From 182ac87070e26d32a01445cec7ca7afa07411468 Mon Sep 17 00:00:00 2001 From: "Borislav Petkov (AMD)" Date: Sat, 29 Jul 2023 16:53:02 +0200 Subject: Documentation/hw-vuln: Unify filename specification in index Most of the index.rst files in Documentation/ refer to other rst files without their file extension in the name. Do that here too. No functional changes. Reported-by: Linus Torvalds Signed-off-by: Borislav Petkov (AMD) Reviewed-by: Greg Kroah-Hartman Link: https://lore.kernel.org/r/20230809102700.29449-2-bp@alien8.de --- Documentation/admin-guide/hw-vuln/index.rst | 14 +++++++------- 1 file changed, 7 insertions(+), 7 deletions(-) (limited to 'Documentation') diff --git a/Documentation/admin-guide/hw-vuln/index.rst b/Documentation/admin-guide/hw-vuln/index.rst index a7d37e124831..de99caabf65a 100644 --- a/Documentation/admin-guide/hw-vuln/index.rst +++ b/Documentation/admin-guide/hw-vuln/index.rst @@ -13,11 +13,11 @@ are configurable at compile, boot or run time. l1tf mds tsx_async_abort - multihit.rst - special-register-buffer-data-sampling.rst - core-scheduling.rst - l1d_flush.rst - processor_mmio_stale_data.rst - cross-thread-rsb.rst + multihit + special-register-buffer-data-sampling + core-scheduling + l1d_flush + processor_mmio_stale_data + cross-thread-rsb srso - gather_data_sampling.rst + gather_data_sampling -- cgit v1.2.3 From 09f9f37c324d90102e8574856ab168c34de1916d Mon Sep 17 00:00:00 2001 From: "Borislav Petkov (AMD)" Date: Wed, 2 Aug 2023 20:07:32 +0200 Subject: Documentation/srso: Document IBPB aspect and fix formatting Add a note about the dependency of the User->User mitigation on the previous Spectre v2 IBPB selection. Make the layout moar pretty. Signed-off-by: Borislav Petkov (AMD) Reviewed-by: Greg Kroah-Hartman Link: https://lore.kernel.org/r/20230809102700.29449-4-bp@alien8.de --- Documentation/admin-guide/hw-vuln/srso.rst | 71 ++++++++++++++++++------------ 1 file changed, 44 insertions(+), 27 deletions(-) (limited to 'Documentation') 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: -- cgit v1.2.3