KVM: selftests: Kill eptPageTablePointer

Replace the struct overlay with explicit bitmasks, which is clearer and
less error-prone. See commit f18b4aebe107 ("kvm: selftests: do not use
bitfields larger than 32-bits for PTEs") for an example of why bitfields
are not preferable.

Remove the unused PAGE_SHIFT_4K definition while at it.

No functional change intended.

Signed-off-by: Yosry Ahmed <yosry.ahmed@linux.dev>
Link: https://patch.msgid.link/20251230230150.4150236-5-seanjc@google.com
Signed-off-by: Sean Christopherson <seanjc@google.com>

diff --git a/tools/testing/selftests/kvm/lib/x86/vmx.c b/tools/testing/selftests/kvm/lib/x86/vmx.c
index 1954ccdfc35389310943b3d3fac99ad5cda47533..85043bb1ec4d8489cd239a06031afc13f86f3f8d 100644 (file)
--- a/tools/testing/selftests/kvm/lib/x86/vmx.c
+++ b/tools/testing/selftests/kvm/lib/x86/vmx.c
@@ -10,10 +10,16 @@
 #include "processor.h"
 #include "vmx.h"
 
-#define PAGE_SHIFT_4K  12
-
 #define KVM_EPT_PAGE_TABLE_MIN_PADDR 0x1c0000
 
+#define EPTP_MT_SHIFT          0 /* EPTP memtype bits 2:0 */
+#define EPTP_PWL_SHIFT         3 /* EPTP page walk length bits 5:3 */
+#define EPTP_AD_ENABLED_SHIFT  6 /* EPTP AD enabled bit 6 */
+
+#define EPTP_WB                        (X86_MEMTYPE_WB << EPTP_MT_SHIFT)
+#define EPTP_PWL_4             (3ULL << EPTP_PWL_SHIFT) /* PWL is (levels - 1) */
+#define EPTP_AD_ENABLED                (1ULL << EPTP_AD_ENABLED_SHIFT)
+
 bool enable_evmcs;
 
 struct hv_enlightened_vmcs *current_evmcs;
@@ -34,14 +40,6 @@ struct eptPageTableEntry {
        uint64_t suppress_ve:1;
 };
 
-struct eptPageTablePointer {
-       uint64_t memory_type:3;
-       uint64_t page_walk_length:3;
-       uint64_t ad_enabled:1;
-       uint64_t reserved_11_07:5;
-       uint64_t address:40;
-       uint64_t reserved_63_52:12;
-};
 int vcpu_enable_evmcs(struct kvm_vcpu *vcpu)
 {
        uint16_t evmcs_ver;
@@ -196,16 +194,15 @@ static inline void init_vmcs_control_fields(struct vmx_pages *vmx)
        vmwrite(PIN_BASED_VM_EXEC_CONTROL, rdmsr(MSR_IA32_VMX_TRUE_PINBASED_CTLS));
 
        if (vmx->eptp_gpa) {
-               uint64_t ept_paddr;
-               struct eptPageTablePointer eptp = {
-                       .memory_type = X86_MEMTYPE_WB,
-                       .page_walk_length = 3, /* + 1 */
-                       .ad_enabled = ept_vpid_cap_supported(VMX_EPT_VPID_CAP_AD_BITS),
-                       .address = vmx->eptp_gpa >> PAGE_SHIFT_4K,
-               };
-
-               memcpy(&ept_paddr, &eptp, sizeof(ept_paddr));
-               vmwrite(EPT_POINTER, ept_paddr);
+               uint64_t eptp = vmx->eptp_gpa | EPTP_WB | EPTP_PWL_4;
+
+               TEST_ASSERT((vmx->eptp_gpa & ~PHYSICAL_PAGE_MASK) == 0,
+                           "Illegal bits set in vmx->eptp_gpa");
+
+               if (ept_vpid_cap_supported(VMX_EPT_VPID_CAP_AD_BITS))
+                       eptp |= EPTP_AD_ENABLED;
+
+               vmwrite(EPT_POINTER, eptp);
                sec_exec_ctl |= SECONDARY_EXEC_ENABLE_EPT;
        }