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Allow consumer to customize physical pager.

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Add support for user-supplied callbacks into phys pager operations,
providing custom getpages(), haspage(), and populate() methods
implementations.  Pager stores user data ptr/val in the object to
provide context.

Add phys_pager_allocate() helper that takes user ops table as one of
the arguments.

Current code for these methods is moved to the 'default' ops table,
assigned automatically when vm_pager_alloc() is used.

Reviewed by:	markj
Tested by:	pho
Sponsored by:	The FreeBSD Foundation
MFC after:	1 week
Differential revision:	https://reviews.freebsd.org/D24652
This commit is contained in:
Konstantin Belousov 2020-09-09 00:00:43 +00:00
parent 6957645145
commit a720b31c2a
Notes: svn2git 2020-12-20 02:59:44 +00:00 
svn path=/head/; revision=365488
4 changed files with 98 additions and 10 deletions
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79
sys/vm/phys_pager.c
View File

@ -51,6 +51,20 @@ static struct pagerlst phys_pager_object_list;
/* protect access to phys_pager_object_list */
static struct mtx phys_pager_mtx;
static int default_phys_pager_getpages(vm_object_t object, vm_page_t *m,
int count, int *rbehind, int *rahead);
static int default_phys_pager_populate(vm_object_t object, vm_pindex_t pidx,
int fault_type, vm_prot_t max_prot, vm_pindex_t *first, vm_pindex_t *last);
static boolean_t default_phys_pager_haspage(vm_object_t object,
vm_pindex_t pindex, int *before, int *after);
struct phys_pager_ops default_phys_pg_ops = {
.phys_pg_getpages = default_phys_pager_getpages,
.phys_pg_populate = default_phys_pager_populate,
.phys_pg_haspage = default_phys_pager_haspage,
.phys_pg_ctor = NULL,
.phys_pg_dtor = NULL,
};
static void
phys_pager_init(void)
{
@ -59,12 +73,13 @@ phys_pager_init(void)
mtx_init(&phys_pager_mtx, "phys_pager list", NULL, MTX_DEF);
}
static vm_object_t
phys_pager_alloc(void *handle, vm_ooffset_t size, vm_prot_t prot,
vm_ooffset_t foff, struct ucred *cred)
vm_object_t
phys_pager_allocate(void *handle, struct phys_pager_ops *ops, void *data,
vm_ooffset_t size, vm_prot_t prot, vm_ooffset_t foff, struct ucred *cred)
{
vm_object_t object, object1;
vm_pindex_t pindex;
bool init;
/*
* Offset should be page aligned.
@ -73,6 +88,7 @@ phys_pager_alloc(void *handle, vm_ooffset_t size, vm_prot_t prot,
return (NULL);
pindex = OFF_TO_IDX(foff + PAGE_MASK + size);
init = true;
if (handle != NULL) {
mtx_lock(&phys_pager_mtx);
@ -97,11 +113,15 @@ phys_pager_alloc(void *handle, vm_ooffset_t size, vm_prot_t prot,
*/
if (pindex > object->size)
object->size = pindex;
init = false;
} else {
object = object1;
object1 = NULL;
object->handle = handle;
vm_object_set_flag(object, OBJ_POPULATE);
object->un_pager.phys.ops = ops;
object->un_pager.phys.data_ptr = data;
if (ops->phys_pg_populate != NULL)
vm_object_set_flag(object, OBJ_POPULATE);
TAILQ_INSERT_TAIL(&phys_pager_object_list,
object, pager_object_list);
}
@ -113,12 +133,25 @@ phys_pager_alloc(void *handle, vm_ooffset_t size, vm_prot_t prot,
vm_object_deallocate(object1);
} else {
object = vm_object_allocate(OBJT_PHYS, pindex);
vm_object_set_flag(object, OBJ_POPULATE);
object->un_pager.phys.ops = ops;
object->un_pager.phys.data_ptr = data;
if (ops->phys_pg_populate != NULL)
vm_object_set_flag(object, OBJ_POPULATE);
}
if (init && ops->phys_pg_ctor != NULL)
ops->phys_pg_ctor(object, prot, foff, cred);
return (object);
}
static vm_object_t
phys_pager_alloc(void *handle, vm_ooffset_t size, vm_prot_t prot,
vm_ooffset_t foff, struct ucred *ucred)
{
return (phys_pager_allocate(handle, &default_phys_pg_ops, NULL,
size, prot, foff, ucred));
}
static void
phys_pager_dealloc(vm_object_t object)
{
@ -130,16 +163,18 @@ phys_pager_dealloc(vm_object_t object)
mtx_unlock(&phys_pager_mtx);
VM_OBJECT_WLOCK(object);
}
object->handle = NULL;
object->type = OBJT_DEAD;
if (object->un_pager.phys.ops->phys_pg_dtor != NULL)
object->un_pager.phys.ops->phys_pg_dtor(object);
object->handle = NULL;
}
/*
* Fill as many pages as vm_fault has allocated for us.
*/
static int
phys_pager_getpages(vm_object_t object, vm_page_t *m, int count, int *rbehind,
int *rahead)
default_phys_pager_getpages(vm_object_t object, vm_page_t *m, int count,
int *rbehind, int *rahead)
{
int i;
@ -161,6 +196,14 @@ phys_pager_getpages(vm_object_t object, vm_page_t *m, int count, int *rbehind,
return (VM_PAGER_OK);
}
static int
phys_pager_getpages(vm_object_t object, vm_page_t *m, int count, int *rbehind,
int *rahead)
{
return (object->un_pager.phys.ops->phys_pg_getpages(object, m,
count, rbehind, rahead));
}
/*
* Implement a pretty aggressive clustered getpages strategy. Hint that
* everything in an entire 4MB window should be prefaulted at once.
@ -185,7 +228,7 @@ SYSCTL_INT(_vm, OID_AUTO, phys_pager_cluster, CTLFLAG_RWTUN,
#define PHYSALLOC 16
static int
phys_pager_populate(vm_object_t object, vm_pindex_t pidx,
default_phys_pager_populate(vm_object_t object, vm_pindex_t pidx,
int fault_type __unused, vm_prot_t max_prot __unused, vm_pindex_t *first,
vm_pindex_t *last)
{
@ -216,6 +259,14 @@ phys_pager_populate(vm_object_t object, vm_pindex_t pidx,
return (VM_PAGER_OK);
}
static int
phys_pager_populate(vm_object_t object, vm_pindex_t pidx, int fault_type,
vm_prot_t max_prot, vm_pindex_t *first, vm_pindex_t *last)
{
return (object->un_pager.phys.ops->phys_pg_populate(object, pidx,
fault_type, max_prot, first, last));
}
static void
phys_pager_putpages(vm_object_t object, vm_page_t *m, int count, boolean_t sync,
int *rtvals)
@ -225,7 +276,7 @@ phys_pager_putpages(vm_object_t object, vm_page_t *m, int count, boolean_t sync,
}
static boolean_t
phys_pager_haspage(vm_object_t object, vm_pindex_t pindex, int *before,
default_phys_pager_haspage(vm_object_t object, vm_pindex_t pindex, int *before,
int *after)
{
vm_pindex_t base, end;
@ -239,6 +290,14 @@ phys_pager_haspage(vm_object_t object, vm_pindex_t pindex, int *before,
return (TRUE);
}
static boolean_t
phys_pager_haspage(vm_object_t object, vm_pindex_t pindex, int *before,
int *after)
{
return (object->un_pager.phys.ops->phys_pg_haspage(object, pindex,
before, after));
}
struct pagerops physpagerops = {
.pgo_init = phys_pager_init,
.pgo_alloc = phys_pager_alloc,

1
sys/vm/vm_object.c
View File

@ -286,6 +286,7 @@ vm_object_init(void)
kernel_object->flags |= OBJ_COLORED;
kernel_object->pg_color = (u_short)atop(VM_MIN_KERNEL_ADDRESS);
#endif
kernel_object->un_pager.phys.ops = &default_phys_pg_ops;
/*
* The lock portion of struct vm_object must be type stable due

11
sys/vm/vm_object.h
View File

@ -173,6 +173,17 @@ struct vm_object {
struct pctrie swp_blks;
vm_ooffset_t writemappings;
} swp;
/*
* Phys pager
*/
struct {
struct phys_pager_ops *ops;
union {
void *data_ptr;
uintptr_t data_val;
};
} phys;
} un_pager;
struct ucred *cred;
vm_ooffset_t charge;

17
sys/vm/vm_pager.h
View File

@ -227,5 +227,22 @@ vm_object_t cdev_pager_allocate(void *handle, enum obj_type tp,
vm_object_t cdev_pager_lookup(void *handle);
void cdev_pager_free_page(vm_object_t object, vm_page_t m);
struct phys_pager_ops {
int (*phys_pg_getpages)(vm_object_t vm_obj, vm_page_t *m, int count,
int *rbehind, int *rahead);
int (*phys_pg_populate)(vm_object_t vm_obj, vm_pindex_t pidx,
int fault_type, vm_prot_t max_prot, vm_pindex_t *first,
vm_pindex_t *last);
boolean_t (*phys_pg_haspage)(vm_object_t obj, vm_pindex_t pindex,
int *before, int *after);
void (*phys_pg_ctor)(vm_object_t vm_obj, vm_prot_t prot,
vm_ooffset_t foff, struct ucred *cred);
void (*phys_pg_dtor)(vm_object_t vm_obj);
};
extern struct phys_pager_ops default_phys_pg_ops;
vm_object_t phys_pager_allocate(void *handle, struct phys_pager_ops *ops,
void *data, vm_ooffset_t size, vm_prot_t prot, vm_ooffset_t foff,
struct ucred *cred);
#endif /* _KERNEL */
#endif /* _VM_PAGER_ */