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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: Sean Christopherson <seanjc@google.com>
This commit is contained in:
Sean Christopherson 2023-05-11 16:33:46 -07:00
parent 7aeae02761
commit ebda79e505
1 changed files with 9 additions and 7 deletions
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16
arch/x86/kvm/mtrr.c
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@ -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;