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Commit d69afbc6 authored by Xiao Guangrong's avatar Xiao Guangrong Committed by Paolo Bonzini
Browse files

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: default avatarXiao Guangrong <guangrong.xiao@linux.intel.com>
Reviewed-by: default avatarWanpeng Li <wanpeng.li@linux.intel.com>
Signed-off-by: default avatarPaolo Bonzini <pbonzini@redhat.com>
parent 6a49f85c

arch/x86/kvm/mmu.c

+6 −8
Original line number Diff line number Diff line
@@ -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;