From: Sean Christopherson Date: Tue, 21 Sep 2021 00:03:00 +0000 (-0700) Subject: KVM: VMX: Drop explicit zeroing of MSR guest values at vCPU creation X-Git-Tag: v5.16-rc1~153^2~110 X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=d06567353e129b460978353cbe2210c23467d6f8;p=thirdparty%2Fkernel%2Flinux.git KVM: VMX: Drop explicit zeroing of MSR guest values at vCPU creation Don't zero out user return and nested MSRs during vCPU creation, and instead rely on vcpu_vmx being zero-allocated. Explicitly zeroing MSRs is not wrong, and is in fact necessary if KVM ever emulates vCPU RESET outside of vCPU creation, but zeroing only a subset of MSRs is confusing. Poking directly into KVM's backing is also undesirable in that it doesn't scale and is error prone. Ideally KVM would have a common RESET path for all MSRs, e.g. by expanding kvm_set_msr(), which would obviate the need for this out-of-bad code (to support standalone RESET). No functional change intended. Signed-off-by: Sean Christopherson Reviewed-by: Vitaly Kuznetsov Signed-off-by: Paolo Bonzini Message-Id: <20210921000303.400537-8-seanjc@google.com> Signed-off-by: Paolo Bonzini --- diff --git a/arch/x86/kvm/vmx/vmx.c b/arch/x86/kvm/vmx/vmx.c index 7c496fd0bb966..65be361669893 100644 --- a/arch/x86/kvm/vmx/vmx.c +++ b/arch/x86/kvm/vmx/vmx.c @@ -6837,10 +6837,8 @@ static int vmx_create_vcpu(struct kvm_vcpu *vcpu) goto free_vpid; } - for (i = 0; i < kvm_nr_uret_msrs; ++i) { - vmx->guest_uret_msrs[i].data = 0; + for (i = 0; i < kvm_nr_uret_msrs; ++i) vmx->guest_uret_msrs[i].mask = -1ull; - } if (boot_cpu_has(X86_FEATURE_RTM)) { /* * TSX_CTRL_CPUID_CLEAR is handled in the CPUID interception. @@ -6897,8 +6895,6 @@ static int vmx_create_vcpu(struct kvm_vcpu *vcpu) if (nested) memcpy(&vmx->nested.msrs, &vmcs_config.nested, sizeof(vmx->nested.msrs)); - else - memset(&vmx->nested.msrs, 0, sizeof(vmx->nested.msrs)); vcpu_setup_sgx_lepubkeyhash(vcpu);