[PATCH] KVM: selftests: Fix nx_huge_pages_test on TDP-disabled hosts

[David Matlack <dmatlack@google.com>]

Map the test's huge page region with 2MiB virtual mappings so that KVM
can shadow the region with huge pages. This fixes nx_huge_pages_test on
hosts where TDP hardware support is disabled.

Purposely do not skip this test on TDP-disabled hosts. While we don't
care about NX Huge Pages on TDP-disabled hosts from a security
perspective, KVM does support it, and so we should test it.

Signed-off-by: David Matlack <dmatlack@google.com>
---
 .../selftests/kvm/include/x86_64/processor.h        |  2 ++
 tools/testing/selftests/kvm/lib/x86_64/processor.c  | 13 +++++++++++++
 .../selftests/kvm/x86_64/nx_huge_pages_test.c       |  9 +++++++--
 3 files changed, 22 insertions(+), 2 deletions(-)

diff --git a/tools/testing/selftests/kvm/include/x86_64/processor.h b/tools/testing/selftests/kvm/include/x86_64/processor.h
index 0cbc71b7af50..4ffaa79fd8d6 100644
--- a/tools/testing/selftests/kvm/include/x86_64/processor.h
+++ b/tools/testing/selftests/kvm/include/x86_64/processor.h
@@ -855,6 +855,8 @@ enum pg_level {
 #define PG_SIZE_1G PG_LEVEL_SIZE(PG_LEVEL_1G)
 
 void __virt_pg_map(struct kvm_vm *vm, uint64_t vaddr, uint64_t paddr, int level);
+void virt_map_2m(struct kvm_vm *vm, uint64_t vaddr, uint64_t paddr,
+		 uint64_t nr_2m_pages);
 
 /*
  * Basic CPU control in CR0
diff --git a/tools/testing/selftests/kvm/lib/x86_64/processor.c b/tools/testing/selftests/kvm/lib/x86_64/processor.c
index 2e6e61bbe81b..df8a1498ea28 100644
--- a/tools/testing/selftests/kvm/lib/x86_64/processor.c
+++ b/tools/testing/selftests/kvm/lib/x86_64/processor.c
@@ -214,6 +214,19 @@ void virt_arch_pg_map(struct kvm_vm *vm, uint64_t vaddr, uint64_t paddr)
 	__virt_pg_map(vm, vaddr, paddr, PG_LEVEL_4K);
 }
 
+void virt_map_2m(struct kvm_vm *vm, uint64_t vaddr, uint64_t paddr,
+		 uint64_t nr_2m_pages)
+{
+	int i;
+
+	for (i = 0; i < nr_2m_pages; i++) {
+		__virt_pg_map(vm, vaddr, paddr, PG_LEVEL_2M);
+
+		vaddr += PG_SIZE_2M;
+		paddr += PG_SIZE_2M;
+	}
+}
+
 static uint64_t *_vm_get_page_table_entry(struct kvm_vm *vm,
 					  struct kvm_vcpu *vcpu,
 					  uint64_t vaddr)
diff --git a/tools/testing/selftests/kvm/x86_64/nx_huge_pages_test.c b/tools/testing/selftests/kvm/x86_64/nx_huge_pages_test.c
index cc6421716400..a850769692b7 100644
--- a/tools/testing/selftests/kvm/x86_64/nx_huge_pages_test.c
+++ b/tools/testing/selftests/kvm/x86_64/nx_huge_pages_test.c
@@ -22,7 +22,8 @@
 #define HPAGE_GPA		(4UL << 30) /* 4G prevents collision w/ slot 0 */
 #define HPAGE_GVA		HPAGE_GPA /* GVA is arbitrary, so use GPA. */
 #define PAGES_PER_2MB_HUGE_PAGE 512
-#define HPAGE_SLOT_NPAGES	(3 * PAGES_PER_2MB_HUGE_PAGE)
+#define HPAGE_SLOT_2MB_PAGES	3
+#define HPAGE_SLOT_NPAGES	(HPAGE_SLOT_2MB_PAGES * PAGES_PER_2MB_HUGE_PAGE)
 
 /*
  * Passed by nx_huge_pages_test.sh to provide an easy warning if this test is
@@ -141,7 +142,11 @@ void run_test(int reclaim_period_ms, bool disable_nx_huge_pages,
 				    HPAGE_GPA, HPAGE_SLOT,
 				    HPAGE_SLOT_NPAGES, 0);
 
-	virt_map(vm, HPAGE_GVA, HPAGE_GPA, HPAGE_SLOT_NPAGES);
+	/*
+	 * Use 2MiB virtual mappings so that KVM can map the region with huge
+	 * pages even if TDP is disabled.
+	 */
+	virt_map_2m(vm, HPAGE_GVA, HPAGE_GPA, HPAGE_SLOT_2MB_PAGES);
 
 	hva = addr_gpa2hva(vm, HPAGE_GPA);
 	memset(hva, RETURN_OPCODE, HPAGE_SLOT_NPAGES * PAGE_SIZE);

base-commit: 372d07084593dc7a399bf9bee815711b1fb1bcf2
prerequisite-patch-id: 2e3661ba8856c29b769499bac525b6943d9284b8
-- 
2.37.3.998.g577e59143f-goog