The CET runtime settings, i.e., CET state control bits(IA32_U_CET/
IA32_S_CET), CET SSP(IA32_PL3_SSP/IA32_PL0_SSP) and SSP table address
(IA32_INTERRUPT_SSP_TABLE_ADDR) are task/thread specific, therefore,
OS needs to save/restore the states properly during context switch,
e.g., task/thread switching, interrupt/exception handling, it uses
xsaves/xrstors to achieve that.
The difference between VMCS CET area fields and xsave CET area, is that
the former is for state retention during Guest/Host context
switch while the latter is for state retention during OS execution.
Linux currently doesn't support CPL1 and CPL2, so SSPs for these level
are skipped here.
Signed-off-by: Zhang Yi Z <yi.z.zhang@xxxxxxxxxxxxxxx>
Signed-off-by: Yang Weijiang <weijiang.yang@xxxxxxxxx>
---
arch/x86/kvm/vmx.c | 13 +++++++++++++
1 file changed, 13 insertions(+)
diff --git a/arch/x86/kvm/vmx.c b/arch/x86/kvm/vmx.c
index 7bbb8b26e901..89ee086e1729 100644
--- a/arch/x86/kvm/vmx.c
+++ b/arch/x86/kvm/vmx.c
@@ -11769,6 +11769,7 @@ static void nested_vmx_entry_exit_ctls_update(struct kvm_vcpu *vcpu)
static void vmx_cpuid_update(struct kvm_vcpu *vcpu)
{
struct vcpu_vmx *vmx = to_vmx(vcpu);
+ unsigned long *msr_bitmap;
if (cpu_has_secondary_exec_ctrls()) {
vmx_compute_secondary_exec_control(vmx);
@@ -11786,6 +11787,18 @@ static void vmx_cpuid_update(struct kvm_vcpu *vcpu)
nested_vmx_cr_fixed1_bits_update(vcpu);
nested_vmx_entry_exit_ctls_update(vcpu);
}
+
+ msr_bitmap = vmx->vmcs01.msr_bitmap;
+
+ if (guest_cpuid_has(vcpu, X86_FEATURE_SHSTK) |
+ guest_cpuid_has(vcpu, X86_FEATURE_IBT)) {
+ vmx_disable_intercept_for_msr(msr_bitmap, MSR_IA32_U_CET, MSR_TYPE_RW);
+ vmx_disable_intercept_for_msr(msr_bitmap, MSR_IA32_S_CET, MSR_TYPE_RW);
+ vmx_disable_intercept_for_msr(msr_bitmap, MSR_IA32_INT_SSP_TAB, MSR_TYPE_RW);
+ vmx_disable_intercept_for_msr(msr_bitmap, MSR_IA32_PL0_SSP, MSR_TYPE_RW);
+ vmx_disable_intercept_for_msr(msr_bitmap, MSR_IA32_PL3_SSP, MSR_TYPE_RW);
+ }
+
}
static void vmx_set_supported_cpuid(u32 func, struct kvm_cpuid_entry2 *entry)
--
2.17.1
