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MTRR: Add cpuid mtrr feature check

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mintsuki 2020-09-28 01:30:12 +02:00
parent c3570f9fc8
commit fed6645044
2 changed files with 18 additions and 0 deletions
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stage2/mm/mtrr.c
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@ -11,6 +11,15 @@ struct mtrr {
uint64_t mask;
};
static bool mtrr_supported(void) {
uint32_t eax, ebx, ecx, edx;
if (cpuid(1, 0, &eax, &ebx, &ecx, &edx))
return false;
return !!(edx & (1 << 12));
}
static bool is_block_in_mtrr_range(struct mtrr *mtrr, uint64_t block_base, uint64_t block_size) {
// False if the MTRR is not valid
if (!(mtrr->mask & (1 << 11)))
@ -28,6 +37,9 @@ static bool is_block_in_mtrr_range(struct mtrr *mtrr, uint64_t block_base, uint6
}
bool mtrr_set_range(uint64_t base, uint64_t size, uint8_t memory_type) {
if (!mtrr_supported())
return false;
uint32_t eax, ebx, ecx, edx;
if (cpuid(0x80000008, 0, &eax, &ebx, &ecx, &edx))
@ -98,6 +110,9 @@ bool mtrr_set_range(uint64_t base, uint64_t size, uint8_t memory_type) {
static struct mtrr *saved_mtrr = NULL;
void mtrr_save(void) {
if (!mtrr_supported())
return;
uint64_t ia32_mtrrcap = rdmsr(0xfe);
uint8_t var_reg_count = ia32_mtrrcap & 0xff;
@ -112,6 +127,9 @@ void mtrr_save(void) {
}
void mtrr_restore(void) {
if (!mtrr_supported())
return;
uint64_t ia32_mtrrcap = rdmsr(0xfe);
uint8_t var_reg_count = ia32_mtrrcap & 0xff;