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 lists.gnu.org (lists.gnu.org [209.51.188.17]) (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 CF02ACA0EE0 for ; Wed, 13 Aug 2025 23:29:41 +0000 (UTC) Received: from localhost ([::1] helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1umKsx-0001Nk-6T; Wed, 13 Aug 2025 19:27:59 -0400 Received: from eggs.gnu.org ([2001:470:142:3::10]) by lists.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1umKsu-0001Mh-NF for qemu-devel@nongnu.org; Wed, 13 Aug 2025 19:27:57 -0400 Received: from mail-pf1-x42e.google.com ([2607:f8b0:4864:20::42e]) by eggs.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_128_GCM_SHA256:128) (Exim 4.90_1) (envelope-from ) id 1umKse-0008Iq-56 for qemu-devel@nongnu.org; Wed, 13 Aug 2025 19:27:56 -0400 Received: by mail-pf1-x42e.google.com with SMTP id d2e1a72fcca58-76e2ea94c7cso400153b3a.2 for ; Wed, 13 Aug 2025 16:27:35 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linaro.org; s=google; t=1755127653; x=1755732453; darn=nongnu.org; h=content-transfer-encoding:subject:cc:to:content-language:from :user-agent:mime-version:date:message-id:from:to:cc:subject:date :message-id:reply-to; bh=671X5sFGwqHEAR/PM0HKyNG8ZucV9LLOvqO6yHtGxIY=; b=C583GXrzN8/M9vguGqtOaYywKFNBzhTTjEkhuNyzh1ant78Li4oFfthbSKSc4EGRFj LWyK0tJtrcQg6q0jqcOcMfUXJQ3LPHSlFCuuONtXEqeYsaajL7EFcK+gr4t3FmHVu4Pb gzx45h23XXxqmOm07utE5IS9jDJLROWBWhYsAixD53IFygeqhLRljRa6ew6u8HaJrdS5 j5z+N1hBuApNwZzsgE6HSv5eCwjY3agUJB0heuLWYEQlAs2LBg6NVCxcxCSobJDsPsPU E0do0KA4Y7UiIyisPZ1/BzYA0PGzlGQCayXRIcvWNXxb6WIbcH/YPCvkHJzZPnFJI1Iw JtOw== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1755127653; x=1755732453; h=content-transfer-encoding:subject:cc:to:content-language:from :user-agent:mime-version:date:message-id:x-gm-message-state:from:to :cc:subject:date:message-id:reply-to; bh=671X5sFGwqHEAR/PM0HKyNG8ZucV9LLOvqO6yHtGxIY=; b=mdbLS32uLdFV1ZLRsWH0x8nIFAwrDUAief1ycft85nkkEBDha/14rS8kvw3zOF4kzM cPzqP3f1zL0uM7dNsiq9XbzKk8QuQ3NKFplr1/bFsCy0qCe5/ToWJPyYLkL6orAbGBxA /VgKWwzedwJ6gpiwEfw16VxnRn2de5yfDtQs/k5TF5007auOwHpVxu96vIWzmHl2lEZ0 ZB1Z8JJu137wv1EGPXZaquOOY0PNWoiMR7wlxpqIVUbeLCKuXho70uISL4ZHkFjY7ur8 PX6q74kyMulSlTH75ONwAs6oME+0IicD+9nSD7bBCnTBegiNRUjoSSlsiilzdBuL1qeQ 8YsQ== X-Forwarded-Encrypted: i=1; AJvYcCVxsG2MnM5KuvMUPDh/6OSH/OAUIAXwpgu5/2ua1mhVvNng90apYp9BUaCKKp4sre8g6+eoO1G6nnRu@nongnu.org X-Gm-Message-State: AOJu0YxNs1UUXoskeju6Y7RCntG6fszpzk70KU3qpd/t2YJ+VSFOzXbc sj3kBMwgdv2P35PuUhLauFhfxQyhJIcLiFYesRAkAefPZ4sNDFgJ8Lya6/suM1MBfek= X-Gm-Gg: ASbGnctetr0gBJrwqE2ClngSUaiRGOZ5uPbgVnT0cVFRwXUwtLUxXEjYpiDHcW7g7X6 17XzJJ5P6ZvH/6kM6not/P3sR3MVIwtdU/ZvYxIYyk8Ki2rBWKIAdhzJdhkXkWwrJe7U/QpqpOg uvhKVP673hhjVv4DYBE16Q/EPsnub094kPlI04RHwtZudeZLzRVtS0YiJ7s2P4Qug0U9eKimUP6 dz9aeW/XtRVP3StAov7IFkrD7fGezbPwRXwp/jmarUvXMyoc9TJh/PX0UnI89t/ETO2d4c5Lbdb 2NdOsXiiQ/+hwZXXlSqw7YD5xNCXbur+5rko3Qz0mrWkMth537v6ewLkQGVHmCSuVNLUjzTsA1d QCEcq8C3tle+oJTCK03SdRyqzLlui1JYJodsHRlI= X-Google-Smtp-Source: AGHT+IHLNkaJfIvv5CCD9tks/OXBzVDSKXibWWP3Z4/VR2Un3vGNBroCQpwE1UPfeLcXxPi8EvMN9A== X-Received: by 2002:a05:6a20:7f9a:b0:23d:b341:c2a4 with SMTP id adf61e73a8af0-240bd28603fmr1161297637.38.1755127652631; Wed, 13 Aug 2025 16:27:32 -0700 (PDT) Received: from [192.168.4.112] ([206.83.105.236]) by smtp.gmail.com with ESMTPSA id d2e1a72fcca58-76bccfd88dbsm32941165b3a.103.2025.08.13.16.27.29 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Wed, 13 Aug 2025 16:27:32 -0700 (PDT) Message-ID: <1c6b4f19-6cb2-4da0-9acc-d63307880de1@linaro.org> Date: Thu, 14 Aug 2025 09:27:25 +1000 MIME-Version: 1.0 User-Agent: Mozilla Thunderbird From: Richard Henderson Content-Language: en-US To: kvmarm@lists.linux.dev, qemu-devel Cc: Marc Zyngier , Peter Maydell , Oliver Upton , =?UTF-8?Q?Alex_Benn=C3=A9e?= Subject: KVM sysreg ids for FEAT_SYSREG128 Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit Received-SPF: pass client-ip=2607:f8b0:4864:20::42e; envelope-from=richard.henderson@linaro.org; helo=mail-pf1-x42e.google.com X-Spam_score_int: -16 X-Spam_score: -1.7 X-Spam_bar: - X-Spam_report: (-1.7 / 5.0 requ) BAYES_00=-1.9, DKIM_INVALID=0.1, DKIM_SIGNED=0.1, RCVD_IN_DNSWL_NONE=-0.0001, T_SPF_HELO_TEMPERROR=0.01, T_SPF_TEMPERROR=0.01 autolearn=no autolearn_force=no X-Spam_action: no action X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Hiya, QEMU (ab)uses the kvm encoding of system register ids in the migration stream. As we implement support for FEAT_D128, it would be good to agree on an encoding for the 128-bit registers so that we can avoid complications with migration later. I don't think this is terribly complicated. Simply adjust the value in the KVM_REG_SIZE_MASK field from U64 to U128. E.g. PAR_EL1 (64-bit) (__ARM64_SYS_REG(3, 0, 7, 4, 0) | KVM_REG_SIZE_U64) PAR_EL1 (128-bit) (__ARM64_SYS_REG(3, 0, 7, 4, 0) | KVM_REG_SIZE_U128) This will currently be cleanly rejected by index_to_params, resulting in ENOENT for the ioctl. When KVM grows support for D128 guests, kvm_sys_reg_{get,set}_user can select the read/write code path based on reg->id & KVM_REG_SIZE_MASK. Comments? r~