[v6,23/30] KVM: selftests: Add functions to allow mapping as shared

Commit Message

Sagi Shahar April 14, 2025, 9:47 p.m. UTC

From: Ackerley Tng <[e-mail]>

virt_map() enforces a private mapping for private memory. Introduce
virt_map_shared() that creates a shared mapping for private as
well as shared memory. This way, the TD does not have to remap its
page tables at runtime.

Signed-off-by: Ackerley Tng <[e-mail]>
Signed-off-by: Sagi Shahar <[e-mail]>
---
 .../testing/selftests/kvm/include/kvm_util.h  | 23 +++++++++++++
 tools/testing/selftests/kvm/lib/kvm_util.c    | 34 +++++++++++++++++++
 .../testing/selftests/kvm/lib/x86/processor.c | 15 ++++++--
 3 files changed, 70 insertions(+), 2 deletions(-)

Patch

diff --git a/tools/testing/selftests/kvm/include/kvm_util.h b/tools/testing/selftests/kvm/include/kvm_util.h
index 813ba634dc49..442e34c6ed84 100644
--- a/tools/testing/selftests/kvm/include/kvm_util.h
+++ b/tools/testing/selftests/kvm/include/kvm_util.h
@@ -621,6 +621,8 @@  vm_vaddr_t vm_vaddr_alloc_page(struct kvm_vm *vm);
 
 void virt_map(struct kvm_vm *vm, uint64_t vaddr, uint64_t paddr,
 	      unsigned int npages);
+void virt_map_shared(struct kvm_vm *vm, uint64_t vaddr, uint64_t paddr,
+		     unsigned int npages);
 void *addr_gpa2hva(struct kvm_vm *vm, vm_paddr_t gpa);
 void *addr_gva2hva(struct kvm_vm *vm, vm_vaddr_t gva);
 vm_paddr_t addr_hva2gpa(struct kvm_vm *vm, void *hva);
@@ -1096,6 +1098,27 @@  static inline void virt_pg_map(struct kvm_vm *vm, uint64_t vaddr, uint64_t paddr
 	virt_arch_pg_map(vm, vaddr, paddr);
 }
 
+/*
+ * VM Virtual Page Map as Shared
+ *
+ * Input Args:
+ *   vm - Virtual Machine
+ *   vaddr - VM Virtual Address
+ *   paddr - VM Physical Address
+ *
+ * Output Args: None
+ *
+ * Return: None
+ *
+ * Within @vm, creates a virtual translation for the page starting
+ * at @vaddr to the page starting at @paddr.
+ */
+void virt_arch_pg_map_shared(struct kvm_vm *vm, uint64_t vaddr, uint64_t paddr);
+
+static inline void virt_pg_map_shared(struct kvm_vm *vm, uint64_t vaddr, uint64_t paddr)
+{
+	virt_arch_pg_map_shared(vm, vaddr, paddr);
+}
 
 /*
  * Address Guest Virtual to Guest Physical
diff --git a/tools/testing/selftests/kvm/lib/kvm_util.c b/tools/testing/selftests/kvm/lib/kvm_util.c
index f8cf49794eed..008f01831036 100644
--- a/tools/testing/selftests/kvm/lib/kvm_util.c
+++ b/tools/testing/selftests/kvm/lib/kvm_util.c
@@ -7,6 +7,7 @@ 
 #include "test_util.h"
 #include "kvm_util.h"
 #include "processor.h"
+#include "sparsebit.h"
 #include "ucall_common.h"
 
 #include <assert.h>
@@ -1604,6 +1605,39 @@  void virt_map(struct kvm_vm *vm, uint64_t vaddr, uint64_t paddr,
 	}
 }
 
+/*
+ * Map a range of VM virtual address to the VM's physical address as shared
+ *
+ * Input Args:
+ *   vm - Virtual Machine
+ *   vaddr - Virtual address to map
+ *   paddr - VM Physical Address
+ *   npages - The number of pages to map
+ *
+ * Output Args: None
+ *
+ * Return: None
+ *
+ * Within the VM given by @vm, creates a virtual translation for
+ * @npages starting at @vaddr to the page range starting at @paddr.
+ */
+void virt_map_shared(struct kvm_vm *vm, uint64_t vaddr, uint64_t paddr,
+		     unsigned int npages)
+{
+	size_t page_size = vm->page_size;
+	size_t size = npages * page_size;
+
+	TEST_ASSERT(vaddr + size > vaddr, "Vaddr overflow");
+	TEST_ASSERT(paddr + size > paddr, "Paddr overflow");
+
+	while (npages--) {
+		virt_pg_map_shared(vm, vaddr, paddr);
+		sparsebit_set(vm->vpages_mapped, vaddr >> vm->page_shift);
+		vaddr += page_size;
+		paddr += page_size;
+	}
+}
+
 /*
  * Address VM Physical to Host Virtual
  *
diff --git a/tools/testing/selftests/kvm/lib/x86/processor.c b/tools/testing/selftests/kvm/lib/x86/processor.c
index 9b2c236e723a..fef63d807c91 100644
--- a/tools/testing/selftests/kvm/lib/x86/processor.c
+++ b/tools/testing/selftests/kvm/lib/x86/processor.c
@@ -181,7 +181,8 @@  static uint64_t *virt_create_upper_pte(struct kvm_vm *vm,
 	return pte;
 }
 
-void __virt_pg_map(struct kvm_vm *vm, uint64_t vaddr, uint64_t paddr, int level)
+static void ___virt_pg_map(struct kvm_vm *vm, uint64_t vaddr, uint64_t paddr,
+			   int level, bool protected)
 {
 	const uint64_t pg_size = PG_LEVEL_SIZE(level);
 	uint64_t *pml4e, *pdpe, *pde;
@@ -231,17 +232,27 @@  void __virt_pg_map(struct kvm_vm *vm, uint64_t vaddr, uint64_t paddr, int level)
 	 * Neither SEV nor TDX supports shared page tables, so only the final
 	 * leaf PTE needs manually set the C/S-bit.
 	 */
-	if (vm_is_gpa_protected(vm, paddr))
+	if (protected)
 		*pte |= vm->arch.c_bit;
 	else
 		*pte |= vm->arch.s_bit;
 }
 
+void __virt_pg_map(struct kvm_vm *vm, uint64_t vaddr, uint64_t paddr, int level)
+{
+	___virt_pg_map(vm, vaddr, paddr, level, vm_is_gpa_protected(vm, paddr));
+}
+
 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_arch_pg_map_shared(struct kvm_vm *vm, uint64_t vaddr, uint64_t paddr)
+{
+	___virt_pg_map(vm, vaddr, paddr, PG_LEVEL_4K, false);
+}
+
 void virt_map_level(struct kvm_vm *vm, uint64_t vaddr, uint64_t paddr,
 		    uint64_t nr_bytes, int level)
 {