hdpmi: VCPI pm calls made NMI-safe

Author: Baron-von-Riedesel

Src/HDPMI/EXTERNAL.INC

@@ -312,6 +312,9 @@ externdef rawjmp_rm_all:near
 if 0;?JHDPMI
 externdef jhdpmicall:near
 endif
+if ?NMISAFE
+externdef oldint02rm:dword
+endif
 _TEXT16 ends
 
 BEGGRP16 segment

Src/HDPMI/HDPMI.ASM

@@ -220,7 +220,7 @@ ifnb <r0exclbl>
 else
 	jz exclbl
 endif
-if ?KDSUPP or ?ALLOWR0IRQ
+if ?KDSUPP or ?ALLOWR0IRQ or ?NMISAFE
 	push eax
 	lea eax, [esp+R3FAULT32+4]
 	cmp eax, ss:[dwHostStack]
@@ -2075,8 +2075,22 @@ endif
 	pop edx
 	pop ecx
 	pop eax
+if ?NMISAFE
+	cmp [ebp+4].LCEFR.dwExc,2  ;v3.24: avoid IRETD for NMI
+	jz @F
+endif
 	pop ebp
 	iretd
+if ?NMISAFE
+@@:
+	mov ebp,[ebp+4].LCEFR.r.rFL
+	xchg ebp,[esp+1*4] ;set flags, get eip
+	xchg ebp,[esp+2*4] ;set eip, get cs
+	mov [esp+3*4],ebp  ;set cs
+	pop ebp
+	popfd
+	retd
+endif
 	align 4
 lpms_call_exc endp
 
@@ -2705,41 +2719,61 @@ endif
 intr01 endp
 
 intr02 proc
-	cmp word ptr [esp.IRET32.rCS],_CSSEL_ ;NMI in ring 0?
-if ?NMI2RM
-	jz intr02_r0	; v3.24: route NMI in PL0 to real-mode
+;--- v3.24: check PL, not CS
+;	cmp word ptr [esp.IRET32.rCS],_CSSEL_ ;NMI in ring 0?
+	push eax
+	lar eax,[esp+4].IRET32.rCSd
+	and ah,60h
+	pop eax
+;--- v3.24: route NMI in PL0 to real-mode for NMI-safe variant
+if ?NMISAFE
+	jz intr02_r0
 else
 	jz iretexit		; skip NMI in PL0
 endif
 	@exception 02
 	@mapexc2int 02
-if ?NMI2RM
+if ?NMISAFE
 ;--- v3.24: route NMI to real-mode if it occured in ring 0
 intr02_r0:
+	push eax
 ;--- save pm segment regs, they will be undefined after @rawjmp_pm
 	push ds
 	push es
 	push fs
 	push gs
 ;--- save/restore global vars that may be modified by mode switches
-	push ss:[taskseg._Eax]
 	push ss:[dwPmDest]
+	push ss:[taskseg._Eax]
 	push ss:[dwHostStack]
 	mov ss:[dwHostStack],esp
-	@rawjmp_rm @F
-_TEXT16 segment
+	mov ax, offset intr02_rm1
+	cmp ss:[oldint02rm],0
+	jnz @F
+	mov ax, offset intr02_rm2
 @@:
+	@rawjmp_rm ax
+_TEXT16 segment
+intr02_rm1:
+	pushf
+	db 9ah
+oldint02rm dd 0
+	@rawjmp_pm intr02_pm
+intr02_rm2:
 	int 02
-	@rawjmp_pm @F
+	@rawjmp_pm intr02_pm
 _TEXT16 ends
-@@:
+;--- v86iret segregs weren't modified; NMI still masked
+intr02_pm:
 	pop ss:[dwHostStack]
-	pop ss:[dwPmDest]
 	pop ss:[taskseg._Eax]
+	pop ss:[dwPmDest]
 	pop gs
 	pop fs
 	pop es
 	pop ds
+	@NMI_ON    ;intr02 (wait until all seg regs are restored!)
+	pop eax
 	iretd
 endif
 intr02 endp
@@ -3303,7 +3337,7 @@ irqrm2pm_1:
 	mov fs, ss:pmstate.rFS
 	mov gs, ss:pmstate.rGS
 
-	@NMI_ON 0
+	@NMI_ON  ;initrmcb_pm
 
 ifdef _DEBUG
 	verw word ptr ss:pmstate.rSSd

Src/HDPMI/HDPMI.INC

@@ -273,11 +273,6 @@ endif
 ifndef ?NMISAFE
 ?NMISAFE		equ 0	;std 0; 1=NMI masked during mode switches
 endif
-if ?NMISAFE
-?NMI2RM			equ 1	;std 1; 1=route NMIs in PL0 to real-mode; 0=skip NMIs in PL0
-else
-?NMI2RM			equ 0
-endif
 ;----------------------------------------------------------------
 
 if ?32BIT
@@ -1397,30 +1392,30 @@ endm
 	db 0Fh,0A2h
 endm
 
-@NMI_ON macro bSave:=<1>
+@NMI_ON macro SaveReg
 if ?NMISAFE
- if bSave
-	push eax
+ ifnb <SaveReg>
+	push SaveReg
  endif
 	mov al,0
 	out 70h,al
 	in al,71h
- if bSave
-	pop eax
+ ifnb <SaveReg>
+	pop SaveReg
  endif
 endif
 endm
 
-@NMI_OFF macro bSave:=<1>
+@NMI_OFF macro SaveReg
 if ?NMISAFE
- if bSave
-	push eax
+ ifnb <SaveReg>
+	push SaveReg
  endif
 	mov al,80h
 	out 70h,al
 	in al,71h
- if bSave
-	pop eax
+ ifnb <SaveReg>
+	pop SaveReg
  endif
 endif
 endm
@@ -1449,7 +1444,11 @@ endm
 endm
 
 @rawjmp_rm macro dest
+ if (opattr dest) and 4
 	mov ss:[wRmDest], offset dest
+ else
+	mov ss:[wRmDest], dest
+ endif
 	jmp _rawjmp_rm
 endm
 

Src/HDPMI/HDPMI.TXT

@@ -1,6 +1,6 @@
 //////////////////////////////////////////////////////////////////////////////
 /                                                                            /
-/               HDPMI - DPMI Server (Version 3.23)                           /
+/               HDPMI - DPMI Server (Version 3.24)                           /
 /                                                                            /
 //////////////////////////////////////////////////////////////////////////////
 

Src/HDPMI/HDPMIHIS.TXT

@@ -5,8 +5,8 @@
 
   � optional extension a for cmdline option -x added.
   � int 31h, ax=508h: top of memory check (?TOPMEM) activated.
-  � optional variant added that will mask NMIs during mode switches and
-    route NMIs that occur in PL0 to real-mode.
+  � optional variant added that's "NMI-safe" and routes NMIs occuring
+    in PL0 to real-mode.
 
   13.10.2025, version 3.23
 

Src/HDPMI/I2FHDPMI.ASM

@@ -11,7 +11,7 @@
 if ?VENDORAPI
 
 @wofs macro ofs
-	dw offset ofs - offset start168a
+	dw offset ofs - $
 endm
 
  ifdef _DEBUG
@@ -25,53 +25,66 @@ _TEXT32 segment
 _I2f168A_Hdpmi proc near public
 
 	push offset iret_with_CF_mod
-	cmp ax, MAX168A
-	jb @F
-	stc
-	ret
-@@:
 	push ebx
-	movzx ebx, ax
-	mov bx, cs:[ebx*2+offset tab168a]
-	add ebx, offset start168a
+	push ecx
+	push edx
+
+APIFUNCS = 1 shl 4                   ;4
+ifdef _DEBUG
+APIFUNCS = APIFUNCS or (1111b shl 0) ;0-3
+endif
+if ?VM
+APIFUNCS = APIFUNCS or (1 shl 5)     ;5
+endif
+if ?PMIOPL eq 0
+APIFUNCS = APIFUNCS or (1111b shl 6) ;6-9 (10 rsvd)
+endif
+if ?NMISAFE
+APIFUNCS = APIFUNCS or (1 shl 11)    ;11
+endif
+	mov edx,APIFUNCS
+	mov ebx,offset tab168a-2
+@@:
+	bsf ecx,edx
+	jz error
+	btr edx,ecx
+	add ebx,2
+	cmp ax,cx
+	jnz @B
+	movzx ecx, word ptr cs:[ebx]
+	add ebx,ecx
+	pop edx
+	pop ecx
 	xchg ebx,[esp]
 	ret
+error:
+	pop edx
+	pop ecx
+	pop ebx
+	stc
+	ret
 	align 2
 tab168a label word
  ifdef _DEBUG
 	@wofs is0000
 	@wofs is0001
 	@wofs is0002
 	@wofs is0003
- else
-	@wofs error
-	@wofs error
-	@wofs error
-	@wofs error
  endif
 	@wofs is0004	; "disable" host
-
  if ?VM
 	@wofs is0005	; set/reset HDPMI=32 (VM)
- else
-	@wofs error
  endif
-
  if ?PMIOPL eq 0
-
 	@wofs is0006	; trap port range
 	@wofs is0007	; release trapped port range
 	@wofs simio		; Simulate IO
 	@wofs is0009	; trap CLI/STI
-;	@wofs is000A	; Simulate HW interrupt
-
+;	@wofs is000A	; Simulate HW interrupt (not yet implemented)
+ endif
+ if ?NMISAFE
+	@wofs is000B	; get/set real-mode NMI address
  endif
-MAX168A equ ($ - offset tab168a) / sizeof word
-
-start168a:
-error:
-	stc
-	ret
  ifdef _DEBUG
 is0000:
 	and ss:gbl.fMode2,not FM2_LOG
@@ -554,6 +567,15 @@ is0009 endp
  
  endif ; ?PMIOPL eq 0
 
+ if ?NMISAFE
+;--- temporary, will be removed when PL0 exceptions work
+is000B proc
+	xchg dx, word ptr ss:[oldint02rm+0]
+	xchg cx, word ptr ss:[oldint02rm+2]
+	ret
+is000B endp
+ endif
+
 _TEXT32 ends
 
 endif

Src/HDPMI/I31SWT.ASM

@@ -254,8 +254,6 @@ else
 	xor ecx, ecx
 	mov ds, ecx
 
-	@NMI_ON 0
-
 	@dprintf "rmcb: will try to alloc a rm-selector"
 
 	mov bx, ss:v86iret.rSS
@@ -310,6 +308,7 @@ if _LTRACE_ and ?RMCBLOG
  endif
 endif
 	push eax
+	@NMI_ON ;rmcb_pm
 	jmp lpms_call_int		;switch to LPMS
 	align 4
 
@@ -531,8 +530,13 @@ endif
 havecsip:
 if ?SAFE301
 	sub eax,5*2
+ if ?NMISAFE
+	mov es:[edx+eax],cx				;flags (will be popped before RETF)
+	mov es:[edx+eax+2],esi
+ else
 	mov es:[edx+eax],esi
 	mov es:[edx+eax+4],cx			;flags (will be popped by an IRET)
+ endif
 	mov si,ss:[wHostSeg]
 	shl esi,16
 	mov si,offset callrmproc_rm2
@@ -586,7 +590,12 @@ error1x:
 _TEXT16 segment
 callrmproc_rm:
 if ?SAFE301
+ if ?NMISAFE
+	popf
+	retf
+ else
 	iret
+ endif
 callrmproc_rm2:
 else
 	popf
@@ -1113,7 +1122,7 @@ endif
 	mov [esp].IRET32.rSP, ebx
 	mov [esp].IRET32.rSSd, edx
 
-	@NMI_ON 0
+	@NMI_ON ;rm2pm
 
 	@checkhoststack