[PATCH 08/15] KVM: MTRR: introduce fixed_mtrr_segment table

[Xiao Guangrong]

This table summarizes the information of fixed MTRRs and introduce some APIs
to abstract its operation which helps us to clean up the code and will be
used in later patches

Signed-off-by: Xiao Guangrong <guangrong.xiao@xxxxxxxxxxxxxxx>
---
 arch/x86/kvm/mtrr.c | 191 ++++++++++++++++++++++++++++++++++++++--------------
 1 file changed, 142 insertions(+), 49 deletions(-)

diff --git a/arch/x86/kvm/mtrr.c b/arch/x86/kvm/mtrr.c
index d3c06d2..888441e 100644
--- a/arch/x86/kvm/mtrr.c
+++ b/arch/x86/kvm/mtrr.c
@@ -102,12 +102,126 @@ bool kvm_mtrr_valid(struct kvm_vcpu *vcpu, u32 msr, u64 data)
 }
 EXPORT_SYMBOL_GPL(kvm_mtrr_valid);
 
+struct fixed_mtrr_segment {
+	u64 start;
+	u64 end;
+
+	/*
+	 * unit corresponds to the MSR entry in this segment, the size
+	 * of unit is covered in one MSR.
+	 */
+	u64 unit_size;
+
+	/* a range is covered in one memory cache type. */
+	u64 range_size;
+
+	/* the start position in kvm_mtrr.fixed_ranges[]. */
+	int range_start;
+};
+
+static struct fixed_mtrr_segment fixed_seg_table[] = {
+	/* MSR_MTRRfix64K_00000, 1 unit. 64K fixed mtrr. */
+	{
+		.start = 0x0,
+		.end = 0x80000,
+		.unit_size = 0x80000,
+		.range_size = 1ULL << 16,
+		.range_start = 0,
+	},
+
+	/*
+	 * MSR_MTRRfix16K_80000 ... MSR_MTRRfix16K_A0000, 2 units,
+	 * 16K fixed mtrr.
+	 */
+	{
+		.start = 0x80000,
+		.end = 0xc0000,
+		.unit_size = (0xc0000 - 0x80000) / 2,
+		.range_size = 1ULL << 14,
+		.range_start = 8,
+	},
+
+	/*
+	 * MSR_MTRRfix4K_C0000 ... MSR_MTRRfix4K_F8000, 8 units,
+	 * 4K fixed mtrr.
+	 */
+	{
+		.start = 0xc0000,
+		.end = 0x100000,
+		.unit_size = (0x100000 - 0xc0000) / 8,
+		.range_size = 1ULL << 12,
+		.range_start = 24,
+	}
+};
+
+static bool fixed_msr_to_seg_unit(u32 msr, int *seg, int *unit)
+{
+	switch (msr) {
+	case MSR_MTRRfix64K_00000:
+		*seg = 0;
+		*unit = 0;
+		break;
+	case MSR_MTRRfix16K_80000 ... MSR_MTRRfix16K_A0000:
+		*seg = 1;
+		*unit = msr - MSR_MTRRfix16K_80000;
+		break;
+	case MSR_MTRRfix4K_C0000 ... MSR_MTRRfix4K_F8000:
+		*seg = 2;
+		*unit = msr - MSR_MTRRfix4K_C0000;
+		break;
+	default:
+		return false;
+	}
+
+	return true;
+}
+
+static void fixed_mtrr_seg_unit_range(int seg, int unit, u64 *start, u64 *end)
+{
+	struct fixed_mtrr_segment *mtrr_seg = &fixed_seg_table[seg];
+
+	*start = mtrr_seg->start + unit * mtrr_seg->unit_size;
+	*end = *start + mtrr_seg->unit_size;
+	WARN_ON(*end > mtrr_seg->end);
+}
+
+static int fixed_mtrr_seg_unit_range_index(int seg, int unit)
+{
+	struct fixed_mtrr_segment *mtrr_seg = &fixed_seg_table[seg];
+
+	WARN_ON(mtrr_seg->start + unit * mtrr_seg->unit_size > mtrr_seg->end);
+
+	/* each unit has 8 ranges. */
+	return mtrr_seg->range_start + 8 * unit;
+}
+
+static bool fixed_msr_to_range(u32 msr, u64 *start, u64 *end)
+{
+	int seg, unit;
+
+	if (!fixed_msr_to_seg_unit(msr, &seg, &unit))
+		return false;
+
+	fixed_mtrr_seg_unit_range(seg, unit, start, end);
+	return true;
+}
+
+static int fixed_msr_to_range_index(u32 msr)
+{
+	int seg, unit;
+
+	if (!fixed_msr_to_seg_unit(msr, &seg, &unit))
+		return -1;
+
+	fixed_mtrr_seg_unit_range_index(seg, unit);
+	return 0;
+}
+
 static void update_mtrr(struct kvm_vcpu *vcpu, u32 msr)
 {
 	struct kvm_mtrr *mtrr_state = &vcpu->arch.mtrr_state;
 	gfn_t start, end, mask;
 	int index;
-	bool is_fixed = true;
 
 	if (msr == MSR_IA32_CR_PAT || !tdp_enabled ||
 	      !kvm_arch_has_noncoherent_dma(vcpu->kvm))
@@ -116,32 +230,19 @@ static void update_mtrr(struct kvm_vcpu *vcpu, u32 msr)
 	if (!mtrr_state->mtrr_enabled && msr != MSR_MTRRdefType)
 		return;
 
+	if (fixed_msr_to_range(msr, &start, &end)) {
+		if (!mtrr_state->fixed_mtrr_enabled)
+			return;
+		goto do_zap;
+	}
+
 	switch (msr) {
-	case MSR_MTRRfix64K_00000:
-		start = 0x0;
-		end = 0x80000;
-		break;
-	case MSR_MTRRfix16K_80000:
-		start = 0x80000;
-		end = 0xa0000;
-		break;
-	case MSR_MTRRfix16K_A0000:
-		start = 0xa0000;
-		end = 0xc0000;
-		break;
-	case MSR_MTRRfix4K_C0000 ... MSR_MTRRfix4K_F8000:
-		index = msr - MSR_MTRRfix4K_C0000;
-		start = 0xc0000 + index * (32 << 10);
-		end = start + (32 << 10);
-		break;
 	case MSR_MTRRdefType:
-		is_fixed = false;
 		start = 0x0;
 		end = ~0ULL;
 		break;
 	default:
 		/* variable range MTRRs. */
-		is_fixed = false;
 		index = (msr - 0x200) / 2;
 		start = mtrr_state->var_ranges[index].base & PAGE_MASK;
 		mask = mtrr_state->var_ranges[index].mask & PAGE_MASK;
@@ -150,38 +251,33 @@ static void update_mtrr(struct kvm_vcpu *vcpu, u32 msr)
 		end = ((start & mask) | ~mask) + 1;
 	}
 
-	if (is_fixed && !mtrr_state->fixed_mtrr_enabled)
-		return;
-
+do_zap:
 	kvm_zap_gfn_range(vcpu->kvm, gpa_to_gfn(start), gpa_to_gfn(end));
 }
 
 int kvm_mtrr_set_msr(struct kvm_vcpu *vcpu, u32 msr, u64 data)
 {
-	u64 *p = (u64 *)&vcpu->arch.mtrr_state.fixed_ranges;
+	int index;
 
 	if (!kvm_mtrr_valid(vcpu, msr, data))
 		return 1;
 
-	if (msr == MSR_MTRRdefType)
+	index = fixed_msr_to_range_index(msr);
+	if (index >= 0)
+		*(u64 *)&vcpu->arch.mtrr_state.fixed_ranges[index] = data;
+	else if (msr == MSR_MTRRdefType)
 		vcpu->arch.mtrr_state.deftype = data;
-	else if (msr == MSR_MTRRfix64K_00000)
-		p[0] = data;
-	else if (msr == MSR_MTRRfix16K_80000 || msr == MSR_MTRRfix16K_A0000)
-		p[1 + msr - MSR_MTRRfix16K_80000] = data;
-	else if (msr >= MSR_MTRRfix4K_C0000 && msr <= MSR_MTRRfix4K_F8000)
-		p[3 + msr - MSR_MTRRfix4K_C0000] = data;
 	else if (msr == MSR_IA32_CR_PAT)
 		vcpu->arch.pat = data;
 	else {	/* Variable MTRRs */
-		int idx, is_mtrr_mask;
+		int is_mtrr_mask;
 
-		idx = (msr - 0x200) / 2;
-		is_mtrr_mask = msr - 0x200 - 2 * idx;
+		index = (msr - 0x200) / 2;
+		is_mtrr_mask = msr - 0x200 - 2 * index;
 		if (!is_mtrr_mask)
-			vcpu->arch.mtrr_state.var_ranges[idx].base = data;
+			vcpu->arch.mtrr_state.var_ranges[index].base = data;
 		else
-			vcpu->arch.mtrr_state.var_ranges[idx].mask = data;
+			vcpu->arch.mtrr_state.var_ranges[index].mask = data;
 	}
 
 	update_mtrr(vcpu, msr);
@@ -190,7 +286,7 @@ int kvm_mtrr_set_msr(struct kvm_vcpu *vcpu, u32 msr, u64 data)
 
 int kvm_mtrr_get_msr(struct kvm_vcpu *vcpu, u32 msr, u64 *pdata)
 {
-	u64 *p = (u64 *)&vcpu->arch.mtrr_state.fixed_ranges;
+	int index;
 
 	/* MSR_MTRRcap is a readonly MSR. */
 	if (msr == MSR_MTRRcap) {
@@ -207,25 +303,22 @@ int kvm_mtrr_get_msr(struct kvm_vcpu *vcpu, u32 msr, u64 *pdata)
 	if (!msr_mtrr_valid(msr))
 		return 1;
 
-	if (msr == MSR_MTRRdefType)
+	index = fixed_msr_to_range_index(msr);
+	if (index >= 0)
+		*pdata = *(u64 *)&vcpu->arch.mtrr_state.fixed_ranges[index];
+	else if (msr == MSR_MTRRdefType)
 		*pdata = vcpu->arch.mtrr_state.deftype;
-	else if (msr == MSR_MTRRfix64K_00000)
-		*pdata = p[0];
-	else if (msr == MSR_MTRRfix16K_80000 || msr == MSR_MTRRfix16K_A0000)
-		*pdata = p[1 + msr - MSR_MTRRfix16K_80000];
-	else if (msr >= MSR_MTRRfix4K_C0000 && msr <= MSR_MTRRfix4K_F8000)
-		*pdata = p[3 + msr - MSR_MTRRfix4K_C0000];
 	else if (msr == MSR_IA32_CR_PAT)
 		*pdata = vcpu->arch.pat;
 	else {	/* Variable MTRRs */
-		int idx, is_mtrr_mask;
+		int is_mtrr_mask;
 
-		idx = (msr - 0x200) / 2;
-		is_mtrr_mask = msr - 0x200 - 2 * idx;
+		index = (msr - 0x200) / 2;
+		is_mtrr_mask = msr - 0x200 - 2 * index;
 		if (!is_mtrr_mask)
-			*pdata = vcpu->arch.mtrr_state.var_ranges[idx].base;
+			*pdata = vcpu->arch.mtrr_state.var_ranges[index].base;
 		else
-			*pdata = vcpu->arch.mtrr_state.var_ranges[idx].mask;
+			*pdata = vcpu->arch.mtrr_state.var_ranges[index].mask;
 	}
 
 	return 0;
-- 
2.1.0

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