Commit ebda79e5 authored by Sean Christopherson's avatar Sean Christopherson
Browse files

KVM: x86: Add helper to query if variable MTRR MSR is base (versus mask) 

Add a helper to query whether a variable MTRR MSR is a base versus as mask
MSR.  Replace the unnecessarily complex math with a simple check on bit 0;
base MSRs are even, mask MSRs are odd.

Link: https://lore.kernel.org/r/20230511233351.635053-4-seanjc@google.com


Signed-off-by: default avatarSean Christopherson <seanjc@google.com>
parent 7aeae027

arch/x86/kvm/mtrr.c

+9 −7
Original line number Diff line number Diff line
@@ -25,6 +25,12 @@ 
#define IA32_MTRR_DEF_TYPE_FE		(1ULL << 10)

#define IA32_MTRR_DEF_TYPE_TYPE_MASK	(0xff)



static bool is_mtrr_base_msr(unsigned int msr)

{

	/* MTRR base MSRs use even numbers, masks use odd numbers. */

	return !(msr & 0x1);

}



static bool msr_mtrr_valid(unsigned msr)

{

	switch (msr) {
@@ -342,10 +348,9 @@ static void set_var_mtrr_msr(struct kvm_vcpu *vcpu, u32 msr, u64 data) 
{

	struct kvm_mtrr *mtrr_state = &vcpu->arch.mtrr_state;

	struct kvm_mtrr_range *tmp, *cur;

	int index, is_mtrr_mask;

	int index;



	index = (msr - 0x200) / 2;

	is_mtrr_mask = msr - 0x200 - 2 * index;

	cur = &mtrr_state->var_ranges[index];



	/* remove the entry if it's in the list. */
@@ -356,7 +361,7 @@ static void set_var_mtrr_msr(struct kvm_vcpu *vcpu, u32 msr, u64 data) 
	 * Set all illegal GPA bits in the mask, since those bits must

	 * implicitly be 0.  The bits are then cleared when reading them.

	 */

	if (!is_mtrr_mask)

	if (is_mtrr_base_msr(msr))

		cur->base = data;

	else

		cur->mask = data | kvm_vcpu_reserved_gpa_bits_raw(vcpu);
@@ -418,11 +423,8 @@ int kvm_mtrr_get_msr(struct kvm_vcpu *vcpu, u32 msr, u64 *pdata) 
	else if (msr == MSR_IA32_CR_PAT)

		*pdata = vcpu->arch.pat;

	else {	/* Variable MTRRs */

		int is_mtrr_mask;



		index = (msr - 0x200) / 2;

		is_mtrr_mask = msr - 0x200 - 2 * index;

		if (!is_mtrr_mask)

		if (is_mtrr_base_msr(msr))

			*pdata = vcpu->arch.mtrr_state.var_ranges[index].base;

		else

			*pdata = vcpu->arch.mtrr_state.var_ranges[index].mask;