linux-stable.git/arch/x86/kernel/cpu/common.c, branch linux-6.8.y

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

2024-04-17T09:23:40+00:00

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 
Cc: Josh Poimboeuf 
Cc: Nikolay Borisov 
Cc: Linus Torvalds 
Cc: Sean Christopherson 
Link: https://lore.kernel.org/r/9592a18a814368e75f8f4b9d74d3883aa4fd1eaf.1712813475.git.jpoimboe@kernel.org
Signed-off-by: Greg Kroah-Hartman

x86/bhi: Enumerate Branch History Injection (BHI) bug

2024-04-10T14:38:24+00:00

commit be482ff9500999f56093738f9219bbabc729d163 upstream.

Mitigation for BHI is selected based on the bug enumeration. Add bits
needed to enumerate BHI bug.

Signed-off-by: Pawan Gupta 
Signed-off-by: Daniel Sneddon 
Signed-off-by: Thomas Gleixner 
Reviewed-by: Alexandre Chartre 
Reviewed-by: Josh Poimboeuf 
Signed-off-by: Daniel Sneddon 
Signed-off-by: Greg Kroah-Hartman

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

2024-03-15T14:48:13+00:00

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 
Signed-off-by: Dave Hansen 
Reviewed-by: Thomas Gleixner 
Acked-by: Josh Poimboeuf 
Signed-off-by: Greg Kroah-Hartman

x86/cpu: Allow reducing x86_phys_bits during early_identify_cpu()

2024-02-26T16:16:15+00:00

In commit fbf6449f84bf ("x86/sev-es: Set x86_virt_bits to the correct
value straight away, instead of a two-phase approach"), the initialization
of c->x86_phys_bits was moved after this_cpu->c_early_init(c).  This is
incorrect because early_init_amd() expected to be able to reduce the
value according to the contents of CPUID leaf 0x8000001f.

Fortunately, the bug was negated by init_amd()'s call to early_init_amd(),
which does reduce x86_phys_bits in the end.  However, this is very
late in the boot process and, most notably, the wrong value is used for
x86_phys_bits when setting up MTRRs.

To fix this, call get_cpu_address_sizes() as soon as X86_FEATURE_CPUID is
set/cleared, and c->extended_cpuid_level is retrieved.

Fixes: fbf6449f84bf ("x86/sev-es: Set x86_virt_bits to the correct value straight away, instead of a two-phase approach")
Signed-off-by: Paolo Bonzini 
Signed-off-by: Dave Hansen 
Cc:stable@vger.kernel.org
Link: https://lore.kernel.org/all/20240131230902.1867092-2-pbonzini%40redhat.com

Merge tag 'x86_tdx_for_6.8' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip

2024-01-18T21:41:48+00:00

Pull x86 TDX updates from Dave Hansen:
 "This contains the initial support for host-side TDX support so that
  KVM can run TDX-protected guests. This does not include the actual
  KVM-side support which will come from the KVM folks. The TDX host
  interactions with kexec also needs to be ironed out before this is
  ready for prime time, so this code is currently Kconfig'd off when
  kexec is on.

  The majority of the code here is the kernel telling the TDX module
  which memory to protect and handing some additional memory over to it
  to use to store TDX module metadata. That sounds pretty simple, but
  the TDX architecture is rather flexible and it takes quite a bit of
  back-and-forth to say, "just protect all memory, please."

  There is also some code tacked on near the end of the series to handle
  a hardware erratum. The erratum can make software bugs such as a
  kernel write to TDX-protected memory cause a machine check and
  masquerade as a real hardware failure. The erratum handling watches
  out for these and tries to provide nicer user errors"

* tag 'x86_tdx_for_6.8' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (21 commits)
  x86/virt/tdx: Make TDX host depend on X86_MCE
  x86/virt/tdx: Disable TDX host support when kexec is enabled
  Documentation/x86: Add documentation for TDX host support
  x86/mce: Differentiate real hardware #MCs from TDX erratum ones
  x86/cpu: Detect TDX partial write machine check erratum
  x86/virt/tdx: Handle TDX interaction with sleep and hibernation
  x86/virt/tdx: Initialize all TDMRs
  x86/virt/tdx: Configure global KeyID on all packages
  x86/virt/tdx: Configure TDX module with the TDMRs and global KeyID
  x86/virt/tdx: Designate reserved areas for all TDMRs
  x86/virt/tdx: Allocate and set up PAMTs for TDMRs
  x86/virt/tdx: Fill out TDMRs to cover all TDX memory regions
  x86/virt/tdx: Add placeholder to construct TDMRs to cover all TDX memory regions
  x86/virt/tdx: Get module global metadata for module initialization
  x86/virt/tdx: Use all system memory when initializing TDX module as TDX memory
  x86/virt/tdx: Add skeleton to enable TDX on demand
  x86/virt/tdx: Add SEAMCALL error printing for module initialization
  x86/virt/tdx: Handle SEAMCALL no entropy error in common code
  x86/virt/tdx: Make INTEL_TDX_HOST depend on X86_X2APIC
  x86/virt/tdx: Define TDX supported page sizes as macros
  ...

Merge tag 'x86-asm-2024-01-08' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip

2024-01-09T01:02:57+00:00

Pull x86 asm updates from Ingo Molnar:
 "Replace magic numbers in GDT descriptor definitions & handling:

   - Introduce symbolic names via macros for descriptor
     types/fields/flags, and then use these symbolic names.

   - Clean up definitions a bit, such as GDT_ENTRY_INIT()

   - Fix/clean up details that became visibly inconsistent after the
     symbol-based code was introduced:

      - Unify accessed flag handling

      - Set the D/B size flag consistently & according to the HW
        specification"

* tag 'x86-asm-2024-01-08' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  x86/asm: Add DB flag to 32-bit percpu GDT entry
  x86/asm: Always set A (accessed) flag in GDT descriptors
  x86/asm: Replace magic numbers in GDT descriptors, script-generated change
  x86/asm: Replace magic numbers in GDT descriptors, preparations
  x86/asm: Provide new infrastructure for GDT descriptors

x86/asm: Always set A (accessed) flag in GDT descriptors

2023-12-20T09:57:51+00:00

We have no known use for having the CPU track whether GDT descriptors
have been accessed or not.

Simplify the code by adding the flag to the common flags and removing
it everywhere else.

Signed-off-by: Vegard Nossum 
Signed-off-by: Ingo Molnar 
Acked-by: Linus Torvalds 
Link: https://lore.kernel.org/r/20231219151200.2878271-5-vegard.nossum@oracle.com

x86/asm: Replace magic numbers in GDT descriptors, script-generated change

2023-12-20T09:57:38+00:00

Actually replace the numeric values by the new symbolic values.

I used this to find all the existing users of the GDT_ENTRY*() macros:

  $ git grep -P 'GDT_ENTRY(_INIT)?\('

Some of the lines will exceed 80 characters, but some of them will be
shorter again in the next couple of patches.

Signed-off-by: Vegard Nossum 
Signed-off-by: Ingo Molnar 
Acked-by: Linus Torvalds 
Link: https://lore.kernel.org/r/20231219151200.2878271-4-vegard.nossum@oracle.com

x86/asm: Replace magic numbers in GDT descriptors, preparations

2023-12-20T09:57:20+00:00

We'd like to replace all the magic numbers in various GDT descriptors
with new, semantically meaningful, symbolic values.

In order to be able to verify that the change doesn't cause any actual
changes to the compiled binary code, I've split the change into two
patches:

 - Part 1 (this commit): everything _but_ actually replacing the numbers
 - Part 2 (the following commit): _only_ replacing the numbers

The reason we need this split for verification is that including new
headers causes some spurious changes to the object files, mostly line
number changes in the debug info but occasionally other subtle codegen
changes.

Signed-off-by: Vegard Nossum 
Signed-off-by: Ingo Molnar 
Acked-by: Linus Torvalds 
Link: https://lore.kernel.org/r/20231219151200.2878271-3-vegard.nossum@oracle.com

x86/virt/tdx: Detect TDX during kernel boot

2023-12-08T17:11:58+00:00

Intel Trust Domain Extensions (TDX) protects guest VMs from malicious
host and certain physical attacks.  A CPU-attested software module
called 'the TDX module' runs inside a new isolated memory range as a
trusted hypervisor to manage and run protected VMs.

Pre-TDX Intel hardware has support for a memory encryption architecture
called MKTME.  The memory encryption hardware underpinning MKTME is also
used for Intel TDX.  TDX ends up "stealing" some of the physical address
space from the MKTME architecture for crypto-protection to VMs.  The
BIOS is responsible for partitioning the "KeyID" space between legacy
MKTME and TDX.  The KeyIDs reserved for TDX are called 'TDX private
KeyIDs' or 'TDX KeyIDs' for short.

During machine boot, TDX microcode verifies that the BIOS programmed TDX
private KeyIDs consistently and correctly programmed across all CPU
packages.  The MSRs are locked in this state after verification.  This
is why MSR_IA32_MKTME_KEYID_PARTITIONING gets used for TDX enumeration:
it indicates not just that the hardware supports TDX, but that all the
boot-time security checks passed.

The TDX module is expected to be loaded by the BIOS when it enables TDX,
but the kernel needs to properly initialize it before it can be used to
create and run any TDX guests.  The TDX module will be initialized by
the KVM subsystem when KVM wants to use TDX.

Detect platform TDX support by detecting TDX private KeyIDs.

The TDX module itself requires one TDX KeyID as the 'TDX global KeyID'
to protect its metadata.  Each TDX guest also needs a TDX KeyID for its
own protection.  Just use the first TDX KeyID as the global KeyID and
leave the rest for TDX guests.  If no TDX KeyID is left for TDX guests,
disable TDX as initializing the TDX module alone is useless.

[ dhansen: add X86_FEATURE, replace helper function ]

Signed-off-by: Kai Huang 
Signed-off-by: Dave Hansen 
Reviewed-by: Kirill A. Shutemov 
Reviewed-by: Isaku Yamahata 
Reviewed-by: David Hildenbrand 
Reviewed-by: Dave Hansen 
Reviewed-by: Kuppuswamy Sathyanarayanan 
Link: https://lore.kernel.org/all/20231208170740.53979-1-dave.hansen%40intel.com