[Xen-devel] [PATCH v6 13/20] xen: setup Xen specific data for PVH

[Juergen Gross <jgross@xxxxxxxx>]

Initialize the needed Xen specific data. This is:

- the Xen start of day page containing the console and Xenstore ring
  page PFN and event channel
- the grant table
- the shared info page

Write back the possibly modified memory map to the hypervisor in case
the guest is reading it from there again.

Set the RSDP address for the guest from the start_info page passed
as boot parameter.

Signed-off-by: Juergen Gross <jgross@xxxxxxxx>
Reviewed-by: Daniel Kiper <daniel.kiper@xxxxxxxxxx>
Reviewed-by: Roger Pau Monné <roger.pau@xxxxxxxxxx>
---
V4: write back memory map to Xen (Roger Pau Monné)
V5: add comment (Daniel Kiper)
---
 grub-core/kern/i386/xen/pvh.c | 123 ++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 123 insertions(+)

diff --git a/grub-core/kern/i386/xen/pvh.c b/grub-core/kern/i386/xen/pvh.c
index 2b68ac333..472085ed1 100644
--- a/grub-core/kern/i386/xen/pvh.c
+++ b/grub-core/kern/i386/xen/pvh.c
@@ -27,6 +27,7 @@
 #include <grub/i386/linux.h>
 #include <grub/machine/kernel.h>
 #include <grub/machine/memory.h>
+#include <xen/hvm/params.h>
 #include <xen/memory.h>
 
 #define XEN_MEMORY_MAP_SIZE   128
@@ -37,6 +38,7 @@ static char hypercall_page[GRUB_XEN_PAGE_SIZE]
   __attribute__ ((aligned (GRUB_XEN_PAGE_SIZE)));
 
 static grub_uint32_t xen_cpuid_base;
+static struct start_info grub_xen_start_page;
 static struct grub_e820_mmap_entry map[XEN_MEMORY_MAP_SIZE];
 static unsigned int nr_map_entries;
 
@@ -111,6 +113,36 @@ grub_xen_hypercall (grub_uint32_t callno, grub_uint32_t a0,
   return res;
 }
 
+static grub_uint32_t
+grub_xen_get_param (int idx)
+{
+  struct xen_hvm_param xhv;
+  int r;
+
+  xhv.domid = DOMID_SELF;
+  xhv.index = idx;
+  r = grub_xen_hypercall (__HYPERVISOR_hvm_op, HVMOP_get_param,
+                         (grub_uint32_t) (&xhv), 0, 0, 0, 0);
+  if (r < 0)
+    grub_xen_panic ("Could not get parameter from Xen!\n");
+  return xhv.value;
+}
+
+static void *
+grub_xen_add_physmap (unsigned int space, void *addr)
+{
+  struct xen_add_to_physmap xatp;
+
+  xatp.domid = DOMID_SELF;
+  xatp.idx = 0;
+  xatp.space = space;
+  xatp.gpfn = (grub_addr_t) addr >> GRUB_XEN_LOG_PAGE_SIZE;
+  if (grub_xen_hypercall (__HYPERVISOR_memory_op, XENMEM_add_to_physmap,
+                         (grub_uint32_t) (&xatp), 0, 0, 0, 0))
+    grub_xen_panic ("Memory_op hypercall failed!\n");
+  return addr;
+}
+
 static void
 grub_xen_sort_mmap (void)
 {
@@ -197,12 +229,103 @@ grub_xen_get_mmap (void)
   grub_xen_sort_mmap ();
 }
 
+static void
+grub_xen_set_mmap (void)
+{
+  struct xen_foreign_memory_map memmap;
+
+  memmap.domid = DOMID_SELF;
+  memmap.map.nr_entries = nr_map_entries;
+  set_xen_guest_handle (memmap.map.buffer, map);
+  grub_xen_hypercall (__HYPERVISOR_memory_op, XENMEM_set_memory_map,
+                     (grub_uint32_t) (&memmap), 0, 0, 0, 0);
+}
+
+static grub_uint64_t
+grub_xen_find_page (grub_uint64_t start)
+{
+  unsigned int i, j;
+  grub_uint64_t last = start;
+
+  /*
+   * Try to find a e820 map hole below 4G.
+   * Relies on page-aligned entries (addr and len) and input (start).
+   */
+
+  for (i = 0; i < nr_map_entries; i++)
+    {
+      if (last > map[i].addr + map[i].len)
+       continue;
+      if (last < map[i].addr)
+       return last;
+      if ((map[i].addr >> 32) || ((map[i].addr + map[i].len) >> 32))
+       break;
+      last = map[i].addr + map[i].len;
+    }
+    if (i == nr_map_entries)
+      return last;
+
+  /* No hole found, use the highest RAM page below 4G and reserve it. */
+  if (nr_map_entries == ARRAY_SIZE (map))
+    grub_xen_panic ("Memory map size limit reached!\n");
+  for (i = 0, j = 0; i < nr_map_entries; i++)
+    {
+      if (map[i].type != GRUB_MEMORY_AVAILABLE)
+       continue;
+      if (map[i].addr >> 32)
+       break;
+      j = i;
+      if ((map[i].addr + map[i].len) >> 32)
+       break;
+    }
+  if (map[j].type != GRUB_MEMORY_AVAILABLE)
+    grub_xen_panic ("No free memory page found!\n");
+  if ((map[j].addr + map[j].len) >> 32)
+    last = (1ULL << 32) - GRUB_XEN_PAGE_SIZE;
+  else
+    last = map[j].addr + map[j].len - GRUB_XEN_PAGE_SIZE;
+  map[nr_map_entries].addr = last;
+  map[nr_map_entries].len = GRUB_XEN_PAGE_SIZE;
+  map[nr_map_entries].type = GRUB_MEMORY_RESERVED;
+  nr_map_entries++;
+  grub_xen_sort_mmap ();
+
+  return last;
+}
+
 void
 grub_xen_setup_pvh (void)
 {
+  grub_addr_t par;
+
   grub_xen_cpuid_base ();
   grub_xen_setup_hypercall_page ();
   grub_xen_get_mmap ();
+
+  /* Setup Xen data. */
+  grub_xen_start_page_addr = &grub_xen_start_page;
+
+  par = grub_xen_get_param (HVM_PARAM_CONSOLE_PFN);
+  grub_xen_start_page_addr->console.domU.mfn = par;
+  grub_xen_xcons = (void *) (grub_addr_t) (par << GRUB_XEN_LOG_PAGE_SIZE);
+  par = grub_xen_get_param (HVM_PARAM_CONSOLE_EVTCHN);
+  grub_xen_start_page_addr->console.domU.evtchn = par;
+
+  par = grub_xen_get_param (HVM_PARAM_STORE_PFN);
+  grub_xen_start_page_addr->store_mfn = par;
+  grub_xen_xenstore = (void *) (grub_addr_t) (par << GRUB_XEN_LOG_PAGE_SIZE);
+  par = grub_xen_get_param (HVM_PARAM_STORE_EVTCHN);
+  grub_xen_start_page_addr->store_evtchn = par;
+
+  par = grub_xen_find_page (0);
+  grub_xen_grant_table = grub_xen_add_physmap (XENMAPSPACE_grant_table,
+                                              (void *) par);
+  par = grub_xen_find_page (par + GRUB_XEN_PAGE_SIZE);
+  grub_xen_shared_info = grub_xen_add_physmap (XENMAPSPACE_shared_info,
+                                              (void *) par);
+  grub_xen_set_mmap ();
+
+  grub_rsdp_addr = pvh_start_info->rsdp_paddr;
 }
 
 grub_err_t
-- 
2.16.4


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