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- // 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 {
- flags = nflags;
- if ((flags) & (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;
- }
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