From nobody Thu Feb 12 14:10:06 2026 Received: from us-smtp-delivery-124.mimecast.com (us-smtp-delivery-124.mimecast.com [170.10.129.124]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id DF26C14AB4 for ; Wed, 12 Jun 2024 02:36:16 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=170.10.129.124 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1718159778; cv=none; b=OvXJf/cKmUCi5/IJEh4QvsElCNg1nBQdx4Mc6DfL8tZ47G0dANrCBGJPUoOj/QidalthLuGj6xVeviYywJUJx4qlt2i3HKfC0F28lHrCgxyesiJFKMfkhS2MsnwoBrgRfzqvsVplHktB0OuuJzIEKVaLk//TcGNvefWL5YlPct4= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1718159778; c=relaxed/simple; bh=clWISYVP+y4RIgSGIBJSTDnPvfKxZ6zB5K37+T0yH4s=; h=From:To:Cc:Subject:Date:Message-Id:In-Reply-To:References: MIME-Version; b=KIkziR6sBk5FM7gAO3MQwVMgmZwlohYSqQ80DKy6BIqZhNgqg6oeVnDRghQUzHO7NM3Ai5zcExOa4UZO0lg1aljmJMspWXOi/tGA6/c+u/LvEJybx+RliQVYjVfjVc77PQLUDZydoeTpkyisWOUC0qqchOE3Bz/H03moBdoTp1g= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=redhat.com; spf=pass smtp.mailfrom=redhat.com; dkim=pass (1024-bit key) header.d=redhat.com header.i=@redhat.com header.b=QLXnRXNw; arc=none smtp.client-ip=170.10.129.124 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=redhat.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=redhat.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=redhat.com header.i=@redhat.com header.b="QLXnRXNw" DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1718159775; 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=Skhula7518PMXu1UZDnu+UyfH0UgWPzNpluBrfVr+JQ=; b=QLXnRXNwDII0UirK0DmqQXRvljBxfTOHqkSmC9YEqJ0Lj/ll7lDqjmAozkwigZRfKPXUnt MCc81Rqfm/tnTXMUtOU0DF5Vu5UJ9T1MLDXn1UP2LbPV3kwoJ3m8xK0wLITRPzbpBFtG4a UsqNfRYvosHEQ082QSVpJ+TF/Wumopk= Received: from mx-prod-mc-04.mail-002.prod.us-west-2.aws.redhat.com (ec2-54-186-198-63.us-west-2.compute.amazonaws.com [54.186.198.63]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.3, cipher=TLS_AES_256_GCM_SHA384) id us-mta-149-5a8JObh9M8incYscAze6kQ-1; Tue, 11 Jun 2024 22:36:08 -0400 X-MC-Unique: 5a8JObh9M8incYscAze6kQ-1 Received: from mx-prod-int-04.mail-002.prod.us-west-2.aws.redhat.com (mx-prod-int-04.mail-002.prod.us-west-2.aws.redhat.com [10.30.177.40]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (2048 bits) server-digest SHA256) (No client certificate requested) by mx-prod-mc-04.mail-002.prod.us-west-2.aws.redhat.com (Postfix) with ESMTPS id 0564C19560AB; Wed, 12 Jun 2024 02:36:06 +0000 (UTC) Received: from virt-mtcollins-01.lab.eng.rdu2.redhat.com (virt-mtcollins-01.lab.eng.rdu2.redhat.com [10.8.1.196]) by mx-prod-int-04.mail-002.prod.us-west-2.aws.redhat.com (Postfix) with ESMTP id 6E96719560AF; Wed, 12 Jun 2024 02:36:03 +0000 (UTC) From: Shaoqin Huang To: Oliver Upton , Marc Zyngier , kvmarm@lists.linux.dev Cc: Eric Auger , Sebastian Ott , Cornelia Huck , Shaoqin Huang , James Morse , Suzuki K Poulose , Zenghui Yu , Catalin Marinas , Will Deacon , linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org Subject: [RFC PATCH v1 1/2] KVM: arm64: Allow BT field in ID_AA64PFR1_EL1 writable Date: Tue, 11 Jun 2024 22:35:51 -0400 Message-Id: <20240612023553.127813-2-shahuang@redhat.com> In-Reply-To: <20240612023553.127813-1-shahuang@redhat.com> References: <20240612023553.127813-1-shahuang@redhat.com> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable X-Scanned-By: MIMEDefang 3.0 on 10.30.177.40 Content-Type: text/plain; charset="utf-8" When migrating from MtCollins to AmpereOne, the BT field value in ID_AA64PFR1_EL1 register is different and not writable. This causes the migration to fail. The BT field means Branch Target Identification mechanism support in AArch64 state. The value 0 means BT is not implemented, the value 1 means BT is implemented. On MtCollins(Migration Src), the BT value is 0. On AmpereOne(Migration Dst), the BT value is 1. As it defined in the ftr_id_aa64dfr0, the samller value is safe. So if we make the BT field writable, on the AmpereOne(Migration Dst) the BT field will be overrided with value 0. Signed-off-by: Shaoqin Huang --- But there is a question, the ARM DDI mentions from Armv8.5, the only permitted value is 0b01. Do you guys know if there are any consequence if the userspace write value 0b0 into this field? Or we should restrict that at some level, like in VMM or kernel level? --- arch/arm64/kvm/sys_regs.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/arch/arm64/kvm/sys_regs.c b/arch/arm64/kvm/sys_regs.c index c9f4f387155f..8e0ea62e14e1 100644 --- a/arch/arm64/kvm/sys_regs.c +++ b/arch/arm64/kvm/sys_regs.c @@ -2292,7 +2292,7 @@ static const struct sys_reg_desc sys_reg_descs[] =3D { ID_AA64PFR0_EL1_GIC | ID_AA64PFR0_EL1_AdvSIMD | ID_AA64PFR0_EL1_FP), }, - ID_SANITISED(ID_AA64PFR1_EL1), + ID_WRITABLE(SYS_ID_AA64PFR1_EL1, ID_AA64PFR1_EL1_BT), ID_UNALLOCATED(4,2), ID_UNALLOCATED(4,3), ID_WRITABLE(ID_AA64ZFR0_EL1, ~ID_AA64ZFR0_EL1_RES0), --=20 2.40.1 From nobody Thu Feb 12 14:10:06 2026 Received: from us-smtp-delivery-124.mimecast.com (us-smtp-delivery-124.mimecast.com [170.10.129.124]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 35D9510795 for ; Wed, 12 Jun 2024 02:36:16 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=170.10.129.124 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1718159777; cv=none; b=vDfggtWimgeIccP1fM1qPmfNA4kj47xvFxiagoqXwXpf39vdNH7y1wfCvc07b4DEeZaEgt2Tgt/bUT+ky1kVQtBJPTB/Bsvbs58i3tZk1nMPBNcs9q8m6ITVkzZy1xgWd7XovRJOu2ljGghIAfJRoPhAM/coH8h7MFaNNge+Rcc= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1718159777; c=relaxed/simple; bh=+C9CpexBYFfnMpqRsSGyPaSylMt0LZhxG8Bqf4uE1vc=; h=From:To:Cc:Subject:Date:Message-Id:In-Reply-To:References: MIME-Version; b=nqUJ1XZV4hO0xsm8GBL1mRIMgUw9amAywSnTOib+Focx3FTJKQ8NmdNsfaC0SXEkT18Q9v66E6ksHHehJ/v+9yiF9RVFZGTIEgYkz5Oj9hMmQ4oRIwPSgs/LeECbUnQVLAu9Nek1ggwCQvgZ+jYsCPfbY624A5A7bME4T8uwga4= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=redhat.com; spf=pass smtp.mailfrom=redhat.com; dkim=pass (1024-bit key) header.d=redhat.com header.i=@redhat.com header.b=h28Zx+zj; arc=none smtp.client-ip=170.10.129.124 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=redhat.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=redhat.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=redhat.com header.i=@redhat.com header.b="h28Zx+zj" DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1718159775; 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=ARgZIxE+11qj8ADHfG2c1X50fN5kwjd0+5g/sQvCIdY=; b=h28Zx+zj/Zy8FcCuIWXGXvo7pkx5mwfsIDTJS8BzGCBvMeIs0P4LcEqWhV5vdC2vlKK9hh 2fWZ4x4T/94QVXk4agD4vaFj7M1KXG5BrvOQfx3WMpdtu+dyBhn90E0BHPNVK59cLZIuoU DCcotD0olWXmnKNo/c8/ulAu79BaLlc= Received: from mx-prod-mc-03.mail-002.prod.us-west-2.aws.redhat.com (ec2-54-186-198-63.us-west-2.compute.amazonaws.com [54.186.198.63]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.3, cipher=TLS_AES_256_GCM_SHA384) id us-mta-529-Hv6NuDmENy6inG_gTUu0Zg-1; Tue, 11 Jun 2024 22:36:10 -0400 X-MC-Unique: Hv6NuDmENy6inG_gTUu0Zg-1 Received: from mx-prod-int-04.mail-002.prod.us-west-2.aws.redhat.com (mx-prod-int-04.mail-002.prod.us-west-2.aws.redhat.com [10.30.177.40]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (2048 bits) server-digest SHA256) (No client certificate requested) by mx-prod-mc-03.mail-002.prod.us-west-2.aws.redhat.com (Postfix) with ESMTPS id AA4F219560B2; Wed, 12 Jun 2024 02:36:08 +0000 (UTC) Received: from virt-mtcollins-01.lab.eng.rdu2.redhat.com (virt-mtcollins-01.lab.eng.rdu2.redhat.com [10.8.1.196]) by mx-prod-int-04.mail-002.prod.us-west-2.aws.redhat.com (Postfix) with ESMTP id 5386619560AD; Wed, 12 Jun 2024 02:36:06 +0000 (UTC) From: Shaoqin Huang To: Oliver Upton , Marc Zyngier , kvmarm@lists.linux.dev Cc: Eric Auger , Sebastian Ott , Cornelia Huck , Shaoqin Huang , James Morse , Suzuki K Poulose , Zenghui Yu , Paolo Bonzini , Shuah Khan , linux-arm-kernel@lists.infradead.org, kvm@vger.kernel.org, linux-kselftest@vger.kernel.org, linux-kernel@vger.kernel.org Subject: [RFC PATCH v1 2/2] KVM: selftests: aarch64: Add writable test for ID_AA64PFR1_EL1 Date: Tue, 11 Jun 2024 22:35:52 -0400 Message-Id: <20240612023553.127813-3-shahuang@redhat.com> In-Reply-To: <20240612023553.127813-1-shahuang@redhat.com> References: <20240612023553.127813-1-shahuang@redhat.com> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable X-Scanned-By: MIMEDefang 3.0 on 10.30.177.40 Content-Type: text/plain; charset="utf-8" Add test for the BT field in the ID_AA64PFR1_EL1 register. Signed-off-by: Shaoqin Huang --- tools/testing/selftests/kvm/aarch64/set_id_regs.c | 6 ++++++ 1 file changed, 6 insertions(+) diff --git a/tools/testing/selftests/kvm/aarch64/set_id_regs.c b/tools/test= ing/selftests/kvm/aarch64/set_id_regs.c index 16e2338686c1..5381b8ec5562 100644 --- a/tools/testing/selftests/kvm/aarch64/set_id_regs.c +++ b/tools/testing/selftests/kvm/aarch64/set_id_regs.c @@ -133,6 +133,11 @@ static const struct reg_ftr_bits ftr_id_aa64pfr0_el1[]= =3D { REG_FTR_END, }; =20 +static const struct reg_ftr_bits ftr_id_aa64pfr1_el1[] =3D { + REG_FTR_BITS(FTR_LOWER_SAFE, ID_AA64PFR1_EL1, BT, 0), + REG_FTR_END, +}; + static const struct reg_ftr_bits ftr_id_aa64mmfr0_el1[] =3D { REG_FTR_BITS(FTR_LOWER_SAFE, ID_AA64MMFR0_EL1, ECV, 0), REG_FTR_BITS(FTR_LOWER_SAFE, ID_AA64MMFR0_EL1, EXS, 0), @@ -199,6 +204,7 @@ static struct test_feature_reg test_regs[] =3D { TEST_REG(SYS_ID_AA64ISAR1_EL1, ftr_id_aa64isar1_el1), TEST_REG(SYS_ID_AA64ISAR2_EL1, ftr_id_aa64isar2_el1), TEST_REG(SYS_ID_AA64PFR0_EL1, ftr_id_aa64pfr0_el1), + TEST_REG(SYS_ID_AA64PFR1_EL1, ftr_id_aa64pfr1_el1), TEST_REG(SYS_ID_AA64MMFR0_EL1, ftr_id_aa64mmfr0_el1), TEST_REG(SYS_ID_AA64MMFR1_EL1, ftr_id_aa64mmfr1_el1), TEST_REG(SYS_ID_AA64MMFR2_EL1, ftr_id_aa64mmfr2_el1), --=20 2.40.1