diff options
| author | Paolo Bonzini <pbonzini@redhat.com> | 2023-08-04 12:42:45 -0400 |
|---|---|---|
| committer | Paolo Bonzini <pbonzini@redhat.com> | 2023-08-04 13:33:06 -0400 |
| commit | 4e15a0ddc3ff40e8ea84032213976ecf774d7f77 (patch) | |
| tree | 950e2a1a88cb352c9ad87800dec88ab997778e32 /arch/x86/kvm/svm/svm.h | |
| parent | 5a7591176c47cce363c1eed704241e5d1c42c5a6 (diff) | |
KVM: SEV: snapshot the GHCB before accessing it
Validation of the GHCB is susceptible to time-of-check/time-of-use vulnerabilities.
To avoid them, we would like to always snapshot the fields that are read in
sev_es_validate_vmgexit(), and not use the GHCB anymore after it returns.
This means:
- invoking sev_es_sync_from_ghcb() before any GHCB access, including before
sev_es_validate_vmgexit()
- snapshotting all fields including the valid bitmap and the sw_scratch field,
which are currently not caching anywhere.
The valid bitmap is the first thing to be copied out of the GHCB; then,
further accesses will use the copy in svm->sev_es.
Fixes: 291bd20d5d88 ("KVM: SVM: Add initial support for a VMGEXIT VMEXIT")
Cc: stable@vger.kernel.org
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Diffstat (limited to 'arch/x86/kvm/svm/svm.h')
| -rw-r--r-- | arch/x86/kvm/svm/svm.h | 26 |
1 files changed, 26 insertions, 0 deletions
diff --git a/arch/x86/kvm/svm/svm.h b/arch/x86/kvm/svm/svm.h index 18af7e712a5a..8239c8de45ac 100644 --- a/arch/x86/kvm/svm/svm.h +++ b/arch/x86/kvm/svm/svm.h @@ -190,10 +190,12 @@ struct vcpu_sev_es_state { /* SEV-ES support */ struct sev_es_save_area *vmsa; struct ghcb *ghcb; + u8 valid_bitmap[16]; struct kvm_host_map ghcb_map; bool received_first_sipi; /* SEV-ES scratch area support */ + u64 sw_scratch; void *ghcb_sa; u32 ghcb_sa_len; bool ghcb_sa_sync; @@ -744,4 +746,28 @@ void sev_es_unmap_ghcb(struct vcpu_svm *svm); void __svm_sev_es_vcpu_run(struct vcpu_svm *svm, bool spec_ctrl_intercepted); void __svm_vcpu_run(struct vcpu_svm *svm, bool spec_ctrl_intercepted); +#define DEFINE_KVM_GHCB_ACCESSORS(field) \ + static __always_inline bool kvm_ghcb_##field##_is_valid(const struct vcpu_svm *svm) \ + { \ + return test_bit(GHCB_BITMAP_IDX(field), \ + (unsigned long *)&svm->sev_es.valid_bitmap); \ + } \ + \ + static __always_inline u64 kvm_ghcb_get_##field##_if_valid(struct vcpu_svm *svm, struct ghcb *ghcb) \ + { \ + return kvm_ghcb_##field##_is_valid(svm) ? ghcb->save.field : 0; \ + } \ + +DEFINE_KVM_GHCB_ACCESSORS(cpl) +DEFINE_KVM_GHCB_ACCESSORS(rax) +DEFINE_KVM_GHCB_ACCESSORS(rcx) +DEFINE_KVM_GHCB_ACCESSORS(rdx) +DEFINE_KVM_GHCB_ACCESSORS(rbx) +DEFINE_KVM_GHCB_ACCESSORS(rsi) +DEFINE_KVM_GHCB_ACCESSORS(sw_exit_code) +DEFINE_KVM_GHCB_ACCESSORS(sw_exit_info_1) +DEFINE_KVM_GHCB_ACCESSORS(sw_exit_info_2) +DEFINE_KVM_GHCB_ACCESSORS(sw_scratch) +DEFINE_KVM_GHCB_ACCESSORS(xcr0) + #endif |