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 mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 1EAA3C433F5 for ; Thu, 4 Nov 2021 00:26:18 +0000 (UTC) Received: from mm01.cs.columbia.edu (mm01.cs.columbia.edu [128.59.11.253]) by mail.kernel.org (Postfix) with ESMTP id BAA96611F0 for ; Thu, 4 Nov 2021 00:26:17 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.4.1 mail.kernel.org BAA96611F0 Authentication-Results: mail.kernel.org; dmarc=fail (p=reject dis=none) header.from=google.com Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=lists.cs.columbia.edu Received: from localhost (localhost [127.0.0.1]) by mm01.cs.columbia.edu (Postfix) with ESMTP id 5BA5E4B192; Wed, 3 Nov 2021 20:26:17 -0400 (EDT) X-Virus-Scanned: at lists.cs.columbia.edu Authentication-Results: mm01.cs.columbia.edu (amavisd-new); dkim=softfail (fail, message has been altered) header.i=@google.com Received: from mm01.cs.columbia.edu ([127.0.0.1]) by localhost (mm01.cs.columbia.edu [127.0.0.1]) (amavisd-new, port 10024) with ESMTP id cG3-m+YDmLZd; Wed, 3 Nov 2021 20:26:16 -0400 (EDT) Received: from mm01.cs.columbia.edu (localhost [127.0.0.1]) by mm01.cs.columbia.edu (Postfix) with ESMTP id 518AD4B168; Wed, 3 Nov 2021 20:26:15 -0400 (EDT) Received: from localhost (localhost [127.0.0.1]) by mm01.cs.columbia.edu (Postfix) with ESMTP id 540A84B1D4 for ; Wed, 3 Nov 2021 20:26:14 -0400 (EDT) X-Virus-Scanned: at lists.cs.columbia.edu Received: from mm01.cs.columbia.edu ([127.0.0.1]) by localhost (mm01.cs.columbia.edu [127.0.0.1]) (amavisd-new, port 10024) with ESMTP id vXYEKnRlfrQp for ; Wed, 3 Nov 2021 20:26:08 -0400 (EDT) Received: from mail-pf1-f201.google.com (mail-pf1-f201.google.com [209.85.210.201]) by mm01.cs.columbia.edu (Postfix) with ESMTPS id EE3734B093 for ; Wed, 3 Nov 2021 20:26:07 -0400 (EDT) Received: by mail-pf1-f201.google.com with SMTP id m26-20020a62a21a000000b0041361973ba7so2330373pff.15 for ; Wed, 03 Nov 2021 17:26:07 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20210112; h=reply-to:date:in-reply-to:message-id:mime-version:references :subject:from:to:cc; bh=d5eBGhjOdraOb8ROBhsskw4veY1ejlVUg/ty/xkC83c=; b=L0C1v+L5WkKOg/1UpzG68qTukZN83qwmMd/ueUN7ewuot9u43aTlXxZMHBpBnaC7/S e6lXD4GKbCtYx2tBTmg/D1dxn24ATg3EXOzk/ufgGhsCdxjkWD3S/Oet9+81xR7BjiXX KsSER1qqH3/ReOXKXEOMxEw+ZWZNMNrHAG+1wsXmgAmQGJdPsauAqWgxGa2bXM3eqrsd MHAblvb9KsqWTWqMYMO09zCzubyhjCK3PZcX9W1VDJfzaXxKjt1+UDPCWwyzZTqBxXQG LYMbx+aWi+q//Eh8G56e8rXxUsD7RwW0EkMLPRzsJeTaMSzf+hbvycjlYJ8jReWzoeCU NYQA== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=x-gm-message-state:reply-to:date:in-reply-to:message-id :mime-version:references:subject:from:to:cc; bh=d5eBGhjOdraOb8ROBhsskw4veY1ejlVUg/ty/xkC83c=; b=AEkKvaJMnUeoBteqAIZGgJCvCE9B+qlsBx0STGFin3U9LJCzwCuW9Gp+OZ/PN1H/S3 JsXZTR/WtMu46Na0GqIp2+COnQ8zpf5JMtxTB9NN9QgC2wtARfEwdua2Tp4s+U3kiab8 +b7trCG/8DSFlTToDh0DGJOSkaNu1S7l+g5wWkDdShhtgcQAiAv2GO99IJqDdhYlCDXT MZS4CWhbMphsXti4aYAtPGBL67FtTXi9K7ovEpFqoldPOTQaFRcWzx8+PLus0nIkHJu9 RvyUgiipWOXrUHb42J1dsyUXr0PPB1esIK69A+vkUQWL5oK+E/63DihuBC9XB581eiM5 Ox2A== X-Gm-Message-State: AOAM533Arex44vj/ou3WQdhuBB2NJNERuY/h1Wb6p8fippKVHz1CfTqq +t5b+ktX/wSi7xfFKwaLCDNToheipDA= X-Google-Smtp-Source: ABdhPJwR/8S2bf9OYImnNTGTvQtJKx+tPqKxegkkAxc8UN7P/Djj1xJRY5WUZbtpalPRRv4cuF26HKA4p5A= X-Received: from seanjc.c.googlers.com ([fda3:e722:ac3:cc00:7f:e700:c0a8:3e5]) (user=seanjc job=sendgmr) by 2002:a17:90a:5285:: with SMTP id w5mr261267pjh.1.1635985566550; Wed, 03 Nov 2021 17:26:06 -0700 (PDT) Date: Thu, 4 Nov 2021 00:25:06 +0000 In-Reply-To: <20211104002531.1176691-1-seanjc@google.com> Message-Id: <20211104002531.1176691-6-seanjc@google.com> Mime-Version: 1.0 References: <20211104002531.1176691-1-seanjc@google.com> X-Mailer: git-send-email 2.33.1.1089.g2158813163f-goog Subject: [PATCH v5.5 05/30] KVM: Resync only arch fields when slots_arch_lock gets reacquired From: Sean Christopherson To: Marc Zyngier , Huacai Chen , Aleksandar Markovic , Paul Mackerras , Anup Patel , Paul Walmsley , Palmer Dabbelt , Albert Ou , Christian Borntraeger , Janosch Frank , Paolo Bonzini Cc: Wanpeng Li , kvm@vger.kernel.org, David Hildenbrand , linux-kernel@vger.kernel.org, Atish Patra , Ben Gardon , "Maciej S . Szmigiero" , Claudio Imbrenda , linux-riscv@lists.infradead.org, Joerg Roedel , kvmarm@lists.cs.columbia.edu, kvm-ppc@vger.kernel.org, linux-arm-kernel@lists.infradead.org, Jim Mattson , Cornelia Huck , linux-mips@vger.kernel.org, kvm-riscv@lists.infradead.org, Vitaly Kuznetsov X-BeenThere: kvmarm@lists.cs.columbia.edu X-Mailman-Version: 2.1.14 Precedence: list Reply-To: Sean Christopherson List-Id: Where KVM/ARM decisions are made List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Errors-To: kvmarm-bounces@lists.cs.columbia.edu Sender: kvmarm-bounces@lists.cs.columbia.edu From: Maciej S. Szmigiero There is no need to copy the whole memslot data after releasing slots_arch_lock for a moment to install temporary memslots copy in kvm_set_memslot() since this lock only protects the arch field of each memslot. Just resync this particular field after reacquiring slots_arch_lock. Note, this also eliminates the need to manually clear the INVALID flag when restoring memslots; the "setting" of the INVALID flag was an unwanted side effect of copying the entire memslots. Signed-off-by: Maciej S. Szmigiero [sean: tweak shortlog, note INVALID flag in changelog, revert comment] Signed-off-by: Sean Christopherson --- virt/kvm/kvm_main.c | 45 +++++++++++++++++++++++++-------------------- 1 file changed, 25 insertions(+), 20 deletions(-) diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c index 6171ddb3e31c..e5c2d10f6111 100644 --- a/virt/kvm/kvm_main.c +++ b/virt/kvm/kvm_main.c @@ -1500,12 +1500,6 @@ static size_t kvm_memslots_size(int slots) (sizeof(struct kvm_memory_slot) * slots); } -static void kvm_copy_memslots(struct kvm_memslots *to, - struct kvm_memslots *from) -{ - memcpy(to, from, kvm_memslots_size(from->used_slots)); -} - /* * Note, at a minimum, the current number of used slots must be allocated, even * when deleting a memslot, as we need a complete duplicate of the memslots for @@ -1524,11 +1518,22 @@ static struct kvm_memslots *kvm_dup_memslots(struct kvm_memslots *old, slots = kvzalloc(new_size, GFP_KERNEL_ACCOUNT); if (likely(slots)) - kvm_copy_memslots(slots, old); + memcpy(slots, old, kvm_memslots_size(old->used_slots)); return slots; } +static void kvm_copy_memslots_arch(struct kvm_memslots *to, + struct kvm_memslots *from) +{ + int i; + + WARN_ON_ONCE(to->used_slots != from->used_slots); + + for (i = 0; i < from->used_slots; i++) + to->memslots[i].arch = from->memslots[i].arch; +} + static int kvm_set_memslot(struct kvm *kvm, const struct kvm_userspace_memory_region *mem, struct kvm_memory_slot *new, int as_id, @@ -1569,9 +1574,10 @@ static int kvm_set_memslot(struct kvm *kvm, slot->flags |= KVM_MEMSLOT_INVALID; /* - * We can re-use the memory from the old memslots. - * It will be overwritten with a copy of the new memslots - * after reacquiring the slots_arch_lock below. + * We can re-use the old memslots, the only difference from the + * newly installed memslots is the invalid flag, which will get + * dropped by update_memslots anyway. We'll also revert to the + * old memslots if preparing the new memory region fails. */ slots = install_new_memslots(kvm, as_id, slots); @@ -1588,12 +1594,14 @@ static int kvm_set_memslot(struct kvm *kvm, mutex_lock(&kvm->slots_arch_lock); /* - * The arch-specific fields of the memslots could have changed - * between releasing the slots_arch_lock in - * install_new_memslots and here, so get a fresh copy of the - * slots. + * The arch-specific fields of the now-active memslots could + * have been modified between releasing slots_arch_lock in + * install_new_memslots and re-acquiring slots_arch_lock above. + * Copy them to the inactive memslots. Arch code is required + * to retrieve memslots *after* acquiring slots_arch_lock, thus + * the active memslots are guaranteed to be fresh. */ - kvm_copy_memslots(slots, __kvm_memslots(kvm, as_id)); + kvm_copy_memslots_arch(slots, __kvm_memslots(kvm, as_id)); } /* @@ -1642,13 +1650,10 @@ static int kvm_set_memslot(struct kvm *kvm, return 0; out_slots: - if (change == KVM_MR_DELETE || change == KVM_MR_MOVE) { - slot = id_to_memslot(slots, new->id); - slot->flags &= ~KVM_MEMSLOT_INVALID; + if (change == KVM_MR_DELETE || change == KVM_MR_MOVE) slots = install_new_memslots(kvm, as_id, slots); - } else { + else mutex_unlock(&kvm->slots_arch_lock); - } kvfree(slots); return r; } -- 2.33.1.1089.g2158813163f-goog _______________________________________________ kvmarm mailing list kvmarm@lists.cs.columbia.edu https://lists.cs.columbia.edu/mailman/listinfo/kvmarm