From 7e71c33f3f19e945a38ab5bcdbfe3531febfc84e Mon Sep 17 00:00:00 2001
From: Abdur-Rahman Mansoor <armansoor@missingno.dev>
Date: Sun, 21 Jul 2024 14:14:04 -0400
Subject: [PATCH] fix: nvme_readwrite and build_prp_list

This fixes the number of PRPs calculation before build_prp_list is
invoked. It also accounts for the fact that the NLB field in the NVMe
I/O read and write commands is a 0-based value, unlike numsectors.
start_sector is also converted into the appropriate LBA number as it
should be before sending the I/O command.
---
 drivers/nvme/nvme.asm | 56 ++++++++++++++++++++++---------------------
 1 file changed, 29 insertions(+), 27 deletions(-)

diff --git a/drivers/nvme/nvme.asm b/drivers/nvme/nvme.asm
index e7547a9..bc16673 100644
--- a/drivers/nvme/nvme.asm
+++ b/drivers/nvme/nvme.asm
@@ -621,18 +621,17 @@ proc alloc_dptr stdcall, ns:dword, prps_ptr:dword, numsectors:dword, prp_list_pt
 	mov 	ecx, dword [esi + NSINFO.pg_sectors]
 	xor 	edx, edx
 	div 	ecx
-	test 	edx, edx
-	jz 	@f
-	inc 	eax
+	;test 	edx, edx
+	;jz 	@f
+	;inc 	eax
 
 @@:
-	mov 	eax, [buf]
-	and 	eax, not (PAGE_SIZE - 1)
-	add 	eax, PAGE_SIZE
-	stdcall build_prp_list, edx, eax, [prp_list_ptr]
+	mov 	edx, [buf]
+	and 	edx, not (PAGE_SIZE - 1)
+	add 	edx, PAGE_SIZE
+	stdcall build_prp_list, eax, edx, [prp_list_ptr]
 	test 	eax, eax
 	jz 	.err
-	DEBUGF  DBG_INFO, "Successfully allocated PRP list at: %x\n", eax
 	mov 	dword [edi + 4], eax
 	jmp 	.success
 	
@@ -669,16 +668,8 @@ proc nvme_readwrite stdcall, ns:dword, buf:dword, start_sector:qword, numsectors
 	; [esp + 16] - virtual pointer to PRP2 PRP list (if allocated, 0 if not)
 	mov 	ebx, esp
 
-	; its important to do a memset here as otherwise a PRP offset error will
-	; probably occur.
-	mov 	eax, [numsectors_ptr]
-	mov 	eax, dword [eax]
 	mov 	esi, [ns]
 	mov 	edi, [buf]
-	mov 	ecx, dword [esi + NSINFO.lbads]
-	imul 	ecx, eax
-	shr 	ecx, 2
-	stdcall memsetdz, edi, ecx
 
 	mov 	eax, [numsectors_ptr]
 	mov 	eax, dword [eax]
@@ -697,14 +688,28 @@ proc nvme_readwrite stdcall, ns:dword, buf:dword, start_sector:qword, numsectors
 	jz 	.dptr_fail
 
 	DEBUGF  DBG_INFO, "PRP1: %x, PRP2: %x\n", [ebx], [ebx + 4]
+
+	mov 	eax, dword [start_sector]
+	mov 	ecx, dword [esi + NSINFO.lbads]
+	xor 	edx, edx
+	div 	ecx
+	DEBUGF  DBG_INFO, "sector start: %u\n", eax
+
+	; According to the NVMe specification, the NLB field in the I/O read and write
+	; commands is a 0-based value (i.e., 0 is equivalant to 1, 1 is equivalant to 2, ...)
+	; As far as I know, KolibriOS doesn't follow this mechanism so let's just decrement the
+	; value and it should have the same effect.
+	mov 	ecx, dword [ebx + 12]
+	dec 	ecx
+
 	stdcall nvme_io_rw, [esi + NSINFO.pci], \
 	                    1,  \
 	                    [esi + NSINFO.nsid], \
 	                    dword [ebx], \
 			    dword [ebx + 4], \
-	                    dword [start_sector], \
+	                    eax, \
 	                    dword [start_sector + 4], \
-	                    dword [ebx + 12], \
+	                    ecx, \
 	                    dword [ebx + 8]
 
 	; assume command completes successfully for now
@@ -1114,23 +1119,20 @@ proc nvme_init stdcall, pci:dword
 	div 	ecx
 	mov 	dword [ebx + NSINFO.pg_sectors], eax
 	invoke  KernelFree, edi
-	if 0
+	if 1
 		invoke  KernelAlloc, 0x4000
 		test 	eax, eax
 		jz 	.exit_fail
 		mov 	edi, eax
-		stdcall memsetdz, edi, 0x4000 / 4
 		invoke  KernelAlloc, 0x8
 		test 	eax, eax
 		jz 	.exit_fail
 		mov 	edx, NVM_CMD_READ
-		mov 	dword [eax], 17
-		;add 	edi, 4094
-		stdcall nvme_readwrite, [esi + pcidev.nsinfo], edi, 0, 0, eax
-		test 	eax, eax
-		jz 	.exit_fail
-		add 	edi, PAGE_SIZE
+		mov 	dword [eax], 23
+		stdcall nvme_readwrite, [esi + pcidev.nsinfo], edi, 0x1000, 0, eax
 	        DEBUGF  DBG_INFO, "STRING: %s\n", edi
+		add 	edi, 0x1fe0
+		DEBUGF  DBG_INFO, "STRING: %s\n", edi
 	end if
 	DEBUGF  DBG_INFO, "nvme%u: Successfully initialized driver\n", [esi + pcidev.num]
       	xor     eax, eax
@@ -1477,7 +1479,7 @@ align 4
 		dd 	 0 ; no close function
 		dd 	 0 ; no closemedia function
 		dd 	 nvme_query_media
-		dd 	 nvme_read
+		dd 	 0
 		dd 	 0 ; no write function (for now)
 		dd 	 0 ; no flush function
 		dd 	 0 ; use default cache size