Merge tag 'v6.6.80' into for/openbmc/dev-6.6

This is the 6.6.80 stable release

# -----BEGIN PGP SIGNATURE-----
#
# iQIzBAABCAAdFiEEZH8oZUiU471FcZm+ONu9yGCSaT4FAmfAV+kACgkQONu9yGCS
# aT6Zmg/8CttkpI/

Merge tag 'v6.6.80' into for/openbmc/dev-6.6

This is the 6.6.80 stable release

# -----BEGIN PGP SIGNATURE-----
#
# iQIzBAABCAAdFiEEZH8oZUiU471FcZm+ONu9yGCSaT4FAmfAV+kACgkQONu9yGCS
# aT6Zmg/8CttkpI/jr/fq7mVbxHBmz06uZndOgjCt4Qocoy06hIYrV/zKCLXqEHSo
# yPzPu6p57fQsJXKZbC6K3H4ZCjkArxT9xXy08jxxYmV091OhZi7fo+otAWgNu2ht
# A8cjRkO4MjQ7WfWlPYL8FBuRgv2aPplhCxAtnQy+Lzos3Mk9PyIcgKKGeDQJ/XcE
# ecIUxR8ftzAb6X0KDYcM0PhXtKTKZwAo1MiHa18TaXz3cIHmvYfTEOk7om7rtPC/
# n7WxJSM9i0NC0AcIpddlX9e6HqOgjk3sKOlj+aHPin2sl9cWgEKixIsb/PJmWVvi
# zNPgfX2MFjX0287K0+TmTPy2rM07bnpv9e0iJDkbc411fEYb2XPxjvp4wPjf5Io3
# 6qOj9OrgRPfTama54j6Tis4cxAtk2gppOA8rxC16okMG39CwEEAbaiZvUezqK4ym
# m8fiKccYMCgYxPXVgn0vLSnbzb+zXv0SB9rKuImZstOiiKbVz+xxBTh+0GFezhto
# TFzmjEBdh2LYbtQRi/TWn+e6nEjE+LJZgmiq886NRSr9wNAGheYLKSRC1mzwyRKJ
# yiA+ue7d1wB+clE+cAcbdVF5YSosV5TggH09Wq64O/pEemC9F2bNWL+oJXODf3NG
# JYkjr7FzD1Ka/oCwDJeloDQqwUc4q5cyS+Fb3fK/zrAJZJ2YGTM=
# =2PCM
# -----END PGP SIGNATURE-----
# gpg: Signature made Thu 27 Feb 2025 22:47:45 ACDT
# gpg: using RSA key 647F28654894E3BD457199BE38DBBDC86092693E
# gpg: Good signature from "Greg Kroah-Hartman <gregkh@kernel.org>" [marginal]
# gpg: gregkh@kernel.org: Verified 9 signatures in the past 5 weeks. Encrypted
# 0 messages.
# gpg: Warning: you have yet to encrypt a message to this key!
# gpg: WARNING: This key is not certified with sufficiently trusted signatures!
# gpg: It is not certain that the signature belongs to the owner.
# Primary key fingerprint: 647F 2865 4894 E3BD 4571 99BE 38DB BDC8 6092 693E

show more ...

x86/cpu/kvm: SRSO: Fix possible missing IBPB on VM-Exit

commit 318e8c339c9a0891c389298bb328ed0762a9935e upstream.

In [1] the meaning of the synthetic IBPB flags has been redefined for a
better sepa

x86/cpu/kvm: SRSO: Fix possible missing IBPB on VM-Exit

commit 318e8c339c9a0891c389298bb328ed0762a9935e upstream.

In [1] the meaning of the synthetic IBPB flags has been redefined for a
better separation of concerns:
- ENTRY_IBPB -- issue IBPB on entry only
- IBPB_ON_VMEXIT -- issue IBPB on VM-Exit only
and the Retbleed mitigations have been updated to match this new
semantics.

Commit [2] was merged shortly before [1], and their interaction was not
handled properly. This resulted in IBPB not being triggered on VM-Exit
in all SRSO mitigation configs requesting an IBPB there.

Specifically, an IBPB on VM-Exit is triggered only when
X86_FEATURE_IBPB_ON_VMEXIT is set. However:

- X86_FEATURE_IBPB_ON_VMEXIT is not set for "spec_rstack_overflow=ibpb",
because before [1] having X86_FEATURE_ENTRY_IBPB was enough. Hence,
an IBPB is triggered on entry but the expected IBPB on VM-exit is
not.

- X86_FEATURE_IBPB_ON_VMEXIT is not set also when
"spec_rstack_overflow=ibpb-vmexit" if X86_FEATURE_ENTRY_IBPB is
already set.

That's because before [1] this was effectively redundant. Hence, e.g.
a "retbleed=ibpb spec_rstack_overflow=bpb-vmexit" config mistakenly
reports the machine still vulnerable to SRSO, despite an IBPB being
triggered both on entry and VM-Exit, because of the Retbleed selected
mitigation config.

- UNTRAIN_RET_VM won't still actually do anything unless
CONFIG_MITIGATION_IBPB_ENTRY is set.

For "spec_rstack_overflow=ibpb", enable IBPB on both entry and VM-Exit
and clear X86_FEATURE_RSB_VMEXIT which is made superfluous by
X86_FEATURE_IBPB_ON_VMEXIT. This effectively makes this mitigation
option similar to the one for 'retbleed=ibpb', thus re-order the code
for the RETBLEED_MITIGATION_IBPB option to be less confusing by having
all features enabling before the disabling of the not needed ones.

For "spec_rstack_overflow=ibpb-vmexit", guard this mitigation setting
with CONFIG_MITIGATION_IBPB_ENTRY to ensure UNTRAIN_RET_VM sequence is
effectively compiled in. Drop instead the CONFIG_MITIGATION_SRSO guard,
since none of the SRSO compile cruft is required in this configuration.
Also, check only that the required microcode is present to effectively
enabled the IBPB on VM-Exit.

Finally, update the KConfig description for CONFIG_MITIGATION_IBPB_ENTRY
to list also all SRSO config settings enabled by this guard.

Fixes: 864bcaa38ee4 ("x86/cpu/kvm: Provide UNTRAIN_RET_VM") [1]
Fixes: d893832d0e1e ("x86/srso: Add IBPB on VMEXIT") [2]
Reported-by: Yosry Ahmed <yosryahmed@google.com>
Signed-off-by: Patrick Bellasi <derkling@google.com>
Reviewed-by: Borislav Petkov (AMD) <bp@alien8.de>
Cc: stable@kernel.org
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

show more ...

Merge tag 'v6.6.58' into for/openbmc/dev-6.6

This is the 6.6.58 stable release

x86/bugs: Do not use UNTRAIN_RET with IBPB on entry

commit c62fa117c32bd1abed9304c58e0da6940f8c7fc2 upstream.

Since X86_FEATURE_ENTRY_IBPB will invalidate all harmful predictions
with IBPB, no soft

x86/bugs: Do not use UNTRAIN_RET with IBPB on entry

commit c62fa117c32bd1abed9304c58e0da6940f8c7fc2 upstream.

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>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

show more ...

x86/bugs: Skip RSB fill at VMEXIT

commit 0fad2878642ec46225af2054564932745ac5c765 upstream.

entry_ibpb() is designed to follow Intel's IBPB specification regardless
of CPU. This includes invalidati

x86/bugs: Skip RSB fill at VMEXIT

commit 0fad2878642ec46225af2054564932745ac5c765 upstream.

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>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

show more ...

Merge tag 'v6.6.29' into dev-6.6

This is the 6.6.29 stable release

x86/bugs: Fix BHI retpoline check

[ Upstream commit 69129794d94c544810e68b2b4eaa7e44063f9bf2 ]

Confusingly, X86_FEATURE_RETPOLINE doesn't mean retpolines are enabled,
as it also includes the origin

x86/bugs: Fix BHI retpoline check

[ Upstream commit 69129794d94c544810e68b2b4eaa7e44063f9bf2 ]

Confusingly, X86_FEATURE_RETPOLINE doesn't mean retpolines are enabled,
as it also includes the original "AMD retpoline" which isn't a retpoline
at all.

Also replace cpu_feature_enabled() with boot_cpu_has() because this is
before alternatives are patched and cpu_feature_enabled()'s fallback
path is slower than plain old boot_cpu_has().

Fixes: ec9404e40e8f ("x86/bhi: Add BHI mitigation knob")
Signed-off-by: Josh Poimboeuf <jpoimboe@kernel.org>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Reviewed-by: Pawan Gupta <pawan.kumar.gupta@linux.intel.com>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Link: https://lore.kernel.org/r/ad3807424a3953f0323c011a643405619f2a4927.1712944776.git.jpoimboe@kernel.org
Signed-off-by: Sasha Levin <sashal@kernel.org>

show more ...

Merge tag 'v6.6.28' into dev-6.6

This is the 6.6.28 stable release

x86/bugs: Replace CONFIG_SPECTRE_BHI_{ON,OFF} with CONFIG_MITIGATION_SPECTRE_BHI

commit 4f511739c54b549061993b53fc0380f48dfca23b upstream.

For consistency with the other CONFIG_MITIGATION_* options

x86/bugs: Replace CONFIG_SPECTRE_BHI_{ON,OFF} with CONFIG_MITIGATION_SPECTRE_BHI

commit 4f511739c54b549061993b53fc0380f48dfca23b upstream.

For consistency with the other CONFIG_MITIGATION_* options, replace the
CONFIG_SPECTRE_BHI_{ON,OFF} options with a single
CONFIG_MITIGATION_SPECTRE_BHI option.

[ mingo: Fix ]

Signed-off-by: Josh Poimboeuf <jpoimboe@kernel.org>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Cc: Sean Christopherson <seanjc@google.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Nikolay Borisov <nik.borisov@suse.com>
Link: https://lore.kernel.org/r/3833812ea63e7fdbe36bf8b932e63f70d18e2a2a.1712813475.git.jpoimboe@kernel.org
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

show more ...

x86/bugs: Remove CONFIG_BHI_MITIGATION_AUTO and spectre_bhi=auto

commit 36d4fe147c870f6d3f6602befd7ef44393a1c87a upstream.

Unlike most other mitigations' "auto" options, spectre_bhi=auto only
mitig

x86/bugs: Remove CONFIG_BHI_MITIGATION_AUTO and spectre_bhi=auto

commit 36d4fe147c870f6d3f6602befd7ef44393a1c87a upstream.

Unlike most other mitigations' "auto" options, spectre_bhi=auto only
mitigates newer systems, which is confusing and not particularly useful.

Remove it.

Signed-off-by: Josh Poimboeuf <jpoimboe@kernel.org>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Reviewed-by: Nikolay Borisov <nik.borisov@suse.com>
Cc: Sean Christopherson <seanjc@google.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Link: https://lore.kernel.org/r/412e9dc87971b622bbbaf64740ebc1f140bff343.1712813475.git.jpoimboe@kernel.org
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

show more ...

x86/bugs: Clarify that syscall hardening isn't a BHI mitigation

commit 5f882f3b0a8bf0788d5a0ee44b1191de5319bb8a upstream.

While syscall hardening helps prevent some BHI attacks, there's still
other

x86/bugs: Clarify that syscall hardening isn't a BHI mitigation

commit 5f882f3b0a8bf0788d5a0ee44b1191de5319bb8a upstream.

While syscall hardening helps prevent some BHI attacks, there's still
other low-hanging fruit remaining. Don't classify it as a mitigation
and make it clear that the system may still be vulnerable if it doesn't
have a HW or SW mitigation enabled.

Fixes: ec9404e40e8f ("x86/bhi: Add BHI mitigation knob")
Signed-off-by: Josh Poimboeuf <jpoimboe@kernel.org>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Sean Christopherson <seanjc@google.com>
Link: https://lore.kernel.org/r/b5951dae3fdee7f1520d5136a27be3bdfe95f88b.1712813475.git.jpoimboe@kernel.org
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

show more ...

x86/bugs: Fix BHI handling of RRSBA

commit 1cea8a280dfd1016148a3820676f2f03e3f5b898 upstream.

The ARCH_CAP_RRSBA check isn't correct: RRSBA may have already been
disabled by the Spectre v2 mitigati

x86/bugs: Fix BHI handling of RRSBA

commit 1cea8a280dfd1016148a3820676f2f03e3f5b898 upstream.

The ARCH_CAP_RRSBA check isn't correct: RRSBA may have already been
disabled by the Spectre v2 mitigation (or can otherwise be disabled by
the BHI mitigation itself if needed). In that case retpolines are fine.

Fixes: ec9404e40e8f ("x86/bhi: Add BHI mitigation knob")
Signed-off-by: Josh Poimboeuf <jpoimboe@kernel.org>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Sean Christopherson <seanjc@google.com>
Link: https://lore.kernel.org/r/6f56f13da34a0834b69163467449be7f58f253dc.1712813475.git.jpoimboe@kernel.org
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

show more ...

x86/bugs: Rename various 'ia32_cap' variables to 'x86_arch_cap_msr'

commit d0485730d2189ffe5d986d4e9e191f1e4d5ffd24 upstream.

So we are using the 'ia32_cap' value in a number of places,
which got i

x86/bugs: Rename various 'ia32_cap' variables to 'x86_arch_cap_msr'

commit d0485730d2189ffe5d986d4e9e191f1e4d5ffd24 upstream.

So we are using the 'ia32_cap' value in a number of places,
which got its name from MSR_IA32_ARCH_CAPABILITIES MSR register.

But there's very little 'IA32' about it - this isn't 32-bit only
code, nor does it originate from there, it's just a historic
quirk that many Intel MSR names are prefixed with IA32_.

This is already clear from the helper method around the MSR:
x86_read_arch_cap_msr(), which doesn't have the IA32 prefix.

So rename 'ia32_cap' to 'x86_arch_cap_msr' to be consistent with
its role and with the naming of the helper function.

Signed-off-by: Ingo Molnar <mingo@kernel.org>
Cc: Josh Poimboeuf <jpoimboe@redhat.com>
Cc: Nikolay Borisov <nik.borisov@suse.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Sean Christopherson <seanjc@google.com>
Link: https://lore.kernel.org/r/9592a18a814368e75f8f4b9d74d3883aa4fd1eaf.1712813475.git.jpoimboe@kernel.org
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

show more ...

x86/bugs: Cache the value of MSR_IA32_ARCH_CAPABILITIES

commit cb2db5bb04d7f778fbc1a1ea2507aab436f1bff3 upstream.

There's no need to keep reading MSR_IA32_ARCH_CAPABILITIES over and
over. It's eve

x86/bugs: Cache the value of MSR_IA32_ARCH_CAPABILITIES

commit cb2db5bb04d7f778fbc1a1ea2507aab436f1bff3 upstream.

There's no need to keep reading MSR_IA32_ARCH_CAPABILITIES over and
over. It's even read in the BHI sysfs function which is a big no-no.
Just read it once and cache it.

Fixes: ec9404e40e8f ("x86/bhi: Add BHI mitigation knob")
Signed-off-by: Josh Poimboeuf <jpoimboe@kernel.org>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Reviewed-by: Nikolay Borisov <nik.borisov@suse.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Sean Christopherson <seanjc@google.com>
Link: https://lore.kernel.org/r/9592a18a814368e75f8f4b9d74d3883aa4fd1eaf.1712813475.git.jpoimboe@kernel.org
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

show more ...

x86/bugs: Fix return type of spectre_bhi_state()

commit 04f4230e2f86a4e961ea5466eda3db8c1762004d upstream.

The definition of spectre_bhi_state() incorrectly returns a const char
* const. This cause

x86/bugs: Fix return type of spectre_bhi_state()

commit 04f4230e2f86a4e961ea5466eda3db8c1762004d upstream.

The definition of spectre_bhi_state() incorrectly returns a const char
* const. This causes the a compiler warning when building with W=1:

warning: type qualifiers ignored on function return type [-Wignored-qualifiers]
2812 | static const char * const spectre_bhi_state(void)

Remove the const qualifier from the pointer.

Fixes: ec9404e40e8f ("x86/bhi: Add BHI mitigation knob")
Reported-by: Sean Christopherson <seanjc@google.com>
Signed-off-by: Daniel Sneddon <daniel.sneddon@linux.intel.com>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Link: https://lore.kernel.org/r/20240409230806.1545822-1-daniel.sneddon@linux.intel.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

show more ...

Merge tag 'v6.6.26' into dev-6.6

This is the 6.6.26 stable release

x86/bhi: Mitigate KVM by default

commit 95a6ccbdc7199a14b71ad8901cb788ba7fb5167b upstream.

BHI mitigation mode spectre_bhi=auto does not deploy the software
mitigation by default. In a cloud enviro

x86/bhi: Mitigate KVM by default

commit 95a6ccbdc7199a14b71ad8901cb788ba7fb5167b upstream.

BHI mitigation mode spectre_bhi=auto does not deploy the software
mitigation by default. In a cloud environment, it is a likely scenario
where userspace is trusted but the guests are not trusted. Deploying
system wide mitigation in such cases is not desirable.

Update the auto mode to unconditionally mitigate against malicious
guests. Deploy the software sequence at VMexit in auto mode also, when
hardware mitigation is not available. Unlike the force =on mode,
software sequence is not deployed at syscalls in auto mode.

Suggested-by: Alexandre Chartre <alexandre.chartre@oracle.com>
Signed-off-by: Pawan Gupta <pawan.kumar.gupta@linux.intel.com>
Signed-off-by: Daniel Sneddon <daniel.sneddon@linux.intel.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Alexandre Chartre <alexandre.chartre@oracle.com>
Reviewed-by: Josh Poimboeuf <jpoimboe@kernel.org>
Signed-off-by: Daniel Sneddon <daniel.sneddon@linux.intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

show more ...

x86/bhi: Add BHI mitigation knob

commit ec9404e40e8f36421a2b66ecb76dc2209fe7f3ef upstream.

Branch history clearing software sequences and hardware control
BHI_DIS_S were defined to mitigate Branch

x86/bhi: Add BHI mitigation knob

commit ec9404e40e8f36421a2b66ecb76dc2209fe7f3ef upstream.

Branch history clearing software sequences and hardware control
BHI_DIS_S were defined to mitigate Branch History Injection (BHI).

Add cmdline spectre_bhi={on|off|auto} to control BHI mitigation:

auto - Deploy the hardware mitigation BHI_DIS_S, if available.
on - Deploy the hardware mitigation BHI_DIS_S, if available,
otherwise deploy the software sequence at syscall entry and
VMexit.
off - Turn off BHI mitigation.

The default is auto mode which does not deploy the software sequence
mitigation. This is because of the hardening done in the syscall
dispatch path, which is the likely target of BHI.

Signed-off-by: Pawan Gupta <pawan.kumar.gupta@linux.intel.com>
Signed-off-by: Daniel Sneddon <daniel.sneddon@linux.intel.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Alexandre Chartre <alexandre.chartre@oracle.com>
Reviewed-by: Josh Poimboeuf <jpoimboe@kernel.org>
Signed-off-by: Daniel Sneddon <daniel.sneddon@linux.intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

show more ...

x86/bugs: Change commas to semicolons in 'spectre_v2' sysfs file

commit 0cd01ac5dcb1e18eb18df0f0d05b5de76522a437 upstream.

Change the format of the 'spectre_v2' vulnerabilities sysfs file
slightly

x86/bugs: Change commas to semicolons in 'spectre_v2' sysfs file

commit 0cd01ac5dcb1e18eb18df0f0d05b5de76522a437 upstream.

Change the format of the 'spectre_v2' vulnerabilities sysfs file
slightly by converting the commas to semicolons, so that mitigations for
future variants can be grouped together and separated by commas.

Signed-off-by: Josh Poimboeuf <jpoimboe@kernel.org>
Signed-off-by: Daniel Sneddon <daniel.sneddon@linux.intel.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Daniel Sneddon <daniel.sneddon@linux.intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

show more ...

x86/srso: Disentangle rethunk-dependent options

Commit 34a3cae7474c6e6f4a85aad4a7b8191b8b35cdcd upstream.

CONFIG_RETHUNK, CONFIG_CPU_UNRET_ENTRY and CONFIG_CPU_SRSO are all
tangled up. De-spaghett

x86/srso: Disentangle rethunk-dependent options

Commit 34a3cae7474c6e6f4a85aad4a7b8191b8b35cdcd upstream.

CONFIG_RETHUNK, CONFIG_CPU_UNRET_ENTRY and CONFIG_CPU_SRSO are all
tangled up. De-spaghettify the code a bit.

Some of the rethunk-related code has been shuffled around within the
'.text..__x86.return_thunk' section, but otherwise there are no
functional changes. srso_alias_untrain_ret() and srso_alias_safe_ret()
((which are very address-sensitive) haven't moved.

Signed-off-by: Josh Poimboeuf <jpoimboe@kernel.org>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Signed-off-by: Borislav Petkov (AMD) <bp@alien8.de>
Acked-by: Borislav Petkov (AMD) <bp@alien8.de>
Link: https://lore.kernel.org/r/2845084ed303d8384905db3b87b77693945302b4.1693889988.git.jpoimboe@kernel.org
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

show more ...

Merge tag 'v6.6.22' into dev-6.6

Linux 6.6.22

x86/rfds: Mitigate Register File Data Sampling (RFDS)

commit 8076fcde016c9c0e0660543e67bff86cb48a7c9c upstream.

RFDS is a CPU vulnerability that may allow userspace to infer kernel
stale data previ

x86/rfds: Mitigate Register File Data Sampling (RFDS)

commit 8076fcde016c9c0e0660543e67bff86cb48a7c9c upstream.

RFDS is a CPU vulnerability that may allow userspace to infer kernel
stale data previously used in floating point registers, vector registers
and integer registers. RFDS only affects certain Intel Atom processors.

Intel released a microcode update that uses VERW instruction to clear
the affected CPU buffers. Unlike MDS, none of the affected cores support
SMT.

Add RFDS bug infrastructure and enable the VERW based mitigation by
default, that clears the affected buffers just before exiting to
userspace. Also add sysfs reporting and cmdline parameter
"reg_file_data_sampling" to control the mitigation.

For details see:
Documentation/admin-guide/hw-vuln/reg-file-data-sampling.rst

Signed-off-by: Pawan Gupta <pawan.kumar.gupta@linux.intel.com>
Signed-off-by: Dave Hansen <dave.hansen@linux.intel.com>
Reviewed-by: Thomas Gleixner <tglx@linutronix.de>
Acked-by: Josh Poimboeuf <jpoimboe@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

show more ...

x86/mmio: Disable KVM mitigation when X86_FEATURE_CLEAR_CPU_BUF is set

commit e95df4ec0c0c9791941f112db699fae794b9862a upstream.

Currently MMIO Stale Data mitigation for CPUs not affected by MDS/TA

x86/mmio: Disable KVM mitigation when X86_FEATURE_CLEAR_CPU_BUF is set

commit e95df4ec0c0c9791941f112db699fae794b9862a upstream.

Currently MMIO Stale Data mitigation for CPUs not affected by MDS/TAA is
to only deploy VERW at VMentry by enabling mmio_stale_data_clear static
branch. No mitigation is needed for kernel->user transitions. If such
CPUs are also affected by RFDS, its mitigation may set
X86_FEATURE_CLEAR_CPU_BUF to deploy VERW at kernel->user and VMentry.
This could result in duplicate VERW at VMentry.

Fix this by disabling mmio_stale_data_clear static branch when
X86_FEATURE_CLEAR_CPU_BUF is enabled.

Signed-off-by: Pawan Gupta <pawan.kumar.gupta@linux.intel.com>
Signed-off-by: Dave Hansen <dave.hansen@linux.intel.com>
Reviewed-by: Dave Hansen <dave.hansen@linux.intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

show more ...

Merge tag 'v6.6.21' into dev-6.6

This is the 6.6.21 stable release

x86/bugs: Use ALTERNATIVE() instead of mds_user_clear static key

commit 6613d82e617dd7eb8b0c40b2fe3acea655b1d611 upstream.

The VERW mitigation at exit-to-user is enabled via a static branch
mds_use

x86/bugs: Use ALTERNATIVE() instead of mds_user_clear static key

commit 6613d82e617dd7eb8b0c40b2fe3acea655b1d611 upstream.

The VERW mitigation at exit-to-user is enabled via a static branch
mds_user_clear. This static branch is never toggled after boot, and can
be safely replaced with an ALTERNATIVE() which is convenient to use in
asm.

Switch to ALTERNATIVE() to use the VERW mitigation late in exit-to-user
path. Also remove the now redundant VERW in exc_nmi() and
arch_exit_to_user_mode().

Signed-off-by: Pawan Gupta <pawan.kumar.gupta@linux.intel.com>
Signed-off-by: Dave Hansen <dave.hansen@linux.intel.com>
Link: https://lore.kernel.org/all/20240213-delay-verw-v8-4-a6216d83edb7%40linux.intel.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

show more ...