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| author | Sean Christopherson <seanjc@google.com> | 2025-09-19 15:32:43 -0700 |
|---|---|---|
| committer | Sean Christopherson <seanjc@google.com> | 2025-09-23 09:27:06 -0700 |
| commit | c5ba49458513bd1ecd669d4ec7124e788b19347c (patch) | |
| tree | 305461bef437fbbec5932e62a2602fa662948d54 /arch/x86/kvm/svm/nested.c | |
| parent | KVM: SVM: Emulate reads and writes to shadow stack MSRs (diff) | |
| download | linux-c5ba49458513bd1ecd669d4ec7124e788b19347c.tar.gz linux-c5ba49458513bd1ecd669d4ec7124e788b19347c.zip | |
KVM: nSVM: Save/load CET Shadow Stack state to/from vmcb12/vmcb02
Transfer the three CET Shadow Stack VMCB fields (S_CET, ISST_ADDR, and
SSP) on VMRUN, #VMEXIT, and loading nested state (saving nested state
simply copies the entire save area). SVM doesn't provide a way to
disallow L1 from enabling Shadow Stacks for L2, i.e. KVM *must* provide
nested support before advertising SHSTK to userspace.
Link: https://lore.kernel.org/r/20250919223258.1604852-37-seanjc@google.com
Signed-off-by: Sean Christopherson <seanjc@google.com>
Diffstat (limited to 'arch/x86/kvm/svm/nested.c')
| -rw-r--r-- | arch/x86/kvm/svm/nested.c | 20 |
1 files changed, 20 insertions, 0 deletions
diff --git a/arch/x86/kvm/svm/nested.c b/arch/x86/kvm/svm/nested.c index 826473f2d7c7..a6443feab252 100644 --- a/arch/x86/kvm/svm/nested.c +++ b/arch/x86/kvm/svm/nested.c @@ -636,6 +636,14 @@ static void nested_vmcb02_prepare_save(struct vcpu_svm *svm, struct vmcb *vmcb12 vmcb_mark_dirty(vmcb02, VMCB_DT); } + if (guest_cpu_cap_has(vcpu, X86_FEATURE_SHSTK) && + (unlikely(new_vmcb12 || vmcb_is_dirty(vmcb12, VMCB_CET)))) { + vmcb02->save.s_cet = vmcb12->save.s_cet; + vmcb02->save.isst_addr = vmcb12->save.isst_addr; + vmcb02->save.ssp = vmcb12->save.ssp; + vmcb_mark_dirty(vmcb02, VMCB_CET); + } + kvm_set_rflags(vcpu, vmcb12->save.rflags | X86_EFLAGS_FIXED); svm_set_efer(vcpu, svm->nested.save.efer); @@ -1044,6 +1052,12 @@ void svm_copy_vmrun_state(struct vmcb_save_area *to_save, to_save->rsp = from_save->rsp; to_save->rip = from_save->rip; to_save->cpl = 0; + + if (kvm_cpu_cap_has(X86_FEATURE_SHSTK)) { + to_save->s_cet = from_save->s_cet; + to_save->isst_addr = from_save->isst_addr; + to_save->ssp = from_save->ssp; + } } void svm_copy_vmloadsave_state(struct vmcb *to_vmcb, struct vmcb *from_vmcb) @@ -1111,6 +1125,12 @@ int nested_svm_vmexit(struct vcpu_svm *svm) vmcb12->save.dr6 = svm->vcpu.arch.dr6; vmcb12->save.cpl = vmcb02->save.cpl; + if (guest_cpu_cap_has(vcpu, X86_FEATURE_SHSTK)) { + vmcb12->save.s_cet = vmcb02->save.s_cet; + vmcb12->save.isst_addr = vmcb02->save.isst_addr; + vmcb12->save.ssp = vmcb02->save.ssp; + } + vmcb12->control.int_state = vmcb02->control.int_state; vmcb12->control.exit_code = vmcb02->control.exit_code; vmcb12->control.exit_code_hi = vmcb02->control.exit_code_hi; |