arch/i386/kernel/cpu/mtrr/state.c

   1 #include <linux/mm.h>
   2 #include <linux/init.h>
   3 #include <asm/io.h>
   4 #include <asm/mtrr.h>
   5 #include <asm/msr.h>
   6 #include "mtrr.h"
   7
   8
   9 /*  Put the processor into a state where MTRRs can be safely set  */
  10 void set_mtrr_prepare_save(struct set_mtrr_context *ctxt)
  11 {
  12         unsigned int cr0;
  13
  14         /*  Disable interrupts locally  */
  15         local_irq_save(ctxt->flags);
  16
  17         if (use_intel() || is_cpu(CYRIX)) {
  18
  19                 /*  Save value of CR4 and clear Page Global Enable (bit 7)  */
  20                 if ( cpu_has_pge ) {
  21                         ctxt->cr4val = read_cr4();
  22                         write_cr4(ctxt->cr4val & (unsigned char) ~(1 << 7));
  23                 }
  24
  25                 /*  Disable and flush caches. Note that wbinvd flushes the TLBs as
  26                     a side-effect  */
  27                 cr0 = read_cr0() | 0x40000000;
  28                 wbinvd();
  29                 write_cr0(cr0);
  30                 wbinvd();
  31
  32                 if (use_intel())
  33                         /*  Save MTRR state */
  34                         rdmsr(MTRRdefType_MSR, ctxt->deftype_lo, ctxt->deftype_hi);
  35                 else
  36                         /* Cyrix ARRs - everything else were excluded at the top */
  37                         ctxt->ccr3 = getCx86(CX86_CCR3);
  38         }
  39 }
  40
  41 void set_mtrr_cache_disable(struct set_mtrr_context *ctxt)
  42 {
  43         if (use_intel())
  44                 /*  Disable MTRRs, and set the default type to uncached  */
  45                 mtrr_wrmsr(MTRRdefType_MSR, ctxt->deftype_lo & 0xf300UL,
  46                       ctxt->deftype_hi);
  47         else if (is_cpu(CYRIX))
  48                 /* Cyrix ARRs - everything else were excluded at the top */
  49                 setCx86(CX86_CCR3, (ctxt->ccr3 & 0x0f) | 0x10);
  50 }
  51
  52 /*  Restore the processor after a set_mtrr_prepare  */
  53 void set_mtrr_done(struct set_mtrr_context *ctxt)
  54 {
  55         if (use_intel() || is_cpu(CYRIX)) {
  56
  57                 /*  Flush caches and TLBs  */
  58                 wbinvd();
  59
  60                 /*  Restore MTRRdefType  */
  61                 if (use_intel())
  62                         /* Intel (P6) standard MTRRs */
  63                         mtrr_wrmsr(MTRRdefType_MSR, ctxt->deftype_lo, ctxt->deftype_hi);
  64                 else
  65                         /* Cyrix ARRs - everything else was excluded at the top */
  66                         setCx86(CX86_CCR3, ctxt->ccr3);
  67
  68                 /*  Enable caches  */
  69                 write_cr0(read_cr0() & 0xbfffffff);
  70
  71                 /*  Restore value of CR4  */
  72                 if ( cpu_has_pge )
  73                         write_cr4(ctxt->cr4val);
  74         }
  75         /*  Re-enable interrupts locally (if enabled previously)  */
  76         local_irq_restore(ctxt->flags);
  77 }
  78