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

Pull kvm updates from Paolo Bonzini:
 "The bulk of the changes here is a largish change to guest_memfd,
  delaying the clearing and encryption of guest-private pages until they
  are actually added to guest page tables. This started as "let's make
  it impossible to misuse the API" for SEV-SNP; but then it ballooned a
  bit.

  The new logic is generally simpler and more ready for hugepage support
  in guest_memfd.

  Summary:

   - fix latent bug in how usage of large pages is determined for
     confidential VMs

   - fix "underline too short" in docs

   - eliminate log spam from limited APIC timer periods

   - disallow pre-faulting of memory before SEV-SNP VMs are initialized

   - delay clearing and encrypting private memory until it is added to
     guest page tables

   - this change also enables another small cleanup: the checks in
     SNP_LAUNCH_UPDATE that limit it to non-populated, private pages can
     now be moved in the common kvm_gmem_populate() function

   - fix compilation error that the RISC-V merge introduced in selftests"

* tag 'for-linus' of git://git.kernel.org/pub/scm/virt/kvm/kvm:
  KVM: x86/mmu: fix determination of max NPT mapping level for private pages
  KVM: riscv: selftests: Fix compile error
  KVM: guest_memfd: abstract how prepared folios are recorded
  KVM: guest_memfd: let kvm_gmem_populate() operate only on private gfns
  KVM: extend kvm_range_has_memory_attributes() to check subset of attributes
  KVM: cleanup and add shortcuts to kvm_range_has_memory_attributes()
  KVM: guest_memfd: move check for already-populated page to common code
  KVM: remove kvm_arch_gmem_prepare_needed()
  KVM: guest_memfd: make kvm_gmem_prepare_folio() operate on a single struct kvm
  KVM: guest_memfd: delay kvm_gmem_prepare_folio() until the memory is passed to the guest
  KVM: guest_memfd: return locked folio from __kvm_gmem_get_pfn
  KVM: rename CONFIG_HAVE_KVM_GMEM_* to CONFIG_HAVE_KVM_ARCH_GMEM_*
  KVM: guest_memfd: do not go through struct page
  KVM: guest_memfd: delay folio_mark_uptodate() until after successful preparation
  KVM: guest_memfd: return folio from __kvm_gmem_get_pfn()
  KVM: x86: disallow pre-fault for SNP VMs before initialization
  KVM: Documentation: Fix title underline too short warning
  KVM: x86: Eliminate log spam from limited APIC timer periods

1 files changed, 7 insertions, 1 deletions

diff --git a/Documentation/virt/kvm/api.rst b/Documentation/virt/kvm/api.rst
index fe722c5dada9..33938468d62d 100644
--- a/Documentation/virt/kvm/api.rst
+++ b/Documentation/virt/kvm/api.rst
@@ -6368,7 +6368,7 @@ a single guest_memfd file, but the bound ranges must not overlap).
 See KVM_SET_USER_MEMORY_REGION2 for additional details.
 
 4.143 KVM_PRE_FAULT_MEMORY
-------------------------
+---------------------------
 
 :Capability: KVM_CAP_PRE_FAULT_MEMORY
 :Architectures: none
@@ -6405,6 +6405,12 @@ for the current vCPU state.  KVM maps memory as if the vCPU generated a
 stage-2 read page fault, e.g. faults in memory as needed, but doesn't break
 CoW.  However, KVM does not mark any newly created stage-2 PTE as Accessed.
 
+In the case of confidential VM types where there is an initial set up of
+private guest memory before the guest is 'finalized'/measured, this ioctl
+should only be issued after completing all the necessary setup to put the
+guest into a 'finalized' state so that the above semantics can be reliably
+ensured.
+
 In some cases, multiple vCPUs might share the page tables.  In this
 case, the ioctl can be called in parallel.