KVM: x86/pmu: Remove redundant check for MSR_IA32_DS_AREA set handler

After commit 2de154f ("KVM: x86/pmu: Provide "error" semantics
for unsupported-but-known PMU MSRs"), the guest_cpuid_has(DS) check
is not necessary any more since if the guest supports X86_FEATURE_DS,
it never returns 1. And if the guest does not support this feature,
the set_msr handler will get false from kvm_pmu_is_valid_msr() before
reaching this point. Therefore, the check will not be true in all cases
and can be safely removed, which also simplifies the code and improves
its readability.

Signed-off-by: Jinrong Liang <cloudliang@tencent.com>
Link: https://lore.kernel.org/r/20230411130338.8592-1-cloudliang@tencent.com
Signed-off-by: Sean Christopherson <seanjc@google.com>

Author: Jinrong Liang

arch/x86/kvm/vmx/pmu_intel.c

@@ -444,8 +444,6 @@ static int intel_pmu_set_msr(struct kvm_vcpu *vcpu, struct msr_data *msr_info)
 		}
 		break;
 	case MSR_IA32_DS_AREA:
-		if (msr_info->host_initiated && data && !guest_cpuid_has(vcpu, X86_FEATURE_DS))
-			return 1;
 		if (is_noncanonical_address(data, vcpu))
 			return 1;