From patchwork Fri Sep 2 15:47:56 2022 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Oliver Upton X-Patchwork-Id: 12964366 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 0E0A2C001B5 for ; Fri, 2 Sep 2022 15:54:23 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S237455AbiIBPyV (ORCPT ); Fri, 2 Sep 2022 11:54:21 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:59324 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S237541AbiIBPxv (ORCPT ); Fri, 2 Sep 2022 11:53:51 -0400 Received: from out0.migadu.com (out0.migadu.com [IPv6:2001:41d0:2:267::]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 1872B57565 for ; Fri, 2 Sep 2022 08:48:16 -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=1662133694; 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=IFb0nw1kmQc9o54dv6z8DN+QQpTAUMEEVUEkFaEPX18=; b=ZVELD/JOd3tkB4ZVOrh91thYGAv273RtRfM8U4a1xvnsTh8fg82X/hhVR/juYQQSlvTpht sHzc4GMiwRdicxUlACT2dFnkTzr+GbNdx7TDyw5qtjuyspFVxP0cxEKJY3cudO5gkFm5xc KHcAuJnhNzbqg8eyUCm+6ENTCD8SZwE= From: Oliver Upton To: Marc Zyngier , James Morse , Alexandru Elisei Cc: linux-arm-kernel@lists.infradead.org, kvmarm@lists.cs.columbia.edu, kvm@vger.kernel.org, Reiji Watanabe , Oliver Upton Subject: [PATCH v2 0/7] KVM: arm64: Use visibility hook to treat ID regs as RAZ Date: Fri, 2 Sep 2022 15:47:56 +0000 Message-Id: <20220902154804.1939819-1-oliver.upton@linux.dev> MIME-Version: 1.0 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 1-3 clean up the ID register accessors, taking advantage of the fact that the generic accessors know how to handle RAZ. Patches 4-6 start switch the handling of potentially nonzero AArch32 ID registers to RAZ/WI. RAZ covers up the architecturally UNKNOWN values, and WI allows for migration off of kernels that may provide garbage. Note that hidden AArch32 ID registers continue to have RAZ behavior with the additional expectation of invariance. Lastly, patch 7 includes a small test for the issue. Applies to 6.0-rc3. Tested with KVM selftests under the fast model w/ asymmetric 32 bit support and no 32 bit support whatsoever. v1 -> v2: - Collect Reiji's r-b tags (thanks!) - Call sysreg_visible_as_raz() from read_id_reg() (Reiji) - Hoist sysreg_user_write_ignore() into kvm_sys_reg_set_user() (Reiji) Oliver Upton (7): KVM: arm64: Use visibility hook to treat ID regs as RAZ KVM: arm64: Remove internal accessor helpers for id regs KVM: arm64: Drop raz parameter from read_id_reg() 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 | 150 +++++++++--------- 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, 225 insertions(+), 86 deletions(-) create mode 100644 tools/testing/selftests/kvm/aarch64/aarch64_only_id_regs.c base-commit: b90cb1053190353cc30f0fef0ef1f378ccc063c5