On 1/26/2024 2:31 PM, Chao Gao wrote:
On Tue, Jan 23, 2024 at 06:41:56PM -0800, Yang Weijiang wrote:
Save constant values to HOST_{S_CET,SSP,INTR_SSP_TABLE} field explicitly.
Kernel IBT is supported and the setting in MSR_IA32_S_CET is static after
post-boot(The exception is BIOS call case but vCPU thread never across it)
and KVM doesn't need to refresh HOST_S_CET field before every VM-Enter/
VM-Exit sequence.
Host supervisor shadow stack is not enabled now and SSP is not accessible
to kernel mode, thus it's safe to set host IA32_INT_SSP_TAB/SSP VMCS field
to 0s. When shadow stack is enabled for CPL3, SSP is reloaded from PL3_SSP
before it exits to userspace. Check SDM Vol 2A/B Chapter 3/4 for SYSCALL/
SYSRET/SYSENTER SYSEXIT/RDSSP/CALL etc.
Prevent KVM module loading if host supervisor shadow stack SHSTK_EN is set
in MSR_IA32_S_CET as KVM cannot co-exit with it correctly.
Suggested-by: Sean Christopherson <seanjc@xxxxxxxxxx>
Suggested-by: Chao Gao <chao.gao@xxxxxxxxx>
Signed-off-by: Yang Weijiang <weijiang.yang@xxxxxxxxx>
Reviewed-by: Maxim Levitsky <mlevitsk@xxxxxxxxxx>
Reviewed-by: Chao Gao <chao.gao@xxxxxxxxx>
two nits below.
---
arch/x86/kvm/vmx/capabilities.h | 4 ++++
arch/x86/kvm/vmx/vmx.c | 15 +++++++++++++++
arch/x86/kvm/x86.c | 14 ++++++++++++++
arch/x86/kvm/x86.h | 1 +
4 files changed, 34 insertions(+)
diff --git a/arch/x86/kvm/vmx/capabilities.h b/arch/x86/kvm/vmx/capabilities.h
index 41a4533f9989..ee8938818c8a 100644
--- a/arch/x86/kvm/vmx/capabilities.h
+++ b/arch/x86/kvm/vmx/capabilities.h
@@ -106,6 +106,10 @@ static inline bool cpu_has_load_perf_global_ctrl(void)
return vmcs_config.vmentry_ctrl & VM_ENTRY_LOAD_IA32_PERF_GLOBAL_CTRL;
}
+static inline bool cpu_has_load_cet_ctrl(void)
s/cet_ctrl/cet_state
+{
+ return (vmcs_config.vmentry_ctrl & VM_ENTRY_LOAD_CET_STATE);
nit: unnecessary brackets.
OK, will fix these nits.
