[PATCH v6 2/8] KVM: x86: Add a helper function for CPUID(0xD,n>=1) enumeration

[Yang Weijiang]

To make the code look clean, wrap CPUID(0xD,n>=1) enumeration
code in a helper function now.

Signed-off-by: Yang Weijiang <weijiang.yang@xxxxxxxxx>
---
 arch/x86/kvm/cpuid.c | 44 ++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 44 insertions(+)

diff --git a/arch/x86/kvm/cpuid.c b/arch/x86/kvm/cpuid.c
index 4992e7c99588..29cbde7538a3 100644
--- a/arch/x86/kvm/cpuid.c
+++ b/arch/x86/kvm/cpuid.c
@@ -313,6 +313,50 @@ static int __do_cpuid_ent_emulated(struct kvm_cpuid_entry2 *entry,
 	return 0;
 }
 
+static inline int __do_cpuid_dx_leaf(struct kvm_cpuid_entry2 *entry, int *nent,
+				     int maxnent, u64 xss_mask, u64 xcr0_mask,
+				     u32 eax_mask)
+{
+	int idx, i;
+	u64 mask;
+	u64 supported;
+
+	for (idx = 1, i = 1; idx < 64; ++idx) {
+		mask = ((u64)1 << idx);
+		if (*nent >= maxnent)
+			return -EINVAL;
+
+		do_cpuid_1_ent(&entry[i], 0xD, idx);
+		if (idx == 1) {
+			entry[i].eax &= eax_mask;
+			cpuid_mask(&entry[i].eax, CPUID_D_1_EAX);
+			supported = xcr0_mask | xss_mask;
+			entry[i].ebx = 0;
+			entry[i].edx = 0;
+			entry[i].ecx &= xss_mask;
+			if (entry[i].eax & (F(XSAVES) | F(XSAVEC))) {
+				entry[i].ebx =
+					xstate_required_size(supported,
+							     true);
+			}
+		} else {
+			supported = (entry[i].ecx & 1) ? xss_mask :
+				     xcr0_mask;
+			if (entry[i].eax == 0 || !(supported & mask))
+				continue;
+			entry[i].ecx &= 1;
+			entry[i].edx = 0;
+			if (entry[i].ecx)
+				entry[i].ebx = 0;
+		}
+		entry[i].flags |=
+			KVM_CPUID_FLAG_SIGNIFCANT_INDEX;
+		++*nent;
+		++i;
+	}
+	return 0;
+}
+
 static inline int __do_cpuid_ent(struct kvm_cpuid_entry2 *entry, u32 function,
 				 u32 index, int *nent, int maxnent)
 {
-- 
2.17.2