linux.git/arch/x86/kernel/cpu/bugs.c, branch v6.13 Linux kernel source tree x86/bugs: Do not use UNTRAIN_RET with IBPB on entry 2024-10-10T08:38:21+00:00 Johannes Wikner kwikner@ethz.ch 2024-10-08T10:58:03+00:00 c62fa117c32bd1abed9304c58e0da6940f8c7fc2 Since X86_FEATURE_ENTRY_IBPB will invalidate all harmful predictions with IBPB, no software-based untraining of returns is needed anymore. Currently, this change affects retbleed and SRSO mitigations so if either of the mitigations is doing IBPB and the other one does the software sequence, the latter is not needed anymore. [ bp: Massage commit message. ] Suggested-by: Borislav Petkov <bp@alien8.de> Signed-off-by: Johannes Wikner <kwikner@ethz.ch> Cc: <stable@kernel.org> 
Since X86_FEATURE_ENTRY_IBPB will invalidate all harmful predictions
with IBPB, no software-based untraining of returns is needed anymore.
Currently, this change affects retbleed and SRSO mitigations so if
either of the mitigations is doing IBPB and the other one does the
software sequence, the latter is not needed anymore.

  [ bp: Massage commit message. ]

Suggested-by: Borislav Petkov <bp@alien8.de>
Signed-off-by: Johannes Wikner <kwikner@ethz.ch>
Cc: <stable@kernel.org>
x86/bugs: Skip RSB fill at VMEXIT 2024-10-10T08:35:53+00:00 Johannes Wikner kwikner@ethz.ch 2024-10-08T10:36:30+00:00 0fad2878642ec46225af2054564932745ac5c765 entry_ibpb() is designed to follow Intel's IBPB specification regardless of CPU. This includes invalidating RSB entries. Hence, if IBPB on VMEXIT has been selected, entry_ibpb() as part of the RET untraining in the VMEXIT path will take care of all BTB and RSB clearing so there's no need to explicitly fill the RSB anymore. [ bp: Massage commit message. ] Suggested-by: Borislav Petkov <bp@alien8.de> Signed-off-by: Johannes Wikner <kwikner@ethz.ch> Cc: <stable@kernel.org> 
entry_ibpb() is designed to follow Intel's IBPB specification regardless
of CPU. This includes invalidating RSB entries.

Hence, if IBPB on VMEXIT has been selected, entry_ibpb() as part of the
RET untraining in the VMEXIT path will take care of all BTB and RSB
clearing so there's no need to explicitly fill the RSB anymore.

  [ bp: Massage commit message. ]

Suggested-by: Borislav Petkov <bp@alien8.de>
Signed-off-by: Johannes Wikner <kwikner@ethz.ch>
Cc: <stable@kernel.org>
x86/bugs: Fix handling when SRSO mitigation is disabled 2024-09-05T09:20:50+00:00 David Kaplan david.kaplan@amd.com 2024-09-04T15:07:11+00:00 1dbb6b1495d472806fef1f4c94f5b3e4c89a3c1d When the SRSO mitigation is disabled, either via mitigations=off or spec_rstack_overflow=off, the warning about the lack of IBPB-enhancing microcode is printed anyway. This is unnecessary since the user has turned off the mitigation. [ bp: Massage, drop SBPB rationale as it doesn't matter because when mitigations are disabled x86_pred_cmd is not being used anyway. ] Signed-off-by: David Kaplan <david.kaplan@amd.com> Signed-off-by: Borislav Petkov (AMD) <bp@alien8.de> Acked-by: Josh Poimboeuf <jpoimboe@kernel.org> Link: https://lore.kernel.org/r/20240904150711.193022-1-david.kaplan@amd.com 
When the SRSO mitigation is disabled, either via mitigations=off or
spec_rstack_overflow=off, the warning about the lack of IBPB-enhancing
microcode is printed anyway.

This is unnecessary since the user has turned off the mitigation.

  [ bp: Massage, drop SBPB rationale as it doesn't matter because when
    mitigations are disabled x86_pred_cmd is not being used anyway. ]

Signed-off-by: David Kaplan <david.kaplan@amd.com>
Signed-off-by: Borislav Petkov (AMD) <bp@alien8.de>
Acked-by: Josh Poimboeuf <jpoimboe@kernel.org>
Link: https://lore.kernel.org/r/20240904150711.193022-1-david.kaplan@amd.com
x86/bugs: Add a separate config for GDS 2024-07-30T12:54:15+00:00 Breno Leitao leitao@debian.org 2024-07-29T16:40:59+00:00 225f2bd064c32397acfe3d9dfd9a2b3bc6d64fd7 Currently, the CONFIG_SPECULATION_MITIGATIONS is halfway populated, where some mitigations have entries in Kconfig, and they could be modified, while others mitigations do not have Kconfig entries, and could not be controlled at build time. Create a new kernel config that allows GDS to be completely disabled, similarly to the "gather_data_sampling=off" or "mitigations=off" kernel command-line. Now, there are two options for GDS mitigation: * CONFIG_MITIGATION_GDS=n -> Mitigation disabled (New) * CONFIG_MITIGATION_GDS=y -> Mitigation enabled (GDS_MITIGATION_FULL) Suggested-by: Josh Poimboeuf <jpoimboe@kernel.org> Signed-off-by: Breno Leitao <leitao@debian.org> Signed-off-by: Borislav Petkov (AMD) <bp@alien8.de> Acked-by: Josh Poimboeuf <jpoimboe@kernel.org> Link: https://lore.kernel.org/r/20240729164105.554296-12-leitao@debian.org 
Currently, the CONFIG_SPECULATION_MITIGATIONS is halfway populated, where some
mitigations have entries in Kconfig, and they could be modified, while others
mitigations do not have Kconfig entries, and could not be controlled at build
time.

Create a new kernel config that allows GDS to be completely disabled,
similarly to the "gather_data_sampling=off" or "mitigations=off" kernel
command-line.

Now, there are two options for GDS mitigation:

* CONFIG_MITIGATION_GDS=n -> Mitigation disabled (New)
* CONFIG_MITIGATION_GDS=y -> Mitigation enabled (GDS_MITIGATION_FULL)

Suggested-by: Josh Poimboeuf <jpoimboe@kernel.org>
Signed-off-by: Breno Leitao <leitao@debian.org>
Signed-off-by: Borislav Petkov (AMD) <bp@alien8.de>
Acked-by: Josh Poimboeuf <jpoimboe@kernel.org>
Link: https://lore.kernel.org/r/20240729164105.554296-12-leitao@debian.org
x86/bugs: Remove GDS Force Kconfig option 2024-07-30T12:53:15+00:00 Breno Leitao leitao@debian.org 2024-07-29T16:40:58+00:00 03267a534bb388acdd2ee685101084d144e8384c Remove the MITIGATION_GDS_FORCE Kconfig option, which aggressively disables AVX as a mitigation for Gather Data Sampling (GDS) vulnerabilities. This option is not widely used by distros. While removing the Kconfig option, retain the runtime configuration ability through the `gather_data_sampling=force` kernel parameter. This allows users to still enable this aggressive mitigation if needed, without baking it into the kernel configuration. Simplify the kernel configuration while maintaining flexibility for runtime mitigation choices. Suggested-by: Borislav Petkov <bp@alien8.de> Signed-off-by: Breno Leitao <leitao@debian.org> Signed-off-by: Borislav Petkov (AMD) <bp@alien8.de> Reviewed-by: Daniel Sneddon <daniel.sneddon@linux.intel.com> Link: https://lore.kernel.org/r/20240729164105.554296-11-leitao@debian.org 
Remove the MITIGATION_GDS_FORCE Kconfig option, which aggressively disables
AVX as a mitigation for Gather Data Sampling (GDS) vulnerabilities. This
option is not widely used by distros.

While removing the Kconfig option, retain the runtime configuration ability
through the `gather_data_sampling=force` kernel parameter. This allows users
to still enable this aggressive mitigation if needed, without baking it into
the kernel configuration.

Simplify the kernel configuration while maintaining flexibility for runtime
mitigation choices.

Suggested-by: Borislav Petkov <bp@alien8.de>
Signed-off-by: Breno Leitao <leitao@debian.org>
Signed-off-by: Borislav Petkov (AMD) <bp@alien8.de>
Reviewed-by: Daniel Sneddon <daniel.sneddon@linux.intel.com>
Link: https://lore.kernel.org/r/20240729164105.554296-11-leitao@debian.org
x86/bugs: Add a separate config for SSB 2024-07-30T12:51:45+00:00 Breno Leitao leitao@debian.org 2024-07-29T16:40:57+00:00 b908cdab061a5ead51d5e1731ca9c1b26699a9bb Currently, the CONFIG_SPECULATION_MITIGATIONS is halfway populated, where some mitigations have entries in Kconfig, and they could be modified, while others mitigations do not have Kconfig entries, and could not be controlled at build time. Create an entry for the SSB CPU mitigation under CONFIG_SPECULATION_MITIGATIONS. This allow users to enable or disable it at compilation time. Signed-off-by: Breno Leitao <leitao@debian.org> Signed-off-by: Borislav Petkov (AMD) <bp@alien8.de> Acked-by: Josh Poimboeuf <jpoimboe@kernel.org> Link: https://lore.kernel.org/r/20240729164105.554296-10-leitao@debian.org 
Currently, the CONFIG_SPECULATION_MITIGATIONS is halfway populated,
where some mitigations have entries in Kconfig, and they could be
modified, while others mitigations do not have Kconfig entries, and
could not be controlled at build time.

Create an entry for the SSB CPU mitigation under
CONFIG_SPECULATION_MITIGATIONS. This allow users to enable or disable
it at compilation time.

Signed-off-by: Breno Leitao <leitao@debian.org>
Signed-off-by: Borislav Petkov (AMD) <bp@alien8.de>
Acked-by: Josh Poimboeuf <jpoimboe@kernel.org>
Link: https://lore.kernel.org/r/20240729164105.554296-10-leitao@debian.org
x86/bugs: Add a separate config for Spectre V2 2024-07-30T12:51:11+00:00 Breno Leitao leitao@debian.org 2024-07-29T16:40:56+00:00 72c70f480a70695523f984651d5da766b862c712 Currently, the CONFIG_SPECULATION_MITIGATIONS is halfway populated, where some mitigations have entries in Kconfig, and they could be modified, while others mitigations do not have Kconfig entries, and could not be controlled at build time. Create an entry for the Spectre V2 CPU mitigation under CONFIG_SPECULATION_MITIGATIONS. This allow users to enable or disable it at compilation time. Signed-off-by: Breno Leitao <leitao@debian.org> Signed-off-by: Borislav Petkov (AMD) <bp@alien8.de> Acked-by: Josh Poimboeuf <jpoimboe@kernel.org> Link: https://lore.kernel.org/r/20240729164105.554296-9-leitao@debian.org 
Currently, the CONFIG_SPECULATION_MITIGATIONS is halfway populated,
where some mitigations have entries in Kconfig, and they could be
modified, while others mitigations do not have Kconfig entries, and
could not be controlled at build time.

Create an entry for the Spectre V2 CPU mitigation under
CONFIG_SPECULATION_MITIGATIONS. This allow users to enable or disable
it at compilation time.

Signed-off-by: Breno Leitao <leitao@debian.org>
Signed-off-by: Borislav Petkov (AMD) <bp@alien8.de>
Acked-by: Josh Poimboeuf <jpoimboe@kernel.org>
Link: https://lore.kernel.org/r/20240729164105.554296-9-leitao@debian.org
x86/bugs: Add a separate config for SRBDS 2024-07-30T12:49:53+00:00 Breno Leitao leitao@debian.org 2024-07-29T16:40:55+00:00 a0b02e3fe3661ea20df4d13adfc94b6affdcc466 Currently, the CONFIG_SPECULATION_MITIGATIONS is halfway populated, where some mitigations have entries in Kconfig, and they could be modified, while others mitigations do not have Kconfig entries, and could not be controlled at build time. Create an entry for the SRBDS CPU mitigation under CONFIG_SPECULATION_MITIGATIONS. This allow users to enable or disable it at compilation time. Signed-off-by: Breno Leitao <leitao@debian.org> Signed-off-by: Borislav Petkov (AMD) <bp@alien8.de> Acked-by: Josh Poimboeuf <jpoimboe@kernel.org> Link: https://lore.kernel.org/r/20240729164105.554296-8-leitao@debian.org 
Currently, the CONFIG_SPECULATION_MITIGATIONS is halfway populated,
where some mitigations have entries in Kconfig, and they could be
modified, while others mitigations do not have Kconfig entries, and
could not be controlled at build time.

Create an entry for the SRBDS CPU mitigation under
CONFIG_SPECULATION_MITIGATIONS. This allow users to enable or disable
it at compilation time.

Signed-off-by: Breno Leitao <leitao@debian.org>
Signed-off-by: Borislav Petkov (AMD) <bp@alien8.de>
Acked-by: Josh Poimboeuf <jpoimboe@kernel.org>
Link: https://lore.kernel.org/r/20240729164105.554296-8-leitao@debian.org
x86/bugs: Add a separate config for Spectre v1 2024-07-30T12:49:28+00:00 Breno Leitao leitao@debian.org 2024-07-29T16:40:54+00:00 ca01c0d8d03089f81c713aec0c63d359bc0f6796 Currently, the CONFIG_SPECULATION_MITIGATIONS is halfway populated, where some mitigations have entries in Kconfig, and they could be modified, while others mitigations do not have Kconfig entries, and could not be controlled at build time. Create an entry for the Spectre v1 CPU mitigation under CONFIG_SPECULATION_MITIGATIONS. This allow users to enable or disable it at compilation time. Signed-off-by: Breno Leitao <leitao@debian.org> Signed-off-by: Borislav Petkov (AMD) <bp@alien8.de> Acked-by: Josh Poimboeuf <jpoimboe@kernel.org> Link: https://lore.kernel.org/r/20240729164105.554296-7-leitao@debian.org 
Currently, the CONFIG_SPECULATION_MITIGATIONS is halfway populated,
where some mitigations have entries in Kconfig, and they could be
modified, while others mitigations do not have Kconfig entries, and
could not be controlled at build time.

Create an entry for the Spectre v1 CPU mitigation under
CONFIG_SPECULATION_MITIGATIONS. This allow users to enable or disable
it at compilation time.

Signed-off-by: Breno Leitao <leitao@debian.org>
Signed-off-by: Borislav Petkov (AMD) <bp@alien8.de>
Acked-by: Josh Poimboeuf <jpoimboe@kernel.org>
Link: https://lore.kernel.org/r/20240729164105.554296-7-leitao@debian.org
x86/bugs: Add a separate config for RETBLEED 2024-07-30T12:48:54+00:00 Breno Leitao leitao@debian.org 2024-07-29T16:40:53+00:00 894e28857c112c5a31517b3837b507f1dcbe9da5 Currently, the CONFIG_SPECULATION_MITIGATIONS is halfway populated, where some mitigations have entries in Kconfig, and they could be modified, while others mitigations do not have Kconfig entries, and could not be controlled at build time. Create an entry for the RETBLEED CPU mitigation under CONFIG_SPECULATION_MITIGATIONS. This allow users to enable or disable it at compilation time. Signed-off-by: Breno Leitao <leitao@debian.org> Signed-off-by: Borislav Petkov (AMD) <bp@alien8.de> Acked-by: Josh Poimboeuf <jpoimboe@kernel.org> Link: https://lore.kernel.org/r/20240729164105.554296-6-leitao@debian.org 
Currently, the CONFIG_SPECULATION_MITIGATIONS is halfway populated,
where some mitigations have entries in Kconfig, and they could be
modified, while others mitigations do not have Kconfig entries, and
could not be controlled at build time.

Create an entry for the RETBLEED CPU mitigation under
CONFIG_SPECULATION_MITIGATIONS. This allow users to enable or disable
it at compilation time.

Signed-off-by: Breno Leitao <leitao@debian.org>
Signed-off-by: Borislav Petkov (AMD) <bp@alien8.de>
Acked-by: Josh Poimboeuf <jpoimboe@kernel.org>
Link: https://lore.kernel.org/r/20240729164105.554296-6-leitao@debian.org