From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from foss.arm.com (foss.arm.com [217.140.110.172]) by smtp.subspace.kernel.org (Postfix) with ESMTP id 748D81C6FF0 for ; Thu, 6 Feb 2025 14:11:27 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=217.140.110.172 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1738851089; cv=none; b=SfHrmSwONyIpL1BLvisi6YZy3t5ii76wgMfjkyg5dHvmqRjCUhBAHOoQKaLGwwLwawyWl1TPWVLIRles+b4/j8MWa5fm0T8jr9+MNBzKFlNYE6uCL1S2tNZSpa88LMCFjXP2NrmaSOAS07N/BgfqSiKj52CHMiM0hD/Ycr+b1FA= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1738851089; c=relaxed/simple; bh=QMVwyTGx+SXosLQgO4jSZEl34uQEE/E7O7A0gqeo5ns=; h=From:To:Cc:Subject:Date:Message-Id:In-Reply-To:References: MIME-Version; b=SSy5gUibW0lwbPE+oru7cAC7qu2mAtCRRSwj144dfDcwUeDFNLeC0McdxXd/WBUHu9Immi7iUO/IA1P3rr+qxrlkevIuw5TKKHigcqXeqp3im7a0Y4k/WuI4l9mAVgqEydipAJKUjakvBocDP9TaMu7zgoPBUKwVslbyKO93bQU= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=arm.com; spf=pass smtp.mailfrom=arm.com; arc=none smtp.client-ip=217.140.110.172 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=arm.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=arm.com Received: from usa-sjc-imap-foss1.foss.arm.com (unknown [10.121.207.14]) by usa-sjc-mx-foss1.foss.arm.com (Postfix) with ESMTP id 0B9F01CE0; Thu, 6 Feb 2025 06:11:50 -0800 (PST) Received: from lakrids.cambridge.arm.com (usa-sjc-imap-foss1.foss.arm.com [10.121.207.14]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPA id 502FA3F63F; Thu, 6 Feb 2025 06:11:24 -0800 (PST) From: Mark Rutland To: linux-arm-kernel@lists.infradead.org Cc: broonie@kernel.org, catalin.marinas@arm.com, eauger@redhat.com, eric.auger@redhat.com, fweimer@redhat.com, jeremy.linton@arm.com, mark.rutland@arm.com, maz@kernel.org, oliver.upton@linux.dev, pbonzini@redhat.com, stable@vger.kernel.org, tabba@google.com, wilco.dijkstra@arm.com, will@kernel.org Subject: [PATCH v2 3/8] KVM: arm64: Remove VHE host restore of CPACR_EL1.ZEN Date: Thu, 6 Feb 2025 14:10:57 +0000 Message-Id: <20250206141102.954688-4-mark.rutland@arm.com> X-Mailer: git-send-email 2.30.2 In-Reply-To: <20250206141102.954688-1-mark.rutland@arm.com> References: <20250206141102.954688-1-mark.rutland@arm.com> Precedence: bulk X-Mailing-List: stable@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit 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 Cc: Catalin Marinas Cc: Fuad Tabba Cc: Marc Zyngier Cc: Mark Brown Cc: Oliver Upton Cc: Will Deacon --- arch/arm64/include/asm/kvm_host.h | 1 - arch/arm64/kvm/fpsimd.c | 16 ---------------- 2 files changed, 17 deletions(-) diff --git a/arch/arm64/include/asm/kvm_host.h b/arch/arm64/include/asm/kvm_host.h index f56c07568591f..ed6841bf21b22 100644 --- a/arch/arm64/include/asm/kvm_host.h +++ b/arch/arm64/include/asm/kvm_host.h @@ -615,7 +615,6 @@ struct cpu_sve_state { struct kvm_host_data { #define KVM_HOST_DATA_FLAG_HAS_SPE 0 #define KVM_HOST_DATA_FLAG_HAS_TRBE 1 -#define KVM_HOST_DATA_FLAG_HOST_SVE_ENABLED 2 #define KVM_HOST_DATA_FLAG_HOST_SME_ENABLED 3 #define KVM_HOST_DATA_FLAG_TRBE_ENABLED 4 #define KVM_HOST_DATA_FLAG_EL1_TRACING_CONFIGURED 5 diff --git a/arch/arm64/kvm/fpsimd.c b/arch/arm64/kvm/fpsimd.c index 332cb3904e68b..4ff0dee1a403f 100644 --- a/arch/arm64/kvm/fpsimd.c +++ b/arch/arm64/kvm/fpsimd.c @@ -65,10 +65,6 @@ void kvm_arch_vcpu_load_fp(struct kvm_vcpu *vcpu) fpsimd_save_and_flush_cpu_state(); *host_data_ptr(fp_owner) = FP_STATE_FREE; - host_data_clear_flag(HOST_SVE_ENABLED); - if (read_sysreg(cpacr_el1) & CPACR_EL1_ZEN_EL0EN) - host_data_set_flag(HOST_SVE_ENABLED); - if (system_supports_sme()) { host_data_clear_flag(HOST_SME_ENABLED); if (read_sysreg(cpacr_el1) & CPACR_EL1_SMEN_EL0EN) @@ -202,18 +198,6 @@ void kvm_arch_vcpu_put_fp(struct kvm_vcpu *vcpu) * when needed. */ 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 by kvm_reset_cptr_el2() in the Hyp code, disabling SVE - * for EL0. To avoid spurious traps, restore the trap state - * seen by kvm_arch_vcpu_load_fp(): - */ - if (host_data_test_flag(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); -- 2.30.2