KVM: selftests: Add vcpu_set_cpuid_property() to set properties

Add vcpu_set_cpuid_property() helper function for setting properties, and
use it instead of open coding an equivalent for MAX_PHY_ADDR.  Future vPMU
testcases will also need to stuff various CPUID properties.
Reviewed-by: Jim Mattson <jmattson@google.com>
Signed-off-by: Jinrong Liang <cloudliang@tencent.com>
Co-developed-by: Sean Christopherson <seanjc@google.com>
Tested-by: Dapeng Mi <dapeng1.mi@linux.intel.com>
Link: https://lore.kernel.org/r/20240109230250.424295-13-seanjc@google.comSigned-off-by: Sean Christopherson <seanjc@google.com>

tools/testing/selftests/kvm/include/x86_64/processor.h

@@ -995,7 +995,9 @@ static inline void vcpu_set_cpuid(struct kvm_vcpu *vcpu)
 	vcpu_ioctl(vcpu, KVM_GET_CPUID2, vcpu->cpuid);
 }
 
-void vcpu_set_cpuid_maxphyaddr(struct kvm_vcpu *vcpu, uint8_t maxphyaddr);
+void vcpu_set_cpuid_property(struct kvm_vcpu *vcpu,
+			     struct kvm_x86_cpu_property property,
+			     uint32_t value);
 
 void vcpu_clear_cpuid_entry(struct kvm_vcpu *vcpu, uint32_t function);
 void vcpu_set_or_clear_cpuid_feature(struct kvm_vcpu *vcpu,

tools/testing/selftests/kvm/lib/x86_64/processor.c

@@ -752,12 +752,21 @@ void vcpu_init_cpuid(struct kvm_vcpu *vcpu, const struct kvm_cpuid2 *cpuid)
 	vcpu_set_cpuid(vcpu);
 }
 
-void vcpu_set_cpuid_maxphyaddr(struct kvm_vcpu *vcpu, uint8_t maxphyaddr)
+void vcpu_set_cpuid_property(struct kvm_vcpu *vcpu,
+			     struct kvm_x86_cpu_property property,
+			     uint32_t value)
 {
-	struct kvm_cpuid_entry2 *entry = vcpu_get_cpuid_entry(vcpu, 0x80000008);
+	struct kvm_cpuid_entry2 *entry;
+
+	entry = __vcpu_get_cpuid_entry(vcpu, property.function, property.index);
+
+	(&entry->eax)[property.reg] &= ~GENMASK(property.hi_bit, property.lo_bit);
+	(&entry->eax)[property.reg] |= value << property.lo_bit;
 
-	entry->eax = (entry->eax & ~0xff) | maxphyaddr;
 	vcpu_set_cpuid(vcpu);
+
+	/* Sanity check that @value doesn't exceed the bounds in any way. */
+	TEST_ASSERT_EQ(kvm_cpuid_property(vcpu->cpuid, property), value);
 }
 
 void vcpu_clear_cpuid_entry(struct kvm_vcpu *vcpu, uint32_t function)

tools/testing/selftests/kvm/x86_64/smaller_maxphyaddr_emulation_test.c

@@ -63,7 +63,7 @@ int main(int argc, char *argv[])
 	vm_init_descriptor_tables(vm);
 	vcpu_init_descriptor_tables(vcpu);
 
-	vcpu_set_cpuid_maxphyaddr(vcpu, MAXPHYADDR);
+	vcpu_set_cpuid_property(vcpu, X86_PROPERTY_MAX_PHY_ADDR, MAXPHYADDR);
 
 	rc = kvm_check_cap(KVM_CAP_EXIT_ON_EMULATION_FAILURE);
 	TEST_ASSERT(rc, "KVM_CAP_EXIT_ON_EMULATION_FAILURE is unavailable");