linux-kernel - [PATCH v2 20/23] KVM: selftests: Stop passing a memslot to nested_map

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Message-ID: <20251021074736.1324328-21-yosry.ahmed@linux.dev>
Date: Tue, 21 Oct 2025 07:47:33 +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 20/23] KVM: selftests: Stop passing a memslot to nested_map_memslot()

On x86, KVM selftests use memslot 0 for all the default regions used by
the test infrastructure. This is an implementation detail.
nested_map_memslot() is currently used to map the default regions by
explicitly passing slot 0, which leaks the library implementation into
the caller.

Rename the function to a very verbose
nested_identity_map_default_memslots() to reflect what it actually does.
Add an assertion that only memslot 0 is being used so that the
implementation does not change from under us.

No functional change intended.

Signed-off-by: Yosry Ahmed <yosry.ahmed@...ux.dev>
---
 tools/testing/selftests/kvm/include/x86/processor.h  |  3 +--
 tools/testing/selftests/kvm/lib/x86/processor.c      | 11 +++++++----
 tools/testing/selftests/kvm/x86/vmx_dirty_log_test.c |  2 +-
 3 files changed, 9 insertions(+), 7 deletions(-)

diff --git a/tools/testing/selftests/kvm/include/x86/processor.h b/tools/testing/selftests/kvm/include/x86/processor.h
index 13e8f4a1f589d..2608152b2fa27 100644
--- a/tools/testing/selftests/kvm/include/x86/processor.h
+++ b/tools/testing/selftests/kvm/include/x86/processor.h
@@ -1459,8 +1459,7 @@ void virt_map_level(struct kvm_vm *vm, uint64_t vaddr, uint64_t paddr,
 
 void nested_map(struct kvm_vm *vm, vm_paddr_t root_gpa,
 		 uint64_t nested_paddr, uint64_t paddr, uint64_t size);
-void nested_map_memslot(struct kvm_vm *vm, vm_paddr_t root_gpa,
-			uint32_t memslot);
+void nested_identity_map_default_memslots(struct kvm_vm *vm, vm_paddr_t root_gpa);
 void nested_identity_map_1g(struct kvm_vm *vm, vm_paddr_t root_gpa,
 			    uint64_t addr, uint64_t size);
 
diff --git a/tools/testing/selftests/kvm/lib/x86/processor.c b/tools/testing/selftests/kvm/lib/x86/processor.c
index 1725f8fde2aa5..958389ec1722d 100644
--- a/tools/testing/selftests/kvm/lib/x86/processor.c
+++ b/tools/testing/selftests/kvm/lib/x86/processor.c
@@ -496,12 +496,15 @@ void nested_map(struct kvm_vm *vm, vm_paddr_t root_gpa,
 /* Prepare an identity extended page table that maps all the
  * physical pages in VM.
  */
-void nested_map_memslot(struct kvm_vm *vm, vm_paddr_t root_gpa,
-			uint32_t memslot)
+void nested_identity_map_default_memslots(struct kvm_vm *vm, vm_paddr_t root_gpa)
 {
+	uint32_t s, memslot = 0;
 	sparsebit_idx_t i, last;
-	struct userspace_mem_region *region =
-		memslot2region(vm, memslot);
+	struct userspace_mem_region *region = memslot2region(vm, memslot);
+
+	/* Only memslot 0 is mapped here, ensure it's the only one being used */
+	for (s = 0; s < NR_MEM_REGIONS; s++)
+		TEST_ASSERT_EQ(vm->memslots[s], 0);
 
 	i = (region->region.guest_phys_addr >> vm->page_shift) - 1;
 	last = i + (region->region.memory_size >> vm->page_shift);
diff --git a/tools/testing/selftests/kvm/x86/vmx_dirty_log_test.c b/tools/testing/selftests/kvm/x86/vmx_dirty_log_test.c
index e54e6111164e7..b8ebb246aaf15 100644
--- a/tools/testing/selftests/kvm/x86/vmx_dirty_log_test.c
+++ b/tools/testing/selftests/kvm/x86/vmx_dirty_log_test.c
@@ -121,7 +121,7 @@ static void test_vmx_dirty_log(bool enable_ept)
 	 */
 	if (enable_ept) {
 		prepare_eptp(vmx, vm);
-		nested_map_memslot(vm, vmx->eptp_gpa, 0);
+		nested_identity_map_default_memslots(vm, vmx->eptp_gpa);
 		nested_map(vm, vmx->eptp_gpa, NESTED_TEST_MEM1, GUEST_TEST_MEM, PAGE_SIZE);
 		nested_map(vm, vmx->eptp_gpa, NESTED_TEST_MEM2, GUEST_TEST_MEM, PAGE_SIZE);
 	}
-- 
2.51.0.869.ge66316f041-goog