From mboxrd@z Thu Jan 1 00:00:00 1970 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 34EF0C25B08 for ; Wed, 17 Aug 2022 21:49:34 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S242431AbiHQVtd (ORCPT ); Wed, 17 Aug 2022 17:49:33 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:52782 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S238964AbiHQVtS (ORCPT ); Wed, 17 Aug 2022 17:49:18 -0400 Received: from out2.migadu.com (out2.migadu.com [188.165.223.204]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id B4177ADCDF for ; Wed, 17 Aug 2022 14:48:39 -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=1660772917; 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; bh=cDVlBOelWFV15LvLWa+pCIh5Az2QchuTMm2O7H0MfZk=; b=puD8I3PkQRNayksEy0wOfU5b0YzxoKZaMjrXlFl+3KOT9ZugR1UJ41zWBQ4rIUp7WgJmYP zer8g0/Qivf8EkqpyOrgj/kSI9u4kcW+RqBS5h0Sw26FxOJKXuml5SvL9BIxtorjjBp7Ck 3/FsLgpUpC7mZFkmblRFxfhBznj563c= From: Oliver Upton To: kvmarm@lists.cs.columbia.edu Cc: kvm@vger.kernel.org, linux-arm-kernel@lists.infradead.org, maz@kernel.org, james.morse@arm.com, alexandru.elisei@arm.com, suzuki.poulose@arm.com, will@kernel.org, Oliver Upton Subject: [PATCH 0/6] KVM: arm64: Treat 32bit ID registers as RAZ/WI on 64bit-only system Date: Wed, 17 Aug 2022 21:48:12 +0000 Message-Id: <20220817214818.3243383-1-oliver.upton@linux.dev> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Migadu-Flow: FLOW_OUT X-Migadu-Auth-User: linux.dev Precedence: bulk List-ID: X-Mailing-List: kvm@vger.kernel.org For reasons unknown, the Arm architecture defines the 64-bit views of the 32-bit ID registers as UNKNOWN [1]. This combines poorly with the fact that KVM unconditionally exposes these registers to userspace, which could throw a wrench in migration between 64-bit only systems. This series reworks KVM's definition of these registers to RAZ/WI with the goal of providing consistent register values across 64-bit machines. Patches 1-2 clean up some of the ID register accessors, taking advantage of the fact that the generic ones already know how to handle RAZ registers. Patches 3-4 wire in a new visibility bit to indicate a register ignores writes from userspace. Patch 5 moves all exposed 32-bit ID registers to have RAZ/WI behavior on 64-bit only systems. Note that hidden 32-bit registers continue to have RAZ behavior and carry the additional requirement of invariance. Lastly, patch 6 tests that userspace and guest indeed see the registers as RAZ/WI. Applies to 6.0-rc1 + the mismatched system fixes [2] picked up earlier today. Tested on the fast model, both with mismatched AArch32 support and no AArch32 support whatoever. [1]: DDI0487H.a Table D12-2 'Instruction encodings for non-Debug System Register accesses' [2]: https://lore.kernel.org/kvmarm/20220816192554.1455559-1-oliver.upton@linux.dev/ Oliver Upton (6): KVM: arm64: Use visibility hook to treat ID regs as RAZ KVM: arm64: Remove internal accessor helpers for id regs KVM: arm64: Spin off helper for calling visibility hook KVM: arm64: Add a visibility bit to ignore user writes KVM: arm64: Treat 32bit ID registers as RAZ/WI on 64bit-only system KVM: selftests: Add test for RAZ/WI AArch32 ID registers arch/arm64/kvm/sys_regs.c | 137 +++++++++--------- arch/arm64/kvm/sys_regs.h | 24 ++- tools/testing/selftests/kvm/.gitignore | 1 + tools/testing/selftests/kvm/Makefile | 1 + .../kvm/aarch64/aarch64_only_id_regs.c | 135 +++++++++++++++++ 5 files changed, 222 insertions(+), 76 deletions(-) create mode 100644 tools/testing/selftests/kvm/aarch64/aarch64_only_id_regs.c -- 2.37.1.595.g718a3a8f04-goog