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Deshab-OS/CODE/UTSM/vmm/virtio_blk.c
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FUCKYOU
2026-07-28 21:11:10 +08:00
/* virtio_blk.c — UTSM virtio-blk 设备模拟后端。
*
* 为 Linux guest 提供 virtio-blk 块设备。guest 的块读写请求经
* virtqueue 传入，本后端桥接到 UTSM 真实块设备（block API，AHCI/SATA）。
*
* Virtio Spec 1.1 §5.2 (Block Device)。
* 请求描述符链： [header(16B, R)] [data(N*512B, R/W)] [status(1B, W)]
* 支持的操作：VIRTIO_BLK_T_IN(读)、VIRTIO_BLK_T_OUT(写)、VIRTIO_BLK_T_GET_ID。
*
* 设计说明：
* - 桥接到 UTSM block API 的第 0 个设备（ahci0 SATA 盘）。
* - guest 把 Arch rootfs 镜像当作 /dev/vda 挂载；镜像需预先写入 SATA 盘
* 的某个分区/LBA 区间（由 mkfat32/build 流程或独立 raw 区提供）。
* - 当前为最小可用：扇区 512B，单队列，无 flush/discard。
*/
#include <utsm/virtio_mmio.h>
#include <utsm/linux_loader.h>
#include <utsm/block.h>
#include <utsm/log.h>
#include <utsm/types.h>
/* virtio-blk 请求头（Virtio Spec 1.1 §5.2.6.2） */
struct virtio_blk_outhdr {
u32 type; /* VIRTIO_BLK_T_* */
u32 reserved; /* (ioprio) */
u64 sector; /* 起始扇区（512B 单位） */
} __attribute__((packed));
#define VIRTIO_BLK_T_IN 0 /* 读 */
#define VIRTIO_BLK_T_OUT 1 /* 写 */
#define VIRTIO_BLK_T_FLUSH 4
#define VIRTIO_BLK_T_GET_ID 8
#define VIRTIO_BLK_S_OK 0
#define VIRTIO_BLK_S_IOERR 1
#define VIRTIO_BLK_S_UNSUPP 2
/* feature bits */
#define VIRTIO_BLK_F_SIZE_MAX 1
#define VIRTIO_BLK_F_SEG_MAX 2
#define VIRTIO_BLK_F_BLK_SIZE 6
#define VIRTIO_BLK_F_FLUSH 9
/* device config 空间（VIRTIO_MMIO_CONFIG 起） */
struct virtio_blk_config {
u64 capacity; /* 总扇区数（512B） */
u32 size_max;
u32 seg_max;
u16 geometry[4];
u32 blk_size;
/* ... 其余字段省略 */
} __attribute__((packed));
/* 后端状态 */
static u64 g_blk_capacity; /* 扇区数 */
static u32 g_blk_sector_size = 512;
static int g_blk_bound = -1; /* 绑定的 UTSM block 设备索引 */
/* 读取 device config 空间 */
static u32 blk_read_config(u32 offset, int width) {
(void)width;
struct virtio_blk_config cfg;
/* 填零后逐字段读取 */
u8 *c = (u8 *)&cfg;
for (u32 i = 0; i < sizeof(cfg); i++) c[i] = 0;
cfg.capacity = g_blk_capacity;
cfg.size_max = 128; /* 单请求最大 128 扇区 */
cfg.seg_max = 32;
cfg.blk_size = g_blk_sector_size;
/* 按 offset 返回 32 位窗口 */
if (offset + 4 <= sizeof(cfg)) {
u32 v;
u8 *src = (u8 *)&cfg + offset;
v = (u32)src[0] | ((u32)src[1] << 8) | ((u32)src[2] << 16) | ((u32)src[3] << 24);
return v;
}
return 0;
}
/* 处理一个块请求描述符链。返回写入 guest 的字节数（用于 used.len）。 */
static u32 blk_handle_chain(struct virtq_desc *desc, u16 head, u32 qnum) {
(void)qnum;
if (!desc) return 0;
/* 第一个描述符：请求头（driver→device，16 字节） */
struct virtio_blk_outhdr *hdr =
(struct virtio_blk_outhdr *)virtio_gpa_to_host(desc[head].addr);
if (!hdr) return 0;
u32 type = hdr->type;
u64 sector = hdr->sector;
/* 沿描述符链找到 data 与 status 描述符 */
u16 cur = head;
u16 data_idx = 0xFFFF, status_idx = 0xFFFF;
int hops = 0;
if (desc[cur].flags & VIRTQ_DESC_F_NEXT) {
data_idx = desc[cur].next;
cur = data_idx;
/* data 之后可能还有 status */
while ((desc[cur].flags & VIRTQ_DESC_F_NEXT) && hops < 16) {
cur = desc[cur].next;
hops++;
}
/* 最后一个是 status（device write，1 字节） */
status_idx = cur;
}
u8 *status = (u8 *)0;
if (status_idx != 0xFFFF && (desc[status_idx].flags & VIRTQ_DESC_F_WRITE)) {
status = (u8 *)virtio_gpa_to_host(desc[status_idx].addr);
}
u32 bytes_done = 0;
u8 result = VIRTIO_BLK_S_OK;
const dkm_block_api *blk = block_get_api();
switch (type) {
case VIRTIO_BLK_T_IN: { /* 读：块设备 → guest data buffer */
if (data_idx == 0xFFFF || g_blk_bound < 0 || !blk) {
result = VIRTIO_BLK_S_IOERR;
break;
}
u8 *dbuf = (u8 *)virtio_gpa_to_host(desc[data_idx].addr);
u32 dlen = desc[data_idx].len;
if (!dbuf) { result = VIRTIO_BLK_S_IOERR; break; }
u32 nsec = dlen / 512;
if (nsec == 0) nsec = 1;
if (blk->read((u32)g_blk_bound, sector, nsec, dbuf) != 0) {
result = VIRTIO_BLK_S_IOERR;
} else {
bytes_done = dlen;
}
break;
}
case VIRTIO_BLK_T_OUT: { /* 写：guest data buffer → 块设备 */
if (data_idx == 0xFFFF || g_blk_bound < 0 || !blk) {
result = VIRTIO_BLK_S_IOERR;
break;
}
const u8 *dbuf = (const u8 *)virtio_gpa_to_host(desc[data_idx].addr);
u32 dlen = desc[data_idx].len;
if (!dbuf) { result = VIRTIO_BLK_S_IOERR; break; }
u32 nsec = dlen / 512;
if (nsec == 0) nsec = 1;
if (blk->write((u32)g_blk_bound, sector, nsec, dbuf) != 0) {
result = VIRTIO_BLK_S_IOERR;
} else {
bytes_done = 0; /* 写操作 used.len=0 */
}
break;
}
case VIRTIO_BLK_T_GET_ID: {
if (data_idx != 0xFFFF) {
char *idbuf = (char *)virtio_gpa_to_host(desc[data_idx].addr);
if (idbuf) {
const char *id = "DESHAB-VIRTIO-BLK";
u32 i = 0;
for (; id[i] && i < desc[data_idx].len - 1; i++) idbuf[i] = id[i];
idbuf[i] = 0;
bytes_done = i + 1;
}
}
break;
}
case VIRTIO_BLK_T_FLUSH:
result = VIRTIO_BLK_S_OK; /* 无写缓存，直接成功 */
break;
default:
result = VIRTIO_BLK_S_UNSUPP;
break;
}
/* 写状态字节 */
if (status) *status = result;
return bytes_done;
}
/* queue_notify：guest 提交了块请求，处理队列。 */
static u16 g_blk_last_avail;
static void blk_queue_notify(u32 queue_idx) {
struct virtq_desc *desc;
struct virtq_avail *avail;
struct virtq_used *used;
u32 qnum;
if (virtio_queue_get_ptrs(VIRTIO_ID_BLOCK, queue_idx,
&desc, &avail, &used, &qnum) != 0) {
return;
}
/* 处理自上次以来的所有新 avail 请求 */
u16 cur = g_blk_last_avail;
u16 used_idx = used->idx;
while (cur != avail->idx) {
u16 head = avail->ring[cur % qnum];
u32 len = blk_handle_chain(desc, head, qnum);
/* 写 used 回执 */
used->ring[used_idx % qnum].id = head;
used->ring[used_idx % qnum].len = len;
used_idx++;
cur++;
}
virtio_queue_bump_used(used, used_idx);
g_blk_last_avail = cur;
}
static void blk_reset(void) {
g_blk_last_avail = 0;
}
/* 后端结构体 */
static struct virtio_backend g_blk_backend = {
.device_id = VIRTIO_ID_BLOCK,
.gpa_base = VIRTIO_MMIO_BLK_GPA,
.irq = 5, /* guest ISA IRQ5（cmdline :5，vector 0x35） */
.num_queues = 1,
.queue_size = 128,
.device_features = (1ULL << VIRTIO_F_VERSION_1) |
(1ULL << VIRTIO_BLK_F_SIZE_MAX) |
(1ULL << VIRTIO_BLK_F_SEG_MAX) |
(1ULL << VIRTIO_BLK_F_BLK_SIZE) |
(1ULL << VIRTIO_BLK_F_FLUSH),
.config_len = sizeof(struct virtio_blk_config),
.read_config = blk_read_config,
.queue_notify = blk_queue_notify,
.reset = blk_reset,
};
void virtio_blk_backend_init(void) {
/* 绑定 UTSM 第 0 个块设备（ahci0 SATA 盘）作为后端存储 */
const dkm_block_api *blk = block_get_api();
if (blk && blk->device_count() > 0) {
g_blk_bound = 0;
u64 ssize = blk->sector_size(0);
if (ssize > 0) g_blk_sector_size = (u32)ssize;
/* 从设备名推算容量不可得，用默认值（guest 端可再探测）。
* 实际 capacity 需读 ATA IDENTIFY；这里给 4GB 占位，
* guest mkfs/mount 会按此上限工作。 */
g_blk_capacity = 8ULL * 1024 * 1024 * 1024 / 512; /* 8GB in sectors */
log_info("[VBLK] bound to UTSM block device 0");
log_hex64("[VBLK] capacity(sectors)=", g_blk_capacity);
} else {
g_blk_bound = -1;
g_blk_capacity = 0;
log_warn("[VBLK] no UTSM block device, blk backend degraded");
}
virtio_mmio_register(&g_blk_backend);
}
FUCKYOU
2026-07-31 13:53:49 +08:00
/* ===== Memory-backed rootfs virtio-blk 后端 =====
*
* 第二个 virtio-blk 设备，后端为内存中的 Arch rootfs 镜像（Limine boot module）。
* guest 看到 /dev/vdb，挂载为真实根文件系统（ext4），switch_root 进入 Arch。
*
* 读写直接操作内存（memcpy），无需块设备 API。 */
/* byte-wise memcpy helper (freestanding, no libc) */
static void rf_memcpy(void *dst, const void *src, u64 n) {
u8 *d = (u8 *)dst;
const u8 *s = (const u8 *)src;
while (n--) *d++ = *s++;
}
static const u8 *g_rootfs_data; /* rootfs 镜像内存指针（HHDM 虚拟地址） */
static u64 g_rootfs_size; /* rootfs 镜像大小（字节） */
static u64 g_rootfs_capacity; /* rootfs 容量（扇区数，512B 单位） */
static u32 rootfs_blk_read_config(u32 offset, int width) {
(void)width;
struct virtio_blk_config cfg;
u8 *c = (u8 *)&cfg;
for (u32 i = 0; i < sizeof(cfg); i++) c[i] = 0;
cfg.capacity = g_rootfs_capacity;
cfg.size_max = 128;
cfg.seg_max = 32;
cfg.blk_size = 512;
if (offset + 4 <= sizeof(cfg)) {
u32 val = 0;
rf_memcpy(&val, c + offset, 4);
return val;
}
if (offset < sizeof(cfg)) {
u32 val = 0;
rf_memcpy(&val, c + offset, 4);
return val;
}
return 0;
}
/* rootfs 请求处理：直接内存拷贝 */
static u32 rootfs_blk_handle_chain(struct virtq_desc *desc, u16 head, u32 qnum) {
(void)qnum;
struct virtio_blk_outhdr hdr;
u8 *hptr = (u8 *)virtio_gpa_to_host(desc[head].addr);
if (!hptr) return 0;
rf_memcpy(&hdr, hptr, sizeof(hdr));
u32 type = hdr.type;
u64 sector = hdr.sector;
u16 data_idx = 0xFFFF;
u16 status_idx = 0xFFFF;
if (desc[head].flags & VIRTQ_DESC_F_NEXT) {
data_idx = desc[head].next;
u16 cur = data_idx;
int hops = 0;
while ((desc[cur].flags & VIRTQ_DESC_F_NEXT) && hops < 16) {
cur = desc[cur].next;
hops++;
}
status_idx = cur;
}
u8 *status = (u8 *)0;
if (status_idx != 0xFFFF && (desc[status_idx].flags & VIRTQ_DESC_F_WRITE)) {
status = (u8 *)virtio_gpa_to_host(desc[status_idx].addr);
}
u32 bytes_done = 0;
u8 result = VIRTIO_BLK_S_OK;
switch (type) {
case VIRTIO_BLK_T_IN: { /* 读：rootfs 内存 → guest */
if (data_idx == 0xFFFF || !g_rootfs_data) {
result = VIRTIO_BLK_S_IOERR;
break;
}
u8 *dbuf = (u8 *)virtio_gpa_to_host(desc[data_idx].addr);
u32 dlen = desc[data_idx].len;
if (!dbuf) { result = VIRTIO_BLK_S_IOERR; break; }
u64 offset = sector * 512ULL;
if (offset + dlen > g_rootfs_size) {
/* 超出范围：截断或填零 */
u64 avail = (offset < g_rootfs_size) ? (g_rootfs_size - offset) : 0;
if (avail > 0) {
rf_memcpy(dbuf, g_rootfs_data + offset, avail);
}
/* 剩余部分填零 */
if (dlen > avail) {
u8 *p = dbuf + avail;
u32 rem = dlen - (u32)avail;
while (rem--) *p++ = 0;
}
bytes_done = dlen;
} else {
rf_memcpy(dbuf, g_rootfs_data + offset, dlen);
bytes_done = dlen;
}
break;
}
case VIRTIO_BLK_T_OUT: /* 写：暂不支持（rootfs 只读） */
result = VIRTIO_BLK_S_IOERR;
break;
case VIRTIO_BLK_T_GET_ID:
if (data_idx != 0xFFFF) {
char *idbuf = (char *)virtio_gpa_to_host(desc[data_idx].addr);
if (idbuf) {
const char *id = "DESHAB-ROOTFS";
u32 i = 0;
for (; id[i] && i < desc[data_idx].len - 1; i++) idbuf[i] = id[i];
idbuf[i] = 0;
bytes_done = i + 1;
}
}
break;
case VIRTIO_BLK_T_FLUSH:
result = VIRTIO_BLK_S_OK;
break;
default:
result = VIRTIO_BLK_S_UNSUPP;
break;
}
if (status) *status = result;
return bytes_done;
}
static u16 g_rootfs_last_avail;
static void rootfs_blk_queue_notify(u32 queue_idx) {
struct virtq_desc *desc;
struct virtq_avail *avail;
struct virtq_used *used;
u32 qnum;
if (virtio_queue_get_ptrs(VIRTIO_ID_BLOCK, queue_idx,
&desc, &avail, &used, &qnum) != 0) {
return;
}
u16 cur = g_rootfs_last_avail;
u16 used_idx = used->idx;
while (cur != avail->idx) {
u16 head = avail->ring[cur % qnum];
u32 len = rootfs_blk_handle_chain(desc, head, qnum);
used->ring[used_idx % qnum].id = head;
used->ring[used_idx % qnum].len = len;
used_idx++;
cur++;
}
virtio_queue_bump_used(used, used_idx);
g_rootfs_last_avail = cur;
}
static void rootfs_blk_reset(void) {
g_rootfs_last_avail = 0;
}
static struct virtio_backend g_rootfs_blk_backend = {
.device_id = VIRTIO_ID_BLOCK,
.gpa_base = VIRTIO_MMIO_ROOTFS_GPA,
.irq = 7, /* guest ISA IRQ7（cmdline :7，vector 0x37） */
.num_queues = 1,
.queue_size = 128,
.device_features = (1ULL << VIRTIO_F_VERSION_1) |
(1ULL << VIRTIO_BLK_F_SIZE_MAX) |
(1ULL << VIRTIO_BLK_F_SEG_MAX) |
(1ULL << VIRTIO_BLK_F_BLK_SIZE) |
(1ULL << VIRTIO_BLK_F_FLUSH),
.config_len = sizeof(struct virtio_blk_config),
.read_config = rootfs_blk_read_config,
.queue_notify = rootfs_blk_queue_notify,
.reset = rootfs_blk_reset,
};
void virtio_rootfs_blk_init(void) {
u64 rootfs_size = 0;
void *rootfs = linux_find_rootfs_module(&rootfs_size);
if (!rootfs || rootfs_size == 0) {
log_warn("[VBLK] no rootfs module, rootfs-blk backend not registered");
return;
}
g_rootfs_data = (const u8 *)rootfs;
g_rootfs_size = rootfs_size;
g_rootfs_capacity = rootfs_size / 512; /* 扇区数 */
if (rootfs_size % 512) g_rootfs_capacity++;
log_info("[VBLK] rootfs-blk backend bound to memory module");
log_hex64("[VBLK] rootfs size=", rootfs_size);
log_hex64("[VBLK] rootfs capacity(sectors)=", g_rootfs_capacity);
virtio_mmio_register(&g_rootfs_blk_backend);
}
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