From patchwork Thu Oct 12 20:54:22 2023 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Oliver Upton X-Patchwork-Id: 13419815 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 vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 29B77CDB47E for ; Thu, 12 Oct 2023 20:54:45 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1442858AbjJLUyo (ORCPT ); Thu, 12 Oct 2023 16:54:44 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:44980 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1442850AbjJLUyo (ORCPT ); Thu, 12 Oct 2023 16:54:44 -0400 Received: from out-209.mta1.migadu.com (out-209.mta1.migadu.com [95.215.58.209]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 1B6BECC for ; Thu, 12 Oct 2023 13:54:42 -0700 (PDT) X-Report-Abuse: Please report any abuse attempt to abuse@migadu.com and include these headers. DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linux.dev; s=key1; t=1697144080; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=gvdyn9/HRYxuf5tqreNHPv4BH2I6iacI5CzV+SKoaOs=; b=TnlFHtGvUlX7QD7ZisA03W6mwEwiwySJJh0O+dJFdWwtH3pAUR6U3L8xrnyQbu1fSwb7Yr jcyZiFFmJBqspsoOroTqnXlYvdUyr1/+apYiuZuM2fVmT1q6wwD5HxHp0wDWw30PGEPHV3 L0jz29fBIUbmf8B8A6QDgH2xo0pMWTU= From: Oliver Upton To: kvmarm@lists.linux.dev Cc: kvm@vger.kernel.org, Marc Zyngier , James Morse , Suzuki K Poulose , Zenghui Yu , Oliver Upton Subject: [PATCH v2 5/5] KVM: arm64: Load the stage-2 MMU context in kvm_vcpu_load_vhe() Date: Thu, 12 Oct 2023 20:54:22 +0000 Message-ID: <20231012205422.3924618-6-oliver.upton@linux.dev> In-Reply-To: <20231012205422.3924618-1-oliver.upton@linux.dev> References: <20231012205422.3924618-1-oliver.upton@linux.dev> MIME-Version: 1.0 X-Migadu-Flow: FLOW_OUT Precedence: bulk List-ID: X-Mailing-List: kvm@vger.kernel.org To date the VHE code has aggressively reloaded the stage-2 MMU context on every guest entry, despite the fact that this isn't necessary. This was probably done for consistency with the nVHE code, which needs to switch in/out the stage-2 MMU context as both the host and guest run at EL1. Hoist __stage2_load() into kvm_vcpu_load_vhe(), thus avoiding a reload on every guest entry/exit. This is likely to be beneficial to systems with one of the speculative AT errata, as there is now one fewer context synchronization event on the guest entry path. Additionally, it is possible that implementations have hitched correctness mitigations on writes to VTTBR_EL2, which are now elided on guest re-entry. Note that __tlb_switch_to_guest() is deliberately left untouched as it can be called outside the context of a running vCPU, or possibly be called in a MMU notifier that needs to switch to a different stage-2 context. Signed-off-by: Oliver Upton --- arch/arm64/kvm/hyp/vhe/switch.c | 15 +++++---------- 1 file changed, 5 insertions(+), 10 deletions(-) diff --git a/arch/arm64/kvm/hyp/vhe/switch.c b/arch/arm64/kvm/hyp/vhe/switch.c index d05b6a08dcde..b0cafd7c5f8f 100644 --- a/arch/arm64/kvm/hyp/vhe/switch.c +++ b/arch/arm64/kvm/hyp/vhe/switch.c @@ -120,6 +120,7 @@ void kvm_vcpu_load_vhe(struct kvm_vcpu *vcpu) { __vcpu_load_switch_sysregs(vcpu); __vcpu_load_activate_traps(vcpu); + __load_stage2(vcpu->arch.hw_mmu, vcpu->arch.hw_mmu->arch); } void kvm_vcpu_put_vhe(struct kvm_vcpu *vcpu) @@ -182,17 +183,11 @@ static int __kvm_vcpu_run_vhe(struct kvm_vcpu *vcpu) sysreg_save_host_state_vhe(host_ctxt); /* - * ARM erratum 1165522 requires us to configure both stage 1 and - * stage 2 translation for the guest context before we clear - * HCR_EL2.TGE. - * - * We have already configured the guest's stage 1 translation in - * kvm_vcpu_load_sysregs_vhe above. We must now call - * __load_stage2 before __activate_traps, because - * __load_stage2 configures stage 2 translation, and - * __activate_traps clear HCR_EL2.TGE (among other things). + * Note that ARM erratum 1165522 requires us to configure both stage 1 + * and stage 2 translation for the guest context before we clear + * HCR_EL2.TGE. The stage 1 and stage 2 guest context has already been + * loaded on the CPU in kvm_vcpu_load_vhe(). */ - __load_stage2(vcpu->arch.hw_mmu, vcpu->arch.hw_mmu->arch); __activate_traps(vcpu); __kvm_adjust_pc(vcpu);