diff options
Diffstat (limited to 'drivers')
| -rw-r--r-- | drivers/xen/Makefile | 1 | ||||
| -rw-r--r-- | drivers/xen/gnttab.c | 216 | ||||
| -rw-r--r-- | drivers/xen/hypervisor.c | 2 |
3 files changed, 219 insertions, 0 deletions
diff --git a/drivers/xen/Makefile b/drivers/xen/Makefile index 9d0f604aaa7..243b13277ac 100644 --- a/drivers/xen/Makefile +++ b/drivers/xen/Makefile @@ -5,3 +5,4 @@ obj-y += hypervisor.o obj-y += events.o obj-y += xenbus.o +obj-y += gnttab.o diff --git a/drivers/xen/gnttab.c b/drivers/xen/gnttab.c new file mode 100644 index 00000000000..becf7a79fbf --- /dev/null +++ b/drivers/xen/gnttab.c @@ -0,0 +1,216 @@ +// SPDX-License-Identifier: GPL-2.0 +/* + * (C) 2006 - Cambridge University + * (C) 2020 - EPAM Systems Inc. + * + * File: gnttab.c [1] + * Author: Steven Smith (sos22@cam.ac.uk) + * Changes: Grzegorz Milos (gm281@cam.ac.uk) + * + * Date: July 2006 + * + * Description: Simple grant tables implementation. About as stupid as it's + * possible to be and still work. + * + * [1] - http://xenbits.xen.org/gitweb/?p=mini-os.git;a=summary + */ +#include <common.h> +#include <linux/compiler.h> +#include <log.h> +#include <malloc.h> + +#include <asm/armv8/mmu.h> +#include <asm/io.h> +#include <asm/xen/system.h> + +#include <linux/bug.h> + +#include <xen/gnttab.h> +#include <xen/hvm.h> + +#include <xen/interface/memory.h> + +DECLARE_GLOBAL_DATA_PTR; + +#define NR_RESERVED_ENTRIES 8 + +/* NR_GRANT_FRAMES must be less than or equal to that configured in Xen */ +#define NR_GRANT_FRAMES 1 +#define NR_GRANT_ENTRIES (NR_GRANT_FRAMES * PAGE_SIZE / sizeof(struct grant_entry_v1)) + +static struct grant_entry_v1 *gnttab_table; +static grant_ref_t gnttab_list[NR_GRANT_ENTRIES]; + +static void put_free_entry(grant_ref_t ref) +{ + unsigned long flags; + + local_irq_save(flags); + gnttab_list[ref] = gnttab_list[0]; + gnttab_list[0] = ref; + local_irq_restore(flags); +} + +static grant_ref_t get_free_entry(void) +{ + unsigned int ref; + unsigned long flags; + + local_irq_save(flags); + ref = gnttab_list[0]; + BUG_ON(ref < NR_RESERVED_ENTRIES || ref >= NR_GRANT_ENTRIES); + gnttab_list[0] = gnttab_list[ref]; + local_irq_restore(flags); + return ref; +} + +/** + * gnttab_grant_access() - Allow access to the given frame. + * The function creates an entry in the grant table according + * to the specified parameters. + * @domid: the id of the domain for which access is allowed + * @frame: the number of the shared frame + * @readonly: determines whether the frame is shared read-only or read-write + * + * Return: relevant grant reference + */ +grant_ref_t gnttab_grant_access(domid_t domid, unsigned long frame, int readonly) +{ + grant_ref_t ref; + + ref = get_free_entry(); + gnttab_table[ref].frame = frame; + gnttab_table[ref].domid = domid; + wmb(); + readonly *= GTF_readonly; + gnttab_table[ref].flags = GTF_permit_access | readonly; + + return ref; +} + +/** + * gnttab_end_access() - End of memory sharing. The function invalidates + * the entry in the grant table. + */ +int gnttab_end_access(grant_ref_t ref) +{ + u16 flags, nflags; + + BUG_ON(ref >= NR_GRANT_ENTRIES || ref < NR_RESERVED_ENTRIES); + + nflags = gnttab_table[ref].flags; + do { + if ((flags = nflags) & (GTF_reading | GTF_writing)) { + printf("WARNING: g.e. still in use! (%x)\n", flags); + return 0; + } + } while ((nflags = synch_cmpxchg(&gnttab_table[ref].flags, flags, 0)) != + flags); + + put_free_entry(ref); + return 1; +} + +grant_ref_t gnttab_alloc_and_grant(void **map) +{ + unsigned long mfn; + grant_ref_t gref; + + *map = (void *)memalign(PAGE_SIZE, PAGE_SIZE); + mfn = virt_to_mfn(*map); + gref = gnttab_grant_access(0, mfn, 0); + return gref; +} + +static const char * const gnttabop_error_msgs[] = GNTTABOP_error_msgs; + +const char *gnttabop_error(int16_t status) +{ + status = -status; + if (status < 0 || status >= ARRAY_SIZE(gnttabop_error_msgs)) + return "bad status"; + else + return gnttabop_error_msgs[status]; +} + +/* Get Xen's suggested physical page assignments for the grant table. */ +void get_gnttab_base(phys_addr_t *gnttab_base, phys_size_t *gnttab_sz) +{ + const void *blob = gd->fdt_blob; + struct fdt_resource res; + int mem; + + mem = fdt_node_offset_by_compatible(blob, -1, "xen,xen"); + if (mem < 0) { + printf("No xen,xen compatible found\n"); + BUG(); + } + + mem = fdt_get_resource(blob, mem, "reg", 0, &res); + if (mem == -FDT_ERR_NOTFOUND) { + printf("No grant table base in the device tree\n"); + BUG(); + } + + *gnttab_base = (phys_addr_t)res.start; + if (gnttab_sz) + *gnttab_sz = (phys_size_t)(res.end - res.start + 1); + + debug("FDT suggests grant table base at %llx\n", + *gnttab_base); +} + +void init_gnttab(void) +{ + struct xen_add_to_physmap xatp; + struct gnttab_setup_table setup; + xen_pfn_t frames[NR_GRANT_FRAMES]; + int i, rc; + + debug("%s\n", __func__); + + for (i = NR_RESERVED_ENTRIES; i < NR_GRANT_ENTRIES; i++) + put_free_entry(i); + + get_gnttab_base((phys_addr_t *)&gnttab_table, NULL); + + for (i = 0; i < NR_GRANT_FRAMES; i++) { + xatp.domid = DOMID_SELF; + xatp.size = 0; + xatp.space = XENMAPSPACE_grant_table; + xatp.idx = i; + xatp.gpfn = PFN_DOWN((unsigned long)gnttab_table) + i; + rc = HYPERVISOR_memory_op(XENMEM_add_to_physmap, &xatp); + if (rc) + printf("XENMEM_add_to_physmap failed; status = %d\n", + rc); + BUG_ON(rc != 0); + } + + setup.dom = DOMID_SELF; + setup.nr_frames = NR_GRANT_FRAMES; + set_xen_guest_handle(setup.frame_list, frames); +} + +void fini_gnttab(void) +{ + struct xen_remove_from_physmap xrtp; + struct gnttab_setup_table setup; + int i, rc; + + debug("%s\n", __func__); + + for (i = 0; i < NR_GRANT_FRAMES; i++) { + xrtp.domid = DOMID_SELF; + xrtp.gpfn = PFN_DOWN((unsigned long)gnttab_table) + i; + rc = HYPERVISOR_memory_op(XENMEM_remove_from_physmap, &xrtp); + if (rc) + printf("XENMEM_remove_from_physmap failed; status = %d\n", + rc); + BUG_ON(rc != 0); + } + + setup.dom = DOMID_SELF; + setup.nr_frames = 0; +} + diff --git a/drivers/xen/hypervisor.c b/drivers/xen/hypervisor.c index 1c7ae94bdf9..58b0865e6a8 100644 --- a/drivers/xen/hypervisor.c +++ b/drivers/xen/hypervisor.c @@ -21,6 +21,7 @@ #include <xen/hvm.h> #include <xen/events.h> +#include <xen/gnttab.h> #include <xen/xenbus.h> #include <xen/interface/memory.h> @@ -238,5 +239,6 @@ void xen_init(void) map_shared_info(NULL); init_events(); init_xenbus(); + init_gnttab(); } |