Commit ed0b58fc authored by Sean Christopherson's avatar Sean Christopherson
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KVM: selftests: Verify parent PTE is PRESENT when getting child PTE 



Verify the parent PTE is PRESENT when getting a child via virt_get_pte()
so that the helper can be used for getting PTEs/GPAs without losing
sanity checks that the walker isn't wandering into the weeds.

Signed-off-by: default avatarSean Christopherson <seanjc@google.com>
Link: https://lore.kernel.org/r/20221006004512.666529-5-seanjc@google.com
parent 91add12d

tools/testing/selftests/kvm/lib/x86_64/processor.c

+13 −8
Original line number Diff line number Diff line
@@ -131,23 +131,28 @@ void virt_arch_pgd_alloc(struct kvm_vm *vm) 
	}

}



static void *virt_get_pte(struct kvm_vm *vm, uint64_t pt_gpa, uint64_t vaddr,

			  int level)

static void *virt_get_pte(struct kvm_vm *vm, uint64_t *parent_pte,

			  uint64_t vaddr, int level)

{

	uint64_t pt_gpa = PTE_GET_PA(*parent_pte);

	uint64_t *page_table = addr_gpa2hva(vm, pt_gpa);

	int index = (vaddr >> PG_LEVEL_SHIFT(level)) & 0x1ffu;



	TEST_ASSERT((*parent_pte & PTE_PRESENT_MASK) || parent_pte == &vm->pgd,

		    "Parent PTE (level %d) not PRESENT for gva: 0x%08lx",

		    level + 1, vaddr);



	return &page_table[index];

}



static uint64_t *virt_create_upper_pte(struct kvm_vm *vm,

				       uint64_t pt_gpa,

				       uint64_t *parent_pte,

				       uint64_t vaddr,

				       uint64_t paddr,

				       int current_level,

				       int target_level)

{

	uint64_t *pte = virt_get_pte(vm, pt_gpa, vaddr, current_level);

	uint64_t *pte = virt_get_pte(vm, parent_pte, vaddr, current_level);



	if (!(*pte & PTE_PRESENT_MASK)) {

		*pte = PTE_PRESENT_MASK | PTE_WRITABLE_MASK;
@@ -197,20 +202,20 @@ void __virt_pg_map(struct kvm_vm *vm, uint64_t vaddr, uint64_t paddr, int level) 
	 * Allocate upper level page tables, if not already present.  Return

	 * early if a hugepage was created.

	 */

	pml4e = virt_create_upper_pte(vm, vm->pgd, vaddr, paddr, PG_LEVEL_512G, level);

	pml4e = virt_create_upper_pte(vm, &vm->pgd, vaddr, paddr, PG_LEVEL_512G, level);

	if (*pml4e & PTE_LARGE_MASK)

		return;



	pdpe = virt_create_upper_pte(vm, PTE_GET_PA(*pml4e), vaddr, paddr, PG_LEVEL_1G, level);

	pdpe = virt_create_upper_pte(vm, pml4e, vaddr, paddr, PG_LEVEL_1G, level);

	if (*pdpe & PTE_LARGE_MASK)

		return;



	pde = virt_create_upper_pte(vm, PTE_GET_PA(*pdpe), vaddr, paddr, PG_LEVEL_2M, level);

	pde = virt_create_upper_pte(vm, pdpe, vaddr, paddr, PG_LEVEL_2M, level);

	if (*pde & PTE_LARGE_MASK)

		return;



	/* Fill in page table entry. */

	pte = virt_get_pte(vm, PTE_GET_PA(*pde), vaddr, PG_LEVEL_4K);

	pte = virt_get_pte(vm, pde, vaddr, PG_LEVEL_4K);

	TEST_ASSERT(!(*pte & PTE_PRESENT_MASK),

		    "PTE already present for 4k page at vaddr: 0x%lx\n", vaddr);

	*pte = PTE_PRESENT_MASK | PTE_WRITABLE_MASK | (paddr & PHYSICAL_PAGE_MASK);