Merge tag 'for-linus' of git://git.kernel.org/pub/scm/virt/kvm/kvm

Pull kvm fixes from Paolo Bonzini:
 "Bugfixes, including a TLB flush fix that affects processors without
  nested page tables"

* tag 'for-linus' of git://git.kernel.org/pub/scm/virt/kvm/kvm:
  kvm: fix previous commit for 32-bit builds
  kvm: avoid speculation-based attacks from out-of-range memslot accesses
  KVM: x86: Unload MMU on guest TLB flush if TDP disabled to force MMU sync
  KVM: x86: Ensure liveliness of nested VM-Enter fail tracepoint message
  selftests: kvm: Add support for customized slot0 memory size
  KVM: selftests: introduce P47V64 for s390x
  KVM: x86: Ensure PV TLB flush tracepoint reflects KVM behavior
  KVM: X86: MMU: Use the correct inherited permissions to get shadow page
  KVM: LAPIC: Write 0 to TMICT should also cancel vmx-preemption timer
  KVM: SVM: Fix SEV SEND_START session length & SEND_UPDATE_DATA query length after commit 238eca821cee

1 files changed, 9 insertions, 1 deletions

diff --git a/include/linux/kvm_host.h b/include/linux/kvm_host.h
index 76102efbf079..8583ed3ff344 100644
--- a/include/linux/kvm_host.h
+++ b/include/linux/kvm_host.h
@@ -1185,7 +1185,15 @@ __gfn_to_memslot(struct kvm_memslots *slots, gfn_t gfn)
 static inline unsigned long
 __gfn_to_hva_memslot(const struct kvm_memory_slot *slot, gfn_t gfn)
 {
-	return slot->userspace_addr + (gfn - slot->base_gfn) * PAGE_SIZE;
+	/*
+	 * The index was checked originally in search_memslots.  To avoid
+	 * that a malicious guest builds a Spectre gadget out of e.g. page
+	 * table walks, do not let the processor speculate loads outside
+	 * the guest's registered memslots.
+	 */
+	unsigned long offset = gfn - slot->base_gfn;
+	offset = array_index_nospec(offset, slot->npages);
+	return slot->userspace_addr + offset * PAGE_SIZE;
 }
 
 static inline int memslot_id(struct kvm *kvm, gfn_t gfn)