tools/kvm/bios/e820.c

   1 #include "kvm/e820.h"
   2
   3 #include "kvm/segment.h"
   4 #include "kvm/bios.h"
   5 #include "kvm/util.h"
   6
   7 #include <asm/processor-flags.h>
   8 #include <asm/e820.h>
   9
  10 static inline void set_fs(u16 seg)
  11 {
  12         asm volatile("movw %0,%%fs" : : "rm" (seg));
  13 }
  14
  15 static inline u8 rdfs8(unsigned long addr)
  16 {
  17         u8 v;
  18
  19         asm volatile("addr32 movb %%fs:%1,%0" : "=q" (v) : "m" (*(u8 *)addr));
  20
  21         return v;
  22 }
  23
  24 static inline u32 rdfs32(unsigned long addr)
  25 {
  26         u32 v;
  27
  28         asm volatile("addr32 movl %%fs:%1,%0" : "=q" (v) : "m" (*(u32 *)addr));
  29
  30         return v;
  31 }
  32
  33 bioscall void e820_query_map(struct biosregs *regs)
  34 {
  35         struct e820map *e820;
  36         u32 map_size;
  37         u16 fs_seg;
  38         u32 ndx;
  39
  40         e820            = (struct e820map *)E820_MAP_START;
  41         fs_seg          = flat_to_seg16(E820_MAP_START);
  42         set_fs(fs_seg);
  43
  44         ndx             = regs->ebx;
  45
  46         map_size        = rdfs32(flat_to_off16((u32)&e820->nr_map, fs_seg));
  47
  48         if (ndx < map_size) {
  49                 u32 start;
  50                 unsigned int i;
  51                 u8 *p;
  52
  53                 fs_seg  = flat_to_seg16(E820_MAP_START);
  54                 set_fs(fs_seg);
  55
  56                 start   = (u32)&e820->map[ndx];
  57
  58                 p       = (void *) regs->edi;
  59
  60                 for (i = 0; i < sizeof(struct e820entry); i++)
  61                         *p++    = rdfs8(flat_to_off16(start + i, fs_seg));
  62         }
  63
  64         regs->eax       = SMAP;
  65         regs->ecx       = sizeof(struct e820entry);
  66         regs->ebx       = ++ndx;
  67
  68         /* Clear CF to indicate success.  */
  69         regs->eflags    &= ~X86_EFLAGS_CF;
  70
  71         if (ndx >= map_size)
  72                 regs->ebx       = 0;    /* end of map */
  73 }