linux-kernel - [PATCH v2 35/46] KVM: VMX: Don't _explicitly_ reconfigure user return MSRs on vCPU INIT

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Date:   Tue, 13 Jul 2021 09:33:13 -0700
From:   Sean Christopherson <seanjc@...gle.com>
To:     Paolo Bonzini <pbonzini@...hat.com>
Cc:     Sean Christopherson <seanjc@...gle.com>,
        Vitaly Kuznetsov <vkuznets@...hat.com>,
        Wanpeng Li <wanpengli@...cent.com>,
        Jim Mattson <jmattson@...gle.com>,
        Joerg Roedel <joro@...tes.org>, kvm@...r.kernel.org,
        linux-kernel@...r.kernel.org, Reiji Watanabe <reijiw@...gle.com>
Subject: [PATCH v2 35/46] KVM: VMX: Don't _explicitly_ reconfigure user return
 MSRs on vCPU INIT

When emulating vCPU INIT, do not unconditionally refresh the list of user
return MSRs that need to be loaded into hardware when running the guest.
Unconditionally refreshing the list is confusing, as the vast majority of
MSRs are not modified on INIT.  The real motivation is to handle the case
where an INIT during long mode obviates the need to load the SYSCALL MSRs,
and that is handled as needed by vmx_set_efer().

Signed-off-by: Sean Christopherson <seanjc@...gle.com>
---
 arch/x86/kvm/vmx/vmx.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/arch/x86/kvm/vmx/vmx.c b/arch/x86/kvm/vmx/vmx.c
index 3045daa3ec30..555235d6c17e 100644
--- a/arch/x86/kvm/vmx/vmx.c
+++ b/arch/x86/kvm/vmx/vmx.c
@@ -4406,6 +4406,8 @@ static void init_vmcs(struct vcpu_vmx *vmx)
 		vmx->pt_desc.guest.output_mask = 0x7F;
 		vmcs_write64(GUEST_IA32_RTIT_CTL, 0);
 	}
+
+	vmx_setup_uret_msrs(vmx);
 }
 
 static void vmx_vcpu_reset(struct kvm_vcpu *vcpu, bool init_event)
@@ -4467,8 +4469,6 @@ static void vmx_vcpu_reset(struct kvm_vcpu *vcpu, bool init_event)
 	if (kvm_mpx_supported())
 		vmcs_write64(GUEST_BNDCFGS, 0);
 
-	vmx_setup_uret_msrs(vmx);
-
 	if (cpu_has_vmx_msr_bitmap())
 		vmx_update_msr_bitmap(&vmx->vcpu);
 
-- 
2.32.0.93.g670b81a890-goog