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

Pull more kvm updates from Paolo Bonzini:
 "This includes the 6.4 changes for RISC-V, and a few bugfix patches for
  other architectures. For x86, this closes a longstanding performance
  issue in the newer and (usually) more scalable page table management
  code.

  RISC-V:
   - ONE_REG interface to enable/disable SBI extensions
   - Zbb extension for Guest/VM
   - AIA CSR virtualization

  x86:
   - Fix a long-standing TDP MMU flaw, where unloading roots on a vCPU
     can result in the root being freed even though the root is
     completely valid and can be reused as-is (with a TLB flush).

  s390:
   - A couple of bugfixes"

* tag 'for-linus' of git://git.kernel.org/pub/scm/virt/kvm/kvm:
  KVM: s390: fix race in gmap_make_secure()
  KVM: s390: pv: fix asynchronous teardown for small VMs
  KVM: x86: Preserve TDP MMU roots until they are explicitly invalidated
  RISC-V: KVM: Virtualize per-HART AIA CSRs
  RISC-V: KVM: Use bitmap for irqs_pending and irqs_pending_mask
  RISC-V: KVM: Add ONE_REG interface for AIA CSRs
  RISC-V: KVM: Implement subtype for CSR ONE_REG interface
  RISC-V: KVM: Initial skeletal support for AIA
  RISC-V: KVM: Drop the _MASK suffix from hgatp.VMID mask defines
  RISC-V: Detect AIA CSRs from ISA string
  RISC-V: Add AIA related CSR defines
  RISC-V: KVM: Allow Zbb extension for Guest/VM
  RISC-V: KVM: Add ONE_REG interface to enable/disable SBI extensions
  RISC-V: KVM: Alphabetize selects
  KVM: RISC-V: Retry fault if vma_lookup() results become invalid

1 files changed, 7 insertions, 0 deletions

diff --git a/arch/s390/mm/gmap.c b/arch/s390/mm/gmap.c
index dfe905c7bd8e..dc90d1eb0d55 100644
--- a/arch/s390/mm/gmap.c
+++ b/arch/s390/mm/gmap.c
@@ -2822,6 +2822,9 @@ EXPORT_SYMBOL_GPL(s390_unlist_old_asce);
  * s390_replace_asce - Try to replace the current ASCE of a gmap with a copy
  * @gmap: the gmap whose ASCE needs to be replaced
  *
+ * If the ASCE is a SEGMENT type then this function will return -EINVAL,
+ * otherwise the pointers in the host_to_guest radix tree will keep pointing
+ * to the wrong pages, causing use-after-free and memory corruption.
  * If the allocation of the new top level page table fails, the ASCE is not
  * replaced.
  * In any case, the old ASCE is always removed from the gmap CRST list.
@@ -2836,6 +2839,10 @@ int s390_replace_asce(struct gmap *gmap)
 
 	s390_unlist_old_asce(gmap);
 
+	/* Replacing segment type ASCEs would cause serious issues */
+	if ((gmap->asce & _ASCE_TYPE_MASK) == _ASCE_TYPE_SEGMENT)
+		return -EINVAL;
+
 	page = alloc_pages(GFP_KERNEL_ACCOUNT, CRST_ALLOC_ORDER);
 	if (!page)
 		return -ENOMEM;