwtlO/hHiWW1VqrBEn8= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1744136546; c=relaxed/simple; bh=ROS5jr/XnGZ06dtqqkVH5FTegaK3TD2euUktm9dfK+A=; h=From:Date:Subject:MIME-Version:Content-Type:Message-Id:References: In-Reply-To:To:Cc; b=gJ2KJlZYqtn+i3Tna5CYwxY1Yau7mVh7kNTg4csKaG3VJib1tqLLFMC+pqD+3NrJMeHKuBn45KU5SdR8j6ww4mP1oMOG5htGEFNsxeNToPIZQOvXJCzTlj+ShBgaK+zz6n6Ul5jG2A5IEZ5bDjNOukC9LRlIJcnbQKCZTklbk8s= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=u4vKl6rv; 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="u4vKl6rv" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 88A7CC4CEE8; Tue, 8 Apr 2025 18:22:23 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1744136546; bh=ROS5jr/XnGZ06dtqqkVH5FTegaK3TD2euUktm9dfK+A=; h=From:Date:Subject:References:In-Reply-To:To:Cc:From; b=u4vKl6rvmfLdqWK4Kul+5+fDibO2yJ5yWaJFerR5uj8Kwks3J+wPO2DeDJgasR4cs ls8MaNp8Ezu/I27KvuyKHIDmv9ucOgh0tYWU6FroXMZY8VJneGO6tvMXElp4X9cHPL UyJ7sqxzMC2IPlEfnmbZD/KsEwNgve1ICU9l+AUg3iH6PqYUaj+r5fKov7uPb22Fgj j30dXXdkGUnBEsXBqQpgp9mgEOJfDpqfCqensolvXKIFXZtOJto16LITogSgwqmbFU oOaDomzF+9fw5c4ik5e14pmgZfq3CCsgrTrIss4+vQ7k4++Qdt7t6aSMrCO43QU7Wm HJ29r5B5BebpA== From: Mark Brown Date: Tue, 08 Apr 2025 19:09:58 +0100 Subject: [PATCH 5.15 v3 03/11] KVM: arm64: Discard any SVE state when entering KVM guests 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: <20250408-stable-sve-5-15-v3-3-ca9a6b850f55@kernel.org> References: <20250408-stable-sve-5-15-v3-0-ca9a6b850f55@kernel.org> In-Reply-To: <20250408-stable-sve-5-15-v3-0-ca9a6b850f55@kernel.org> To: Greg Kroah-Hartman , Marc Zyngier , James Morse , Suzuki K Poulose , Catalin Marinas , Will Deacon , Oleg Nesterov , Oliver Upton Cc: linux-arm-kernel@lists.infradead.org, kvmarm@lists.cs.columbia.edu, linux-kernel@vger.kernel.org, stable@vger.kernel.org, Mark Brown , Mark Rutland X-Mailer: b4 0.15-dev-c25d1 X-Developer-Signature: v=1; a=openpgp-sha256; l=3562; i=broonie@kernel.org; h=from:subject:message-id; bh=ROS5jr/XnGZ06dtqqkVH5FTegaK3TD2euUktm9dfK+A=; b=owEBbQGS/pANAwAKASTWi3JdVIfQAcsmYgBn9WlN98cQ/PSAdnjHKGF2x/DeH/D/JoC7PCjo5IQz vy8RWU+JATMEAAEKAB0WIQSt5miqZ1cYtZ/in+ok1otyXVSH0AUCZ/VpTQAKCRAk1otyXVSH0DySB/ 9phxVh+yQ1r2/VJPq78DO5XvJd9IID/lMbU4lEYeOwXylwsQWtN43or0QjkjMPjnX2pyBGCaE1T+AD Neht04TMqS+Fdrg8Y8jvuEtFY0KBT2S9a4ioZdpnaVeCXhvtPGXsCajBGJtwiLvJt8oSbrvt0gAVyk MG4krlmzmmn7+GffR1EAg+OTuoy/6w1atZldRfrh/mkWDIAHLLiu6tz4nrTD47CKo6s4IJrJCkrLmY I7X8/7muNEluxJXGX/X7CWtUEYbZ1c5TrpFc8J1tVVKSqZilOVWguyQ1a5zmLP3BMOFipST4qrd54f PKIGN/lgN76BgMMPzN5B6tnZcR3Ys8 X-Developer-Key: i=broonie@kernel.org; a=openpgp; fpr=3F2568AAC26998F9E813A1C5C3F436CA30F5D8EB [ Upstream commit 93ae6b01bafee8fa385aa25ee7ebdb40057f6abe ] Since 8383741ab2e773a99 (KVM: arm64: Get rid of host SVE tracking/saving) KVM has not tracked the host SVE state, relying on the fact that we currently disable SVE whenever we perform a syscall. This may not be true in future since performance optimisation may result in us keeping SVE enabled in order to avoid needing to take access traps to reenable it. Handle this by clearing TIF_SVE and converting the stored task state to FPSIMD format when preparing to run the guest. This is done with a new call fpsimd_kvm_prepare() to keep the direct state manipulation functions internal to fpsimd.c. Signed-off-by: Mark Brown Reviewed-by: Catalin Marinas Reviewed-by: Marc Zyngier Link: https://lore.kernel.org/r/20221115094640.112848-2-broonie@kernel.org Signed-off-by: Will Deacon [ Mark: trivial backport to v6.1 ] Signed-off-by: Mark Rutland Signed-off-by: Mark Brown --- arch/arm64/include/asm/fpsimd.h | 1 + arch/arm64/kernel/fpsimd.c | 23 +++++++++++++++++++++++ arch/arm64/kvm/fpsimd.c | 4 +++- 3 files changed, 27 insertions(+), 1 deletion(-) diff --git a/arch/arm64/include/asm/fpsimd.h b/arch/arm64/include/asm/fpsim= d.h index 9a62884183e5..f7faf0f4507c 100644 --- a/arch/arm64/include/asm/fpsimd.h +++ b/arch/arm64/include/asm/fpsimd.h @@ -44,6 +44,7 @@ extern void fpsimd_signal_preserve_current_state(void); extern void fpsimd_preserve_current_state(void); extern void fpsimd_restore_current_state(void); extern void fpsimd_update_current_state(struct user_fpsimd_state const *st= ate); +extern void fpsimd_kvm_prepare(void); =20 extern void fpsimd_bind_state_to_cpu(struct user_fpsimd_state *state, void *sve_state, unsigned int sve_vl); diff --git a/arch/arm64/kernel/fpsimd.c b/arch/arm64/kernel/fpsimd.c index e22571e57ae1..57e89361edcb 100644 --- a/arch/arm64/kernel/fpsimd.c +++ b/arch/arm64/kernel/fpsimd.c @@ -1108,6 +1108,29 @@ void fpsimd_signal_preserve_current_state(void) sve_to_fpsimd(current); } =20 +/* + * Called by KVM when entering the guest. + */ +void fpsimd_kvm_prepare(void) +{ + if (!system_supports_sve()) + return; + + /* + * KVM does not save host SVE state since we can only enter + * the guest from a syscall so the ABI means that only the + * non-saved SVE state needs to be saved. If we have left + * SVE enabled for performance reasons then update the task + * state to be FPSIMD only. + */ + get_cpu_fpsimd_context(); + + if (test_and_clear_thread_flag(TIF_SVE)) + sve_to_fpsimd(current); + + put_cpu_fpsimd_context(); +} + /* * Associate current's FPSIMD context with this cpu * The caller must have ownership of the cpu FPSIMD context before calling diff --git a/arch/arm64/kvm/fpsimd.c b/arch/arm64/kvm/fpsimd.c index 24734bfcfaa0..16e29f03dcbf 100644 --- a/arch/arm64/kvm/fpsimd.c +++ b/arch/arm64/kvm/fpsimd.c @@ -70,12 +70,14 @@ int kvm_arch_vcpu_run_map_fp(struct kvm_vcpu *vcpu) void kvm_arch_vcpu_load_fp(struct kvm_vcpu *vcpu) { BUG_ON(!current->mm); - BUG_ON(test_thread_flag(TIF_SVE)); =20 vcpu->arch.flags &=3D ~KVM_ARM64_FP_ENABLED; vcpu->arch.flags |=3D KVM_ARM64_FP_HOST; =20 + fpsimd_kvm_prepare(); + vcpu->arch.flags &=3D ~KVM_ARM64_HOST_SVE_ENABLED; + if (read_sysreg(cpacr_el1) & CPACR_EL1_ZEN_EL0EN) vcpu->arch.flags |=3D KVM_ARM64_HOST_SVE_ENABLED; } --=20 2.39.5