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, 24 insertions, 25 deletions

diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c
index d0788d0a72cc..92901656a0d4 100644
--- a/virt/kvm/kvm_main.c
+++ b/virt/kvm/kvm_main.c
@@ -2398,48 +2398,47 @@ static int kvm_vm_ioctl_clear_dirty_log(struct kvm *kvm,
 #endif /* CONFIG_KVM_GENERIC_DIRTYLOG_READ_PROTECT */
 
 #ifdef CONFIG_KVM_GENERIC_MEMORY_ATTRIBUTES
+static u64 kvm_supported_mem_attributes(struct kvm *kvm)
+{
+	if (!kvm || kvm_arch_has_private_mem(kvm))
+		return KVM_MEMORY_ATTRIBUTE_PRIVATE;
+
+	return 0;
+}
+
 /*
  * Returns true if _all_ gfns in the range [@start, @end) have attributes
- * matching @attrs.
+ * such that the bits in @mask match @attrs.
  */
 bool kvm_range_has_memory_attributes(struct kvm *kvm, gfn_t start, gfn_t end,
-				     unsigned long attrs)
+				     unsigned long mask, unsigned long attrs)
 {
 	XA_STATE(xas, &kvm->mem_attr_array, start);
 	unsigned long index;
-	bool has_attrs;
 	void *entry;
 
-	rcu_read_lock();
+	mask &= kvm_supported_mem_attributes(kvm);
+	if (attrs & ~mask)
+		return false;
 
-	if (!attrs) {
-		has_attrs = !xas_find(&xas, end - 1);
-		goto out;
-	}
+	if (end == start + 1)
+		return (kvm_get_memory_attributes(kvm, start) & mask) == attrs;
+
+	guard(rcu)();
+	if (!attrs)
+		return !xas_find(&xas, end - 1);
 
-	has_attrs = true;
 	for (index = start; index < end; index++) {
 		do {
 			entry = xas_next(&xas);
 		} while (xas_retry(&xas, entry));
 
-		if (xas.xa_index != index || xa_to_value(entry) != attrs) {
-			has_attrs = false;
-			break;
-		}
+		if (xas.xa_index != index ||
+		    (xa_to_value(entry) & mask) != attrs)
+			return false;
 	}
 
-out:
-	rcu_read_unlock();
-	return has_attrs;
-}
-
-static u64 kvm_supported_mem_attributes(struct kvm *kvm)
-{
-	if (!kvm || kvm_arch_has_private_mem(kvm))
-		return KVM_MEMORY_ATTRIBUTE_PRIVATE;
-
-	return 0;
+	return true;
 }
 
 static __always_inline void kvm_handle_gfn_range(struct kvm *kvm,
@@ -2534,7 +2533,7 @@ static int kvm_vm_set_mem_attributes(struct kvm *kvm, gfn_t start, gfn_t end,
 	mutex_lock(&kvm->slots_lock);
 
 	/* Nothing to do if the entire range as the desired attributes. */
-	if (kvm_range_has_memory_attributes(kvm, start, end, attributes))
+	if (kvm_range_has_memory_attributes(kvm, start, end, ~0, attributes))
 		goto out_unlock;
 
 	/*