KVM: x86: Add helper to get variable MTRR range from MSR index

Add a helper to dedup the logic for retrieving a variable MTRR range
structure given a variable MTRR MSR index.

No functional change intended.

Reviewed-by: Kai Huang <kai.huang@intel.com>
Link: https://lore.kernel.org/r/20230511233351.635053-5-seanjc@google.com
Signed-off-by: Sean Christopherson <seanjc@google.com>

diff --git a/arch/x86/kvm/mtrr.c b/arch/x86/kvm/mtrr.c
index f65ce4b..59851db 100644 (file)
--- a/arch/x86/kvm/mtrr.c
+++ b/arch/x86/kvm/mtrr.c
@@ -31,6 +31,14 @@ static bool is_mtrr_base_msr(unsigned int msr)
        return !(msr & 0x1);
 }
 
+static struct kvm_mtrr_range *var_mtrr_msr_to_range(struct kvm_vcpu *vcpu,
+                                                   unsigned int msr)
+{
+       int index = (msr - 0x200) / 2;
+
+       return &vcpu->arch.mtrr_state.var_ranges[index];
+}
+
 static bool msr_mtrr_valid(unsigned msr)
 {
        switch (msr) {
@@ -314,7 +322,6 @@ static void update_mtrr(struct kvm_vcpu *vcpu, u32 msr)
 {
        struct kvm_mtrr *mtrr_state = &vcpu->arch.mtrr_state;
        gfn_t start, end;
-       int index;
 
        if (msr == MSR_IA32_CR_PAT || !tdp_enabled ||
              !kvm_arch_has_noncoherent_dma(vcpu->kvm))
@@ -332,8 +339,7 @@ static void update_mtrr(struct kvm_vcpu *vcpu, u32 msr)
                end = ~0ULL;
        } else {
                /* variable range MTRRs. */
-               index = (msr - 0x200) / 2;
-               var_mtrr_range(&mtrr_state->var_ranges[index], &start, &end);
+               var_mtrr_range(var_mtrr_msr_to_range(vcpu, msr), &start, &end);
        }
 
        kvm_zap_gfn_range(vcpu->kvm, gpa_to_gfn(start), gpa_to_gfn(end));
@@ -348,14 +354,12 @@ 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;
 
-       index = (msr - 0x200) / 2;
-       cur = &mtrr_state->var_ranges[index];
+       cur = var_mtrr_msr_to_range(vcpu, msr);
 
        /* remove the entry if it's in the list. */
        if (var_mtrr_range_is_valid(cur))
-               list_del(&mtrr_state->var_ranges[index].node);
+               list_del(&cur->node);
 
        /*
         * Set all illegal GPA bits in the mask, since those bits must
@@ -423,11 +427,10 @@ 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 */
-               index = (msr - 0x200) / 2;
                if (is_mtrr_base_msr(msr))
-                       *pdata = vcpu->arch.mtrr_state.var_ranges[index].base;
+                       *pdata = var_mtrr_msr_to_range(vcpu, msr)->base;
                else
-                       *pdata = vcpu->arch.mtrr_state.var_ranges[index].mask;
+                       *pdata = var_mtrr_msr_to_range(vcpu, msr)->mask;
 
                *pdata &= ~kvm_vcpu_reserved_gpa_bits_raw(vcpu);
        }