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spf=none smtp.mailfrom=linux-arm-kernel-bounces+patchwork-linux-arm=patchwork.kernel.org@lists.infradead.org DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=bombadil.20170209; h=Sender: Content-Transfer-Encoding:Content-Type:Cc:List-Subscribe:List-Help:List-Post: List-Archive:List-Unsubscribe:List-Id:MIME-Version:References:In-Reply-To: Message-Id:Date:Subject:To:From:Reply-To:Content-ID:Content-Description: Resent-Date:Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID: List-Owner; bh=vSwX4YfNP7ZwBk8/o0h6YGeT6d+eAMUavuku8DfQXy0=; b=IyKqIrz7R0B1Zd 4IqFOF4AXOtL+nhTbGy6gVaQpSsdk0rQPG6Ge7BO69JbWQSOiUEh/WJazeTw2NK2wPN9dZwlNddFd il5/J3jSFtgVQ2bN0GeXFMy4tebm8k7N+L2BSkjrVHh3ABLaIvcmQVStNHL9WRnVHGrvNEHmi5hKs 927+/3AZhDpr/iTS81FJ4duJOBRl54Val2cf0lFABt8z1GBUPCdLe81NJqTBdu9Wm0/98w8mQxpal dZzm+lJU726202WCeuMlhfnlndUHIRVUl3Vj/16mQgS+FJ/xu2aOoV01KOzqx7oX/2sQvY9dauOdZ 1waih5gWxNknm9NKSFcw==; Received: from localhost ([127.0.0.1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.92.3 #3 (Red Hat Linux)) id 1j4A6d-0001kQ-3B; Tue, 18 Feb 2020 21:08:35 +0000 Received: from mga14.intel.com ([192.55.52.115]) by bombadil.infradead.org with esmtps (Exim 4.92.3 #3 (Red Hat Linux)) id 1j4A5r-0000zb-0G for linux-arm-kernel@lists.infradead.org; Tue, 18 Feb 2020 21:07:49 +0000 X-Amp-Result: SKIPPED(no attachment in message) X-Amp-File-Uploaded: False Received: from orsmga002.jf.intel.com ([10.7.209.21]) by fmsmga103.fm.intel.com with ESMTP/TLS/DHE-RSA-AES256-GCM-SHA384; 18 Feb 2020 13:07:46 -0800 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.70,457,1574150400"; d="scan'208";a="253856443" Received: from sjchrist-coffee.jf.intel.com ([10.54.74.202]) by orsmga002.jf.intel.com with ESMTP; 18 Feb 2020 13:07:46 -0800 From: Sean Christopherson To: Paolo Bonzini Subject: [PATCH v6 14/22] KVM: Clean up local variable usage in __kvm_set_memory_region() Date: Tue, 18 Feb 2020 13:07:28 -0800 Message-Id: <20200218210736.16432-15-sean.j.christopherson@intel.com> X-Mailer: git-send-email 2.24.1 In-Reply-To: <20200218210736.16432-1-sean.j.christopherson@intel.com> References: <20200218210736.16432-1-sean.j.christopherson@intel.com> MIME-Version: 1.0 X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20200218_130747_049807_5FAFF978 X-CRM114-Status: GOOD ( 18.25 ) X-Spam-Score: -5.0 (-----) X-Spam-Report: SpamAssassin version 3.4.3 on bombadil.infradead.org summary: Content analysis details: (-5.0 points) pts rule name description ---- ---------------------- -------------------------------------------------- -5.0 RCVD_IN_DNSWL_HI RBL: Sender listed at https://www.dnswl.org/, high trust [192.55.52.115 listed in list.dnswl.org] -0.0 SPF_PASS SPF: sender matches SPF record 0.0 SPF_HELO_NONE SPF: HELO does not publish an SPF Record X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: Wanpeng Li , kvm@vger.kernel.org, David Hildenbrand , Peter Xu , linux-mips@vger.kernel.org, Paul Mackerras , kvmarm@lists.cs.columbia.edu, Janosch Frank , Marc Zyngier , Joerg Roedel , Christian Borntraeger , Julien Thierry , Suzuki K Poulose , kvm-ppc@vger.kernel.org, linux-arm-kernel@lists.infradead.org, Jim Mattson , Cornelia Huck , Christoffer Dall , Sean Christopherson , linux-kernel@vger.kernel.org, James Morse , Vitaly Kuznetsov , =?utf-8?q?Philippe_Mathieu-Daud?= =?utf-8?q?=C3=A9?= Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+patchwork-linux-arm=patchwork.kernel.org@lists.infradead.org Clean up __kvm_set_memory_region() to achieve several goals: - Remove local variables that serve no real purpose - Improve the readability of the code - Better show the relationship between the 'old' and 'new' memslot - Prepare for dynamically sizing memslots - Document subtle gotchas (via comments) Note, using 'tmp' to hold the initial memslot is not strictly necessary at this juncture, e.g. 'old' could be directly copied from id_to_memslot(), but keep the pointer usage as id_to_memslot() will be able to return a NULL pointer once memslots are dynamically sized. Signed-off-by: Sean Christopherson --- virt/kvm/kvm_main.c | 50 +++++++++++++++++++++++---------------------- 1 file changed, 26 insertions(+), 24 deletions(-) diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c index 1ef5e04f7b93..00ece4a5cdbb 100644 --- a/virt/kvm/kvm_main.c +++ b/virt/kvm/kvm_main.c @@ -1071,13 +1071,11 @@ static int kvm_delete_memslot(struct kvm *kvm, int __kvm_set_memory_region(struct kvm *kvm, const struct kvm_userspace_memory_region *mem) { - int r; - gfn_t base_gfn; - unsigned long npages; - struct kvm_memory_slot *slot; struct kvm_memory_slot old, new; - int as_id, id; + struct kvm_memory_slot *tmp; enum kvm_mr_change change; + int as_id, id; + int r; r = check_memory_region_flags(mem); if (r) @@ -1102,54 +1100,58 @@ int __kvm_set_memory_region(struct kvm *kvm, if (mem->guest_phys_addr + mem->memory_size < mem->guest_phys_addr) return -EINVAL; - slot = id_to_memslot(__kvm_memslots(kvm, as_id), id); - base_gfn = mem->guest_phys_addr >> PAGE_SHIFT; - npages = mem->memory_size >> PAGE_SHIFT; - - if (npages > KVM_MEM_MAX_NR_PAGES) - return -EINVAL; - /* * Make a full copy of the old memslot, the pointer will become stale * when the memslots are re-sorted by update_memslots(), and the old * memslot needs to be referenced after calling update_memslots(), e.g. - * to free its resources and for arch specific behavior. + * to free its resources and for arch specific behavior. Kill @tmp + * after making a copy to deter potentially dangerous usage. */ - old = *slot; + tmp = id_to_memslot(__kvm_memslots(kvm, as_id), id); + old = *tmp; + tmp = NULL; + if (!mem->memory_size) return kvm_delete_memslot(kvm, mem, &old, as_id); - new = old; - new.id = id; - new.base_gfn = base_gfn; - new.npages = npages; + new.base_gfn = mem->guest_phys_addr >> PAGE_SHIFT; + new.npages = mem->memory_size >> PAGE_SHIFT; new.flags = mem->flags; new.userspace_addr = mem->userspace_addr; + if (new.npages > KVM_MEM_MAX_NR_PAGES) + return -EINVAL; + if (!old.npages) { change = KVM_MR_CREATE; + new.dirty_bitmap = NULL; + memset(&new.arch, 0, sizeof(new.arch)); } else { /* Modify an existing slot. */ if ((new.userspace_addr != old.userspace_addr) || - (npages != old.npages) || + (new.npages != old.npages) || ((new.flags ^ old.flags) & KVM_MEM_READONLY)) return -EINVAL; - if (base_gfn != old.base_gfn) + if (new.base_gfn != old.base_gfn) change = KVM_MR_MOVE; else if (new.flags != old.flags) change = KVM_MR_FLAGS_ONLY; else /* Nothing to change. */ return 0; + + /* Copy dirty_bitmap and arch from the current memslot. */ + new.dirty_bitmap = old.dirty_bitmap; + memcpy(&new.arch, &old.arch, sizeof(new.arch)); } if ((change == KVM_MR_CREATE) || (change == KVM_MR_MOVE)) { /* Check for overlaps */ - kvm_for_each_memslot(slot, __kvm_memslots(kvm, as_id)) { - if (slot->id == id) + kvm_for_each_memslot(tmp, __kvm_memslots(kvm, as_id)) { + if (tmp->id == id) continue; - if (!((base_gfn + npages <= slot->base_gfn) || - (base_gfn >= slot->base_gfn + slot->npages))) + if (!((new.base_gfn + new.npages <= tmp->base_gfn) || + (new.base_gfn >= tmp->base_gfn + tmp->npages))) return -EEXIST; } }