From patchwork Fri May 26 23:44:31 2023 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Yu Zhao X-Patchwork-Id: 13257475 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 bombadil.infradead.org (bombadil.infradead.org [198.137.202.133]) (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 411F7C7EE31 for ; Fri, 26 May 2023 23:45:25 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=bombadil.20210309; h=Sender: Content-Transfer-Encoding:Content-Type:List-Subscribe:List-Help:List-Post: List-Archive:List-Unsubscribe:List-Id:Cc:To:From:Subject:References: Mime-Version:Message-Id:In-Reply-To:Date:Reply-To:Content-ID: Content-Description:Resent-Date:Resent-From:Resent-Sender:Resent-To:Resent-Cc :Resent-Message-ID:List-Owner; bh=RXb8lmJQ6LwYODSTird6sAz5ei7H4YB8JznpiQIRG0c=; b=KrSZa01frM3Aur6LYeSLLtUzR4 tzLt3Q+H+M/LXXuo6hzczQZOGZtzi6xCqeu95gxmOYhnxxpEobV46TzAZj5RNCCJASjkyz58B12j3 gQBBPuC/sl5J9J/4F8QZoSs5jOr2ZneI/p3oJpQpnpRcmbjktbHvD2mK7hvmfme37g9Wz/u0786yn v8JNpah0yEDC9xqkBn0hF21FdYqoyo3mFPR5PERdkkc/Y+uIo8dNRTXJObEPeL3d/8kFSUhIzZO8L HHkbKsCzaTjte16zd+AgF2CkeCynCvkD7YNTKuZZzIZBPSn8byXMA8+SQFlQLkykEZOB2w/3DSiAo w9ut28Ug==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.96 #2 (Red Hat Linux)) id 1q2h7E-004KcF-0W; Fri, 26 May 2023 23:45:00 +0000 Received: from mail-yb1-xb4a.google.com ([2607:f8b0:4864:20::b4a]) by bombadil.infradead.org with esmtps (Exim 4.96 #2 (Red Hat Linux)) id 1q2h74-004KRl-0n for linux-arm-kernel@lists.infradead.org; Fri, 26 May 2023 23:44:51 +0000 Received: by mail-yb1-xb4a.google.com with SMTP id 3f1490d57ef6-babb53e6952so2824745276.0 for ; Fri, 26 May 2023 16:44:49 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20221208; t=1685144689; x=1687736689; h=cc:to:from:subject:references:mime-version:message-id:in-reply-to :date:from:to:cc:subject:date:message-id:reply-to; bh=Bguo3hUZaLYxse9v+ik+MX3ufqUdHR10jXNpIhPD3cE=; b=Y62V38pt3Kf7P9M2YivEC5661SUHDQjGPJeLNpi65nB4y+p3TsqoRR0z/9AOIr1Kjf gl3yg0EBv9UJcyGGhkoV+eP5nxHHEckaVjNM+WV0ph8y6N8NKNrOoxejQzf6xVLF0GNF CMPzW7iyFKrk0I+YLOBH1dB2cwpR8z8XT9p+1tlyni+H85cDXJGB/ZGkaiDpbVC82/o/ GKwW1qcFloQI+vCY/C+X0I8xbKAWwMlWN0KpQsh6osmLARaX2g1tNlgMEbkEwKadQaPu 8s3poXNR7qoLyRgjp4108zRCziAP6oNak8GIUn6lV7gRCswVoQjlt0PKr+oTkaiyWyY0 Ciug== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20221208; t=1685144689; x=1687736689; h=cc:to:from:subject:references:mime-version:message-id:in-reply-to :date:x-gm-message-state:from:to:cc:subject:date:message-id:reply-to; bh=Bguo3hUZaLYxse9v+ik+MX3ufqUdHR10jXNpIhPD3cE=; b=JmvOnLWCHTqHbY9dkbTNgcjD7OLXYnucMi5DvQnqdgMz9H9DWyc/DMljl8hdyGOCPw ps9HMFq+F17/SvRslqTD3nGWeIWOGw18VQr/QUz8FY7yVwz+/Qq/caE6oEc96Cr3lwHb pQGYP7FVJyid8skKjkiUMtbk2V48rfMUejlqfdG0C3R0lHZ+4TQD26BVSSIpN2g3x2eA Xu31g33uv/zS1fqVIvQhNzk8KbU99n28EEbjX4oPZDTRPDTm4DpdrZmGcPNWRlJGoBGr t843eDs1sYMG5Mpwxw82Y9eJntRXfouZ9LcCMCUw5Pnypt7iaRbhT/s1vPradEaBsjFD AOoA== X-Gm-Message-State: AC+VfDxVMfBg8swSUCKv0SNdljLgjqTmZmDGpWGLg6bxloFFlegr+03t R7MbzjSiSWbPQ6kKjhX30tdu5Sm6t/c= X-Google-Smtp-Source: ACHHUZ72Yke0umLVJsAYBjLDCmB2C1ZbHNslgBIJrMfaEGzX80HaCkEwKhsoBR2khvT0ady9wDj4p4x/v3M= X-Received: from yuzhao.bld.corp.google.com ([2620:15c:183:200:910f:8a15:592b:2087]) (user=yuzhao job=sendgmr) by 2002:a25:3cb:0:b0:ba8:337a:d8a3 with SMTP id 194-20020a2503cb000000b00ba8337ad8a3mr1807757ybd.11.1685144689141; Fri, 26 May 2023 16:44:49 -0700 (PDT) Date: Fri, 26 May 2023 17:44:31 -0600 In-Reply-To: <20230526234435.662652-1-yuzhao@google.com> Message-Id: <20230526234435.662652-7-yuzhao@google.com> Mime-Version: 1.0 References: <20230526234435.662652-1-yuzhao@google.com> X-Mailer: git-send-email 2.41.0.rc0.172.g3f132b7071-goog Subject: [PATCH mm-unstable v2 06/10] kvm/powerpc: make radix page tables RCU safe From: Yu Zhao To: Andrew Morton , Paolo Bonzini Cc: Alistair Popple , Anup Patel , Ben Gardon , Borislav Petkov , Catalin Marinas , Chao Peng , Christophe Leroy , Dave Hansen , Fabiano Rosas , Gaosheng Cui , Gavin Shan , "H. Peter Anvin" , Ingo Molnar , James Morse , "Jason A. Donenfeld" , Jason Gunthorpe , Jonathan Corbet , Marc Zyngier , Masami Hiramatsu , Michael Ellerman , Michael Larabel , Mike Rapoport , Nicholas Piggin , Oliver Upton , Paul Mackerras , Peter Xu , Sean Christopherson , Steven Rostedt , Suzuki K Poulose , Thomas Gleixner , Thomas Huth , Will Deacon , Zenghui Yu , kvmarm@lists.linux.dev, kvm@vger.kernel.org, linux-arm-kernel@lists.infradead.org, linux-doc@vger.kernel.org, linux-kernel@vger.kernel.org, linux-mm@kvack.org, linuxppc-dev@lists.ozlabs.org, linux-trace-kernel@vger.kernel.org, x86@kernel.org, linux-mm@google.com, Yu Zhao X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20230526_164450_284545_48F399C9 X-CRM114-Status: GOOD ( 11.31 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org KVM page tables are currently not RCU safe against remapping, i.e., kvmppc_unmap_free_pmd_entry_table() et al. The previous mmu_notifier_ops members rely on kvm->mmu_lock to synchronize with that operation. However, the new mmu_notifier_ops member test_clear_young() provides a fast path that does not take kvm->mmu_lock. To implement kvm_arch_test_clear_young() for that path, orphan page tables need to be freed by RCU. Unmapping, specifically kvm_unmap_radix(), does not free page tables, hence not a concern. Signed-off-by: Yu Zhao --- arch/powerpc/kvm/book3s_64_mmu_radix.c | 6 ++++-- 1 file changed, 4 insertions(+), 2 deletions(-) diff --git a/arch/powerpc/kvm/book3s_64_mmu_radix.c b/arch/powerpc/kvm/book3s_64_mmu_radix.c index 461307b89c3a..3b65b3b11041 100644 --- a/arch/powerpc/kvm/book3s_64_mmu_radix.c +++ b/arch/powerpc/kvm/book3s_64_mmu_radix.c @@ -1469,13 +1469,15 @@ int kvmppc_radix_init(void) { unsigned long size = sizeof(void *) << RADIX_PTE_INDEX_SIZE; - kvm_pte_cache = kmem_cache_create("kvm-pte", size, size, 0, pte_ctor); + kvm_pte_cache = kmem_cache_create("kvm-pte", size, size, + SLAB_TYPESAFE_BY_RCU, pte_ctor); if (!kvm_pte_cache) return -ENOMEM; size = sizeof(void *) << RADIX_PMD_INDEX_SIZE; - kvm_pmd_cache = kmem_cache_create("kvm-pmd", size, size, 0, pmd_ctor); + kvm_pmd_cache = kmem_cache_create("kvm-pmd", size, size, + SLAB_TYPESAFE_BY_RCU, pmd_ctor); if (!kvm_pmd_cache) { kmem_cache_destroy(kvm_pte_cache); return -ENOMEM;