KVM: selftests: Drop reserved bit checks from PTE accessor

Drop the reserved bit checks from the helper to retrieve a PTE, there's
very little value in sanity checking the constructed page tables as any
will quickly be noticed in the form of an unexpected #PF.  The checks
also place unnecessary restrictions on the usage of the helpers, e.g. if
a test _wanted_ to set reserved bits for whatever reason.

Removing the NX check in particular allows for the removal of the @vcpu
param, which will in turn allow the helper to be reused nearly verbatim
for addr_gva2gpa().

Signed-off-by: Sean Christopherson <seanjc@google.com>
Link: https://lore.kernel.org/r/20221006004512.666529-3-seanjc@google.com

diff --git a/tools/testing/selftests/kvm/include/x86_64/processor.h b/tools/testing/selftests/kvm/include/x86_64/processor.h
index 30d5df1..53d52a5 100644 (file)
--- a/tools/testing/selftests/kvm/include/x86_64/processor.h
+++ b/tools/testing/selftests/kvm/include/x86_64/processor.h
@@ -827,8 +827,7 @@ static inline uint8_t wrmsr_safe(uint32_t msr, uint64_t val)
 
 bool kvm_is_tdp_enabled(void);
 
-uint64_t *vm_get_page_table_entry(struct kvm_vm *vm, struct kvm_vcpu *vcpu,
-                                 uint64_t vaddr);
+uint64_t *vm_get_page_table_entry(struct kvm_vm *vm, uint64_t vaddr);
 
 uint64_t kvm_hypercall(uint64_t nr, uint64_t a0, uint64_t a1, uint64_t a2,
                       uint64_t a3);

diff --git a/tools/testing/selftests/kvm/lib/x86_64/processor.c b/tools/testing/selftests/kvm/lib/x86_64/processor.c
index 90b3599..9e19683 100644 (file)
--- a/tools/testing/selftests/kvm/lib/x86_64/processor.c
+++ b/tools/testing/selftests/kvm/lib/x86_64/processor.c
@@ -241,29 +241,11 @@ void virt_map_level(struct kvm_vm *vm, uint64_t vaddr, uint64_t paddr,
        }
 }
 
-uint64_t *vm_get_page_table_entry(struct kvm_vm *vm, struct kvm_vcpu *vcpu,
-                                 uint64_t vaddr)
+uint64_t *vm_get_page_table_entry(struct kvm_vm *vm, uint64_t vaddr)
 {
        uint16_t index[4];
        uint64_t *pml4e, *pdpe, *pde;
        uint64_t *pte;
-       struct kvm_sregs sregs;
-       uint64_t rsvd_mask = 0;
-
-       /* Set the high bits in the reserved mask. */
-       if (vm->pa_bits < 52)
-               rsvd_mask = GENMASK_ULL(51, vm->pa_bits);
-
-       /*
-        * SDM vol 3, fig 4-11 "Formats of CR3 and Paging-Structure Entries
-        * with 4-Level Paging and 5-Level Paging".
-        * If IA32_EFER.NXE = 0 and the P flag of a paging-structure entry is 1,
-        * the XD flag (bit 63) is reserved.
-        */
-       vcpu_sregs_get(vcpu, &sregs);
-       if ((sregs.efer & EFER_NX) == 0) {
-               rsvd_mask |= PTE_NX_MASK;
-       }
 
        TEST_ASSERT(vm->mode == VM_MODE_PXXV48_4K, "Attempt to use "
                "unknown or unsupported guest mode, mode: 0x%x", vm->mode);
@@ -286,24 +268,18 @@ uint64_t *vm_get_page_table_entry(struct kvm_vm *vm, struct kvm_vcpu *vcpu,
        pml4e = addr_gpa2hva(vm, vm->pgd);
        TEST_ASSERT(pml4e[index[3]] & PTE_PRESENT_MASK,
                "Expected pml4e to be present for gva: 0x%08lx", vaddr);
-       TEST_ASSERT((pml4e[index[3]] & (rsvd_mask | PTE_LARGE_MASK)) == 0,
-               "Unexpected reserved bits set.");
 
        pdpe = addr_gpa2hva(vm, PTE_GET_PFN(pml4e[index[3]]) * vm->page_size);
        TEST_ASSERT(pdpe[index[2]] & PTE_PRESENT_MASK,
                "Expected pdpe to be present for gva: 0x%08lx", vaddr);
        TEST_ASSERT(!(pdpe[index[2]] & PTE_LARGE_MASK),
                "Expected pdpe to map a pde not a 1-GByte page.");
-       TEST_ASSERT((pdpe[index[2]] & rsvd_mask) == 0,
-               "Unexpected reserved bits set.");
 
        pde = addr_gpa2hva(vm, PTE_GET_PFN(pdpe[index[2]]) * vm->page_size);
        TEST_ASSERT(pde[index[1]] & PTE_PRESENT_MASK,
                "Expected pde to be present for gva: 0x%08lx", vaddr);
        TEST_ASSERT(!(pde[index[1]] & PTE_LARGE_MASK),
                "Expected pde to map a pte not a 2-MByte page.");
-       TEST_ASSERT((pde[index[1]] & rsvd_mask) == 0,
-               "Unexpected reserved bits set.");
 
        pte = addr_gpa2hva(vm, PTE_GET_PFN(pde[index[1]]) * vm->page_size);
        TEST_ASSERT(pte[index[0]] & PTE_PRESENT_MASK,

diff --git a/tools/testing/selftests/kvm/x86_64/emulator_error_test.c b/tools/testing/selftests/kvm/x86_64/emulator_error_test.c
index bde247f..1abb347 100644 (file)
--- a/tools/testing/selftests/kvm/x86_64/emulator_error_test.c
+++ b/tools/testing/selftests/kvm/x86_64/emulator_error_test.c
@@ -180,7 +180,7 @@ int main(int argc, char *argv[])
        hva = addr_gpa2hva(vm, MEM_REGION_GPA);
        memset(hva, 0, PAGE_SIZE);
 
-       pte = vm_get_page_table_entry(vm, vcpu, MEM_REGION_GVA);
+       pte = vm_get_page_table_entry(vm, MEM_REGION_GVA);
        *pte |= BIT_ULL(MAXPHYADDR);
 
        vcpu_run(vcpu);