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author | Frans Kaashoek <[email protected]> | 2019-08-12 07:20:32 -0400 |
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committer | Frans Kaashoek <[email protected]> | 2019-08-12 07:20:32 -0400 |
commit | e398a9815c8dc65d556333f9bb65c61ca5be2954 (patch) | |
tree | 97328ea95fd1c41b5c399c570b3fb3ede815a369 | |
parent | d96a8c5661ac27c82e577edc6714832b970586dc (diff) | |
download | xv6-labs-e398a9815c8dc65d556333f9bb65c61ca5be2954.tar.gz xv6-labs-e398a9815c8dc65d556333f9bb65c61ca5be2954.tar.bz2 xv6-labs-e398a9815c8dc65d556333f9bb65c61ca5be2954.zip |
Wrap state of disk driver in a struct so that it is easier to support
several disks (e.g., in a mount lab).
-rw-r--r-- | kernel/virtio_disk.c | 140 |
1 files changed, 71 insertions, 69 deletions
diff --git a/kernel/virtio_disk.c b/kernel/virtio_disk.c index 14c718d..3cff024 100644 --- a/kernel/virtio_disk.c +++ b/kernel/virtio_disk.c @@ -20,36 +20,38 @@ // the address of virtio mmio register r. #define R(r) ((volatile uint32 *)(VIRTIO0 + (r))) -struct spinlock vdisk_lock; - -// memory for virtio descriptors &c for queue 0. -// this is a global instead of allocated because it has -// to be multiple contiguous pages, which kalloc() -// doesn't support. -__attribute__ ((aligned (PGSIZE))) -static char pages[2*PGSIZE]; -static struct VRingDesc *desc; -static uint16 *avail; -static struct UsedArea *used; - -// our own book-keeping. -static char free[NUM]; // is a descriptor free? -static uint16 used_idx; // we've looked this far in used[2..NUM]. - -// track info about in-flight operations, -// for use when completion interrupt arrives. -// indexed by first descriptor index of chain. -static struct { - struct buf *b; - char status; -} info[NUM]; +static struct disk { + // memory for virtio descriptors &c for queue 0. + // this is a global instead of allocated because it must + // be multiple contiguous pages, which kalloc() + // doesn't support, and page aligned. + char pages[2*PGSIZE]; + struct VRingDesc *desc; + uint16 *avail; + struct UsedArea *used; + + // our own book-keeping. + char free[NUM]; // is a descriptor free? + uint16 used_idx; // we've looked this far in used[2..NUM]. + + // track info about in-flight operations, + // for use when completion interrupt arrives. + // indexed by first descriptor index of chain. + struct { + struct buf *b; + char status; + } info[NUM]; + + struct spinlock vdisk_lock; + +} __attribute__ ((aligned (PGSIZE))) disk; void virtio_disk_init(void) { uint32 status = 0; - initlock(&vdisk_lock, "virtio_disk"); + initlock(&disk.vdisk_lock, "virtio_disk"); if(*R(VIRTIO_MMIO_MAGIC_VALUE) != 0x74726976 || *R(VIRTIO_MMIO_VERSION) != 1 || @@ -93,19 +95,19 @@ virtio_disk_init(void) if(max < NUM) panic("virtio disk max queue too short"); *R(VIRTIO_MMIO_QUEUE_NUM) = NUM; - memset(pages, 0, sizeof(pages)); - *R(VIRTIO_MMIO_QUEUE_PFN) = ((uint64)pages) >> PGSHIFT; + memset(disk.pages, 0, sizeof(disk.pages)); + *R(VIRTIO_MMIO_QUEUE_PFN) = ((uint64)disk.pages) >> PGSHIFT; // desc = pages -- num * VRingDesc // avail = pages + 0x40 -- 2 * uint16, then num * uint16 // used = pages + 4096 -- 2 * uint16, then num * vRingUsedElem - desc = (struct VRingDesc *) pages; - avail = (uint16*)(((char*)desc) + NUM*sizeof(struct VRingDesc)); - used = (struct UsedArea *) (pages + PGSIZE); + disk.desc = (struct VRingDesc *) disk.pages; + disk.avail = (uint16*)(((char*)disk.desc) + NUM*sizeof(struct VRingDesc)); + disk.used = (struct UsedArea *) (disk.pages + PGSIZE); for(int i = 0; i < NUM; i++) - free[i] = 1; + disk.free[i] = 1; // plic.c and trap.c arrange for interrupts from VIRTIO0_IRQ. } @@ -115,8 +117,8 @@ static int alloc_desc() { for(int i = 0; i < NUM; i++){ - if(free[i]){ - free[i] = 0; + if(disk.free[i]){ + disk.free[i] = 0; return i; } } @@ -129,11 +131,11 @@ free_desc(int i) { if(i >= NUM) panic("virtio_disk_intr 1"); - if(free[i]) + if(disk.free[i]) panic("virtio_disk_intr 2"); - desc[i].addr = 0; - free[i] = 1; - wakeup(&free[0]); + disk.desc[i].addr = 0; + disk.free[i] = 1; + wakeup(&disk.free[0]); } // free a chain of descriptors. @@ -142,8 +144,8 @@ free_chain(int i) { while(1){ free_desc(i); - if(desc[i].flags & VRING_DESC_F_NEXT) - i = desc[i].next; + if(disk.desc[i].flags & VRING_DESC_F_NEXT) + i = disk.desc[i].next; else break; } @@ -168,7 +170,7 @@ virtio_disk_rw(struct buf *b, int write) { uint64 sector = b->blockno * (BSIZE / 512); - acquire(&vdisk_lock); + acquire(&disk.vdisk_lock); // the spec says that legacy block operations use three // descriptors: one for type/reserved/sector, one for @@ -180,7 +182,7 @@ virtio_disk_rw(struct buf *b, int write) if(alloc3_desc(idx) == 0) { break; } - sleep(&free[0], &vdisk_lock); + sleep(&disk.free[0], &disk.vdisk_lock); } // format the three descriptors. @@ -201,67 +203,67 @@ virtio_disk_rw(struct buf *b, int write) // buf0 is on a kernel stack, which is not direct mapped, // thus the call to kvmpa(). - desc[idx[0]].addr = (uint64) kvmpa((uint64) &buf0); - desc[idx[0]].len = sizeof(buf0); - desc[idx[0]].flags = VRING_DESC_F_NEXT; - desc[idx[0]].next = idx[1]; + disk.desc[idx[0]].addr = (uint64) kvmpa((uint64) &buf0); + disk.desc[idx[0]].len = sizeof(buf0); + disk.desc[idx[0]].flags = VRING_DESC_F_NEXT; + disk.desc[idx[0]].next = idx[1]; - desc[idx[1]].addr = (uint64) b->data; - desc[idx[1]].len = BSIZE; + disk.desc[idx[1]].addr = (uint64) b->data; + disk.desc[idx[1]].len = BSIZE; if(write) - desc[idx[1]].flags = 0; // device reads b->data + disk.desc[idx[1]].flags = 0; // device reads b->data else - desc[idx[1]].flags = VRING_DESC_F_WRITE; // device writes b->data - desc[idx[1]].flags |= VRING_DESC_F_NEXT; - desc[idx[1]].next = idx[2]; + disk.desc[idx[1]].flags = VRING_DESC_F_WRITE; // device writes b->data + disk.desc[idx[1]].flags |= VRING_DESC_F_NEXT; + disk.desc[idx[1]].next = idx[2]; - info[idx[0]].status = 0; - desc[idx[2]].addr = (uint64) &info[idx[0]].status; - desc[idx[2]].len = 1; - desc[idx[2]].flags = VRING_DESC_F_WRITE; // device writes the status - desc[idx[2]].next = 0; + disk.info[idx[0]].status = 0; + disk.desc[idx[2]].addr = (uint64) &disk.info[idx[0]].status; + disk.desc[idx[2]].len = 1; + disk.desc[idx[2]].flags = VRING_DESC_F_WRITE; // device writes the status + disk.desc[idx[2]].next = 0; // record struct buf for virtio_disk_intr(). b->disk = 1; - info[idx[0]].b = b; + disk.info[idx[0]].b = b; // avail[0] is flags // avail[1] tells the device how far to look in avail[2...]. // avail[2...] are desc[] indices the device should process. // we only tell device the first index in our chain of descriptors. - avail[2 + (avail[1] % NUM)] = idx[0]; + disk.avail[2 + (disk.avail[1] % NUM)] = idx[0]; __sync_synchronize(); - avail[1] = avail[1] + 1; + disk.avail[1] = disk.avail[1] + 1; *R(VIRTIO_MMIO_QUEUE_NOTIFY) = 0; // value is queue number // Wait for virtio_disk_intr() to say request has finished. while(b->disk == 1) { - sleep(b, &vdisk_lock); + sleep(b, &disk.vdisk_lock); } - info[idx[0]].b = 0; + disk.info[idx[0]].b = 0; free_chain(idx[0]); - release(&vdisk_lock); + release(&disk.vdisk_lock); } void virtio_disk_intr() { - acquire(&vdisk_lock); + acquire(&disk.vdisk_lock); - while((used_idx % NUM) != (used->id % NUM)){ - int id = used->elems[used_idx].id; + while((disk.used_idx % NUM) != (disk.used->id % NUM)){ + int id = disk.used->elems[disk.used_idx].id; - if(info[id].status != 0) + if(disk.info[id].status != 0) panic("virtio_disk_intr status"); - info[id].b->disk = 0; // disk is done with buf - wakeup(info[id].b); + disk.info[id].b->disk = 0; // disk is done with buf + wakeup(disk.info[id].b); - used_idx = (used_idx + 1) % NUM; + disk.used_idx = (disk.used_idx + 1) % NUM; } - release(&vdisk_lock); + release(&disk.vdisk_lock); } |