[PATCH v3 1/5] kvm: nested: Introduce read_and_check_msr_entry()

[Aaron Lewis <aaronlewis@google.com>]

Add the function read_and_check_msr_entry() which just pulls some code
out of nested_vmx_store_msr().  This will be useful as reusable code in
upcoming patches.

Reviewed-by: Liran Alon <liran.alon@oracle.com>
Reviewed-by: Jim Mattson <jmattson@google.com>
Signed-off-by: Aaron Lewis <aaronlewis@google.com>
---
 arch/x86/kvm/vmx/nested.c | 35 ++++++++++++++++++++++-------------
 1 file changed, 22 insertions(+), 13 deletions(-)

diff --git a/arch/x86/kvm/vmx/nested.c b/arch/x86/kvm/vmx/nested.c
index e76eb4f07f6c..7b058d7b9fcc 100644
--- a/arch/x86/kvm/vmx/nested.c
+++ b/arch/x86/kvm/vmx/nested.c
@@ -929,6 +929,26 @@ static u32 nested_vmx_load_msr(struct kvm_vcpu *vcpu, u64 gpa, u32 count)
 	return i + 1;
 }
 
+static bool read_and_check_msr_entry(struct kvm_vcpu *vcpu, u64 gpa, int i,
+				     struct vmx_msr_entry *e)
+{
+	if (kvm_vcpu_read_guest(vcpu,
+				gpa + i * sizeof(*e),
+				e, 2 * sizeof(u32))) {
+		pr_debug_ratelimited(
+			"%s cannot read MSR entry (%u, 0x%08llx)\n",
+			__func__, i, gpa + i * sizeof(*e));
+		return false;
+	}
+	if (nested_vmx_store_msr_check(vcpu, e)) {
+		pr_debug_ratelimited(
+			"%s check failed (%u, 0x%x, 0x%x)\n",
+			__func__, i, e->index, e->reserved);
+		return false;
+	}
+	return true;
+}
+
 static int nested_vmx_store_msr(struct kvm_vcpu *vcpu, u64 gpa, u32 count)
 {
 	u64 data;
@@ -940,20 +960,9 @@ static int nested_vmx_store_msr(struct kvm_vcpu *vcpu, u64 gpa, u32 count)
 		if (unlikely(i >= max_msr_list_size))
 			return -EINVAL;
 
-		if (kvm_vcpu_read_guest(vcpu,
-					gpa + i * sizeof(e),
-					&e, 2 * sizeof(u32))) {
-			pr_debug_ratelimited(
-				"%s cannot read MSR entry (%u, 0x%08llx)\n",
-				__func__, i, gpa + i * sizeof(e));
+		if (!read_and_check_msr_entry(vcpu, gpa, i, &e))
 			return -EINVAL;
-		}
-		if (nested_vmx_store_msr_check(vcpu, &e)) {
-			pr_debug_ratelimited(
-				"%s check failed (%u, 0x%x, 0x%x)\n",
-				__func__, i, e.index, e.reserved);
-			return -EINVAL;
-		}
+
 		if (kvm_get_msr(vcpu, e.index, &data)) {
 			pr_debug_ratelimited(
 				"%s cannot read MSR (%u, 0x%x)\n",
-- 
2.24.0.432.g9d3f5f5b63-goog