linux-kernel - [PATCH v2 5/7] KVM: mmu: Refactor memslot copy

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-Id: <20210429211833.3361994-6-bgardon@google.com>
Date:   Thu, 29 Apr 2021 14:18:31 -0700
From:   Ben Gardon <bgardon@...gle.com>
To:     linux-kernel@...r.kernel.org, kvm@...r.kernel.org
Cc:     Paolo Bonzini <pbonzini@...hat.com>, Peter Xu <peterx@...hat.com>,
        Sean Christopherson <seanjc@...gle.com>,
        Peter Shier <pshier@...gle.com>,
        Junaid Shahid <junaids@...gle.com>,
        Jim Mattson <jmattson@...gle.com>,
        Yulei Zhang <yulei.kernel@...il.com>,
        Wanpeng Li <kernellwp@...il.com>,
        Vitaly Kuznetsov <vkuznets@...hat.com>,
        Xiao Guangrong <xiaoguangrong.eric@...il.com>,
        Ben Gardon <bgardon@...gle.com>
Subject: [PATCH v2 5/7] KVM: mmu: Refactor memslot copy

Factor out copying kvm_memslots from allocating the memory for new ones
in preparation for adding a new lock to protect the arch-specific fields
of the memslots.

No functional change intended.

Signed-off-by: Ben Gardon <bgardon@...gle.com>
---
 virt/kvm/kvm_main.c | 23 ++++++++++++++++-------
 1 file changed, 16 insertions(+), 7 deletions(-)

diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c
index 2799c6660cce..c8010f55e368 100644
--- a/virt/kvm/kvm_main.c
+++ b/virt/kvm/kvm_main.c
@@ -1306,6 +1306,18 @@ static struct kvm_memslots *install_new_memslots(struct kvm *kvm,
 	return old_memslots;
 }
 
+static size_t kvm_memslots_size(int slots)
+{
+	return sizeof(struct kvm_memslots) +
+	       (sizeof(struct kvm_memory_slot) * slots);
+}
+
+static void kvm_copy_memslots(struct kvm_memslots *from,
+			      struct kvm_memslots *to)
+{
+	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
@@ -1315,19 +1327,16 @@ static struct kvm_memslots *kvm_dup_memslots(struct kvm_memslots *old,
 					     enum kvm_mr_change change)
 {
 	struct kvm_memslots *slots;
-	size_t old_size, new_size;
-
-	old_size = sizeof(struct kvm_memslots) +
-		   (sizeof(struct kvm_memory_slot) * old->used_slots);
+	size_t new_size;
 
 	if (change == KVM_MR_CREATE)
-		new_size = old_size + sizeof(struct kvm_memory_slot);
+		new_size = kvm_memslots_size(old->used_slots + 1);
 	else
-		new_size = old_size;
+		new_size = kvm_memslots_size(old->used_slots);
 
 	slots = kvzalloc(new_size, GFP_KERNEL_ACCOUNT);
 	if (likely(slots))
-		memcpy(slots, old, old_size);
+		kvm_copy_memslots(old, slots);
 
 	return slots;
 }
-- 
2.31.1.527.g47e6f16901-goog