linux-kernel - [PATCH v2 11/23] KVM: selftests: Make sure vm->vpages

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Message-ID: <20251021074736.1324328-12-yosry.ahmed@linux.dev>
Date: Tue, 21 Oct 2025 07:47:24 +0000
From: Yosry Ahmed <yosry.ahmed@...ux.dev>
To: Sean Christopherson <seanjc@...gle.com>
Cc: Paolo Bonzini <pbonzini@...hat.com>,
	Jim Mattson <jmattson@...gle.com>,
	kvm@...r.kernel.org,
	linux-kernel@...r.kernel.org,
	Yosry Ahmed <yosry.ahmed@...ux.dev>
Subject: [PATCH v2 11/23] KVM: selftests: Make sure vm->vpages_mapped is always up-to-date

Call paths leading to __virt_pg_map() are currently:
(a) virt_pg_map() -> virt_arch_pg_map() -> __virt_pg_map()
(b) virt_map_level() -> __virt_pg_map()

For (a), calls to virt_pg_map() from kvm_util.c make sure they update
vm->vpages_mapped, but other callers do not. Move the sparsebit_set()
call into virt_pg_map() to make sure all callers are captured.

For (b), call sparsebit_set_num() from virt_map_level().

It's tempting to have a single the call inside __virt_pg_map(), however:
- The call path in (a) is not x86-specific, while (b) is. Moving the
  call into __virt_pg_map() would require doing something similar for
  other archs implementing virt_pg_map().

- Incoming changes will reusue __virt_pg_map() for nested PTEs, which
  should not update vm->vpages_mapped. This means we'd need to break out
  a triple underscore version that does not update vm->vpages_mapped.

Signed-off-by: Yosry Ahmed <yosry.ahmed@...ux.dev>
---
 tools/testing/selftests/kvm/include/kvm_util.h  | 1 +
 tools/testing/selftests/kvm/lib/kvm_util.c      | 3 ---
 tools/testing/selftests/kvm/lib/x86/processor.c | 2 ++
 3 files changed, 3 insertions(+), 3 deletions(-)

diff --git a/tools/testing/selftests/kvm/include/kvm_util.h b/tools/testing/selftests/kvm/include/kvm_util.h
index bcbcfb4deb9a2..15c69af11a684 100644
--- a/tools/testing/selftests/kvm/include/kvm_util.h
+++ b/tools/testing/selftests/kvm/include/kvm_util.h
@@ -1206,6 +1206,7 @@ void virt_arch_pg_map(struct kvm_vm *vm, uint64_t vaddr, uint64_t paddr);
 static inline void virt_pg_map(struct kvm_vm *vm, uint64_t vaddr, uint64_t paddr)
 {
 	virt_arch_pg_map(vm, vaddr, paddr);
+	sparsebit_set(vm->vpages_mapped, vaddr >> vm->page_shift);
 }
 
 
diff --git a/tools/testing/selftests/kvm/lib/kvm_util.c b/tools/testing/selftests/kvm/lib/kvm_util.c
index 5e6b51768f67f..473c533774898 100644
--- a/tools/testing/selftests/kvm/lib/kvm_util.c
+++ b/tools/testing/selftests/kvm/lib/kvm_util.c
@@ -1490,8 +1490,6 @@ static vm_vaddr_t ____vm_vaddr_alloc(struct kvm_vm *vm, size_t sz,
 		pages--, vaddr += vm->page_size, paddr += vm->page_size) {
 
 		virt_pg_map(vm, vaddr, paddr);
-
-		sparsebit_set(vm->vpages_mapped, vaddr >> vm->page_shift);
 	}
 
 	return vaddr_start;
@@ -1605,7 +1603,6 @@ void virt_map(struct kvm_vm *vm, uint64_t vaddr, uint64_t paddr,
 
 	while (npages--) {
 		virt_pg_map(vm, vaddr, paddr);
-		sparsebit_set(vm->vpages_mapped, vaddr >> vm->page_shift);
 
 		vaddr += page_size;
 		paddr += page_size;
diff --git a/tools/testing/selftests/kvm/lib/x86/processor.c b/tools/testing/selftests/kvm/lib/x86/processor.c
index c484e83255c70..4ee9fc844ee66 100644
--- a/tools/testing/selftests/kvm/lib/x86/processor.c
+++ b/tools/testing/selftests/kvm/lib/x86/processor.c
@@ -285,6 +285,8 @@ void virt_map_level(struct kvm_vm *vm, uint64_t vaddr, uint64_t paddr,
 
 	for (i = 0; i < nr_pages; i++) {
 		__virt_pg_map(vm, vaddr, paddr, level);
+		sparsebit_set_num(vm->vpages_mapped, vaddr >> vm->page_shift,
+				  nr_bytes / PAGE_SIZE);
 
 		vaddr += pg_size;
 		paddr += pg_size;
-- 
2.51.0.869.ge66316f041-goog