KVM: MTRR: introduce var_mtrr_range

It gets the range for the specified variable MTRR

Signed-off-by: Xiao Guangrong <guangrong.xiao@linux.intel.com>
[Simplify boolean operations. - Paolo]
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

diff --git a/arch/x86/kvm/mtrr.c b/arch/x86/kvm/mtrr.c
index cfeeaef..b081e3b 100644 (file)
--- a/arch/x86/kvm/mtrr.c
+++ b/arch/x86/kvm/mtrr.c
@@ -241,10 +241,25 @@ static int fixed_msr_to_range_index(u32 msr)
        return fixed_mtrr_seg_unit_range_index(seg, unit);
 }
 
+static void var_mtrr_range(struct kvm_mtrr_range *range, u64 *start, u64 *end)
+{
+       u64 mask;
+
+       *start = range->base & PAGE_MASK;
+
+       mask = range->mask & PAGE_MASK;
+       mask |= ~0ULL << boot_cpu_data.x86_phys_bits;
+
+       /* This cannot overflow because writing to the reserved bits of
+        * variable MTRRs causes a #GP.
+        */
+       *end = (*start | ~mask) + 1;
+}
+
 static void update_mtrr(struct kvm_vcpu *vcpu, u32 msr)
 {
        struct kvm_mtrr *mtrr_state = &vcpu->arch.mtrr_state;
-       gfn_t start, end, mask;
+       gfn_t start, end;
        int index;
 
        if (msr == MSR_IA32_CR_PAT || !tdp_enabled ||
@@ -264,11 +279,7 @@ static void update_mtrr(struct kvm_vcpu *vcpu, u32 msr)
        } else {
                /* variable range MTRRs. */
                index = (msr - 0x200) / 2;
-               start = mtrr_state->var_ranges[index].base & PAGE_MASK;
-               mask = mtrr_state->var_ranges[index].mask & PAGE_MASK;
-               mask |= ~0ULL << cpuid_maxphyaddr(vcpu);
-
-               end = ((start & mask) | ~mask) + 1;
+               var_mtrr_range(&mtrr_state->var_ranges[index], &start, &end);
        }
 
        kvm_zap_gfn_range(vcpu->kvm, gpa_to_gfn(start), gpa_to_gfn(end));