senduipi
Send User Inter-Processor Interrupt
Sends a User IPI to another processor.
Pseudocode Operation
IF (!UINTR_enabled) THEN #UD;
uipi_index ← src_reg[63:0];
upid ← retrieve_UPID_from_index(uipi_index);
post_user_interrupt_to_target(upid);
SEND_IPI_TO_TARGET_CPU();Example
Encoding
Operands
-
dest
64-bit general-purpose register (e.g. RAX)
Related
More in UINTR
Reference
Instruction Forms
| Opcode | Instruction | Op/En | 64/32-bit Mode | CPUID | Description |
|---|---|---|---|---|---|
| F3 0F C7 /6 | SENDUIPI reg | A | V/I | UINTR | Send interprocessor user interrupt. |
Instruction Operand Encoding
| Op/En | Tuple Type | Operand 1 | Operand 2 | Operand 3 | Operand 4 |
|---|---|---|---|---|---|
| A | N/A | ModRM:reg (r) | N/A | N/A | N/A |
Description
The SENDUIPI instruction sends the user interprocessor interrupt (IPI) indicated by its register operand. (The operand always has 64 bits; operand-size overrides such as the prefix 66 are ignored.) SENDUIPI uses a data structure called the user-interrupt target table (UITT). This table is located at the linear address UITTADDR (in the IA32_UINTR_TT MSR); it comprises UITTSZ+1 16-byte entries, where UITTSZ = IA32_UINT_MISC[31:0]. SENDUIPI uses the UITT entry (UITTE) indexed by the instruction's register operand. Each UITTE has the following format:
• Bit 0: V, a valid bit. • Bits 7:1 are reserved and must be 0. • Bits 15:8: UV, the user-interrupt vector (in the range 0-63, so bits 15:14 must be 0). • Bits 63:16 are reserved.
• Bits 127:64: UPIDADDR, the linear address of a user posted-interrupt descriptor (UPID). (UPIDADDR is 64byte aligned, so bits 69:64 of each UITTE must be 0.) Each UPID has the following format (fields and bits not referenced are reserved):
• Bit 0 (ON) indicates an outstanding notification. If this bit is set, there is a notification outstanding for one or more user interrupts in PIR.
• Bit 1 (SN) indicates that notifications should be suppressed. If this bit is set, agents (including SENDUIPI) should not send notifications when posting user interrupts in this descriptor. • Bits 23:16 (NV) contain the notification vector. This is used by agents sending user-interrupt notifications (including SENDUIPI).
• Bits 63:32 (NDST) contain the notification destination. This is the target physical APIC ID (in xAPIC mode, bits 47:40 are the 8-bit APIC ID; in x2APIC mode, the entire field forms the 32-bit APIC ID).
• Bits 127:64 (PIF) contain posted-interrupt requests. There is one bit for each user-interrupt vector. There is a user-interrupt request for a vector if the corresponding bit is 1. Although SENDUIPI may be executed at any privilege level, all of the instruction’s memory accesses (to a UITTE and a UPID) are performed with supervisor privilege. SENDUIPI sends a user interrupt by posting a user interrupt with vector V in the UPID referenced by UPIDADDR and then sending, as an ordinary IPI, any notification interrupt specified in that UPID.
Operation
IF reg > UITTSZ; THEN #GP(0); FI; read tempUITTE from 16 bytes at UITTADDR+ (reg « 4); IF tempUITTE.V = 0 or tempUITTE sets any reserved bit THEN #GP(0); FI; read tempUPID from 16 bytes at tempUITTE.UPIDADDR;// under lock IF tempUPID sets any reserved bits or bits that must be zero THEN #GP(0); // release lock FI; tempUPID.PIR[tempUITTE.UV] := 1; IF tempUPID.SN = tempUPID.ON = 0 THEN tempUPID.ON := 1; sendNotify := 1; ELSE sendNotify := 0; FI; write tempUPID to 16 bytes at tempUITTE.UPIDADDR;// release lock IF sendNotify = 1 THEN IF local APIC is in x2APIC mode THEN send ordinary IPI with vector tempUPID.NV to 32-bit physical APIC ID tempUPID.NDST; ELSE send ordinary IPI with vector tempUPID.NV to 8-bit physical APIC ID tempUPID.NDST[15:8]; FI; FI;