From patchwork Tue Apr 8 18:10:04 2025 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Mark Brown X-Patchwork-Id: 14043557 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from bombadil.infradead.org (bombadil.infradead.org [198.137.202.133]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id E5DA0C36010 for ; Tue, 8 Apr 2025 18:40:32 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=bombadil.20210309; h=Sender:List-Subscribe:List-Help :List-Post:List-Archive:List-Unsubscribe:List-Id:Cc:To:In-Reply-To:References :Message-Id:Content-Transfer-Encoding:Content-Type:MIME-Version:Subject:Date: From:Reply-To:Content-ID:Content-Description:Resent-Date:Resent-From: Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID:List-Owner; bh=mC0NXmwp3hUFyxgYzqhl2oziOdKHiyicw+7VAZXZeac=; b=PsAxBjPt7M4PZZoBOAWjgGGqC9 zQhJIcA7poBIdTn4QLZnmO+s8cDFwWRSMP2ox49FQ+qz7Sf+XltQcRp9T5ndHa0uCxE0+jWao7hGE pVZUj4f0fUpaOUzVvAVlufxipoyNVWT0WBiILvSagVlNG0XJH4VWLoZmJeJhzMsFSAbXYdx4qQCPq STKLM9UpMbaTbbwsKjHc25QFAuEKSoSnoPgvm9Eeyfr1wIK3kZRzHOOEpDr1E8B7pfefwSHhpl8Fb 4BerwlYFuig2OfQ1Wy1FLespqRTO/bcjWDJNkYSsf9evr93ljMJCET2Bq2h31OClnVyaLK4knHrhh hnTaKgvw==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.98.2 #2 (Red Hat Linux)) id 1u2Drw-000000058X5-0WUi; Tue, 08 Apr 2025 18:40:20 +0000 Received: from nyc.source.kernel.org ([147.75.193.91]) by bombadil.infradead.org with esmtps (Exim 4.98.2 #2 (Red Hat Linux)) id 1u2Dax-000000055xB-0GBT for linux-arm-kernel@lists.infradead.org; Tue, 08 Apr 2025 18:22:48 +0000 Received: from smtp.kernel.org (transwarp.subspace.kernel.org [100.75.92.58]) by nyc.source.kernel.org (Postfix) with ESMTP id B7D71A48FE6; Tue, 8 Apr 2025 18:17:17 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 447B5C4CEE9; Tue, 8 Apr 2025 18:22:43 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1744136566; bh=94B73exkvxZIp7PjZglkCZBY40cUsa7OpOScJsLUoog=; h=From:Date:Subject:References:In-Reply-To:To:Cc:From; b=PqvFcV7MB/OV15mYLd+gHbJSSGEFznA0DxuB2PBVbE7W4085ugfWvdYgDdqylxt0D 5Qf8xVh99HLh+fKnd2NjKZhzt+EWmXLHwyigsSDpr15dXYkK61Z1L0wpkS+63S3UIX VDmmarfGl2Rew/V8277bDGLIJhb8WcQTFMbR+lKVFoJt6GJyUgSPufX2MdteB94LdM k8/Xr+4PPugCU8ewDKtPgqt4dfjQXSu+ahYrKUlAz5YxyztryMEG92aO2m+3jBS/0p VJOjQSlPKG/bRt/8FgZkC/Ecp1b5NjOKiVIhaVKd8jIPWIY2F2jf/Q4A3RXFhGe/91 sDMg42jnTHkDg== From: Mark Brown Date: Tue, 08 Apr 2025 19:10:04 +0100 Subject: [PATCH 5.15 v3 09/11] KVM: arm64: Remove VHE host restore of CPACR_EL1.ZEN MIME-Version: 1.0 Message-Id: <20250408-stable-sve-5-15-v3-9-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 , Fuad Tabba X-Mailer: b4 0.15-dev-c25d1 X-Developer-Signature: v=1; a=openpgp-sha256; l=3514; i=broonie@kernel.org; h=from:subject:message-id; bh=z0T8Mw2Gv92zuKeVWJq8mDeqr184OynN7N95pkdbt3E=; b=owEBbQGS/pANAwAKASTWi3JdVIfQAcsmYgBn9WlSA5GbnGtX3RsCslIUJ3vjbvkc54JHy7pM4Ogz TkYpdP2JATMEAAEKAB0WIQSt5miqZ1cYtZ/in+ok1otyXVSH0AUCZ/VpUgAKCRAk1otyXVSH0IPdB/ 9qgLuVL0XNOu2uxbW9SdLR/JkjAJ1tmBtaOhOGfqkAa2zW4epsXR3iVIJeSj2NMMTJJ4mC5NMC4zk4 HBymsKA7vqRIQQ/RCtlTpNj2B6hpg+ZvYPgZr//O0LXVN1G7iI7KtBRocC3zDiYwLPe+qrsosUbTjD LcfEnXdqe/J6yRBkmo1GdiC1K1OEG8YNK6CmQmLTG7PKwv/3tf8VqL97zm+qKb5FGxXwD5qsoow7WU qXzvZOdEnMYa7hJF2oUd6ZWsJoQvzrZYHQ7nm7XoOzfDAx7oO5QQcw3/4kxOvHwNzK3Ypzw3liOMYQ 5qZaSqkTIyH7q5lHnF3Q1Jh5h/8J2o X-Developer-Key: i=broonie@kernel.org; a=openpgp; fpr=3F2568AAC26998F9E813A1C5C3F436CA30F5D8EB X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20250408_112247_240977_6943A7E5 X-CRM114-Status: GOOD ( 16.13 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org From: Mark Rutland [ Upstream commit 459f059be702056d91537b99a129994aa6ccdd35 ] When KVM is in VHE mode, the host kernel tries to save and restore the configuration of CPACR_EL1.ZEN (i.e. CPTR_EL2.ZEN when HCR_EL2.E2H=1) across kvm_arch_vcpu_load_fp() and kvm_arch_vcpu_put_fp(), since the configuration may be clobbered by hyp when running a vCPU. This logic is currently redundant. The VHE hyp code unconditionally configures CPTR_EL2.ZEN to 0b01 when returning to the host, permitting host kernel usage of SVE. Now that the host eagerly saves and unbinds its own FPSIMD/SVE/SME state, there's no need to save/restore the state of the EL0 SVE trap. The kernel can safely save/restore state without trapping, as described above, and will restore userspace state (including trap controls) before returning to userspace. Remove the redundant logic. Signed-off-by: Mark Rutland Reviewed-by: Mark Brown Tested-by: Mark Brown Acked-by: Will Deacon Cc: Catalin Marinas Cc: Fuad Tabba Cc: Marc Zyngier Cc: Oliver Upton Reviewed-by: Oliver Upton Link: https://lore.kernel.org/r/20250210195226.1215254-4-mark.rutland@arm.com Signed-off-by: Marc Zyngier [Rework for refactoring of where the flags are stored -- broonie] Signed-off-by: Mark Brown --- arch/arm64/include/asm/kvm_host.h | 1 - arch/arm64/kvm/fpsimd.c | 15 --------------- 2 files changed, 16 deletions(-) diff --git a/arch/arm64/include/asm/kvm_host.h b/arch/arm64/include/asm/kvm_host.h index 06e8d4645ecd..3d4e2396a2d7 100644 --- a/arch/arm64/include/asm/kvm_host.h +++ b/arch/arm64/include/asm/kvm_host.h @@ -421,7 +421,6 @@ struct kvm_vcpu_arch { #define KVM_ARM64_DEBUG_DIRTY (1 << 0) #define KVM_ARM64_FP_ENABLED (1 << 1) /* guest FP regs loaded */ #define KVM_ARM64_FP_HOST (1 << 2) /* host FP regs loaded */ -#define KVM_ARM64_HOST_SVE_ENABLED (1 << 4) /* SVE enabled for EL0 */ #define KVM_ARM64_GUEST_HAS_SVE (1 << 5) /* SVE exposed to guest */ #define KVM_ARM64_VCPU_SVE_FINALIZED (1 << 6) /* SVE config completed */ #define KVM_ARM64_GUEST_HAS_PTRAUTH (1 << 7) /* PTRAUTH exposed to guest */ diff --git a/arch/arm64/kvm/fpsimd.c b/arch/arm64/kvm/fpsimd.c index 1ef9d6cb91ee..1360ddd4137b 100644 --- a/arch/arm64/kvm/fpsimd.c +++ b/arch/arm64/kvm/fpsimd.c @@ -83,9 +83,6 @@ void kvm_arch_vcpu_load_fp(struct kvm_vcpu *vcpu) */ fpsimd_save_and_flush_cpu_state(); vcpu->arch.flags &= ~KVM_ARM64_FP_HOST; - - if (read_sysreg(cpacr_el1) & CPACR_EL1_ZEN_EL0EN) - vcpu->arch.flags |= KVM_ARM64_HOST_SVE_ENABLED; } /* @@ -142,18 +139,6 @@ void kvm_arch_vcpu_put_fp(struct kvm_vcpu *vcpu) } fpsimd_save_and_flush_cpu_state(); - } else if (has_vhe() && system_supports_sve()) { - /* - * The FPSIMD/SVE state in the CPU has not been touched, and we - * have SVE (and VHE): CPACR_EL1 (alias CPTR_EL2) has been - * reset to CPACR_EL1_DEFAULT by the Hyp code, disabling SVE - * for EL0. To avoid spurious traps, restore the trap state - * seen by kvm_arch_vcpu_load_fp(): - */ - if (vcpu->arch.flags & KVM_ARM64_HOST_SVE_ENABLED) - sysreg_clear_set(CPACR_EL1, 0, CPACR_EL1_ZEN_EL0EN); - else - sysreg_clear_set(CPACR_EL1, CPACR_EL1_ZEN_EL0EN, 0); } local_irq_restore(flags);