linux-kernel - [PATCH v6 22/33] KVM: VMX: Don't toggle VM_ENTRY_IA32E

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Date:   Tue, 30 Aug 2022 15:37:26 +0200
From:   Vitaly Kuznetsov <vkuznets@...hat.com>
To:     kvm@...r.kernel.org, Paolo Bonzini <pbonzini@...hat.com>
Cc:     Sean Christopherson <seanjc@...gle.com>,
        Wanpeng Li <wanpengli@...cent.com>,
        Jim Mattson <jmattson@...gle.com>,
        Michael Kelley <mikelley@...rosoft.com>,
        Yuan Yao <yuan.yao@...ux.intel.com>,
        Maxim Levitsky <mlevitsk@...hat.com>,
        linux-hyperv@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: [PATCH v6 22/33] KVM: VMX: Don't toggle VM_ENTRY_IA32E_MODE for 32-bit kernels/KVM

From: Sean Christopherson <seanjc@...gle.com>

Don't toggle VM_ENTRY_IA32E_MODE in 32-bit kernels/KVM and instead bug
the VM if KVM attempts to run the guest with EFER.LMA=1. KVM doesn't
support running 64-bit guests with 32-bit hosts.

Signed-off-by: Sean Christopherson <seanjc@...gle.com>
Signed-off-by: Vitaly Kuznetsov <vkuznets@...hat.com>
---
 arch/x86/kvm/vmx/vmx.c | 5 +++++
 1 file changed, 5 insertions(+)

diff --git a/arch/x86/kvm/vmx/vmx.c b/arch/x86/kvm/vmx/vmx.c
index 9a9cdd4ea34d..7b73fee34598 100644
--- a/arch/x86/kvm/vmx/vmx.c
+++ b/arch/x86/kvm/vmx/vmx.c
@@ -3039,10 +3039,15 @@ int vmx_set_efer(struct kvm_vcpu *vcpu, u64 efer)
 		return 0;
 
 	vcpu->arch.efer = efer;
+#ifdef CONFIG_X86_64
 	if (efer & EFER_LMA)
 		vm_entry_controls_setbit(vmx, VM_ENTRY_IA32E_MODE);
 	else
 		vm_entry_controls_clearbit(vmx, VM_ENTRY_IA32E_MODE);
+#else
+	if (KVM_BUG_ON(efer & EFER_LMA, vcpu->kvm))
+		return 1;
+#endif
 
 	vmx_setup_uret_msrs(vmx);
 	return 0;
-- 
2.37.2