[PATCH 19/25] KVM: X86: Introduce kvm_get_supported_cpuid_internal()

[Rick Edgecombe <rick.p.edgecombe@intel.com>]

From: Xiaoyao Li <xiaoyao.li@intel.com>

TDX module reports a set of configurable CPUIDs. Directly report these
bits to userspace and allow them to be set is not good nor right. If a
bit is unknown/unsupported to KVM, it should be reported as unsupported
thus inconfigurable to userspace.

Introduce and export kvm_get_supported_cpuid_internal() for TDX to get
the supported CPUID list of KVM. So that TDX can use it to cap the
configurable CPUID list reported by TDX module.

Signed-off-by: Xiaoyao Li <xiaoyao.li@intel.com>
Signed-off-by: Rick Edgecombe <rick.p.edgecombe@intel.com>
---
uAPI breakout v1:
 - New patch
---
 arch/x86/kvm/cpuid.c | 25 +++++++++++++++++++++++++
 arch/x86/kvm/cpuid.h |  2 ++
 2 files changed, 27 insertions(+)

diff --git a/arch/x86/kvm/cpuid.c b/arch/x86/kvm/cpuid.c
index 7310d8a8a503..499479c769d8 100644
--- a/arch/x86/kvm/cpuid.c
+++ b/arch/x86/kvm/cpuid.c
@@ -1487,6 +1487,31 @@ int kvm_dev_ioctl_get_cpuid(struct kvm_cpuid2 *cpuid,
 	return r;
 }
 
+int kvm_get_supported_cpuid_internal(struct kvm_cpuid2 *cpuid, const u32 *funcs,
+				     int funcs_len)
+{
+	struct kvm_cpuid_array array = {
+		.nent = 0,
+	};
+	int i, r;
+
+	if (cpuid->nent < 1 || cpuid->nent > KVM_MAX_CPUID_ENTRIES)
+		return -E2BIG;
+
+	array.maxnent = cpuid->nent;
+	array.entries = cpuid->entries;
+
+	for (i = 0; i < funcs_len; i++) {
+		r = get_cpuid_func(&array, funcs[i], KVM_GET_SUPPORTED_CPUID);
+		if (r)
+			return r;
+	}
+
+	cpuid->nent = array.nent;
+	return 0;
+}
+EXPORT_SYMBOL_GPL(kvm_get_supported_cpuid_internal);
+
 struct kvm_cpuid_entry2 *kvm_find_cpuid_entry2(
 	struct kvm_cpuid_entry2 *entries, int nent, u32 function, u64 index)
 {
diff --git a/arch/x86/kvm/cpuid.h b/arch/x86/kvm/cpuid.h
index 00570227e2ae..5cc13d1b7991 100644
--- a/arch/x86/kvm/cpuid.h
+++ b/arch/x86/kvm/cpuid.h
@@ -13,6 +13,8 @@ void kvm_set_cpu_caps(void);
 
 void kvm_update_cpuid_runtime(struct kvm_vcpu *vcpu);
 void kvm_update_pv_runtime(struct kvm_vcpu *vcpu);
+int kvm_get_supported_cpuid_internal(struct kvm_cpuid2 *cpuid, const u32 *funcs,
+				     int func_len);
 struct kvm_cpuid_entry2 *kvm_find_cpuid_entry2(struct kvm_cpuid_entry2 *entries,
 					       int nent, u32 function, u64 index);
 struct kvm_cpuid_entry2 *kvm_find_cpuid_entry_index(struct kvm_vcpu *vcpu,
-- 
2.34.1