Merge branch kvm-arm64/mte-map-shared into kvmarm-master/next

* kvm-arm64/mte-map-shared:
  : .
  : Update the MTE support to allow the VMM to use shared mappings
  : to back the memslots exposed to MTE-enabled guests.
  :
  : Patches courtesy of Catalin Marinas and Peter Collingbourne.
  : .
  : Fix a number of issues with MTE, such as races on the tags
  : being initialised vs the PG_mte_tagged flag as well as the
  : lack of support for VM_SHARED when KVM is involved.
  :
  : Patches from Catalin Marinas and Peter Collingbourne.
  : .
  Documentation: document the ABI changes for KVM_CAP_ARM_MTE
  KVM: arm64: permit all VM_MTE_ALLOWED mappings with MTE enabled
  KVM: arm64: unify the tests for VMAs in memslots when MTE is enabled
  arm64: mte: Lock a page for MTE tag initialisation
  mm: Add PG_arch_3 page flag
  KVM: arm64: Simplify the sanitise_mte_tags() logic
  arm64: mte: Fix/clarify the PG_mte_tagged semantics
  mm: Do not enable PG_arch_2 for all 64-bit architectures

Signed-off-by: Marc Zyngier <maz@kernel.org>

1 files changed, 10 insertions, 11 deletions

diff --git a/arch/arm64/kernel/mte.c b/arch/arm64/kernel/mte.c
index 7467217c1eaf..f5bcb0dc6267 100644
--- a/arch/arm64/kernel/mte.c
+++ b/arch/arm64/kernel/mte.c
@@ -41,19 +41,17 @@ static void mte_sync_page_tags(struct page *page, pte_t old_pte,
 	if (check_swap && is_swap_pte(old_pte)) {
 		swp_entry_t entry = pte_to_swp_entry(old_pte);
 
-		if (!non_swap_entry(entry) && mte_restore_tags(entry, page))
-			return;
+		if (!non_swap_entry(entry))
+			mte_restore_tags(entry, page);
 	}
 
 	if (!pte_is_tagged)
 		return;
 
-	/*
-	 * Test PG_mte_tagged again in case it was racing with another
-	 * set_pte_at().
-	 */
-	if (!test_and_set_bit(PG_mte_tagged, &page->flags))
+	if (try_page_mte_tagging(page)) {
 		mte_clear_page_tags(page_address(page));
+		set_page_mte_tagged(page);
+	}
 }
 
 void mte_sync_tags(pte_t old_pte, pte_t pte)
@@ -69,9 +67,11 @@ void mte_sync_tags(pte_t old_pte, pte_t pte)
 
 	/* if PG_mte_tagged is set, tags have already been initialised */
 	for (i = 0; i < nr_pages; i++, page++) {
-		if (!test_bit(PG_mte_tagged, &page->flags))
+		if (!page_mte_tagged(page)) {
 			mte_sync_page_tags(page, old_pte, check_swap,
 					   pte_is_tagged);
+			set_page_mte_tagged(page);
+		}
 	}
 
 	/* ensure the tags are visible before the PTE is set */
@@ -96,8 +96,7 @@ int memcmp_pages(struct page *page1, struct page *page2)
 	 * pages is tagged, set_pte_at() may zero or change the tags of the
 	 * other page via mte_sync_tags().
 	 */
-	if (test_bit(PG_mte_tagged, &page1->flags) ||
-	    test_bit(PG_mte_tagged, &page2->flags))
+	if (page_mte_tagged(page1) || page_mte_tagged(page2))
 		return addr1 != addr2;
 
 	return ret;
@@ -454,7 +453,7 @@ static int __access_remote_tags(struct mm_struct *mm, unsigned long addr,
 			put_page(page);
 			break;
 		}
-		WARN_ON_ONCE(!test_bit(PG_mte_tagged, &page->flags));
+		WARN_ON_ONCE(!page_mte_tagged(page));
 
 		/* limit access to the end of the page */
 		offset = offset_in_page(addr);