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KVM: MMU: fix decoding cache type from MTRR 

There are some bugs in current get_mtrr_type();
1: bit 1 of mtrr_state->enabled is corresponding bit 11 of
   IA32_MTRR_DEF_TYPE MSR which completely control MTRR's enablement
   that means other bits are ignored if it is cleared

2: the fixed MTRR ranges are controlled by bit 0 of
   mtrr_state->enabled (bit 10 of IA32_MTRR_DEF_TYPE)

3: if MTRR is disabled, UC is applied to all of physical memory rather
   than mtrr_state->def_type

Signed-off-by: Xiao Guangrong <guangrong.xiao@linux.intel.com>
Reviewed-by: Wanpeng Li <wanpeng.li@linux.intel.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
This commit is contained in:
Xiao Guangrong 2015-05-13 14:42:19 +08:00 committed by Paolo Bonzini
parent 6a49f85c7a
commit d69afbc6b1
1 changed files with 6 additions and 8 deletions
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14
arch/x86/kvm/mmu.c
View File

@ -2431,19 +2431,20 @@ EXPORT_SYMBOL_GPL(kvm_mmu_unprotect_page);
static int get_mtrr_type(struct mtrr_state_type *mtrr_state,
u64 start, u64 end)
{
int i;
u64 base, mask;
u8 prev_match, curr_match;
int num_var_ranges = KVM_NR_VAR_MTRR;
int i, num_var_ranges = KVM_NR_VAR_MTRR;
if (!mtrr_state->enabled)
return 0xFF;
/* MTRR is completely disabled, use UC for all of physical memory. */
if (!(mtrr_state->enabled & 0x2))
return MTRR_TYPE_UNCACHABLE;
/* Make end inclusive end, instead of exclusive */
end--;
/* Look in fixed ranges. Just return the type as per start */
if (mtrr_state->have_fixed && (start < 0x100000)) {
if (mtrr_state->have_fixed && (mtrr_state->enabled & 0x1) &&
(start < 0x100000)) {
int idx;
if (start < 0x80000) {
@ -2466,9 +2467,6 @@ static int get_mtrr_type(struct mtrr_state_type *mtrr_state,
* Look of multiple ranges matching this address and pick type
* as per MTRR precedence
*/
if (!(mtrr_state->enabled & 2))
return mtrr_state->def_type;
prev_match = 0xFF;
for (i = 0; i < num_var_ranges; ++i) {
unsigned short start_state, end_state;