vmptrld

Load Pointer to VMCS

VMPTRLD m64

Loads the current VMCS pointer from memory.

Details

Loads a pointer to the Virtual Machine Control Structure (VMCS) from memory and sets it as the current VMCS. The instruction reads a 64-bit VMCS physical address from memory, validates the region, and sets CF/ZF on failure. This is a privileged instruction (CPL=0) requiring VMX support and execution in VMX root mode; the VMCS region must be 4KB-aligned.

Pseudocode Operation

if (CPL != 0 || VMX_ROOT == 0) raise #UD
VMCS_PTR ← [m64]
if (!validate_vmcs_region(VMCS_PTR)) { RFLAGS.CF ← 1; RFLAGS.ZF ← 0; } else { CURRENT_VMCS ← VMCS_PTR; RFLAGS.CF ← 0; RFLAGS.ZF ← 0; }

Example

VMPTRLD [rbp-8]

Encoding

Binary Layout

ModRM

Format VMX

Opcode NP 0F C7 /6

Extension VMX

Operands

dest
64-bit memory operand (quadword)

Reference (Intel® SDM)

Instruction Forms

Opcode	Instruction	Op/En	64/32-bit Mode	CPUID	Description
NP 0F C7 /6	VMPTRLD m64	M			Loads the current VMCS pointer from memory.

Description

Marks the current-VMCS pointer valid and loads it with the physical address in the instruction operand. The instruction fails if its operand is not properly aligned, sets unsupported physical-address bits, or is equal to the VMXON pointer. In addition, the instruction fails if the 32 bits in memory referenced by the operand do not match the VMCS revision identifier supported by this processor.1 The operand of this instruction is always 64 bits and is always in memory.

Operation

IF (register operand) or (not in VMX operation) or (CR0.PE = 0) or (RFLAGS.VM = 1) or (IA32_EFER.LMA = 1 and CS.L = 0)
THEN #UD;
ELSIF in VMX non-root operation
THEN VMexit;
ELSIF CPL > 0
THEN #GP(0);
ELSE
addr := contents of 64-bit in-memory source operand;
IF addr is not 4KB-aligned OR
addr sets any bits beyond the physical-address width2,3
THEN VMfail(VMPTRLD with invalid physical address);
ELSIF addr = VMXON pointer
THEN VMfail(VMPTRLD with VMXON pointer);
ELSE
rev := 32 bits located at physical address addr;
IF rev[30:0] ≠ VMCS revision identifier supported by processor OR
rev[31] = 1 AND processor does not support 1-setting of “VMCS shadowing”
THEN VMfail(VMPTRLD with incorrect VMCS revision identifier);
ELSE
current-VMCS pointer := addr;
VMsucceed;
FI;
FI;

1.  Software should consult the VMX capability MSR VMX_BASIC to discover the VMCS revision identifier supported by this processor
(see Appendix A, “VMX Capability Reporting Facility”).
2.   If IA32_VMX_BASIC[48] is read as 1, VMfail occurs if addr sets any bits in the range 63:32; see Appendix A.1.
3.  Usually, the processor’s physical-address width is the value enumerated in CPUID.80000008H:EAX[7:0] (at most 52). If
IA32_TME_ACTIVATE[0] = 1 (indicating that TME has been configured), the width is reduced by the value of IA32_TME_ACTI-
VATE[39:36] when a logical processor is outside secure arbitration mode (SEAM; see Chapter 35); the value is not reduced in SEAM.
IA32_TME_ACTIVATE[39:36] is the number of physical-address bits reserved to encode TDX-private key identifiers. This number is
never greater than IA32_TME_ACTIVATE[35:32], which is the number physical-address bits used for key identifiers generally.


VMPTRLD—Load Pointer to Virtual-Machine Control Structure                                                             33-17  Vol. 3C


FI;

Flags Affected

See the operation section and Section 33.2.

Exceptions

Protected Mode Exceptions

#GP(0) If the current privilege level is not 0. If the memory source operand effective address is outside the CS, DS, ES, FS, or GS segment limit. If the DS, ES, FS, or GS register contains an unusable segment. If the source operand is located in an execute-only code segment. #PF(fault-code) If a page fault occurs in accessing the memory source operand. #SS(0) If the memory source operand effective address is outside the SS segment limit. If the SS register contains an unusable segment. #UD If operand is a register. If not in VMX operation.

Real-Address Mode Exceptions

#UD The VMPTRLD instruction is not recognized in real-address mode.

Virtual-8086 Mode Exceptions

#UD The VMPTRLD instruction is not recognized in virtual-8086 mode.

Compatibility Mode Exceptions

#UD The VMPTRLD instruction is not recognized in compatibility mode.

64-Bit Mode Exceptions

#GP(0) If the current privilege level is not 0. If the source operand is in the CS, DS, ES, FS, or GS segments and the memory address is in a non-canonical form. #PF(fault-code) If a page fault occurs in accessing the memory source operand. #SS(0) If the source operand is in the SS segment and the memory address is in a non-canonical form. #UD If operand is a register. If not in VMX operation.