[RFC PATCH 1/3] Add helper methods to get segment limits

[Mohammed Gamal <m.gamal005@gmail.com>]

This adds helper methods to get segment limits for kvm_x86_ops and x86_emulate_ops. Hooks are added for SVM and VMX

Signed-off-by: Mohammed Gamal <m.gamal005@gmail.com>
---
 arch/x86/include/asm/kvm_emulate.h |    1 +
 arch/x86/include/asm/kvm_host.h    |    1 +
 arch/x86/kvm/svm.c                 |    8 ++++++++
 arch/x86/kvm/vmx.c                 |    8 ++++++++
 arch/x86/kvm/x86.c                 |   12 ++++++++++++
 5 files changed, 30 insertions(+), 0 deletions(-)

diff --git a/arch/x86/include/asm/kvm_emulate.h b/arch/x86/include/asm/kvm_emulate.h
index 51cfd73..ce90048 100644
--- a/arch/x86/include/asm/kvm_emulate.h
+++ b/arch/x86/include/asm/kvm_emulate.h
@@ -138,6 +138,7 @@ struct x86_emulate_ops {
 	u16 (*get_segment_selector)(int seg, struct kvm_vcpu *vcpu);
 	void (*set_segment_selector)(u16 sel, int seg, struct kvm_vcpu *vcpu);
 	unsigned long (*get_cached_segment_base)(int seg, struct kvm_vcpu *vcpu);
+	u32 (*get_cached_segment_limit)(int seg, struct kvm_vcpu *vcpu);
 	void (*get_gdt)(struct desc_ptr *dt, struct kvm_vcpu *vcpu);
 	ulong (*get_cr)(int cr, struct kvm_vcpu *vcpu);
 	int (*set_cr)(int cr, ulong val, struct kvm_vcpu *vcpu);
diff --git a/arch/x86/include/asm/kvm_host.h b/arch/x86/include/asm/kvm_host.h
index 502e53f..e32efc4 100644
--- a/arch/x86/include/asm/kvm_host.h
+++ b/arch/x86/include/asm/kvm_host.h
@@ -468,6 +468,7 @@ struct kvm_x86_ops {
 	int (*get_msr)(struct kvm_vcpu *vcpu, u32 msr_index, u64 *pdata);
 	int (*set_msr)(struct kvm_vcpu *vcpu, u32 msr_index, u64 data);
 	u64 (*get_segment_base)(struct kvm_vcpu *vcpu, int seg);
+	u32 (*get_segment_limit)(struct kvm_vcpu *vcpu, int seg);
 	void (*get_segment)(struct kvm_vcpu *vcpu,
 			    struct kvm_segment *var, int seg);
 	int (*get_cpl)(struct kvm_vcpu *vcpu);
diff --git a/arch/x86/kvm/svm.c b/arch/x86/kvm/svm.c
index 56c9b6b..504761d 100644
--- a/arch/x86/kvm/svm.c
+++ b/arch/x86/kvm/svm.c
@@ -1038,6 +1038,13 @@ static u64 svm_get_segment_base(struct kvm_vcpu *vcpu, int seg)
 	return s->base;
 }
 
+static u32 svm_get_segment_limit(struct kvm_vcpu *vcpu, int seg)
+{
+	struct vmcb_seg *s = svm_seg(vcpu, seg);
+
+	return s->limit;
+}
+
 static void svm_get_segment(struct kvm_vcpu *vcpu,
 			    struct kvm_segment *var, int seg)
 {
@@ -3461,6 +3468,7 @@ static struct kvm_x86_ops svm_x86_ops = {
 	.get_msr = svm_get_msr,
 	.set_msr = svm_set_msr,
 	.get_segment_base = svm_get_segment_base,
+	.get_segment_limit = svm_get_segment_limit,
 	.get_segment = svm_get_segment,
 	.set_segment = svm_set_segment,
 	.get_cpl = svm_get_cpl,
diff --git a/arch/x86/kvm/vmx.c b/arch/x86/kvm/vmx.c
index ebaaeaf..c9c14da 100644
--- a/arch/x86/kvm/vmx.c
+++ b/arch/x86/kvm/vmx.c
@@ -2004,6 +2004,13 @@ static u64 vmx_get_segment_base(struct kvm_vcpu *vcpu, int seg)
 	return vmcs_readl(sf->base);
 }
 
+static u32 vmx_get_segment_limit(struct kvm_vcpu *vcpu, int seg)
+{
+	struct kvm_vmx_segment_field *sf = &kvm_vmx_segment_fields[seg];
+
+	return vmcs_read32(sf->limit);
+}
+
 static void vmx_get_segment(struct kvm_vcpu *vcpu,
 			    struct kvm_segment *var, int seg)
 {
@@ -4307,6 +4314,7 @@ static struct kvm_x86_ops vmx_x86_ops = {
 	.get_msr = vmx_get_msr,
 	.set_msr = vmx_set_msr,
 	.get_segment_base = vmx_get_segment_base,
+	.get_segment_limit = vmx_get_segment_limit,
 	.get_segment = vmx_get_segment,
 	.set_segment = vmx_set_segment,
 	.get_cpl = vmx_get_cpl,
diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
index 7070b41..6a6aa92 100644
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -3674,6 +3674,11 @@ static unsigned long get_segment_base(struct kvm_vcpu *vcpu, int seg)
 	return kvm_x86_ops->get_segment_base(vcpu, seg);
 }
 
+static u32 get_segment_limit (struct kvm_vcpu *vcpu, int seg)
+{
+	return kvm_x86_ops->get_segment_limit(vcpu, seg);
+}
+
 int emulate_invlpg(struct kvm_vcpu *vcpu, gva_t address)
 {
 	kvm_mmu_invlpg(vcpu, address);
@@ -3790,6 +3795,12 @@ static unsigned long emulator_get_cached_segment_base(int seg,
 	return get_segment_base(vcpu, seg);
 }
 
+static u32 emulate_get_cached_segment_limit(int seg,
+					    struct kvm_vcpu *vcpu)
+{
+	return get_segment_limit(vcpu, seg);
+}
+
 static bool emulator_get_cached_descriptor(struct desc_struct *desc, int seg,
 					   struct kvm_vcpu *vcpu)
 {
@@ -3876,6 +3887,7 @@ static struct x86_emulate_ops emulate_ops = {
 	.get_segment_selector = emulator_get_segment_selector,
 	.set_segment_selector = emulator_set_segment_selector,
 	.get_cached_segment_base = emulator_get_cached_segment_base,
+	.get_cached_segment_limit = emulate_get_cached_segment_limit,
 	.get_gdt             = emulator_get_gdt,
 	.get_cr              = emulator_get_cr,
 	.set_cr              = emulator_set_cr,
-- 
1.7.0.4