diff options
Diffstat (limited to 'drivers/xen')
| -rw-r--r-- | drivers/xen/grant-table.c | 171 |
1 files changed, 167 insertions, 4 deletions
diff --git a/drivers/xen/grant-table.c b/drivers/xen/grant-table.c index 0518d0404942..301869f60dc7 100644 --- a/drivers/xen/grant-table.c +++ b/drivers/xen/grant-table.c @@ -44,6 +44,7 @@ #include <xen/page.h> #include <xen/grant_table.h> #include <xen/interface/memory.h> +#include <xen/hvc-console.h> #include <asm/xen/hypercall.h> #include <asm/pgtable.h> @@ -53,7 +54,10 @@ /* External tools reserve first few grant table entries. */ #define NR_RESERVED_ENTRIES 8 #define GNTTAB_LIST_END 0xffffffff -#define GREFS_PER_GRANT_FRAME (PAGE_SIZE / sizeof(struct grant_entry_v1)) +#define GREFS_PER_GRANT_FRAME \ +(grant_table_version == 1 ? \ +(PAGE_SIZE / sizeof(struct grant_entry_v1)) : \ +(PAGE_SIZE / sizeof(union grant_entry_v2))) static grant_ref_t **gnttab_list; static unsigned int nr_grant_frames; @@ -66,6 +70,7 @@ EXPORT_SYMBOL_GPL(xen_hvm_resume_frames); static union { struct grant_entry_v1 *v1; + union grant_entry_v2 *v2; void *addr; } gnttab_shared; @@ -120,6 +125,9 @@ struct gnttab_ops { static struct gnttab_ops *gnttab_interface; +/*This reflects status of grant entries, so act as a global value*/ +static grant_status_t *grstatus; + static int grant_table_version; static struct gnttab_free_callback *gnttab_free_callback_list; @@ -127,6 +135,7 @@ static struct gnttab_free_callback *gnttab_free_callback_list; static int gnttab_expand(unsigned int req_entries); #define RPP (PAGE_SIZE / sizeof(grant_ref_t)) +#define SPP (PAGE_SIZE / sizeof(grant_status_t)) static inline grant_ref_t *__gnttab_entry(grant_ref_t entry) { @@ -199,6 +208,7 @@ static void put_free_entry(grant_ref_t ref) } /* + * Following applies to gnttab_update_entry_v1 and gnttab_update_entry_v2. * Introducing a valid entry into the grant table: * 1. Write ent->domid. * 2. Write ent->frame: @@ -217,6 +227,15 @@ static void gnttab_update_entry_v1(grant_ref_t ref, domid_t domid, gnttab_shared.v1[ref].flags = flags; } +static void gnttab_update_entry_v2(grant_ref_t ref, domid_t domid, + unsigned long frame, unsigned flags) +{ + gnttab_shared.v2[ref].hdr.domid = domid; + gnttab_shared.v2[ref].full_page.frame = frame; + wmb(); + gnttab_shared.v2[ref].hdr.flags = GTF_permit_access | flags; +} + /* * Public grant-issuing interface functions */ @@ -248,6 +267,11 @@ static int gnttab_query_foreign_access_v1(grant_ref_t ref) return gnttab_shared.v1[ref].flags & (GTF_reading|GTF_writing); } +static int gnttab_query_foreign_access_v2(grant_ref_t ref) +{ + return grstatus[ref] & (GTF_reading|GTF_writing); +} + int gnttab_query_foreign_access(grant_ref_t ref) { return gnttab_interface->query_foreign_access(ref); @@ -272,6 +296,29 @@ static int gnttab_end_foreign_access_ref_v1(grant_ref_t ref, int readonly) return 1; } +static int gnttab_end_foreign_access_ref_v2(grant_ref_t ref, int readonly) +{ + gnttab_shared.v2[ref].hdr.flags = 0; + mb(); + if (grstatus[ref] & (GTF_reading|GTF_writing)) { + return 0; + } else { + /* The read of grstatus needs to have acquire + semantics. On x86, reads already have + that, and we just need to protect against + compiler reorderings. On other + architectures we may need a full + barrier. */ +#ifdef CONFIG_X86 + barrier(); +#else + mb(); +#endif + } + + return 1; +} + int gnttab_end_foreign_access_ref(grant_ref_t ref, int readonly) { return gnttab_interface->end_foreign_access_ref(ref, readonly); @@ -345,6 +392,37 @@ static unsigned long gnttab_end_foreign_transfer_ref_v1(grant_ref_t ref) return frame; } +static unsigned long gnttab_end_foreign_transfer_ref_v2(grant_ref_t ref) +{ + unsigned long frame; + u16 flags; + u16 *pflags; + + pflags = &gnttab_shared.v2[ref].hdr.flags; + + /* + * If a transfer is not even yet started, try to reclaim the grant + * reference and return failure (== 0). + */ + while (!((flags = *pflags) & GTF_transfer_committed)) { + if (sync_cmpxchg(pflags, flags, 0) == flags) + return 0; + cpu_relax(); + } + + /* If a transfer is in progress then wait until it is completed. */ + while (!(flags & GTF_transfer_completed)) { + flags = *pflags; + cpu_relax(); + } + + rmb(); /* Read the frame number /after/ reading completion status. */ + frame = gnttab_shared.v2[ref].full_page.frame; + BUG_ON(frame == 0); + + return frame; +} + unsigned long gnttab_end_foreign_transfer_ref(grant_ref_t ref) { return gnttab_interface->end_foreign_transfer_ref(ref); @@ -592,6 +670,11 @@ int gnttab_unmap_refs(struct gnttab_unmap_grant_ref *unmap_ops, } EXPORT_SYMBOL_GPL(gnttab_unmap_refs); +static unsigned nr_status_frames(unsigned nr_grant_frames) +{ + return (nr_grant_frames * GREFS_PER_GRANT_FRAME + SPP - 1) / SPP; +} + static int gnttab_map_frames_v1(unsigned long *frames, unsigned int nr_gframes) { int rc; @@ -606,7 +689,56 @@ static int gnttab_map_frames_v1(unsigned long *frames, unsigned int nr_gframes) static void gnttab_unmap_frames_v1(void) { - arch_gnttab_unmap_shared(gnttab_shared.addr, nr_grant_frames); + arch_gnttab_unmap(gnttab_shared.addr, nr_grant_frames); +} + +static int gnttab_map_frames_v2(unsigned long *frames, unsigned int nr_gframes) +{ + uint64_t *sframes; + unsigned int nr_sframes; + struct gnttab_get_status_frames getframes; + int rc; + + nr_sframes = nr_status_frames(nr_gframes); + + /* No need for kzalloc as it is initialized in following hypercall + * GNTTABOP_get_status_frames. + */ + sframes = kmalloc(nr_sframes * sizeof(uint64_t), GFP_ATOMIC); + if (!sframes) + return -ENOMEM; + + getframes.dom = DOMID_SELF; + getframes.nr_frames = nr_sframes; + set_xen_guest_handle(getframes.frame_list, sframes); + + rc = HYPERVISOR_grant_table_op(GNTTABOP_get_status_frames, + &getframes, 1); + if (rc == -ENOSYS) { + kfree(sframes); + return -ENOSYS; + } + + BUG_ON(rc || getframes.status); + + rc = arch_gnttab_map_status(sframes, nr_sframes, + nr_status_frames(gnttab_max_grant_frames()), + &grstatus); + BUG_ON(rc); + kfree(sframes); + + rc = arch_gnttab_map_shared(frames, nr_gframes, + gnttab_max_grant_frames(), + &gnttab_shared.addr); + BUG_ON(rc); + + return 0; +} + +static void gnttab_unmap_frames_v2(void) +{ + arch_gnttab_unmap(gnttab_shared.addr, nr_grant_frames); + arch_gnttab_unmap(grstatus, nr_status_frames(nr_grant_frames)); } static int gnttab_map(unsigned int start_idx, unsigned int end_idx) @@ -640,6 +772,9 @@ static int gnttab_map(unsigned int start_idx, unsigned int end_idx) return rc; } + /* No need for kzalloc as it is initialized in following hypercall + * GNTTABOP_setup_table. + */ frames = kmalloc(nr_gframes * sizeof(unsigned long), GFP_ATOMIC); if (!frames) return -ENOMEM; @@ -672,10 +807,38 @@ static struct gnttab_ops gnttab_v1_ops = { .query_foreign_access = gnttab_query_foreign_access_v1, }; +static struct gnttab_ops gnttab_v2_ops = { + .map_frames = gnttab_map_frames_v2, + .unmap_frames = gnttab_unmap_frames_v2, + .update_entry = gnttab_update_entry_v2, + .end_foreign_access_ref = gnttab_end_foreign_access_ref_v2, + .end_foreign_transfer_ref = gnttab_end_foreign_transfer_ref_v2, + .query_foreign_access = gnttab_query_foreign_access_v2, +}; + static void gnttab_request_version(void) { - grant_table_version = 1; - gnttab_interface = &gnttab_v1_ops; + int rc; + struct gnttab_set_version gsv; + + gsv.version = 2; + rc = HYPERVISOR_grant_table_op(GNTTABOP_set_version, &gsv, 1); + if (rc == 0) { + grant_table_version = 2; + gnttab_interface = &gnttab_v2_ops; + } else if (grant_table_version == 2) { + /* + * If we've already used version 2 features, + * but then suddenly discover that they're not + * available (e.g. migrating to an older + * version of Xen), almost unbounded badness + * can happen. + */ + panic("we need grant tables version 2, but only version 1 is available"); + } else { + grant_table_version = 1; + gnttab_interface = &gnttab_v1_ops; + } printk(KERN_INFO "Grant tables using version %d layout.\n", grant_table_version); } |