[PATCH v10 27/28] KVM: selftests: Add a new VM guest mode to run user level code
From: Sohil Mehta
Date: Fri Sep 11 2026 - 18:04:39 EST
From: "Xin Li (Intel)" <xin@xxxxxxxxx>
Add a new VM guest mode VM_MODE_PXXV48_4K_USER to set the user bit of
guest page table entries, thus allow user level code to run in guests.
Suggested-by: Sean Christopherson <seanjc@xxxxxxxxxx>
Signed-off-by: Xin Li (Intel) <xin@xxxxxxxxx>
Signed-off-by: Sohil Mehta <sohil.mehta@xxxxxxxxx>
---
v10:
- Treat as new patch (last posted in v2).
---
tools/testing/selftests/kvm/include/kvm_util.h | 1 +
tools/testing/selftests/kvm/lib/kvm_util.c | 5 ++++-
tools/testing/selftests/kvm/lib/x86/processor.c | 16 ++++++++++++----
3 files changed, 17 insertions(+), 5 deletions(-)
diff --git a/tools/testing/selftests/kvm/include/kvm_util.h b/tools/testing/selftests/kvm/include/kvm_util.h
index 5a7a455b5387..981adfcbd5fa 100644
--- a/tools/testing/selftests/kvm/include/kvm_util.h
+++ b/tools/testing/selftests/kvm/include/kvm_util.h
@@ -191,6 +191,7 @@ enum vm_guest_mode {
VM_MODE_P40V48_16K,
VM_MODE_P40V48_64K,
VM_MODE_PXXVYY_4K, /* For 48-bit or 57-bit VA, depending on host support */
+ VM_MODE_PXXVYY_4K_USER, /* For 48bits VA but ANY bits PA with USER bit set */
VM_MODE_P47V64_4K,
VM_MODE_P44V64_4K,
VM_MODE_P36V48_4K,
diff --git a/tools/testing/selftests/kvm/lib/kvm_util.c b/tools/testing/selftests/kvm/lib/kvm_util.c
index 9ddc047d5c27..e79fddedaf39 100644
--- a/tools/testing/selftests/kvm/lib/kvm_util.c
+++ b/tools/testing/selftests/kvm/lib/kvm_util.c
@@ -210,6 +210,7 @@ const char *vm_guest_mode_string(u32 i)
[VM_MODE_P40V48_16K] = "PA-bits:40, VA-bits:48, 16K pages",
[VM_MODE_P40V48_64K] = "PA-bits:40, VA-bits:48, 64K pages",
[VM_MODE_PXXVYY_4K] = "PA-bits:ANY, VA-bits:48 or 57, 4K pages",
+ [VM_MODE_PXXVYY_4K_USER]= "PA-bits:ANY, VA-bits:48, 4K user pages",
[VM_MODE_P47V64_4K] = "PA-bits:47, VA-bits:64, 4K pages",
[VM_MODE_P44V64_4K] = "PA-bits:44, VA-bits:64, 4K pages",
[VM_MODE_P36V48_4K] = "PA-bits:36, VA-bits:48, 4K pages",
@@ -246,6 +247,7 @@ const struct vm_guest_mode_params vm_guest_mode_params[] = {
[VM_MODE_P40V48_16K] = { 40, 48, 0x4000, 14 },
[VM_MODE_P40V48_64K] = { 40, 48, 0x10000, 16 },
[VM_MODE_PXXVYY_4K] = { 0, 0, 0x1000, 12 },
+ [VM_MODE_PXXVYY_4K_USER]= { 0, 0, 0x1000, 12 },
[VM_MODE_P47V64_4K] = { 47, 64, 0x1000, 12 },
[VM_MODE_P44V64_4K] = { 44, 64, 0x1000, 12 },
[VM_MODE_P36V48_4K] = { 36, 48, 0x1000, 12 },
@@ -337,6 +339,7 @@ struct kvm_vm *____vm_create(struct vm_shape shape)
vm->mmu.pgtable_levels = 3;
break;
case VM_MODE_PXXVYY_4K:
+ case VM_MODE_PXXVYY_4K_USER:
#ifdef __x86_64__
kvm_get_cpu_address_width(&vm->pa_bits, &vm->va_bits);
kvm_init_vm_address_properties(vm);
@@ -355,7 +358,7 @@ struct kvm_vm *____vm_create(struct vm_shape shape)
vm->mmu.pgtable_levels = 4;
}
#else
- TEST_FAIL("VM_MODE_PXXVYY_4K not supported on non-x86 platforms");
+ TEST_FAIL("VM_MODE_PXXVYY_4K(_USER) not supported on non-x86 platforms");
#endif
break;
case VM_MODE_P47V64_4K:
diff --git a/tools/testing/selftests/kvm/lib/x86/processor.c b/tools/testing/selftests/kvm/lib/x86/processor.c
index d31fa81ea075..51d713c4c9de 100644
--- a/tools/testing/selftests/kvm/lib/x86/processor.c
+++ b/tools/testing/selftests/kvm/lib/x86/processor.c
@@ -167,6 +167,9 @@ bool kvm_is_tdp_enabled(void)
static void virt_mmu_init(struct kvm_vm *vm, struct kvm_mmu *mmu,
struct pte_masks *pte_masks)
{
+ TEST_ASSERT(vm->mode == VM_MODE_PXXVYY_4K || vm->mode == VM_MODE_PXXVYY_4K_USER,
+ "Unknown or unsupported guest mode: 0x%x", vm->mode);
+
/* If needed, create the top-level page table. */
if (!mmu->pgd_created) {
mmu->pgd = vm_alloc_page_table(vm);
@@ -181,7 +184,7 @@ static void virt_mmu_init(struct kvm_vm *vm, struct kvm_mmu *mmu,
void virt_arch_pgd_alloc(struct kvm_vm *vm)
{
- TEST_ASSERT(vm->mode == VM_MODE_PXXVYY_4K,
+ TEST_ASSERT(vm->mode == VM_MODE_PXXVYY_4K || vm->mode == VM_MODE_PXXVYY_4K_USER,
"Unknown or unsupported guest mode: 0x%x", vm->mode);
struct pte_masks pte_masks = (struct pte_masks){
@@ -239,6 +242,8 @@ static u64 *virt_create_upper_pte(struct kvm_vm *vm,
*pte = PTE_PRESENT_MASK(mmu) | PTE_READABLE_MASK(mmu) |
PTE_WRITABLE_MASK(mmu) | PTE_EXECUTABLE_MASK(mmu) |
PTE_ALWAYS_SET_MASK(mmu);
+ if (vm->mode == VM_MODE_PXXVYY_4K_USER)
+ *pte |= PTE_USER_MASK(mmu);
if (current_level == target_level)
*pte |= PTE_HUGE_MASK(mmu) | (gpa & PHYSICAL_PAGE_MASK);
else
@@ -266,7 +271,7 @@ void __virt_pg_map(struct kvm_vm *vm, struct kvm_mmu *mmu, gva_t gva,
u64 *pte = &mmu->pgd;
int current_level;
- TEST_ASSERT(vm->mode == VM_MODE_PXXVYY_4K,
+ TEST_ASSERT(vm->mode == VM_MODE_PXXVYY_4K || vm->mode == VM_MODE_PXXVYY_4K_USER,
"Unknown or unsupported guest mode: 0x%x", vm->mode);
TEST_ASSERT((gva % pg_size) == 0,
@@ -316,6 +321,9 @@ void __virt_pg_map(struct kvm_vm *vm, struct kvm_mmu *mmu, gva_t gva,
*pte |= PTE_C_BIT_MASK(mmu);
else
*pte |= PTE_S_BIT_MASK(mmu);
+
+ if (vm->mode == VM_MODE_PXXVYY_4K_USER)
+ *pte |= PTE_USER_MASK(mmu);
}
void virt_arch_pg_map(struct kvm_vm *vm, gva_t gva, gpa_t gpa)
@@ -372,7 +380,7 @@ static u64 *__vm_get_page_table_entry(struct kvm_vm *vm,
TEST_ASSERT(*level >= PG_LEVEL_NONE && *level <= mmu->pgtable_levels,
"Invalid PG_LEVEL_* '%d'", *level);
- TEST_ASSERT(vm->mode == VM_MODE_PXXVYY_4K,
+ TEST_ASSERT(vm->mode == VM_MODE_PXXVYY_4K || vm->mode == VM_MODE_PXXVYY_4K_USER,
"Unknown or unsupported guest mode: 0x%x", vm->mode);
TEST_ASSERT(sparsebit_is_set(vm->vpages_valid, (gva >> vm->page_shift)),
"Invalid virtual address, gva: 0x%lx", gva);
@@ -645,7 +653,7 @@ static void vcpu_init_sregs(struct kvm_vm *vm, struct kvm_vcpu *vcpu)
{
struct kvm_sregs sregs;
- TEST_ASSERT(vm->mode == VM_MODE_PXXVYY_4K,
+ TEST_ASSERT(vm->mode == VM_MODE_PXXVYY_4K || vm->mode == VM_MODE_PXXVYY_4K_USER,
"Unknown or unsupported guest mode: 0x%x", vm->mode);
/* Set mode specific system register values. */
--
2.43.0