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>
Newer processors supports a hardware control BHI_DIS_S to mitigate
Branch History Injection (BHI). Setting BHI_DIS_S protects the kernel
from userspace BHI attacks without having to manually overwrite the
branch history.
Define MSR_SPEC_CTRL bit BHI_DIS_S and its enumeration CPUID.BHI_CTRL.
Mitigation is enabled later.
Signed-off-by: Daniel Sneddon <daniel.sneddon@linux.intel.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>
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>
We want to fix:
0e11073247 ("x86/retpoline: Do the necessary fixup to the Zen3/4 srso return thunk for !SRSO")
So merge in Linus's latest into x86/urgent to have it available.
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Older versions of clang show a warning for amd.c after a fix for a gcc
warning:
arch/x86/kernel/cpu/microcode/amd.c:478:47: error: format specifies type \
'unsigned char' but the argument has type 'u16' (aka 'unsigned short') [-Werror,-Wformat]
"amd-ucode/microcode_amd_fam%02hhxh.bin", family);
~~~~~~ ^~~~~~
%02hx
In clang-16 and higher, this warning is disabled by default, but clang-15 is
still supported, and it's trivial to avoid by adapting the types according
to the range of the passed data and the format string.
[ bp: Massage commit message. ]
Fixes: 2e9064facc ("x86/microcode/amd: Fix snprintf() format string warning in W=1 build")
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Borislav Petkov (AMD) <bp@alien8.de>
Link: https://lore.kernel.org/r/20240405204919.1003409-1-arnd@kernel.org
Pull networking fixes from Jakub Kicinski:
"Including fixes from netfilter, bluetooth and bpf.
Fairly usual collection of driver and core fixes. The large selftest
accompanying one of the fixes is also becoming a common occurrence.
Current release - regressions:
- ipv6: fix infinite recursion in fib6_dump_done()
- net/rds: fix possible null-deref in newly added error path
Current release - new code bugs:
- net: do not consume a full cacheline for system_page_pool
- bpf: fix bpf_arena-related file descriptor leaks in the verifier
- drv: ice: fix freeing uninitialized pointers, fixing misuse of the
newfangled __free() auto-cleanup
Previous releases - regressions:
- x86/bpf: fixes the BPF JIT with retbleed=stuff
- xen-netfront: add missing skb_mark_for_recycle, fix page pool
accounting leaks, revealed by recently added explicit warning
- tcp: fix bind() regression for v6-only wildcard and v4-mapped-v6
non-wildcard addresses
- Bluetooth:
- replace "hci_qca: Set BDA quirk bit if fwnode exists in DT" with
better workarounds to un-break some buggy Qualcomm devices
- set conn encrypted before conn establishes, fix re-connecting to
some headsets which use slightly unusual sequence of msgs
- mptcp:
- prevent BPF accessing lowat from a subflow socket
- don't account accept() of non-MPC client as fallback to TCP
- drv: mana: fix Rx DMA datasize and skb_over_panic
- drv: i40e: fix VF MAC filter removal
Previous releases - always broken:
- gro: various fixes related to UDP tunnels - netns crossing
problems, incorrect checksum conversions, and incorrect packet
transformations which may lead to panics
- bpf: support deferring bpf_link dealloc to after RCU grace period
- nf_tables:
- release batch on table validation from abort path
- release mutex after nft_gc_seq_end from abort path
- flush pending destroy work before exit_net release
- drv: r8169: skip DASH fw status checks when DASH is disabled"
* tag 'net-6.9-rc3' of git://git.kernel.org/pub/scm/linux/kernel/git/netdev/net: (81 commits)
netfilter: validate user input for expected length
net/sched: act_skbmod: prevent kernel-infoleak
net: usb: ax88179_178a: avoid the interface always configured as random address
net: dsa: sja1105: Fix parameters order in sja1110_pcs_mdio_write_c45()
net: ravb: Always update error counters
net: ravb: Always process TX descriptor ring
netfilter: nf_tables: discard table flag update with pending basechain deletion
netfilter: nf_tables: Fix potential data-race in __nft_flowtable_type_get()
netfilter: nf_tables: reject new basechain after table flag update
netfilter: nf_tables: flush pending destroy work before exit_net release
netfilter: nf_tables: release mutex after nft_gc_seq_end from abort path
netfilter: nf_tables: release batch on table validation from abort path
Revert "tg3: Remove residual error handling in tg3_suspend"
tg3: Remove residual error handling in tg3_suspend
net: mana: Fix Rx DMA datasize and skb_over_panic
net/sched: fix lockdep splat in qdisc_tree_reduce_backlog()
net: phy: micrel: lan8814: Fix when enabling/disabling 1-step timestamping
net: stmmac: fix rx queue priority assignment
net: txgbe: fix i2c dev name cannot match clkdev
net: fec: Set mac_managed_pm during probe
...
Modifying a MCA bank's MCA_CTL bits which control which error types to
be reported is done over
/sys/devices/system/machinecheck/
├── machinecheck0
│ ├── bank0
│ ├── bank1
│ ├── bank10
│ ├── bank11
...
sysfs nodes by writing the new bit mask of events to enable.
When the write is accepted, the kernel deletes all current timers and
reinits all banks.
Doing that in parallel can lead to initializing a timer which is already
armed and in the timer wheel, i.e., in use already:
ODEBUG: init active (active state 0) object: ffff888063a28000 object
type: timer_list hint: mce_timer_fn+0x0/0x240 arch/x86/kernel/cpu/mce/core.c:2642
WARNING: CPU: 0 PID: 8120 at lib/debugobjects.c:514
debug_print_object+0x1a0/0x2a0 lib/debugobjects.c:514
Fix that by grabbing the sysfs mutex as the rest of the MCA sysfs code
does.
Reported by: Yue Sun <samsun1006219@gmail.com>
Reported by: xingwei lee <xrivendell7@gmail.com>
Signed-off-by: Borislav Petkov (AMD) <bp@alien8.de>
Cc: <stable@kernel.org>
Link: https://lore.kernel.org/r/CAEkJfYNiENwQY8yV1LYJ9LjJs%2Bx_-PqMv98gKig55=2vbzffRw@mail.gmail.com
The host SNP worthiness can determined later, after alternatives have
been patched, in snp_rmptable_init() depending on cmdline options like
iommu=pt which is incompatible with SNP, for example.
Which means that one cannot use X86_FEATURE_SEV_SNP and will need to
have a special flag for that control.
Use that newly added CC_ATTR_HOST_SEV_SNP in the appropriate places.
Move kdump_sev_callback() to its rightful place, while at it.
Fixes: 216d106c7f ("x86/sev: Add SEV-SNP host initialization support")
Signed-off-by: Borislav Petkov (AMD) <bp@alien8.de>
Reviewed-by: Tom Lendacky <thomas.lendacky@amd.com>
Tested-by: Srikanth Aithal <sraithal@amd.com>
Link: https://lore.kernel.org/r/20240327154317.29909-6-bp@alien8.de
There are few uses of CoCo that don't rely on working cryptography and
hence a working RNG. Unfortunately, the CoCo threat model means that the
VM host cannot be trusted and may actively work against guests to
extract secrets or manipulate computation. Since a malicious host can
modify or observe nearly all inputs to guests, the only remaining source
of entropy for CoCo guests is RDRAND.
If RDRAND is broken -- due to CPU hardware fault -- the RNG as a whole
is meant to gracefully continue on gathering entropy from other sources,
but since there aren't other sources on CoCo, this is catastrophic.
This is mostly a concern at boot time when initially seeding the RNG, as
after that the consequences of a broken RDRAND are much more
theoretical.
So, try at boot to seed the RNG using 256 bits of RDRAND output. If this
fails, panic(). This will also trigger if the system is booted without
RDRAND, as RDRAND is essential for a safe CoCo boot.
Add this deliberately to be "just a CoCo x86 driver feature" and not
part of the RNG itself. Many device drivers and platforms have some
desire to contribute something to the RNG, and add_device_randomness()
is specifically meant for this purpose.
Any driver can call it with seed data of any quality, or even garbage
quality, and it can only possibly make the quality of the RNG better or
have no effect, but can never make it worse.
Rather than trying to build something into the core of the RNG, consider
the particular CoCo issue just a CoCo issue, and therefore separate it
all out into driver (well, arch/platform) code.
[ bp: Massage commit message. ]
Signed-off-by: Jason A. Donenfeld <Jason@zx2c4.com>
Signed-off-by: Borislav Petkov (AMD) <bp@alien8.de>
Reviewed-by: Elena Reshetova <elena.reshetova@intel.com>
Reviewed-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Reviewed-by: Theodore Ts'o <tytso@mit.edu>
Cc: stable@vger.kernel.org
Link: https://lore.kernel.org/r/20240326160735.73531-1-Jason@zx2c4.com
The following commit:
d69c1382e1 ("x86/kvm: Convert FPU handling to a single swap buffer")
reworked KVM FPU handling, but forgot to update the comments
in xstate_op_valid(): fpu_swap_kvm_fpu() doesn't exist anymore,
fpu_swap_kvm_fpstate() is used instead.
Update the comments accordingly.
[ mingo: Improved the changelog. ]
Signed-off-by: Li RongQing <lirongqing@baidu.com>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Link: https://lore.kernel.org/r/20240403091803.818-1-lirongqing@baidu.com
Pull KVM fixes from Paolo Bonzini:
"ARM:
- Ensure perf events programmed to count during guest execution are
actually enabled before entering the guest in the nVHE
configuration
- Restore out-of-range handler for stage-2 translation faults
- Several fixes to stage-2 TLB invalidations to avoid stale
translations, possibly including partial walk caches
- Fix early handling of architectural VHE-only systems to ensure E2H
is appropriately set
- Correct a format specifier warning in the arch_timer selftest
- Make the KVM banner message correctly handle all of the possible
configurations
RISC-V:
- Remove redundant semicolon in num_isa_ext_regs()
- Fix APLIC setipnum_le/be write emulation
- Fix APLIC in_clrip[x] read emulation
x86:
- Fix a bug in KVM_SET_CPUID{2,} where KVM looks at the wrong CPUID
entries (old vs. new) and ultimately neglects to clear PV_UNHALT
from vCPUs with HLT-exiting disabled
- Documentation fixes for SEV
- Fix compat ABI for KVM_MEMORY_ENCRYPT_OP
- Fix a 14-year-old goof in a declaration shared by host and guest;
the enabled field used by Linux when running as a guest pushes the
size of "struct kvm_vcpu_pv_apf_data" from 64 to 68 bytes. This is
really unconsequential because KVM never consumes anything beyond
the first 64 bytes, but the resulting struct does not match the
documentation
Selftests:
- Fix spelling mistake in arch_timer selftest"
* tag 'for-linus' of git://git.kernel.org/pub/scm/virt/kvm/kvm: (25 commits)
KVM: arm64: Rationalise KVM banner output
arm64: Fix early handling of FEAT_E2H0 not being implemented
KVM: arm64: Ensure target address is granule-aligned for range TLBI
KVM: arm64: Use TLBI_TTL_UNKNOWN in __kvm_tlb_flush_vmid_range()
KVM: arm64: Don't pass a TLBI level hint when zapping table entries
KVM: arm64: Don't defer TLB invalidation when zapping table entries
KVM: selftests: Fix __GUEST_ASSERT() format warnings in ARM's arch timer test
KVM: arm64: Fix out-of-IPA space translation fault handling
KVM: arm64: Fix host-programmed guest events in nVHE
RISC-V: KVM: Fix APLIC in_clrip[x] read emulation
RISC-V: KVM: Fix APLIC setipnum_le/be write emulation
RISC-V: KVM: Remove second semicolon
KVM: selftests: Fix spelling mistake "trigged" -> "triggered"
Documentation: kvm/sev: clarify usage of KVM_MEMORY_ENCRYPT_OP
Documentation: kvm/sev: separate description of firmware
KVM: SEV: fix compat ABI for KVM_MEMORY_ENCRYPT_OP
KVM: selftests: Check that PV_UNHALT is cleared when HLT exiting is disabled
KVM: x86: Use actual kvm_cpuid.base for clearing KVM_FEATURE_PV_UNHALT
KVM: x86: Introduce __kvm_get_hypervisor_cpuid() helper
KVM: SVM: Return -EINVAL instead of -EBUSY on attempt to re-init SEV/SEV-ES
...
Given that acpi_pm_read_early() returns a u32 (masked to 24 bits), several
variables that store its return value are improved by adjusting their data
types from unsigned long to u32. Specifically, change deltapm's type from
long to u32 because its value fits into 32 bits and it cannot be negative.
These data type improvements resolve the following two Coccinelle/
coccicheck warnings reported by do_div.cocci:
arch/x86/kernel/apic/apic.c:734:1-7: WARNING: do_div() does a 64-by-32
division, please consider using div64_long instead.
arch/x86/kernel/apic/apic.c:742:2-8: WARNING: do_div() does a 64-by-32
division, please consider using div64_long instead.
Signed-off-by: Thorsten Blum <thorsten.blum@toblux.com>
Signed-off-by: Dave Hansen <dave.hansen@linux.intel.com>
Reviewed-by: Dave Hansen <dave.hansen@linux.intel.com>
Link: https://lore.kernel.org/all/20240318104721.117741-3-thorsten.blum%40toblux.com
Tony encountered this OOPS when the last CPU of a domain goes
offline while running a kernel built with CONFIG_NO_HZ_FULL:
BUG: kernel NULL pointer dereference, address: 0000000000000000
#PF: supervisor read access in kernel mode
#PF: error_code(0x0000) - not-present page
PGD 0
Oops: 0000 [#1] PREEMPT SMP NOPTI
...
RIP: 0010:__find_nth_andnot_bit+0x66/0x110
...
Call Trace:
<TASK>
? __die()
? page_fault_oops()
? exc_page_fault()
? asm_exc_page_fault()
cpumask_any_housekeeping()
mbm_setup_overflow_handler()
resctrl_offline_cpu()
resctrl_arch_offline_cpu()
cpuhp_invoke_callback()
cpuhp_thread_fun()
smpboot_thread_fn()
kthread()
ret_from_fork()
ret_from_fork_asm()
</TASK>
The NULL pointer dereference is encountered while searching for another
online CPU in the domain (of which there are none) that can be used to
run the MBM overflow handler.
Because the kernel is configured with CONFIG_NO_HZ_FULL the search for
another CPU (in its effort to prefer those CPUs that aren't marked
nohz_full) consults the mask representing the nohz_full CPUs,
tick_nohz_full_mask. On a kernel with CONFIG_CPUMASK_OFFSTACK=y
tick_nohz_full_mask is not allocated unless the kernel is booted with
the "nohz_full=" parameter and because of that any access to
tick_nohz_full_mask needs to be guarded with tick_nohz_full_enabled().
Replace the IS_ENABLED(CONFIG_NO_HZ_FULL) with tick_nohz_full_enabled().
The latter ensures tick_nohz_full_mask can be accessed safely and can be
used whether kernel is built with CONFIG_NO_HZ_FULL enabled or not.
[ Use Ingo's suggestion that combines the two NO_HZ checks into one. ]
Fixes: a4846aaf39 ("x86/resctrl: Add cpumask_any_housekeeping() for limbo/overflow")
Reported-by: Tony Luck <tony.luck@intel.com>
Signed-off-by: Reinette Chatre <reinette.chatre@intel.com>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Reviewed-by: Babu Moger <babu.moger@amd.com>
Link: https://lore.kernel.org/r/ff8dfc8d3dcb04b236d523d1e0de13d2ef585223.1711993956.git.reinette.chatre@intel.com
Closes: https://lore.kernel.org/lkml/ZgIFT5gZgIQ9A9G7@agluck-desk3/
Currently for DeviceTree bootup, x86 code does the default mapping of
CPUs to NUMA, which is wrong. This can cause incorrect mapping and WARNs
on SMT enabled systems:
CPU #1's smt-sibling CPU #0 is not on the same node! [node: 1 != 0]. Ignoring dependency.
WARNING: CPU: 1 PID: 0 at topology_sane.isra.0+0x5c/0x6d
match_smt+0xf6/0xfc
set_cpu_sibling_map.cold+0x24f/0x512
start_secondary+0x5c/0x110
Call the set_apicid_to_node() function in dtb_cpu_setup() for setting
the NUMA to CPU mapping for DeviceTree platforms.
Signed-off-by: Saurabh Sengar <ssengar@linux.microsoft.com>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Link: https://lore.kernel.org/r/1712068830-4513-4-git-send-email-ssengar@linux.microsoft.com
x86_dtb_parse_smp_config() must be set by DeviceTree platform for
parsing SMP configuration. Set the parse_smp_cfg pointer to
x86_dtb_parse_smp_config() by default so that all the dtb platforms
need not to assign it explicitly. Today there are only two platforms
using DeviceTree in x86, ce4100 and hv_vtl. Remove the explicit
assignment of x86_dtb_parse_smp_config() function from these.
Signed-off-by: Saurabh Sengar <ssengar@linux.microsoft.com>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Link: https://lore.kernel.org/r/1712068830-4513-3-git-send-email-ssengar@linux.microsoft.com
KVM/arm64 fixes for 6.9, part #1
- Ensure perf events programmed to count during guest execution
are actually enabled before entering the guest in the nVHE
configuration.
- Restore out-of-range handler for stage-2 translation faults.
- Several fixes to stage-2 TLB invalidations to avoid stale
translations, possibly including partial walk caches.
- Fix early handling of architectural VHE-only systems to ensure E2H is
appropriately set.
- Correct a format specifier warning in the arch_timer selftest.
- Make the KVM banner message correctly handle all of the possible
configurations.
The commit:
59bec00ace ("x86/percpu: Introduce %rip-relative addressing to PER_CPU_VAR()")
made PER_CPU_VAR() to use rip-relative addressing, hence
INCREMENT_CALL_DEPTH macro and skl_call_thunk_template got rip-relative
asm code inside of it. A follow up commit:
17bce3b2ae ("x86/callthunks: Handle %rip-relative relocations in call thunk template")
changed x86_call_depth_emit_accounting() to use apply_relocation(),
but mistakenly assumed that the code is being patched in-place (where
the destination of the relocation matches the address of the code),
using *pprog as the destination ip. This is not true for the call depth
accounting, emitted by the BPF JIT, so the calculated address was wrong,
JIT-ed BPF progs on kernels with call depth tracking got broken and
usually caused a page fault.
Pass the destination IP when the BPF JIT emits call depth accounting.
Fixes: 17bce3b2ae ("x86/callthunks: Handle %rip-relative relocations in call thunk template")
Signed-off-by: Joan Bruguera Micó <joanbrugueram@gmail.com>
Reviewed-by: Uros Bizjak <ubizjak@gmail.com>
Acked-by: Ingo Molnar <mingo@kernel.org>
Cc: Alexei Starovoitov <ast@kernel.org>
Cc: Daniel Borkmann <daniel@iogearbox.net>
Link: https://lore.kernel.org/r/20240401185821.224068-3-ubizjak@gmail.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Pull x86 perf fixes from Borislav Petkov:
- Define the correct set of default hw events on AMD Zen4
- Use the correct stalled cycles PMCs on AMD Zen2 and newer
- Fix detection of the LBR freeze feature on AMD
* tag 'perf_urgent_for_v6.9_rc2' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
perf/x86/amd/core: Define a proper ref-cycles event for Zen 4 and later
perf/x86/amd/core: Update and fix stalled-cycles-* events for Zen 2 and later
perf/x86/amd/lbr: Use freeze based on availability
x86/cpufeatures: Add new word for scattered features
When split_lock_detect=off (or similar) is specified in
CONFIG_CMDLINE, its effect is lost. The flow is currently this:
setup_arch():
-> early_cpu_init()
-> early_identify_cpu()
-> sld_setup()
-> sld_state_setup()
-> Looks for split_lock_detect in boot_command_line
-> e820__memory_setup()
-> Assemble final command line:
boot_command_line = builtin_cmdline + boot_cmdline
-> parse_early_param()
There were earlier attempts at fixing this in:
8d48bf8206 ("x86/boot: Pull up cmdline preparation and early param parsing")
later reverted in:
fbe6183998 ("Revert "x86/boot: Pull up cmdline preparation and early param parsing"")
... because parse_early_param() can't be called before
e820__memory_setup().
In this patch, we just move the command line concatenation to the
beginning of early_cpu_init(). This should fix sld_state_setup(), while
not running in the same issues as the earlier attempt.
The order is now:
setup_arch():
-> Assemble final command line:
boot_command_line = builtin_cmdline + boot_cmdline
-> early_cpu_init()
-> early_identify_cpu()
-> sld_setup()
-> sld_state_setup()
-> Looks for split_lock_detect in boot_command_line
-> e820__memory_setup()
-> parse_early_param()
Signed-off-by: Julian Stecklina <julian.stecklina@cyberus-technology.de>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Cc: Kees Cook <keescook@chromium.org>
Cc: linux-kernel@vger.kernel.org
panic() prints a uniform prompt: "Kernel panic - not syncing:",
but die() messages don't have any of that, the message is the
raw user-defined message with no prefix.
There's companies that collect thousands of die() messages per week,
but w/o a prompt in dmesg, it's hard to write scripts to collect and
analize the reasons.
Add a uniform "Oops:" prefix like other architectures.
[ mingo: Rewrote changelog. ]
Signed-off-by: Alex Shi <alexs@kernel.org>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Link: https://lore.kernel.org/r/20240327024419.471433-1-alexs@kernel.org
SEV-SNP requires encrypted memory to be validated before access.
Because the ROM memory range is not part of the e820 table, it is not
pre-validated by the BIOS. Therefore, if a SEV-SNP guest kernel wishes
to access this range, the guest must first validate the range.
The current SEV-SNP code does indeed scan the ROM range during early
boot and thus attempts to validate the ROM range in probe_roms().
However, this behavior is neither sufficient nor necessary for the
following reasons:
* With regards to sufficiency, if EFI_CONFIG_TABLES are not enabled and
CONFIG_DMI_SCAN_MACHINE_NON_EFI_FALLBACK is set, the kernel will
attempt to access the memory at SMBIOS_ENTRY_POINT_SCAN_START (which
falls in the ROM range) prior to validation.
For example, Project Oak Stage 0 provides a minimal guest firmware
that currently meets these configuration conditions, meaning guests
booting atop Oak Stage 0 firmware encounter a problematic call chain
during dmi_setup() -> dmi_scan_machine() that results in a crash
during boot if SEV-SNP is enabled.
* With regards to necessity, SEV-SNP guests generally read garbage
(which changes across boots) from the ROM range, meaning these scans
are unnecessary. The guest reads garbage because the legacy ROM range
is unencrypted data but is accessed via an encrypted PMD during early
boot (where the PMD is marked as encrypted due to potentially mapping
actually-encrypted data in other PMD-contained ranges).
In one exceptional case, EISA probing treats the ROM range as
unencrypted data, which is inconsistent with other probing.
Continuing to allow SEV-SNP guests to use garbage and to inconsistently
classify ROM range encryption status can trigger undesirable behavior.
For instance, if garbage bytes appear to be a valid signature, memory
may be unnecessarily reserved for the ROM range. Future code or other
use cases may result in more problematic (arbitrary) behavior that
should be avoided.
While one solution would be to overhaul the early PMD mapping to always
treat the ROM region of the PMD as unencrypted, SEV-SNP guests do not
currently rely on data from the ROM region during early boot (and even
if they did, they would be mostly relying on garbage data anyways).
As a simpler solution, skip the ROM range scans (and the otherwise-
necessary range validation) during SEV-SNP guest early boot. The
potential SEV-SNP guest crash due to lack of ROM range validation is
thus avoided by simply not accessing the ROM range.
In most cases, skip the scans by overriding problematic x86_init
functions during sme_early_init() to SNP-safe variants, which can be
likened to x86_init overrides done for other platforms (ex: Xen); such
overrides also avoid the spread of cc_platform_has() checks throughout
the tree.
In the exceptional EISA case, still use cc_platform_has() for the
simplest change, given (1) checks for guest type (ex: Xen domain status)
are already performed here, and (2) these checks occur in a subsys
initcall instead of an x86_init function.
[ bp: Massage commit message, remove "we"s. ]
Fixes: 9704c07bf9 ("x86/kernel: Validate ROM memory before accessing when SEV-SNP is active")
Signed-off-by: Kevin Loughlin <kevinloughlin@google.com>
Signed-off-by: Borislav Petkov (AMD) <bp@alien8.de>
Cc: <stable@kernel.org>
Link: https://lore.kernel.org/r/20240313121546.2964854-1-kevinloughlin@google.com
Systems with a large number of CPUs may generate a large number of
machine check records when things go seriously wrong. But Linux has
a fixed-size buffer that can only capture a few dozen errors.
Allocate space based on the number of CPUs (with a minimum value based
on the historical fixed buffer that could store 80 records).
[ bp: Rename local var from tmpp to something more telling: gpool. ]
Signed-off-by: Tony Luck <tony.luck@intel.com>
Signed-off-by: Borislav Petkov (AMD) <bp@alien8.de>
Reviewed-by: Sohil Mehta <sohil.mehta@intel.com>
Reviewed-by: Avadhut Naik <avadhut.naik@amd.com>
Link: https://lore.kernel.org/r/20240307192704.37213-1-tony.luck@intel.com
The commit to improve NMI stall debuggability:
344da544f1 ("x86/nmi: Print reasons why backtrace NMIs are ignored")
... has shown value, but widespread use has also identified a few
opportunities for improvement.
The systems have (as usual) shown far more creativity than that commit's
author, demonstrating yet again that failing CPUs can do whatever they want.
In addition, the current message format is less friendly than one might
like to those attempting to use these messages to identify failing CPUs.
Therefore, separately flag CPUs that, during the full time that the
stack-backtrace request was waiting, were always in an NMI handler,
were never in an NMI handler, or exited one NMI handler.
Also, split the message identifying the CPU and the time since that CPU's
last NMI-related activity so that a single line identifies the CPU without
any other variable information, greatly reducing the processing overhead
required to identify repeat-offender CPUs.
Co-developed-by: Breno Leitao <leitao@debian.org>
Signed-off-by: Breno Leitao <leitao@debian.org>
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Link: https://lore.kernel.org/r/ab4d70c8-c874-42dc-b206-643018922393@paulmck-laptop
Disable XSAVES only on machines which haven't loaded the microcode
revision containing the erratum fix.
This will come in handy when running archaic OSes as guests. OSes whose
brilliant programmers thought that CPUID is overrated and one should not
query it but use features directly, ala shoot first, ask questions
later... but only if you're alive after the shooting.
Signed-off-by: Borislav Petkov (AMD) <bp@alien8.de>
Tested-by: "Maciej S. Szmigiero" <maciej.szmigiero@oracle.com>
Cc: Boris Ostrovsky <boris.ostrovsky@oracle.com>
Link: https://lore.kernel.org/r/20240324200525.GBZgCHhYFsBj12PrKv@fat_crate.local
Currently, the LBR code assumes that LBR Freeze is supported on all processors
when X86_FEATURE_AMD_LBR_V2 is available i.e. CPUID leaf 0x80000022[EAX]
bit 1 is set. This is incorrect as the availability of the feature is
additionally dependent on CPUID leaf 0x80000022[EAX] bit 2 being set,
which may not be set for all Zen 4 processors.
Define a new feature bit for LBR and PMC freeze and set the freeze enable bit
(FLBRI) in DebugCtl (MSR 0x1d9) conditionally.
It should still be possible to use LBR without freeze for profile-guided
optimization of user programs by using an user-only branch filter during
profiling. When the user-only filter is enabled, branches are no longer
recorded after the transition to CPL 0 upon PMI arrival. When branch
entries are read in the PMI handler, the branch stack does not change.
E.g.
$ perf record -j any,u -e ex_ret_brn_tkn ./workload
Since the feature bit is visible under flags in /proc/cpuinfo, it can be
used to determine the feasibility of use-cases which require LBR Freeze
to be supported by the hardware such as profile-guided optimization of
kernels.
Fixes: ca5b7c0d96 ("perf/x86/amd/lbr: Add LbrExtV2 branch record support")
Signed-off-by: Sandipan Das <sandipan.das@amd.com>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Link: https://lore.kernel.org/r/69a453c97cfd11c6f2584b19f937fe6df741510f.1711091584.git.sandipan.das@amd.com
Pull x86 fixes from Thomas Gleixner:
- Ensure that the encryption mask at boot is properly propagated on
5-level page tables, otherwise the PGD entry is incorrectly set to
non-encrypted, which causes system crashes during boot.
- Undo the deferred 5-level page table setup as it cannot work with
memory encryption enabled.
- Prevent inconsistent XFD state on CPU hotplug, where the MSR is reset
to the default value but the cached variable is not, so subsequent
comparisons might yield the wrong result and as a consequence the
result prevents updating the MSR.
- Register the local APIC address only once in the MPPARSE enumeration
to prevent triggering the related WARN_ONs() in the APIC and topology
code.
- Handle the case where no APIC is found gracefully by registering a
fake APIC in the topology code. That makes all related topology
functions work correctly and does not affect the actual APIC driver
code at all.
- Don't evaluate logical IDs during early boot as the local APIC IDs
are not yet enumerated and the invoked function returns an error
code. Nothing requires the logical IDs before the final CPUID
enumeration takes place, which happens after the enumeration.
- Cure the fallout of the per CPU rework on UP which misplaced the
copying of boot_cpu_data to per CPU data so that the final update to
boot_cpu_data got lost which caused inconsistent state and boot
crashes.
- Use copy_from_kernel_nofault() in the kprobes setup as there is no
guarantee that the address can be safely accessed.
- Reorder struct members in struct saved_context to work around another
kmemleak false positive
- Remove the buggy code which tries to update the E820 kexec table for
setup_data as that is never passed to the kexec kernel.
- Update the resource control documentation to use the proper units.
- Fix a Kconfig warning observed with tinyconfig
* tag 'x86-urgent-2024-03-24' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
x86/boot/64: Move 5-level paging global variable assignments back
x86/boot/64: Apply encryption mask to 5-level pagetable update
x86/cpu: Add model number for another Intel Arrow Lake mobile processor
x86/fpu: Keep xfd_state in sync with MSR_IA32_XFD
Documentation/x86: Document that resctrl bandwidth control units are MiB
x86/mpparse: Register APIC address only once
x86/topology: Handle the !APIC case gracefully
x86/topology: Don't evaluate logical IDs during early boot
x86/cpu: Ensure that CPU info updates are propagated on UP
kprobes/x86: Use copy_from_kernel_nofault() to read from unsafe address
x86/pm: Work around false positive kmemleak report in msr_build_context()
x86/kexec: Do not update E820 kexec table for setup_data
x86/config: Fix warning for 'make ARCH=x86_64 tinyconfig'
Commit 63bed96604 ("x86/startup_64: Defer assignment of 5-level paging
global variables") moved assignment of 5-level global variables to later
in the boot in order to avoid having to use RIP relative addressing in
order to set them. However, when running with 5-level paging and SME
active (mem_encrypt=on), the variables are needed as part of the page
table setup needed to encrypt the kernel (using pgd_none(), p4d_offset(),
etc.). Since the variables haven't been set, the page table manipulation
is done as if 4-level paging is active, causing the system to crash on
boot.
While only a subset of the assignments that were moved need to be set
early, move all of the assignments back into check_la57_support() so that
these assignments aren't spread between two locations. Instead of just
reverting the fix, this uses the new RIP_REL_REF() macro when assigning
the variables.
Fixes: 63bed96604 ("x86/startup_64: Defer assignment of 5-level paging global variables")
Signed-off-by: Tom Lendacky <thomas.lendacky@amd.com>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Reviewed-by: Ard Biesheuvel <ardb@kernel.org>
Link: https://lore.kernel.org/r/2ca419f4d0de719926fd82353f6751f717590a86.1711122067.git.thomas.lendacky@amd.com
When running with 5-level page tables, the kernel mapping PGD entry is
updated to point to the P4D table. The assignment uses _PAGE_TABLE_NOENC,
which, when SME is active (mem_encrypt=on), results in a page table
entry without the encryption mask set, causing the system to crash on
boot.
Change the assignment to use _PAGE_TABLE instead of _PAGE_TABLE_NOENC so
that the encryption mask is set for the PGD entry.
Fixes: 533568e06b ("x86/boot/64: Use RIP_REL_REF() to access early_top_pgt[]")
Signed-off-by: Tom Lendacky <thomas.lendacky@amd.com>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Reviewed-by: Ard Biesheuvel <ardb@kernel.org>
Link: https://lore.kernel.org/r/8f20345cda7dbba2cf748b286e1bc00816fe649a.1711122067.git.thomas.lendacky@amd.com
Commit 672365477a ("x86/fpu: Update XFD state where required") and
commit 8bf26758ca ("x86/fpu: Add XFD state to fpstate") introduced a
per CPU variable xfd_state to keep the MSR_IA32_XFD value cached, in
order to avoid unnecessary writes to the MSR.
On CPU hotplug MSR_IA32_XFD is reset to the init_fpstate.xfd, which
wipes out any stale state. But the per CPU cached xfd value is not
reset, which brings them out of sync.
As a consequence a subsequent xfd_update_state() might fail to update
the MSR which in turn can result in XRSTOR raising a #NM in kernel
space, which crashes the kernel.
To fix this, introduce xfd_set_state() to write xfd_state together
with MSR_IA32_XFD, and use it in all places that set MSR_IA32_XFD.
Fixes: 672365477a ("x86/fpu: Update XFD state where required")
Signed-off-by: Adamos Ttofari <attofari@amazon.de>
Signed-off-by: Chang S. Bae <chang.seok.bae@intel.com>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Reviewed-by: Thomas Gleixner <tglx@linutronix.de>
Link: https://lore.kernel.org/r/20240322230439.456571-1-chang.seok.bae@intel.com
Closes: https://lore.kernel.org/lkml/20230511152818.13839-1-attofari@amazon.de
The APIC address is registered twice. First during the early detection and
afterwards when actually scanning the table for APIC IDs. The APIC and
topology core warn about the second attempt.
Restrict it to the early detection call.
Fixes: 81287ad65d ("x86/apic: Sanitize APIC address setup")
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Borislav Petkov (AMD) <bp@alien8.de>
Tested-by: Guenter Roeck <linux@roeck-us.net>
Link: https://lore.kernel.org/r/20240322185305.297774848@linutronix.de
If there is no local APIC enumerated and registered then the topology
bitmaps are empty. Therefore, topology_init_possible_cpus() will die with
a division by zero exception.
Prevent this by registering a fake APIC id to populate the topology
bitmap. This also allows to use all topology query interfaces
unconditionally. It does not affect the actual APIC code because either
the local APIC address was not registered or no local APIC could be
detected.
Fixes: f1f758a805 ("x86/topology: Add a mechanism to track topology via APIC IDs")
Reported-by: Guenter Roeck <linux@roeck-us.net>
Reported-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Borislav Petkov (AMD) <bp@alien8.de>
Tested-by: Guenter Roeck <linux@roeck-us.net>
Link: https://lore.kernel.org/r/20240322185305.242709302@linutronix.de
The local APICs have not yet been enumerated so the logical ID evaluation
from the topology bitmaps does not work and would return an error code.
Skip the evaluation during the early boot CPUID evaluation and only apply
it on the final run.
Fixes: 380414be78 ("x86/cpu/topology: Use topology logical mapping mechanism")
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Borislav Petkov (AMD) <bp@alien8.de>
Tested-by: Guenter Roeck <linux@roeck-us.net>
Link: https://lore.kernel.org/r/20240322185305.186943142@linutronix.de
The boot sequence evaluates CPUID information twice:
1) During early boot
2) When finalizing the early setup right before
mitigations are selected and alternatives are patched.
In both cases the evaluation is stored in boot_cpu_data, but on UP the
copying of boot_cpu_data to the per CPU info of the boot CPU happens
between #1 and #2. So any update which happens in #2 is never propagated to
the per CPU info instance.
Consolidate the whole logic and copy boot_cpu_data right before applying
alternatives as that's the point where boot_cpu_data is in it's final
state and not supposed to change anymore.
This also removes the voodoo mb() from smp_prepare_cpus_common() which
had absolutely no purpose.
Fixes: 71eb4893cf ("x86/percpu: Cure per CPU madness on UP")
Reported-by: Guenter Roeck <linux@roeck-us.net>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Borislav Petkov (AMD) <bp@alien8.de>
Tested-by: Guenter Roeck <linux@roeck-us.net>
Link: https://lore.kernel.org/r/20240322185305.127642785@linutronix.de
Read from an unsafe address with copy_from_kernel_nofault() in
arch_adjust_kprobe_addr() because this function is used before checking
the address is in text or not. Syzcaller bot found a bug and reported
the case if user specifies inaccessible data area,
arch_adjust_kprobe_addr() will cause a kernel panic.
[ mingo: Clarified the comment. ]
Fixes: cc66bb9145 ("x86/ibt,kprobes: Cure sym+0 equals fentry woes")
Reported-by: Qiang Zhang <zzqq0103.hey@gmail.com>
Tested-by: Jinghao Jia <jinghao7@illinois.edu>
Signed-off-by: Masami Hiramatsu (Google) <mhiramat@kernel.org>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Link: https://lore.kernel.org/r/171042945004.154897.2221804961882915806.stgit@devnote2
On AMD processors that support extended CPUID leaf 0x80000026, use the
extended leaf to parse the topology information. In case of a failure,
fall back to parsing the information from CPUID leaf 0xb.
CPUID leaf 0x80000026 exposes the "CCX" and "CCD (Die)" information on
AMD processors which have been mapped to TOPO_TILE_DOMAIN and
TOPO_DIE_DOMAIN respectively.
Since this information was previously not available via CPUID leaf 0xb
or 0x8000001e, the "die_id", "logical_die_id", "max_die_per_pkg",
"die_cpus", and "die_cpus_list" will differ with this addition on
AMD processors that support extended CPUID leaf 0x80000026 and contain
more than one "CCD (Die)" on the package.
For example, following are the changes in the values reported by
"/sys/kernel/debug/x86/topo/cpus/16" after applying this patch on a 4th
Generation AMD EPYC System (1 x 128C/256T):
(CPU16 is the first CPU of the second CCD on the package)
tip:x86/apic tip:x86/apic
+ this patch
online: 1 1
initial_apicid: 80 80
apicid: 80 80
pkg_id: 0 0
die_id: 0 4 *
cu_id: 255 255
core_id: 64 64
logical_pkg_id: 0 0
logical_die_id: 0 4 *
llc_id: 8 8
l2c_id: 65535 65535
amd_node_id: 0 0
amd_nodes_per_pkg: 1 1
num_threads: 256 256
num_cores: 128 128
max_dies_per_pkg: 1 8 *
max_threads_per_core:2 2
[ prateek: commit log, updated comment in topoext_amd.c, changed has_0xb
to has_topoext, rebased the changes on tip:x86/apic, tested the
changes on 4th Gen AMD EPYC system ]
[ mingo: tidy up the changelog a bit more ]
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: K Prateek Nayak <kprateek.nayak@amd.com>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Link: https://lore.kernel.org/r/20240314050432.1710-1-kprateek.nayak@amd.com
crashkernel reservation failed on a Thinkpad t440s laptop recently.
Actually the memblock reservation succeeded, but later insert_resource()
failed.
Test steps:
kexec load -> /* make sure add crashkernel param eg. crashkernel=160M */
kexec reboot ->
dmesg|grep "crashkernel reserved";
crashkernel memory range like below reserved successfully:
0x00000000d0000000 - 0x00000000da000000
But no such "Crash kernel" region in /proc/iomem
The background story:
Currently the E820 code reserves setup_data regions for both the current
kernel and the kexec kernel, and it inserts them into the resources list.
Before the kexec kernel reboots nobody passes the old setup_data, and
kexec only passes fresh SETUP_EFI/SETUP_IMA/SETUP_RNG_SEED if needed.
Thus the old setup data memory is not used at all.
Due to old kernel updates the kexec e820 table as well so kexec kernel
sees them as E820_TYPE_RESERVED_KERN regions, and later the old setup_data
regions are inserted into resources list in the kexec kernel by
e820__reserve_resources().
Note, due to no setup_data is passed in for those old regions they are not
early reserved (by function early_reserve_memory), and the crashkernel
memblock reservation will just treat them as usable memory and it could
reserve the crashkernel region which overlaps with the old setup_data
regions. And just like the bug I noticed here, kdump insert_resource
failed because e820__reserve_resources has added the overlapped chunks
in /proc/iomem already.
Finally, looking at the code, the old setup_data regions are not used
at all as no setup_data is passed in by the kexec boot loader. Although
something like SETUP_PCI etc could be needed, kexec should pass
the info as new setup_data so that kexec kernel can take care of them.
This should be taken care of in other separate patches if needed.
Thus drop the useless buggy code here.
Signed-off-by: Dave Young <dyoung@redhat.com>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Cc: Jiri Bohac <jbohac@suse.cz>
Cc: Eric DeVolder <eric.devolder@oracle.com>
Cc: Baoquan He <bhe@redhat.com>
Cc: Ard Biesheuvel <ardb@kernel.org>
Cc: Kees Cook <keescook@chromium.org>
Cc: "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com>
Link: https://lore.kernel.org/r/Zf0T3HCG-790K-pZ@darkstar.users.ipa.redhat.com
The stack of a task has been separated from the memory of a task_struct
struture for a long time on x86, as a result __{start,end}_init_task no
longer mark the start and end of the init_task structure, but its stack
only.
Rename __{start,end}_init_task to __{start,end}_init_stack.
Note other architectures are not affected because __{start,end}_init_task
are used on x86 only.
Signed-off-by: Xin Li (Intel) <xin@zytor.com>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Reviewed-by: Juergen Gross <jgross@suse.com>
Link: https://lore.kernel.org/r/20240322081616.3346181-1-xin@zytor.com
The only useful piece of arch/x86/kernel/topology.c is the definition
of arch_cpu_is_hotpluggable() that can be moved elsewhere (other
architectures tend to put it into setup.c), so do that and delete
the rest of the file.
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Link: https://lore.kernel.org/r/12422874.O9o76ZdvQC@kreacher
