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authorSean Christopherson <sean.j.christopherson@intel.com>2020-02-18 13:07:31 -0800
committerPaolo Bonzini <pbonzini@redhat.com>2020-03-16 17:57:26 +0100
commit0577d1abe704c315bb5cdfc71f4ca7b9b5358f59 (patch)
tree8040b969d89f86242bc5699dd4ecc1534f47d795 /virt/kvm/arm
parent2a49f61dfcdc25ec06b41f7466ccb94a7a9d2624 (diff)
KVM: Terminate memslot walks via used_slots
Refactor memslot handling to treat the number of used slots as the de facto size of the memslot array, e.g. return NULL from id_to_memslot() when an invalid index is provided instead of relying on npages==0 to detect an invalid memslot. Rework the sorting and walking of memslots in advance of dynamically sizing memslots to aid bisection and debug, e.g. with luck, a bug in the refactoring will bisect here and/or hit a WARN instead of randomly corrupting memory. Alternatively, a global null/invalid memslot could be returned, i.e. so callers of id_to_memslot() don't have to explicitly check for a NULL memslot, but that approach runs the risk of introducing difficult-to- debug issues, e.g. if the global null slot is modified. Constifying the return from id_to_memslot() to combat such issues is possible, but would require a massive refactoring of arch specific code and would still be susceptible to casting shenanigans. Add function comments to update_memslots() and search_memslots() to explicitly (and loudly) state how memslots are sorted. Opportunistically stuff @hva with a non-canonical value when deleting a private memslot on x86 to detect bogus usage of the freed slot. No functional change intended. Tested-by: Christoffer Dall <christoffer.dall@arm.com> Tested-by: Marc Zyngier <maz@kernel.org> Signed-off-by: Sean Christopherson <sean.j.christopherson@intel.com> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Diffstat (limited to 'virt/kvm/arm')
-rw-r--r--virt/kvm/arm/mmu.c9
1 files changed, 7 insertions, 2 deletions
diff --git a/virt/kvm/arm/mmu.c b/virt/kvm/arm/mmu.c
index 8f22efa095f4..e3b9ee268823 100644
--- a/virt/kvm/arm/mmu.c
+++ b/virt/kvm/arm/mmu.c
@@ -1534,8 +1534,13 @@ void kvm_mmu_wp_memory_region(struct kvm *kvm, int slot)
{
struct kvm_memslots *slots = kvm_memslots(kvm);
struct kvm_memory_slot *memslot = id_to_memslot(slots, slot);
- phys_addr_t start = memslot->base_gfn << PAGE_SHIFT;
- phys_addr_t end = (memslot->base_gfn + memslot->npages) << PAGE_SHIFT;
+ phys_addr_t start, end;
+
+ if (WARN_ON_ONCE(!memslot))
+ return;
+
+ start = memslot->base_gfn << PAGE_SHIFT;
+ end = (memslot->base_gfn + memslot->npages) << PAGE_SHIFT;
spin_lock(&kvm->mmu_lock);
stage2_wp_range(kvm, start, end);