From patchwork Mon Feb 10 19:52:21 2025 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Mark Rutland X-Patchwork-Id: 13969078 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 D268CC0219E for ; Mon, 10 Feb 2025 19:58:34 +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:Content-Transfer-Encoding: MIME-Version:References:In-Reply-To:Message-Id:Date:Subject:Cc:To:From: Reply-To:Content-Type:Content-ID:Content-Description:Resent-Date:Resent-From: Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID:List-Owner; bh=Hzp555q3uN9xMyPMM4TJiYxzGE1jyH4/0JVr6ONzpGQ=; b=ziMGcSJ8MJA0WSkyxtQQU6mt0v Um/9g+cP+lz+r2ZWBAQZfPXg0mGZmE8RArO6WgtSvfgN295aijz8dPDHHsYKjaEj+N1CeJcG2Jx1W yr3NHcMz13s9oOBgkoFDAzBOZu+syj2J4HXmB3L0MvnWpGBREeXd+YxGTnTr9Ru0FfxnO6q+zb2zO y8/eloOyIi+jjmf+L0yLC/8IFz/U1vlx9XgLahNWZgVtjS6dnwsS8ms9SWgxBTxpsbaS11p7zECbu SSSCzoCMspJeOWvklCvlNmKm7FqIFfDMkvtQOUFBLYnMmiGqAB6uoXSy/r06BtAIPkjdL+HYaLPED 5fajZoYg==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.98 #2 (Red Hat Linux)) id 1thZvG-00000001FcX-10Ga; Mon, 10 Feb 2025 19:58:26 +0000 Received: from foss.arm.com ([217.140.110.172]) by bombadil.infradead.org with esmtp (Exim 4.98 #2 (Red Hat Linux)) id 1thZq8-00000001Efv-05hW for linux-arm-kernel@lists.infradead.org; Mon, 10 Feb 2025 19:53:09 +0000 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 547241477; Mon, 10 Feb 2025 11:53:29 -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 D76DC3F58B; Mon, 10 Feb 2025 11:53:04 -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 v3 3/8] KVM: arm64: Remove VHE host restore of CPACR_EL1.ZEN Date: Mon, 10 Feb 2025 19:52:21 +0000 Message-Id: <20250210195226.1215254-4-mark.rutland@arm.com> X-Mailer: git-send-email 2.30.2 In-Reply-To: <20250210195226.1215254-1-mark.rutland@arm.com> References: <20250210195226.1215254-1-mark.rutland@arm.com> MIME-Version: 1.0 X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20250210_115308_193374_DE88867A X-CRM114-Status: GOOD ( 14.84 ) 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 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 --- 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);