linux-kernel - [RESEND v13 09/11] KVM: VMX: Add VMCS dump and sanity check for CET states

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Date:   Thu, 16 Jul 2020 11:16:25 +0800
From:   Yang Weijiang <weijiang.yang@...el.com>
To:     kvm@...r.kernel.org, linux-kernel@...r.kernel.org,
        pbonzini@...hat.com, sean.j.christopherson@...el.com,
        jmattson@...gle.com
Cc:     yu.c.zhang@...ux.intel.com, Yang Weijiang <weijiang.yang@...el.com>
Subject: [RESEND v13 09/11] KVM: VMX: Add VMCS dump and sanity check for CET states

Dump CET VMCS states for debug purpose. Since CET kernel protection is
not enabled, if related MSRs in host are filled by mistake, warn once on
detecting it.

Signed-off-by: Yang Weijiang <weijiang.yang@...el.com>
---
 arch/x86/kvm/vmx/vmx.c | 23 +++++++++++++++++++++++
 1 file changed, 23 insertions(+)

diff --git a/arch/x86/kvm/vmx/vmx.c b/arch/x86/kvm/vmx/vmx.c
index d465ff990094..5d4250b9dec8 100644
--- a/arch/x86/kvm/vmx/vmx.c
+++ b/arch/x86/kvm/vmx/vmx.c
@@ -6056,6 +6056,12 @@ void dump_vmcs(void)
 		pr_err("InterruptStatus = %04x\n",
 		       vmcs_read16(GUEST_INTR_STATUS));
 
+	if (vmentry_ctl & VM_ENTRY_LOAD_CET_STATE) {
+		pr_err("S_CET = 0x%016lx\n", vmcs_readl(GUEST_S_CET));
+		pr_err("SSP = 0x%016lx\n", vmcs_readl(GUEST_SSP));
+		pr_err("SSP TABLE = 0x%016lx\n",
+		       vmcs_readl(GUEST_INTR_SSP_TABLE));
+	}
 	pr_err("*** Host State ***\n");
 	pr_err("RIP = 0x%016lx  RSP = 0x%016lx\n",
 	       vmcs_readl(HOST_RIP), vmcs_readl(HOST_RSP));
@@ -6130,6 +6136,12 @@ void dump_vmcs(void)
 	if (secondary_exec_control & SECONDARY_EXEC_ENABLE_VPID)
 		pr_err("Virtual processor ID = 0x%04x\n",
 		       vmcs_read16(VIRTUAL_PROCESSOR_ID));
+	if (vmexit_ctl & VM_EXIT_LOAD_CET_STATE) {
+		pr_err("S_CET = 0x%016lx\n", vmcs_readl(HOST_S_CET));
+		pr_err("SSP = 0x%016lx\n", vmcs_readl(HOST_SSP));
+		pr_err("SSP TABLE = 0x%016lx\n",
+		       vmcs_readl(HOST_INTR_SSP_TABLE));
+	}
 }
 
 /*
@@ -8205,6 +8217,7 @@ static __init int hardware_setup(void)
 	unsigned long host_bndcfgs;
 	struct desc_ptr dt;
 	int r, i, ept_lpage_level;
+	u64 cet_msr;
 
 	store_idt(&dt);
 	host_idt_base = dt.address;
@@ -8365,6 +8378,16 @@ static __init int hardware_setup(void)
 			return r;
 	}
 
+	if (boot_cpu_has(X86_FEATURE_IBT) || boot_cpu_has(X86_FEATURE_SHSTK)) {
+		rdmsrl(MSR_IA32_S_CET, cet_msr);
+		WARN_ONCE(cet_msr, "KVM: CET S_CET in host will be lost!\n");
+	}
+
+	if (boot_cpu_has(X86_FEATURE_SHSTK)) {
+		rdmsrl(MSR_IA32_PL0_SSP, cet_msr);
+		WARN_ONCE(cet_msr, "KVM: CET PL0_SSP in host will be lost!\n");
+	}
+
 	vmx_set_cpu_caps();
 
 	r = alloc_kvm_area();
-- 
2.17.2