diff options
Diffstat (limited to 'Documentation')
| -rw-r--r-- | Documentation/admin-guide/hw-vuln/srso.rst | 71 |
1 files changed, 44 insertions, 27 deletions
diff --git a/Documentation/admin-guide/hw-vuln/srso.rst b/Documentation/admin-guide/hw-vuln/srso.rst index 32eb5e6db272..af59a9395662 100644 --- a/Documentation/admin-guide/hw-vuln/srso.rst +++ b/Documentation/admin-guide/hw-vuln/srso.rst @@ -42,42 +42,59 @@ The sysfs file showing SRSO mitigation status is: The possible values in this file are: - - 'Not affected' The processor is not vulnerable + * 'Not affected': - - 'Vulnerable: no microcode' The processor is vulnerable, no - microcode extending IBPB functionality - to address the vulnerability has been - applied. + The processor is not vulnerable - - 'Mitigation: microcode' Extended IBPB functionality microcode - patch has been applied. It does not - address User->Kernel and Guest->Host - transitions protection but it does - address User->User and VM->VM attack - vectors. + * 'Vulnerable: no microcode': - (spec_rstack_overflow=microcode) + The processor is vulnerable, no microcode extending IBPB + functionality to address the vulnerability has been applied. - - 'Mitigation: safe RET' Software-only mitigation. It complements - the extended IBPB microcode patch - functionality by addressing User->Kernel - and Guest->Host transitions protection. + * 'Mitigation: microcode': - Selected by default or by - spec_rstack_overflow=safe-ret + Extended IBPB functionality microcode patch has been applied. It does + not address User->Kernel and Guest->Host transitions protection but it + does address User->User and VM->VM attack vectors. - - 'Mitigation: IBPB' Similar protection as "safe RET" above - but employs an IBPB barrier on privilege - domain crossings (User->Kernel, - Guest->Host). + Note that User->User mitigation is controlled by how the IBPB aspect in + the Spectre v2 mitigation is selected: - (spec_rstack_overflow=ibpb) + * conditional IBPB: + + where each process can select whether it needs an IBPB issued + around it PR_SPEC_DISABLE/_ENABLE etc, see :doc:`spectre` + + * strict: + + i.e., always on - by supplying spectre_v2_user=on on the kernel + command line + + (spec_rstack_overflow=microcode) + + * 'Mitigation: safe RET': + + Software-only mitigation. It complements the extended IBPB microcode + patch functionality by addressing User->Kernel and Guest->Host + transitions protection. + + Selected by default or by spec_rstack_overflow=safe-ret + + * 'Mitigation: IBPB': + + Similar protection as "safe RET" above but employs an IBPB barrier on + privilege domain crossings (User->Kernel, Guest->Host). + + (spec_rstack_overflow=ibpb) + + * 'Mitigation: IBPB on VMEXIT': + + Mitigation addressing the cloud provider scenario - the Guest->Host + transitions only. + + (spec_rstack_overflow=ibpb-vmexit) - - 'Mitigation: IBPB on VMEXIT' Mitigation addressing the cloud provider - scenario - the Guest->Host transitions - only. - (spec_rstack_overflow=ibpb-vmexit) In order to exploit vulnerability, an attacker needs to: |