diff mbox series

[RFC,v5,09/38] KVM: arm64: Deny changes to locked memslots

Message ID 20211117153842.302159-10-alexandru.elisei@arm.com (mailing list archive)
State New, archived
Headers show
Series KVM: arm64: Add Statistical Profiling Extension (SPE) support | expand

Commit Message

Alexandru Elisei Nov. 17, 2021, 3:38 p.m. UTC 
Forbid userspace from making changes to a locked memslot. If userspace
wants to modify a locked memslot, then they will need to unlock it.

One special case is allowed: memslots locked for read, but not for write,
can have dirty page logging turned on.

Signed-off-by: Alexandru Elisei <alexandru.elisei@arm.com>
---
 arch/arm64/kvm/mmu.c | 15 +++++++++++++++
 1 file changed, 15 insertions(+)
diff mbox series

Patch

diff --git a/arch/arm64/kvm/mmu.c b/arch/arm64/kvm/mmu.c
index 072e2aba371f..bc2a546f65c3 100644
--- a/arch/arm64/kvm/mmu.c
+++ b/arch/arm64/kvm/mmu.c
@@ -1890,8 +1890,23 @@  int kvm_arch_prepare_memory_region(struct kvm *kvm,
 {
 	hva_t hva = mem->userspace_addr;
 	hva_t reg_end = hva + mem->memory_size;
+	struct kvm_memory_slot *old;
 	int ret = 0;
 
+	/*
+	 * Forbid all changes to locked memslots with the exception of turning
+	 * on dirty page logging for memslots locked only for reads.
+	 */
+	old = id_to_memslot(kvm_memslots(kvm), memslot->id);
+	if (old && memslot_is_locked(old)) {
+		if (change == KVM_MR_FLAGS_ONLY &&
+		    memslot_is_logging(memslot) &&
+		    !(old->arch.flags & KVM_MEMSLOT_LOCK_WRITE))
+			memcpy(&memslot->arch, &old->arch, sizeof(old->arch));
+		else
+			return -EBUSY;
+	}
+
 	if (change != KVM_MR_CREATE && change != KVM_MR_MOVE &&
 			change != KVM_MR_FLAGS_ONLY)
 		return 0;