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