Although APIC initialization will typically clear out the LDR before
setting it, the APIC cleanup code should reset the LDR.
This was discovered with a 32-bit KVM guest jumping into a kdump
kernel. The stale bits in the LDR triggered a bug in the KVM APIC
implementation which caused the destination mapping for VCPUs to be
corrupted.
Note that this isn't intended to paper over the KVM APIC bug. The kernel
has to clear the LDR when resetting the APIC registers except when X2APIC
is enabled.
This lacks a Fixes tag because missing to clear LDR goes way back into pre
git history.
[ tglx: Made x2apic_enabled a function call as required ]
Signed-off-by: Bandan Das <bsd@redhat.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Cc: stable@vger.kernel.org
Link: https://lkml.kernel.org/r/20190826101513.5080-3-bsd@redhat.com
Legacy apic init uses bigsmp for smp systems with 8 and more CPUs. The
bigsmp APIC implementation uses physical destination mode, but it
nevertheless initializes LDR and DFR. The LDR even ends up incorrectly with
multiple bit being set.
This does not cause a functional problem because LDR and DFR are ignored
when physical destination mode is active, but it triggered a problem on a
32-bit KVM guest which jumps into a kdump kernel.
The multiple bits set unearthed a bug in the KVM APIC implementation. The
code which creates the logical destination map for VCPUs ignores the
disabled state of the APIC and ends up overwriting an existing valid entry
and as a result, APIC calibration hangs in the guest during kdump
initialization.
Remove the bogus LDR/DFR initialization.
This is not intended to work around the KVM APIC bug. The LDR/DFR
ininitalization is wrong on its own.
The issue goes back into the pre git history. The fixes tag is the commit
in the bitkeeper import which introduced bigsmp support in 2003.
git://git.kernel.org/pub/scm/linux/kernel/git/tglx/history.git
Fixes: db7b9e9f26b8 ("[PATCH] Clustered APIC setup for >8 CPU systems")
Suggested-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Bandan Das <bsd@redhat.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Cc: stable@vger.kernel.org
Link: https://lkml.kernel.org/r/20190826101513.5080-2-bsd@redhat.com
32-bit processes running on a 64-bit kernel are not always detected
correctly, causing the process to crash when uretprobes are installed.
The reason for the crash is that in_ia32_syscall() is used to determine the
process's mode, which only works correctly when called from a syscall.
In the case of uretprobes, however, the function is called from a exception
and always returns 'false' on a 64-bit kernel. In consequence this leads to
corruption of the process's return address.
Fix this by using user_64bit_mode() instead of in_ia32_syscall(), which
is correct in any situation.
[ tglx: Add a comment and the following historical info ]
This should have been detected by the rename which happened in commit
abfb9498ee ("x86/entry: Rename is_{ia32,x32}_task() to in_{ia32,x32}_syscall()")
which states in the changelog:
The is_ia32_task()/is_x32_task() function names are a big misnomer: they
suggests that the compat-ness of a system call is a task property, which
is not true, the compatness of a system call purely depends on how it
was invoked through the system call layer.
.....
and then it went and blindly renamed every call site.
Sadly enough this was already mentioned here:
8faaed1b9f ("uprobes/x86: Introduce sizeof_long(), cleanup adjust_ret_addr() and
arch_uretprobe_hijack_return_addr()")
where the changelog says:
TODO: is_ia32_task() is not what we actually want, TS_COMPAT does
not necessarily mean 32bit. Fortunately syscall-like insns can't be
probed so it actually works, but it would be better to rename and
use is_ia32_frame().
and goes all the way back to:
0326f5a94d ("uprobes/core: Handle breakpoint and singlestep exceptions")
Oh well. 7+ years until someone actually tried a uretprobe on a 32bit
process on a 64bit kernel....
Fixes: 0326f5a94d ("uprobes/core: Handle breakpoint and singlestep exceptions")
Signed-off-by: Sebastian Mayr <me@sam.st>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Cc: Masami Hiramatsu <mhiramat@kernel.org>
Cc: Dmitry Safonov <dsafonov@virtuozzo.com>
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: Srikar Dronamraju <srikar@linux.vnet.ibm.com>
Cc: stable@vger.kernel.org
Link: https://lkml.kernel.org/r/20190728152617.7308-1-me@sam.st
Hyper-V guests use the default native_sched_clock() in
pv_ops.time.sched_clock on x86. But native_sched_clock() directly uses the
raw TSC value, which can be discontinuous in a Hyper-V VM.
Add the generic hv_setup_sched_clock() to set the sched clock function
appropriately. On x86, this sets pv_ops.time.sched_clock to read the
Hyper-V reference TSC value that is scaled and adjusted to be continuous.
Also move the Hyper-V reference TSC initialization much earlier in the boot
process so no discontinuity is observed when pv_ops.time.sched_clock
calculates its offset.
[ tglx: Folded build fix ]
Signed-off-by: Tianyu Lan <Tianyu.Lan@microsoft.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Michael Kelley <mikelley@microsoft.com>
Link: https://lkml.kernel.org/r/20190814123216.32245-3-Tianyu.Lan@microsoft.com
This variable has no users anymore. Remove it and tell the
IOMMU code via its new functions about requested DMA modes.
Reviewed-by: Borislav Petkov <bp@suse.de>
Signed-off-by: Joerg Roedel <jroedel@suse.de>
This option allows userspace to pass the RSDP address to the kernel, which
makes it possible for a user to modify the workings of hardware. Reject
the option when the kernel is locked down. This requires some reworking
of the existing RSDP command line logic, since the early boot code also
makes use of a command-line passed RSDP when locating the SRAT table
before the lockdown code has been initialised. This is achieved by
separating the command line RSDP path in the early boot code from the
generic RSDP path, and then copying the command line RSDP into boot
params in the kernel proper if lockdown is not enabled. If lockdown is
enabled and an RSDP is provided on the command line, this will only be
used when parsing SRAT (which shouldn't permit kernel code execution)
and will be ignored in the rest of the kernel.
(Modified by Matthew Garrett in order to handle the early boot RSDP
environment)
Signed-off-by: Josh Boyer <jwboyer@redhat.com>
Signed-off-by: David Howells <dhowells@redhat.com>
Signed-off-by: Matthew Garrett <mjg59@google.com>
Reviewed-by: Kees Cook <keescook@chromium.org>
cc: Dave Young <dyoung@redhat.com>
cc: linux-acpi@vger.kernel.org
Signed-off-by: James Morris <jmorris@namei.org>
Writing to MSRs should not be allowed if the kernel is locked down, since
it could lead to execution of arbitrary code in kernel mode. Based on a
patch by Kees Cook.
Signed-off-by: Matthew Garrett <mjg59@google.com>
Signed-off-by: David Howells <dhowells@redhat.com>
Acked-by: Kees Cook <keescook@chromium.org>
Reviewed-by: Thomas Gleixner <tglx@linutronix.de>
cc: x86@kernel.org
Signed-off-by: James Morris <jmorris@namei.org>
IO port access would permit users to gain access to PCI configuration
registers, which in turn (on a lot of hardware) give access to MMIO
register space. This would potentially permit root to trigger arbitrary
DMA, so lock it down by default.
This also implicitly locks down the KDADDIO, KDDELIO, KDENABIO and
KDDISABIO console ioctls.
Signed-off-by: Matthew Garrett <mjg59@google.com>
Signed-off-by: David Howells <dhowells@redhat.com>
Reviewed-by: Kees Cook <keescook@chromium.org>
cc: x86@kernel.org
Signed-off-by: James Morris <jmorris@namei.org>
This is a preparatory patch for kexec_file_load() lockdown. A locked down
kernel needs to prevent unsigned kernel images from being loaded with
kexec_file_load(). Currently, the only way to force the signature
verification is compiling with KEXEC_VERIFY_SIG. This prevents loading
usigned images even when the kernel is not locked down at runtime.
This patch splits KEXEC_VERIFY_SIG into KEXEC_SIG and KEXEC_SIG_FORCE.
Analogous to the MODULE_SIG and MODULE_SIG_FORCE for modules, KEXEC_SIG
turns on the signature verification but allows unsigned images to be
loaded. KEXEC_SIG_FORCE disallows images without a valid signature.
Signed-off-by: Jiri Bohac <jbohac@suse.cz>
Signed-off-by: David Howells <dhowells@redhat.com>
Signed-off-by: Matthew Garrett <mjg59@google.com>
cc: kexec@lists.infradead.org
Signed-off-by: James Morris <jmorris@namei.org>
Kexec reboot in case secure boot being enabled does not keep the secure
boot mode in new kernel, so later one can load unsigned kernel via legacy
kexec_load. In this state, the system is missing the protections provided
by secure boot.
Adding a patch to fix this by retain the secure_boot flag in original
kernel.
secure_boot flag in boot_params is set in EFI stub, but kexec bypasses the
stub. Fixing this issue by copying secure_boot flag across kexec reboot.
Signed-off-by: Dave Young <dyoung@redhat.com>
Signed-off-by: David Howells <dhowells@redhat.com>
Signed-off-by: Matthew Garrett <mjg59@google.com>
Reviewed-by: Kees Cook <keescook@chromium.org>
cc: kexec@lists.infradead.org
Signed-off-by: James Morris <jmorris@namei.org>
Both the 64bit and the 32bit handle_irq() implementation check the irq
descriptor pointer with IS_ERR_OR_NULL() and return failure. That can be
done simpler in the common do_IRQ() code.
This reduces the 64bit handle_irq() function to a wrapper around
generic_handle_irq_desc(). Invoke it directly from do_IRQ() to spare the
extra function call.
[ tglx: Got rid of the #ifdef and massaged changelog ]
Signed-off-by: Heiner Kallweit <hkallweit1@gmail.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Link: https://lkml.kernel.org/r/2ec758c7-9aaa-73ab-f083-cc44c86aa741@gmail.com
Some newer machines do not advertise legacy timers. The kernel can handle
that situation if the TSC and the CPU frequency are enumerated by CPUID or
MSRs and the CPU supports TSC deadline timer. If the CPU does not support
TSC deadline timer the local APIC timer frequency has to be known as well.
Some Ryzens machines do not advertize legacy timers, but there is no
reliable way to determine the bus frequency which feeds the local APIC
timer when the machine allows overclocking of that frequency.
As there is no legacy timer the local APIC timer calibration crashes due to
a NULL pointer dereference when accessing the not installed global clock
event device.
Switch the calibration loop to a non interrupt based one, which polls
either TSC (if frequency is known) or jiffies. The latter requires a global
clockevent. As the machines which do not have a global clockevent installed
have a known TSC frequency this is a non issue. For older machines where
TSC frequency is not known, there is no known case where the legacy timers
do not exist as that would have been reported long ago.
Reported-by: Daniel Drake <drake@endlessm.com>
Reported-by: Jiri Slaby <jslaby@suse.cz>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Tested-by: Daniel Drake <drake@endlessm.com>
Cc: stable@vger.kernel.org
Link: https://lkml.kernel.org/r/alpine.DEB.2.21.1908091443030.21433@nanos.tec.linutronix.de
Link: http://bugzilla.opensuse.org/show_bug.cgi?id=1142926#c12
Fix
arch/x86/kernel/apic/probe_32.c: In function ‘default_setup_apic_routing’:
arch/x86/kernel/apic/probe_32.c:146:7: warning: this statement may fall through [-Wimplicit-fallthrough=]
if (!APIC_XAPIC(version)) {
^
arch/x86/kernel/apic/probe_32.c:151:3: note: here
case X86_VENDOR_HYGON:
^~~~
for 32-bit builds.
Signed-off-by: Borislav Petkov <bp@suse.de>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Link: https://lkml.kernel.org/r/20190811154036.29805-1-bp@alien8.de
Currently, failure of cpuhp_setup_state() is ignored and the syscore ops
and the control interfaces can still be added even after the failure. But,
this error handling will cause a few issues:
1. The CPUs may have different values in the IA32_UMWAIT_CONTROL
MSR because there is no way to roll back the control MSR on
the CPUs which already set the MSR before the failure.
2. If the sysfs interface is added successfully, there will be a mismatch
between the global control value and the control MSR:
- The interface shows the default global control value. But,
the control MSR is not set to the value because the CPU online
function, which is supposed to set the MSR to the value,
is not installed.
- If the sysadmin changes the global control value through
the interface, the control MSR on all current online CPUs is
set to the new value. But, the control MSR on newly onlined CPUs
after the value change will not be set to the new value due to
lack of the CPU online function.
3. On resume from suspend/hibernation, the boot CPU restores the control
MSR to the global control value through the syscore ops. But, the
control MSR on all APs is not set due to lake of the CPU online
function.
To solve the issues and enforce consistent behavior on the failure
of the CPU hotplug setup, make the following changes:
1. Cache the original control MSR value which is configured by
hardware or BIOS before kernel boot. This value is likely to
be 0. But it could be a different number as well. Cache the
control MSR only once before the MSR is changed.
2. Add the CPU offline function so that the MSR is restored to the
original control value on all CPUs on the failure.
3. On the failure, exit from cpumait_init() so that the syscore ops
and the control interfaces are not added.
Reported-by: Valdis Kletnieks <valdis.kletnieks@vt.edu>
Suggested-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Fenghua Yu <fenghua.yu@intel.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Link: https://lkml.kernel.org/r/1565401237-60936-1-git-send-email-fenghua.yu@intel.com
Pull x86 fixes from Thomas Gleixner:
"A few fixes for x86:
- Don't reset the carefully adjusted build flags for the purgatory
and remove the unwanted flags instead. The 'reset all' approach led
to build fails under certain circumstances.
- Unbreak CLANG build of the purgatory by avoiding the builtin
memcpy/memset implementations.
- Address missing prototype warnings by including the proper header
- Fix yet more fall-through issues"
* 'x86-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
x86/lib/cpu: Address missing prototypes warning
x86/purgatory: Use CFLAGS_REMOVE rather than reset KBUILD_CFLAGS
x86/purgatory: Do not use __builtin_memcpy and __builtin_memset
x86: mtrr: cyrix: Mark expected switch fall-through
x86/ptrace: Mark expected switch fall-through
Pull kvm fixes from Paolo Bonzini:
"Bugfixes (arm and x86) and cleanups"
* tag 'for-linus' of git://git.kernel.org/pub/scm/virt/kvm/kvm:
selftests: kvm: Adding config fragments
KVM: selftests: Update gitignore file for latest changes
kvm: remove unnecessary PageReserved check
KVM: arm/arm64: vgic: Reevaluate level sensitive interrupts on enable
KVM: arm: Don't write junk to CP15 registers on reset
KVM: arm64: Don't write junk to sysregs on reset
KVM: arm/arm64: Sync ICH_VMCR_EL2 back when about to block
x86: kvm: remove useless calls to kvm_para_available
KVM: no need to check return value of debugfs_create functions
KVM: remove kvm_arch_has_vcpu_debugfs()
KVM: Fix leak vCPU's VMCS value into other pCPU
KVM: Check preempted_in_kernel for involuntary preemption
KVM: LAPIC: Don't need to wakeup vCPU twice afer timer fire
arm64: KVM: hyp: debug-sr: Mark expected switch fall-through
KVM: arm64: Update kvm_arm_exception_class and esr_class_str for new EC
KVM: arm: vgic-v3: Mark expected switch fall-through
arm64: KVM: regmap: Fix unexpected switch fall-through
KVM: arm/arm64: Introduce kvm_pmu_vcpu_init() to setup PMU counter index
KVM/arm fixes for 5.3
- A bunch of switch/case fall-through annotation, fixing one actual bug
- Fix PMU reset bug
- Add missing exception class debug strings
Secure Encrypted Virtualization is an x86-specific feature, so it shouldn't
appear in generic kernel code because it forces non-x86 architectures to
define the sev_active() function, which doesn't make a lot of sense.
To solve this problem, add an x86 elfcorehdr_read() function to override
the generic weak implementation. To do that, it's necessary to make
read_from_oldmem() public so that it can be used outside of vmcore.c.
Also, remove the export for sev_active() since it's only used in files that
won't be built as modules.
Signed-off-by: Thiago Jung Bauermann <bauerman@linux.ibm.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Lianbo Jiang <lijiang@redhat.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20190806044919.10622-6-bauerman@linux.ibm.com
Mark switch cases where we are expecting to fall through.
Fix the following warning (Building: allnoconfig i386):
arch/x86/kernel/ptrace.c:202:6: warning: this statement may fall through [-Wimplicit-fallthrough=]
if (unlikely(value == 0))
^
arch/x86/kernel/ptrace.c:206:2: note: here
default:
^~~~~~~
Signed-off-by: Gustavo A. R. Silva <gustavo@embeddedor.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Kees Cook <keescook@chromium.org>
Link: https://lkml.kernel.org/r/20190805195654.GA17831@embeddedor
- More changes on simplifying locking mechanisms (Chris)
- Selftests fixes and improvements (Chris)
- More work around engine tracking for better handling (Chris, Tvrtko)
- HDCP debug and info improvements (Ram, Ashuman)
- Add DSI properties (Vandita)
- Rework on sdvo support for better debuggability before fixing bugs (Ville)
- Display PLLs fixes and improvements, specially targeting Ice Lake (Imre, Matt, Ville)
- Perf fixes and improvements (Lionel)
- Enumerate scratch buffers (Lionel)
- Add infra to hold off preemption on a request (Lionel)
- Ice Lake color space fixes (Uma)
- Type-C fixes and improvements (Lucas)
- Fix and improvements around workarounds (Chris, John, Tvrtko)
- GuC related fixes and improvements (Chris, Daniele, Michal, Tvrtko)
- Fix on VLV/CHV display power domain (Ville)
- Improvements around Watermark (Ville)
- Favor intel_ types on intel_atomic functions (Ville)
- Don’t pass stack garbage to pcode (Ville)
- Improve display tracepoints (Steven)
- Don’t overestimate 4:2:0 link symbol clock (Ville)
- Add support for 4th pipe and transcoder (Lucas)
- Introduce initial support for Tiger Lake platform (Daniele, Lucas, Mahesh, Jose, Imre, Mika, Vandita, Rodrigo, Michel)
- PPGTT allocation simplification (Chris)
- Standardize function names and suffixes to make clean, symmetric and let checkpatch happy (Janusz)
- Skip SINK_COUNT read on CH7511 (Ville)
- Fix on kernel documentation (Chris, Michal)
- Add modular FIA (Anusha, Lucas)
- Fix EHL display (Matt, Vivek)
- Enable hotplug retry (Imre, Jose)
- Disable preemption under GVT (Chris)
- OA; Reconfigure context on the fly (Chris)
- Fixes and improvements around engine reset. (Chris)
- Small clean up on display pipe fault mask (Ville)
- Make sure cdclk is high enough for DP audio on VLV/CHV (Ville)
- Drop some wmb() and improve pwrite flush (Chris)
- Fix critical PSR regression (DK)
- Remove unused variables (YueHaibing)
- Use dev_get_drvdata for simplification (Chunhong)
- Use upstream version of header tests (Jani)
drm-intel-next-2019-07-08:
- Signal fence completion from i915_request_wait (Chris)
- Fixes and improvements around rings pin/unpin (Chris)
- Display uncore prep patches (Daniele)
- Execlists preemption improvements (Chris)
- Selftests fixes and improvements (Chris)
- More Elkhartlake enabling work (Vandita, Jose, Matt, Vivek)
- Defer address space cleanup to an RCU worker (Chris)
- Implicit dev_priv removal and GT compartmentalization and other related follow-ups (Tvrtko, Chris)
- Prevent dereference of engine before NULL check in error capture (Chris)
- GuC related fixes (Daniele, Robert)
- Many changes on active tracking, timelines and locking mechanisms (Chris)
- Disable SAMPLER_STATE prefetching on Gen11 (HW W/a) (Kenneth)
- I915_perf fixes (Lionel)
- Add Ice Lake PCI ID (Mika)
- eDP backlight fix (Lee)
- Fix various gen2 tracepoints (Ville)
- Some irq vfunc clean-up and improvements (Ville)
- Move OA files to separated folder (Michal)
- Display self contained headers clean-up (Jani)
- Preparation for 4th pile (Lucas)
- Move atomic commit, watermark and other places to use more intel_crtc_state (Maarten)
- Many Ice Lake Type C and Thunderbolt fixes (Imre)
- Fix some Ice Lake hw w/a whitelist regs (Lionel)
- Fix memleak in runtime wakeref tracking (Mika)
- Remove unused Private PPAT manager (Michal)
- Don't check PPGTT presence on PPGTT-only platforms (Michal)
- Fix ICL DSI suspend/resume (Chris)
- Fix ICL Bandwidth issues (Ville)
- Add N & CTS values for 10/12 bit deep color (Aditya)
- Moving more GT related stuff under gt folder (Chris)
- Forcewake related fixes (Chris)
- Show support for accurate sw PMU busyness tracking (Chris)
- Handle gtt double alloc failures (Chris)
- Upgrade to new GuC version (Michal)
- Improve w/a debug dumps and pull engine w/a initialization into a common (Chris)
- Look for instdone on all engines at hangcheck (Tvrtko)
- Engine lookup simplification (Chris)
- Many plane color formats fixes and improvements (Ville)
- Fix some compilation issues (YueHaibing)
- GTT page directory clean up and improvements (Mika)
Signed-off-by: Dave Airlie <airlied@redhat.com>
From: Rodrigo Vivi <rodrigo.vivi@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20190801201314.GA23635@intel.com
Most code in arch/x86/kernel/kvm.c is called through x86_hyper_kvm, and thus only
runs if KVM has been detected. There is no need to check again for the CPUID
base.
Cc: Sergio Lopez <slp@redhat.com>
Cc: Jan Kiszka <jan.kiszka@siemens.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
We currently do not process SRAO (Software Recoverable Action Optional)
machine checks if they are logged with the overflow bit set to 1 in the
machine check bank status register. This is overly conservative.
There are two cases where we could end up with an SRAO+OVER log based
on the SDM volume 3 overwrite rules in "Table 15-8. Overwrite Rules for
UC, CE, and UCR Errors"
1) First a corrected error is logged, then the SRAO error overwrites.
The second error overwrites the first because uncorrected errors
have a higher severity than corrected errors.
2) The SRAO error was logged first, followed by a correcetd error.
In this case the first error is retained in the bank.
So in either case the machine check bank will contain the address
of the SRAO error. So we can process that even if the overflow bit
was set.
Reported-by: Yongkai Wu <yongkaiwu@tencent.com>
Signed-off-by: Tony Luck <tony.luck@intel.com>
Signed-off-by: Borislav Petkov <bp@suse.de>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: linux-edac <linux-edac@vger.kernel.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: x86-ml <x86@kernel.org>
Link: https://lkml.kernel.org/r/20190718182920.32621-1-tony.luck@intel.com
When performing guest side polling, it is not necessary to
also perform host side polling.
So disable host side polling, via the new MSR interface,
when loading cpuidle-haltpoll driver.
Signed-off-by: Marcelo Tosatti <mtosatti@redhat.com>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Add a cpuidle driver that calls the architecture default_idle routine.
To be used in conjunction with the haltpoll governor.
Signed-off-by: Marcelo Tosatti <mtosatti@redhat.com>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Intel provided the following information:
On all current Atom processors, instructions that use a segment register
value (e.g. a load or store) will not speculatively execute before the
last writer of that segment retires. Thus they will not use a
speculatively written segment value.
That means on ATOMs there is no speculation through SWAPGS, so the SWAPGS
entry paths can be excluded from the extra LFENCE if PTI is disabled.
Create a separate bug flag for the through SWAPGS speculation and mark all
out-of-order ATOMs and AMD/HYGON CPUs as not affected. The in-order ATOMs
are excluded from the whole mitigation mess anyway.
Reported-by: Andrew Cooper <andrew.cooper3@citrix.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Tyler Hicks <tyhicks@canonical.com>
Reviewed-by: Josh Poimboeuf <jpoimboe@redhat.com>
All callers of apic->send_IPI_all() and apic->send_IPI_allbutself() contain
the decision logic for shorthand invocation already and invoke
send_IPI_mask() if the prereqisites are not satisfied.
Implement shorthand support for x2apic.
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://lkml.kernel.org/r/20190722105221.134696837@linutronix.de
All callers of apic->send_IPI_all() and apic->send_IPI_allbutself() contain
the decision logic for shorthand invocation already and invoke
send_IPI_mask() if the prereqisites are not satisfied.
Remove the now redundant decision logic in the APIC code and the duplicate
helper in probe_64.c.
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://lkml.kernel.org/r/20190722105221.042964120@linutronix.de
All callers of apic->send_IPI_all() and apic->send_IPI_allbutself() contain
the decision logic for shorthand invocation already and invoke
send_IPI_mask() if the prereqisites are not satisfied.
Remove the now redundant decision logic in the 32bit implementation.
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://lkml.kernel.org/r/20190722105220.860244707@linutronix.de
Nadav noticed that the cpumask allocations in native_send_call_func_ipi()
are noticeable in microbenchmarks.
Use the new cpumask_or_equal() function to simplify the decision whether
the supplied target CPU mask is either equal to cpu_online_mask or equal to
cpu_online_mask except for the CPU on which the function is invoked.
cpumask_or_equal() or's the target mask and the cpumask of the current CPU
together and compares it to cpu_online_mask.
If the result is false, use the mask based IPI function, otherwise check
whether the current CPU is set in the target mask and invoke either the
send_IPI_all() or the send_IPI_allbutselt() APIC callback.
Make the shorthand decision also depend on the static key which enables
shorthand mode. That allows to remove the extra cpumask comparison with
cpu_callout_mask.
Reported-by: Nadav Amit <namit@vmware.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://lkml.kernel.org/r/20190722105220.768238809@linutronix.de
