linux-kernel - [PATCH v1 3/8] kvm:vmx Enable loading CET state bit while guest CR4.CET is being set.

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Date:   Wed, 26 Dec 2018 16:15:27 +0800
From:   Yang Weijiang <weijiang.yang@...el.com>
To:     pbonzini@...hat.com, rkrcmar@...hat.com,
        linux-kernel@...r.kernel.org, kvm@...r.kernel.org, mst@...hat.com,
        yu-cheng.yu@...el.com, yi.z.zhang@...el.com, hjl.tools@...il.com
Cc:     Yang Weijiang <weijiang.yang@...el.com>,
        Zhang Yi Z <yi.z.zhang@...ux.intel.com>
Subject: [PATCH v1 3/8] kvm:vmx  Enable loading CET state bit while guest CR4.CET is being set.

This bit controls whether guest CET states will be loaded on guest entry.

Signed-off-by: Zhang Yi Z <yi.z.zhang@...ux.intel.com>
Signed-off-by: Yang Weijiang <weijiang.yang@...el.com>
---
 arch/x86/kvm/vmx.c | 19 +++++++++++++++++++
 1 file changed, 19 insertions(+)

diff --git a/arch/x86/kvm/vmx.c b/arch/x86/kvm/vmx.c
index 7bbb8b26e901..25fa6bd2fb95 100644
--- a/arch/x86/kvm/vmx.c
+++ b/arch/x86/kvm/vmx.c
@@ -1045,6 +1045,8 @@ struct vcpu_vmx {
 
 	bool req_immediate_exit;
 
+	bool vcpu_cet_on;
+
 	/* Support for PML */
 #define PML_ENTITY_NUM		512
 	struct page *pml_pg;
@@ -5409,6 +5411,23 @@ static int vmx_set_cr4(struct kvm_vcpu *vcpu, unsigned long cr4)
 			return 1;
 	}
 
+	/*
+	 * When CET.CR4 is being set, it means we're enabling CET for
+	 * the guest, then enable loading CET state bit in entry control.
+	 * Otherwise, clear loading CET bit to disable guest CET.
+	 */
+	if (cr4 & X86_CR4_CET) {
+		if (!to_vmx(vcpu)->vcpu_cet_on) {
+			vmcs_set_bits(VM_ENTRY_CONTROLS,
+				      VM_ENTRY_LOAD_GUEST_CET_STATE);
+			to_vmx(vcpu)->vcpu_cet_on = 1;
+		}
+	} else if (to_vmx(vcpu)->vcpu_cet_on) {
+		vmcs_clear_bits(VM_ENTRY_CONTROLS,
+				VM_ENTRY_LOAD_GUEST_CET_STATE);
+		to_vmx(vcpu)->vcpu_cet_on = 0;
+	}
+
 	if (to_vmx(vcpu)->nested.vmxon && !nested_cr4_valid(vcpu, cr4))
 		return 1;
 
-- 
2.17.1