@@ -38,6 +38,7 @@ menuconfig KVM
select HAVE_KVM_VCPU_RUN_PID_CHANGE
select SCHED_INFO
select GUEST_PERF_EVENTS if PERF_EVENTS
+ select HAVE_KVM_USERFAULT
help
Support hosting virtualized guest machines.
@@ -1493,7 +1493,7 @@ static int user_mem_abort(struct kvm_vcpu *vcpu, phys_addr_t fault_ipa,
* logging_active is guaranteed to never be true for VM_PFNMAP
* memslots.
*/
- if (logging_active) {
+ if (logging_active || kvm_memslot_userfault(memslot)) {
force_pte = true;
vma_shift = PAGE_SHIFT;
} else {
@@ -1582,6 +1582,13 @@ static int user_mem_abort(struct kvm_vcpu *vcpu, phys_addr_t fault_ipa,
mmu_seq = vcpu->kvm->mmu_invalidate_seq;
mmap_read_unlock(current->mm);
+ if (kvm_gfn_userfault(kvm, memslot, gfn)) {
+ kvm_prepare_memory_fault_exit(vcpu, gfn << PAGE_SHIFT,
+ PAGE_SIZE, write_fault,
+ exec_fault, false, true);
+ return -EFAULT;
+ }
+
pfn = __kvm_faultin_pfn(memslot, gfn, write_fault ? FOLL_WRITE : 0,
&writable, &page);
if (pfn == KVM_PFN_ERR_HWPOISON) {
@@ -2073,6 +2080,23 @@ void kvm_arch_commit_memory_region(struct kvm *kvm,
enum kvm_mr_change change)
{
bool log_dirty_pages = new && new->flags & KVM_MEM_LOG_DIRTY_PAGES;
+ u32 new_flags = new ? new->flags : 0;
+ u32 changed_flags = (new_flags) ^ (old ? old->flags : 0);
+
+ /*
+ * If KVM_MEM_USERFAULT has been enabled, drop all the stage-2 mappings
+ * so that we can respect userfault-ness.
+ */
+ if ((changed_flags & KVM_MEM_USERFAULT) &&
+ (new_flags & KVM_MEM_USERFAULT) &&
+ change == KVM_MR_FLAGS_ONLY)
+ kvm_arch_flush_shadow_memslot(kvm, old);
+
+ /*
+ * Nothing left to do if not toggling dirty logging.
+ */
+ if (!(changed_flags & KVM_MEM_LOG_DIRTY_PAGES))
+ return;
/*
* At this point memslot has been committed and there is an
Adhering to the requirements of KVM Userfault: 1. When it is toggled on, zap the second stage with kvm_arch_flush_shadow_memslot(). This is to respect userfault-ness. 2. When KVM_MEM_USERFAULT is enabled, restrict new second-stage mappings to be PAGE_SIZE, just like when dirty logging is enabled. Do not zap the second stage when KVM_MEM_USERFAULT is disabled to remain consistent with the behavior when dirty logging is disabled. Signed-off-by: James Houghton <jthoughton@google.com> --- arch/arm64/kvm/Kconfig | 1 + arch/arm64/kvm/mmu.c | 26 +++++++++++++++++++++++++- 2 files changed, 26 insertions(+), 1 deletion(-)