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 X-Spam-Level: X-Spam-Status: No, score=-13.1 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,INCLUDES_PATCH,MAILING_LIST_MULTI, SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED,USER_AGENT_GIT autolearn=unavailable autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id AABFCC63798 for ; Tue, 27 Oct 2020 00:34:29 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 7FE2F217A0 for ; Tue, 27 Oct 2020 00:34:29 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1603758869; bh=7R5xqVgNV8SBj5rHvCGLv44NHswCNNGcoAZYxRlZAjE=; h=From:To:Cc:Subject:Date:In-Reply-To:References:List-ID:From; b=PbIGDA4r9AaaTchCy1fIYIWV9fVi1adxtl0wrdK8NSsNdUKEyfjz4qPE3C45l3+dB Us+UjTJkSsi71Ljm+ePCkEtUrFEUZobhtSe/itoT+exMKhDpv6+C0O4wYxlgfZ9MGo 24zAVHkhELgSqZCyBm9NWV5EcmkGeSnm3GYncXBs= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2443566AbgJ0AbR (ORCPT ); Mon, 26 Oct 2020 20:31:17 -0400 Received: from mail.kernel.org ([198.145.29.99]:52566 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S2409452AbgJZXve (ORCPT ); Mon, 26 Oct 2020 19:51:34 -0400 Received: from sasha-vm.mshome.net (c-73-47-72-35.hsd1.nh.comcast.net [73.47.72.35]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id E48B521D41; Mon, 26 Oct 2020 23:51:32 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1603756293; bh=7R5xqVgNV8SBj5rHvCGLv44NHswCNNGcoAZYxRlZAjE=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=NfsS28eJ5UYslL7njdlhPkECF0XEi0Xn+XwMlbFc5TvzuwosYKiKFVLAHPaFTRx5b EGBCXFdnqDQ7dMCeaY393gFKIuY/BBMMB6A92TqqhlbSQR3zCNTY+9Kr2/16p2M/Xf b24JfX0Q/ixx/uF1OEBITm0AFjLf8E87n3cTiagc= From: Sasha Levin To: linux-kernel@vger.kernel.org, stable@vger.kernel.org Cc: Fabiano Rosas , Satheesh Rajendran , Greg Kurz , David Gibson , Paul Mackerras , Sasha Levin , kvm-ppc@vger.kernel.org, linuxppc-dev@lists.ozlabs.org Subject: [PATCH AUTOSEL 5.9 121/147] KVM: PPC: Book3S HV: Do not allocate HPT for a nested guest Date: Mon, 26 Oct 2020 19:48:39 -0400 Message-Id: <20201026234905.1022767-121-sashal@kernel.org> X-Mailer: git-send-email 2.25.1 In-Reply-To: <20201026234905.1022767-1-sashal@kernel.org> References: <20201026234905.1022767-1-sashal@kernel.org> MIME-Version: 1.0 X-stable: review X-Patchwork-Hint: Ignore Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: stable@vger.kernel.org From: Fabiano Rosas [ Upstream commit 05e6295dc7de859c9d56334805485c4d20bebf25 ] The current nested KVM code does not support HPT guests. This is informed/enforced in some ways: - Hosts < P9 will not be able to enable the nested HV feature; - The nested hypervisor MMU capabilities will not contain KVM_CAP_PPC_MMU_HASH_V3; - QEMU reflects the MMU capabilities in the 'ibm,arch-vec-5-platform-support' device-tree property; - The nested guest, at 'prom_parse_mmu_model' ignores the 'disable_radix' kernel command line option if HPT is not supported; - The KVM_PPC_CONFIGURE_V3_MMU ioctl will fail if trying to use HPT. There is, however, still a way to start a HPT guest by using max-compat-cpu=power8 at the QEMU machine options. This leads to the guest being set to use hash after QEMU calls the KVM_PPC_ALLOCATE_HTAB ioctl. With the guest set to hash, the nested hypervisor goes through the entry path that has no knowledge of nesting (kvmppc_run_vcpu) and crashes when it tries to execute an hypervisor-privileged (mtspr HDEC) instruction at __kvmppc_vcore_entry: root@L1:~ $ qemu-system-ppc64 -machine pseries,max-cpu-compat=power8 ... [ 538.543303] CPU: 83 PID: 25185 Comm: CPU 0/KVM Not tainted 5.9.0-rc4 #1 [ 538.543355] NIP: c00800000753f388 LR: c00800000753f368 CTR: c0000000001e5ec0 [ 538.543417] REGS: c0000013e91e33b0 TRAP: 0700 Not tainted (5.9.0-rc4) [ 538.543470] MSR: 8000000002843033 CR: 22422882 XER: 20040000 [ 538.543546] CFAR: c00800000753f4b0 IRQMASK: 3 GPR00: c0080000075397a0 c0000013e91e3640 c00800000755e600 0000000080000000 GPR04: 0000000000000000 c0000013eab19800 c000001394de0000 00000043a054db72 GPR08: 00000000003b1652 0000000000000000 0000000000000000 c0080000075502e0 GPR12: c0000000001e5ec0 c0000007ffa74200 c0000013eab19800 0000000000000008 GPR16: 0000000000000000 c00000139676c6c0 c000000001d23948 c0000013e91e38b8 GPR20: 0000000000000053 0000000000000000 0000000000000001 0000000000000000 GPR24: 0000000000000001 0000000000000001 0000000000000000 0000000000000001 GPR28: 0000000000000001 0000000000000053 c0000013eab19800 0000000000000001 [ 538.544067] NIP [c00800000753f388] __kvmppc_vcore_entry+0x90/0x104 [kvm_hv] [ 538.544121] LR [c00800000753f368] __kvmppc_vcore_entry+0x70/0x104 [kvm_hv] [ 538.544173] Call Trace: [ 538.544196] [c0000013e91e3640] [c0000013e91e3680] 0xc0000013e91e3680 (unreliable) [ 538.544260] [c0000013e91e3820] [c0080000075397a0] kvmppc_run_core+0xbc8/0x19d0 [kvm_hv] [ 538.544325] [c0000013e91e39e0] [c00800000753d99c] kvmppc_vcpu_run_hv+0x404/0xc00 [kvm_hv] [ 538.544394] [c0000013e91e3ad0] [c0080000072da4fc] kvmppc_vcpu_run+0x34/0x48 [kvm] [ 538.544472] [c0000013e91e3af0] [c0080000072d61b8] kvm_arch_vcpu_ioctl_run+0x310/0x420 [kvm] [ 538.544539] [c0000013e91e3b80] [c0080000072c7450] kvm_vcpu_ioctl+0x298/0x778 [kvm] [ 538.544605] [c0000013e91e3ce0] [c0000000004b8c2c] sys_ioctl+0x1dc/0xc90 [ 538.544662] [c0000013e91e3dc0] [c00000000002f9a4] system_call_exception+0xe4/0x1c0 [ 538.544726] [c0000013e91e3e20] [c00000000000d140] system_call_common+0xf0/0x27c [ 538.544787] Instruction dump: [ 538.544821] f86d1098 60000000 60000000 48000099 e8ad0fe8 e8c500a0 e9264140 75290002 [ 538.544886] 7d1602a6 7cec42a6 40820008 7d0807b4 <7d164ba6> 7d083a14 f90d10a0 480104fd [ 538.544953] ---[ end trace 74423e2b948c2e0c ]--- This patch makes the KVM_PPC_ALLOCATE_HTAB ioctl fail when running in the nested hypervisor, causing QEMU to abort. Reported-by: Satheesh Rajendran Signed-off-by: Fabiano Rosas Reviewed-by: Greg Kurz Reviewed-by: David Gibson Signed-off-by: Paul Mackerras Signed-off-by: Sasha Levin --- arch/powerpc/kvm/book3s_hv.c | 6 ++++++ 1 file changed, 6 insertions(+) diff --git a/arch/powerpc/kvm/book3s_hv.c b/arch/powerpc/kvm/book3s_hv.c index 3bd3118c76330..e2b476d76506a 100644 --- a/arch/powerpc/kvm/book3s_hv.c +++ b/arch/powerpc/kvm/book3s_hv.c @@ -5257,6 +5257,12 @@ static long kvm_arch_vm_ioctl_hv(struct file *filp, case KVM_PPC_ALLOCATE_HTAB: { u32 htab_order; + /* If we're a nested hypervisor, we currently only support radix */ + if (kvmhv_on_pseries()) { + r = -EOPNOTSUPP; + break; + } + r = -EFAULT; if (get_user(htab_order, (u32 __user *)argp)) break; -- 2.25.1