1 // Initialize MTRRs - mostly useful on KVM.
3 // Copyright (C) 2006 Fabrice Bellard
5 // This file may be distributed under the terms of the GNU LGPLv3 license.
7 #include "util.h" // dprintf
8 #include "biosvar.h" // GET_EBDA
10 #define MSR_MTRRcap 0x000000fe
11 #define MSR_MTRRfix64K_00000 0x00000250
12 #define MSR_MTRRfix16K_80000 0x00000258
13 #define MSR_MTRRfix16K_A0000 0x00000259
14 #define MSR_MTRRfix4K_C0000 0x00000268
15 #define MSR_MTRRfix4K_C8000 0x00000269
16 #define MSR_MTRRfix4K_D0000 0x0000026a
17 #define MSR_MTRRfix4K_D8000 0x0000026b
18 #define MSR_MTRRfix4K_E0000 0x0000026c
19 #define MSR_MTRRfix4K_E8000 0x0000026d
20 #define MSR_MTRRfix4K_F0000 0x0000026e
21 #define MSR_MTRRfix4K_F8000 0x0000026f
22 #define MSR_MTRRdefType 0x000002ff
24 #define MTRRphysBase_MSR(reg) (0x200 + 2 * (reg))
25 #define MTRRphysMask_MSR(reg) (0x200 + 2 * (reg) + 1)
27 static u64 rdmsr(unsigned index)
29 unsigned long long ret;
31 asm ("rdmsr" : "=A"(ret) : "c"(index));
35 static void wrmsr(unsigned index, u64 val)
37 asm volatile ("wrmsr" : : "c"(index), "A"(val));
40 static void wrmsr_smp(u32 index, u64 val)
42 // XXX - should run this on other CPUs also.
50 dprintf(3, "init mtrr\n");
53 u32 ram_size = GET_GLOBAL(RamSize);
60 mtrr_cap = rdmsr(MSR_MTRRcap);
61 vcnt = mtrr_cap & 0xff;
62 fix = mtrr_cap & 0x100;
63 wc = mtrr_cap & 0x400;
67 for (i = 0; i < 8; ++i)
68 if (ram_size >= 65536 * (i + 1))
70 wrmsr_smp(MSR_MTRRfix64K_00000, u.val);
72 for (i = 0; i < 8; ++i)
73 if (ram_size >= 65536 * 8 + 16384 * (i + 1))
75 wrmsr_smp(MSR_MTRRfix16K_80000, u.val);
76 wrmsr_smp(MSR_MTRRfix16K_A0000, 0);
77 wrmsr_smp(MSR_MTRRfix4K_C0000, 0);
78 wrmsr_smp(MSR_MTRRfix4K_C8000, 0);
79 wrmsr_smp(MSR_MTRRfix4K_D0000, 0);
80 wrmsr_smp(MSR_MTRRfix4K_D8000, 0);
81 wrmsr_smp(MSR_MTRRfix4K_E0000, 0);
82 wrmsr_smp(MSR_MTRRfix4K_E8000, 0);
83 wrmsr_smp(MSR_MTRRfix4K_F0000, 0);
84 wrmsr_smp(MSR_MTRRfix4K_F8000, 0);
85 /* Mark 3.5-4GB as UC, anything not specified defaults to WB */
86 wrmsr_smp(MTRRphysBase_MSR(0), 0xe0000000ull | 0);
87 wrmsr_smp(MTRRphysMask_MSR(0), ~(0x20000000ull - 1) | 0x800);
88 wrmsr_smp(MSR_MTRRdefType, 0xc06);