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grant_table.c
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Editing: grant_table.c
/****************************************************************************** * gnttab.c * * Two sets of functionality: * 1. Granting foreign access to our memory reservation. * 2. Accessing others' memory reservations via grant references. * (i.e., mechanisms for both sender and recipient of grant references) * * Copyright (c) 2005, Christopher Clark * Copyright (c) 2004, K A Fraser */ #include <sys/cdefs.h> __FBSDID("$FreeBSD$"); #include <sys/param.h> #include <sys/systm.h> #include <sys/bus.h> #include <sys/conf.h> #include <sys/module.h> #include <sys/kernel.h> #include <sys/lock.h> #include <sys/malloc.h> #include <sys/mman.h> #include <sys/limits.h> #include <sys/rman.h> #include <machine/resource.h> #include <machine/cpu.h> #include <xen/xen-os.h> #include <xen/hypervisor.h> #include <machine/xen/synch_bitops.h> #include <xen/hypervisor.h> #include <xen/gnttab.h> #include <vm/vm.h> #include <vm/vm_kern.h> #include <vm/vm_extern.h> #include <vm/pmap.h> /* External tools reserve first few grant table entries. */ #define NR_RESERVED_ENTRIES 8 #define GREFS_PER_GRANT_FRAME (PAGE_SIZE / sizeof(grant_entry_t)) static grant_ref_t **gnttab_list; static unsigned int nr_grant_frames; static unsigned int boot_max_nr_grant_frames; static int gnttab_free_count; static grant_ref_t gnttab_free_head; static struct mtx gnttab_list_lock; /* * Resource representing allocated physical address space * for the grant table metainfo */ static struct resource *gnttab_pseudo_phys_res; /* Resource id for allocated physical address space. */ static int gnttab_pseudo_phys_res_id; static grant_entry_t *shared; static struct gnttab_free_callback *gnttab_free_callback_list = NULL; static int gnttab_expand(unsigned int req_entries); #define RPP (PAGE_SIZE / sizeof(grant_ref_t)) #define gnttab_entry(entry) (gnttab_list[(entry) / RPP][(entry) % RPP]) static int get_free_entries(int count, int *entries) { int ref, error; grant_ref_t head; mtx_lock(&gnttab_list_lock); if ((gnttab_free_count < count) && ((error = gnttab_expand(count - gnttab_free_count)) != 0)) { mtx_unlock(&gnttab_list_lock); return (error); } ref = head = gnttab_free_head; gnttab_free_count -= count; while (count-- > 1) head = gnttab_entry(head); gnttab_free_head = gnttab_entry(head); gnttab_entry(head) = GNTTAB_LIST_END; mtx_unlock(&gnttab_list_lock); *entries = ref; return (0); } static void do_free_callbacks(void) { struct gnttab_free_callback *callback, *next; callback = gnttab_free_callback_list; gnttab_free_callback_list = NULL; while (callback != NULL) { next = callback->next; if (gnttab_free_count >= callback->count) { callback->next = NULL; callback->fn(callback->arg); } else { callback->next = gnttab_free_callback_list; gnttab_free_callback_list = callback; } callback = next; } } static inline void check_free_callbacks(void) { if (__predict_false(gnttab_free_callback_list != NULL)) do_free_callbacks(); } static void put_free_entry(grant_ref_t ref) { mtx_lock(&gnttab_list_lock); gnttab_entry(ref) = gnttab_free_head; gnttab_free_head = ref; gnttab_free_count++; check_free_callbacks(); mtx_unlock(&gnttab_list_lock); } /* * Public grant-issuing interface functions */ int gnttab_grant_foreign_access(domid_t domid, unsigned long frame, int readonly, grant_ref_t *result) { int error, ref; error = get_free_entries(1, &ref); if (__predict_false(error)) return (error); shared[ref].frame = frame; shared[ref].domid = domid; wmb(); shared[ref].flags = GTF_permit_access | (readonly ? GTF_readonly : 0); if (result) *result = ref; return (0); } void gnttab_grant_foreign_access_ref(grant_ref_t ref, domid_t domid, unsigned long frame, int readonly) { shared[ref].frame = frame; shared[ref].domid = domid; wmb(); shared[ref].flags = GTF_permit_access | (readonly ? GTF_readonly : 0); } int gnttab_query_foreign_access(grant_ref_t ref) { uint16_t nflags; nflags = shared[ref].flags; return (nflags & (GTF_reading|GTF_writing)); } int gnttab_end_foreign_access_ref(grant_ref_t ref) { uint16_t flags, nflags; nflags = shared[ref].flags; do { if ( (flags = nflags) & (GTF_reading|GTF_writing) ) { printf("%s: WARNING: g.e. still in use!\n", __func__); return (0); } } while ((nflags = synch_cmpxchg(&shared[ref].flags, flags, 0)) != flags); return (1); } void gnttab_end_foreign_access(grant_ref_t ref, void *page) { if (gnttab_end_foreign_access_ref(ref)) { put_free_entry(ref); if (page != NULL) { free(page, M_DEVBUF); } } else { /* XXX This needs to be fixed so that the ref and page are placed on a list to be freed up later. */ printf("%s: WARNING: leaking g.e. and page still in use!\n", __func__); } } void gnttab_end_foreign_access_references(u_int count, grant_ref_t *refs) { grant_ref_t *last_ref; grant_ref_t head; grant_ref_t tail; head = GNTTAB_LIST_END; tail = *refs; last_ref = refs + count; while (refs != last_ref) { if (gnttab_end_foreign_access_ref(*refs)) { gnttab_entry(*refs) = head; head = *refs; } else { /* * XXX This needs to be fixed so that the ref * is placed on a list to be freed up later. */ printf("%s: WARNING: leaking g.e. still in use!\n", __func__); count--; } refs++; } if (count != 0) { mtx_lock(&gnttab_list_lock); gnttab_free_count += count; gnttab_entry(tail) = gnttab_free_head; gnttab_free_head = head; check_free_callbacks(); mtx_unlock(&gnttab_list_lock); } } int gnttab_grant_foreign_transfer(domid_t domid, unsigned long pfn, grant_ref_t *result) { int error, ref; error = get_free_entries(1, &ref); if (__predict_false(error)) return (error); gnttab_grant_foreign_transfer_ref(ref, domid, pfn); *result = ref; return (0); } void gnttab_grant_foreign_transfer_ref(grant_ref_t ref, domid_t domid, unsigned long pfn) { shared[ref].frame = pfn; shared[ref].domid = domid; wmb(); shared[ref].flags = GTF_accept_transfer; } unsigned long gnttab_end_foreign_transfer_ref(grant_ref_t ref) { unsigned long frame; uint16_t flags; /* * If a transfer is not even yet started, try to reclaim the grant * reference and return failure (== 0). */ while (!((flags = shared[ref].flags) & GTF_transfer_committed)) { if ( synch_cmpxchg(&shared[ref].flags, flags, 0) == flags ) return (0); cpu_spinwait(); } /* If a transfer is in progress then wait until it is completed. */ while (!(flags & GTF_transfer_completed)) { flags = shared[ref].flags; cpu_spinwait(); } /* Read the frame number /after/ reading completion status. */ rmb(); frame = shared[ref].frame; KASSERT(frame != 0, ("grant table inconsistent")); return (frame); } unsigned long gnttab_end_foreign_transfer(grant_ref_t ref) { unsigned long frame = gnttab_end_foreign_transfer_ref(ref); put_free_entry(ref); return (frame); } void gnttab_free_grant_reference(grant_ref_t ref) { put_free_entry(ref); } void gnttab_free_grant_references(grant_ref_t head) { grant_ref_t ref; int count = 1; if (head == GNTTAB_LIST_END) return; ref = head; while (gnttab_entry(ref) != GNTTAB_LIST_END) { ref = gnttab_entry(ref); count++; } mtx_lock(&gnttab_list_lock); gnttab_entry(ref) = gnttab_free_head; gnttab_free_head = head; gnttab_free_count += count; check_free_callbacks(); mtx_unlock(&gnttab_list_lock); } int gnttab_alloc_grant_references(uint16_t count, grant_ref_t *head) { int ref, error; error = get_free_entries(count, &ref); if (__predict_false(error)) return (error); *head = ref; return (0); } int gnttab_empty_grant_references(const grant_ref_t *private_head) { return (*private_head == GNTTAB_LIST_END); } int gnttab_claim_grant_reference(grant_ref_t *private_head) { grant_ref_t g = *private_head; if (__predict_false(g == GNTTAB_LIST_END)) return (g); *private_head = gnttab_entry(g); return (g); } void gnttab_release_grant_reference(grant_ref_t *private_head, grant_ref_t release) { gnttab_entry(release) = *private_head; *private_head = release; } void gnttab_request_free_callback(struct gnttab_free_callback *callback, void (*fn)(void *), void *arg, uint16_t count) { mtx_lock(&gnttab_list_lock); if (callback->next) goto out; callback->fn = fn; callback->arg = arg; callback->count = count; callback->next = gnttab_free_callback_list; gnttab_free_callback_list = callback; check_free_callbacks(); out: mtx_unlock(&gnttab_list_lock); } void gnttab_cancel_free_callback(struct gnttab_free_callback *callback) { struct gnttab_free_callback **pcb; mtx_lock(&gnttab_list_lock); for (pcb = &gnttab_free_callback_list; *pcb; pcb = &(*pcb)->next) { if (*pcb == callback) { *pcb = callback->next; break; } } mtx_unlock(&gnttab_list_lock); } static int grow_gnttab_list(unsigned int more_frames) { unsigned int new_nr_grant_frames, extra_entries, i; new_nr_grant_frames = nr_grant_frames + more_frames; extra_entries = more_frames * GREFS_PER_GRANT_FRAME; for (i = nr_grant_frames; i < new_nr_grant_frames; i++) { gnttab_list[i] = (grant_ref_t *) malloc(PAGE_SIZE, M_DEVBUF, M_NOWAIT); if (!gnttab_list[i]) goto grow_nomem; } for (i = GREFS_PER_GRANT_FRAME * nr_grant_frames; i < GREFS_PER_GRANT_FRAME * new_nr_grant_frames - 1; i++) gnttab_entry(i) = i + 1; gnttab_entry(i) = gnttab_free_head; gnttab_free_head = GREFS_PER_GRANT_FRAME * nr_grant_frames; gnttab_free_count += extra_entries; nr_grant_frames = new_nr_grant_frames; check_free_callbacks(); return (0); grow_nomem: for ( ; i >= nr_grant_frames; i--) free(gnttab_list[i], M_DEVBUF); return (ENOMEM); } static unsigned int __max_nr_grant_frames(void) { struct gnttab_query_size query; int rc; query.dom = DOMID_SELF; rc = HYPERVISOR_grant_table_op(GNTTABOP_query_size, &query, 1); if ((rc < 0) || (query.status != GNTST_okay)) return (4); /* Legacy max supported number of frames */ return (query.max_nr_frames); } static inline unsigned int max_nr_grant_frames(void) { unsigned int xen_max = __max_nr_grant_frames(); if (xen_max > boot_max_nr_grant_frames) return (boot_max_nr_grant_frames); return (xen_max); } #ifdef notyet /* * XXX needed for backend support * */ static int map_pte_fn(pte_t *pte, struct page *pmd_page, unsigned long addr, void *data) { unsigned long **frames = (unsigned long **)data; set_pte_at(&init_mm, addr, pte, pfn_pte_ma((*frames)[0], PAGE_KERNEL)); (*frames)++; return 0; } static int unmap_pte_fn(pte_t *pte, struct page *pmd_page, unsigned long addr, void *data) { set_pte_at(&init_mm, addr, pte, __pte(0)); return 0; } #endif static vm_paddr_t resume_frames; static int gnttab_map(unsigned int start_idx, unsigned int end_idx) { struct xen_add_to_physmap xatp; unsigned int i = end_idx; /* * Loop backwards, so that the first hypercall has the largest index, * ensuring that the table will grow only once. */ do { xatp.domid = DOMID_SELF; xatp.idx = i; xatp.space = XENMAPSPACE_grant_table; xatp.gpfn = (resume_frames >> PAGE_SHIFT) + i; if (HYPERVISOR_memory_op(XENMEM_add_to_physmap, &xatp)) panic("HYPERVISOR_memory_op failed to map gnttab"); } while (i-- > start_idx); if (shared == NULL) { vm_offset_t area; area = kva_alloc(PAGE_SIZE * max_nr_grant_frames()); KASSERT(area, ("can't allocate VM space for grant table")); shared = (grant_entry_t *)area; } for (i = start_idx; i <= end_idx; i++) { pmap_kenter((vm_offset_t) shared + i * PAGE_SIZE, resume_frames + i * PAGE_SIZE); } return (0); } int gnttab_resume(device_t dev) { unsigned int max_nr_gframes, nr_gframes; nr_gframes = nr_grant_frames; max_nr_gframes = max_nr_grant_frames(); if (max_nr_gframes < nr_gframes) return (ENOSYS); if (!resume_frames) { KASSERT(dev != NULL, ("No resume frames and no device provided")); gnttab_pseudo_phys_res = xenmem_alloc(dev, &gnttab_pseudo_phys_res_id, PAGE_SIZE * max_nr_gframes); if (gnttab_pseudo_phys_res == NULL) panic("Unable to reserve physical memory for gnttab"); resume_frames = rman_get_start(gnttab_pseudo_phys_res); } return (gnttab_map(0, nr_gframes - 1)); } static int gnttab_expand(unsigned int req_entries) { int error; unsigned int cur, extra; cur = nr_grant_frames; extra = howmany(req_entries, GREFS_PER_GRANT_FRAME); if (cur + extra > max_nr_grant_frames()) return (ENOSPC); error = gnttab_map(cur, cur + extra - 1); if (!error) error = grow_gnttab_list(extra); return (error); } MTX_SYSINIT(gnttab, &gnttab_list_lock, "GNTTAB LOCK", MTX_DEF | MTX_RECURSE); /*------------------ Private Device Attachment Functions --------------------*/ /** * \brief Identify instances of this device type in the system. * * \param driver The driver performing this identify action. * \param parent The NewBus parent device for any devices this method adds. */ static void granttable_identify(driver_t *driver __unused, device_t parent) { KASSERT(xen_domain(), ("Trying to attach grant-table device on non Xen domain")); /* * A single device instance for our driver is always present * in a system operating under Xen. */ if (BUS_ADD_CHILD(parent, 0, driver->name, 0) == NULL) panic("unable to attach Xen Grant-table device"); } /** * \brief Probe for the existence of the Xen Grant-table device * * \param dev NewBus device_t for this instance. * * \return Always returns 0 indicating success. */ static int granttable_probe(device_t dev) { device_set_desc(dev, "Xen Grant-table Device"); return (BUS_PROBE_NOWILDCARD); } /** * \brief Attach the Xen Grant-table device. * * \param dev NewBus device_t for this instance. * * \return On success, 0. Otherwise an errno value indicating the * type of failure. */ static int granttable_attach(device_t dev) { int i; unsigned int max_nr_glist_frames; unsigned int nr_init_grefs; nr_grant_frames = 1; boot_max_nr_grant_frames = __max_nr_grant_frames(); /* Determine the maximum number of frames required for the * grant reference free list on the current hypervisor. */ max_nr_glist_frames = (boot_max_nr_grant_frames * GREFS_PER_GRANT_FRAME / (PAGE_SIZE / sizeof(grant_ref_t))); gnttab_list = malloc(max_nr_glist_frames * sizeof(grant_ref_t *), M_DEVBUF, M_NOWAIT); if (gnttab_list == NULL) return (ENOMEM); for (i = 0; i < nr_grant_frames; i++) { gnttab_list[i] = (grant_ref_t *) malloc(PAGE_SIZE, M_DEVBUF, M_NOWAIT); if (gnttab_list[i] == NULL) goto ini_nomem; } if (gnttab_resume(dev)) return (ENODEV); nr_init_grefs = nr_grant_frames * GREFS_PER_GRANT_FRAME; for (i = NR_RESERVED_ENTRIES; i < nr_init_grefs - 1; i++) gnttab_entry(i) = i + 1; gnttab_entry(nr_init_grefs - 1) = GNTTAB_LIST_END; gnttab_free_count = nr_init_grefs - NR_RESERVED_ENTRIES; gnttab_free_head = NR_RESERVED_ENTRIES; if (bootverbose) printf("Grant table initialized\n"); return (0); ini_nomem: for (i--; i >= 0; i--) free(gnttab_list[i], M_DEVBUF); free(gnttab_list, M_DEVBUF); return (ENOMEM); } /*-------------------- Private Device Attachment Data -----------------------*/ static device_method_t granttable_methods[] = { /* Device interface */ DEVMETHOD(device_identify, granttable_identify), DEVMETHOD(device_probe, granttable_probe), DEVMETHOD(device_attach, granttable_attach), DEVMETHOD_END }; DEFINE_CLASS_0(granttable, granttable_driver, granttable_methods, 0); devclass_t granttable_devclass; DRIVER_MODULE_ORDERED(granttable, xenpv, granttable_driver, granttable_devclass, NULL, NULL, SI_ORDER_FIRST);
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