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git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip
Pull objtool updates from Ingo Molnar:
- Mark arch_cpu_idle_dead() __noreturn, make all architectures &
drivers that did this inconsistently follow this new, common
convention, and fix all the fallout that objtool can now detect
statically
- Fix/improve the ORC unwinder becoming unreliable due to
UNWIND_HINT_EMPTY ambiguity, split it into UNWIND_HINT_END_OF_STACK
and UNWIND_HINT_UNDEFINED to resolve it
- Fix noinstr violations in the KCSAN code and the lkdtm/stackleak code
- Generate ORC data for __pfx code
- Add more __noreturn annotations to various kernel startup/shutdown
and panic functions
- Misc improvements & fixes
* tag 'objtool-core-2023-04-27' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (52 commits)
x86/hyperv: Mark hv_ghcb_terminate() as noreturn
scsi: message: fusion: Mark mpt_halt_firmware() __noreturn
x86/cpu: Mark {hlt,resume}_play_dead() __noreturn
btrfs: Mark btrfs_assertfail() __noreturn
objtool: Include weak functions in global_noreturns check
cpu: Mark nmi_panic_self_stop() __noreturn
cpu: Mark panic_smp_self_stop() __noreturn
arm64/cpu: Mark cpu_park_loop() and friends __noreturn
x86/head: Mark *_start_kernel() __noreturn
init: Mark start_kernel() __noreturn
init: Mark [arch_call_]rest_init() __noreturn
objtool: Generate ORC data for __pfx code
x86/linkage: Fix padding for typed functions
objtool: Separate prefix code from stack validation code
objtool: Remove superfluous dead_end_function() check
objtool: Add symbol iteration helpers
objtool: Add WARN_INSN()
scripts/objdump-func: Support multiple functions
context_tracking: Fix KCSAN noinstr violation
objtool: Add stackleak instrumentation to uaccess safe list
...
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git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip
Pull x86 APIC updates from Thomas Gleixner:
- Fix the incorrect handling of atomic offset updates in
reserve_eilvt_offset()
The check for the return value of atomic_cmpxchg() is not compared
against the old value, it is compared against the new value, which
makes it two round on success.
Convert it to atomic_try_cmpxchg() which does the right thing.
- Handle IO/APIC less systems correctly
When IO/APIC is not advertised by ACPI then the computation of the
lower bound for dynamically allocated interrupts like MSI goes wrong.
This lower bound is used to exclude the IO/APIC legacy GSI space as
that must stay reserved for the legacy interrupts.
In case that the system, e.g. VM, does not advertise an IO/APIC the
lower bound stays at 0.
0 is an invalid interrupt number except for the legacy timer
interrupt on x86. The return value is unchecked in the core code, so
it ends up to allocate interrupt number 0 which is subsequently
considered to be invalid by the caller, e.g. the MSI allocation code.
A similar problem was already cured for device tree based systems
years ago, but that missed - or did not envision - the zero IO/APIC
case.
Consolidate the zero check and return the provided "from" argument to
the core code call site, which is guaranteed to be greater than 0.
- Simplify the X2APIC cluster CPU mask logic for CPU hotplug
Per cluster CPU masks are required for X2APIC in cluster mode to
determine the correct cluster for a target CPU when calculating the
destination for IPIs
These masks are established when CPUs are borught up. The first CPU
in a cluster must allocate a new cluster CPU mask. As this happens
during the early startup of a CPU, where memory allocations cannot be
done, the mask has to be allocated by the control CPU.
The current implementation allocates a clustermask just in case and
if the to be brought up CPU is the first in a cluster the CPU takes
over this allocation from a global pointer.
This works nicely in the fully serialized CPU bringup scenario which
is used today, but would fail completely for parallel bringup of
CPUs.
The cluster association of a CPU can be computed from the APIC ID
which is enumerated by ACPI/MADT.
So the cluster CPU masks can be preallocated and associated upfront
and the upcoming CPUs just need to set their corresponding bit.
Aside of preparing for parallel bringup this is a valuable
simplification on its own.
- Remove global variables which control the early startup of secondary
CPUs on 64-bit
The only information which is needed by a starting CPU is the Linux
CPU number. The CPU number allows it to retrieve the rest of the
required data from already existing per CPU storage.
So instead of initial_stack, early_gdt_desciptor and initial_gs
provide a new variable smpboot_control which contains the Linux CPU
number for now. The starting CPU can retrieve and compute all
required information for startup from there.
Aside of being a cleanup, this is also preparing for parallel CPU
bringup, where starting CPUs will look up their Linux CPU number via
the APIC ID, when smpboot_control has the corresponding control bit
set.
- Make cc_vendor globally accesible
Subsequent parallel bringup changes require access to cc_vendor
because confidental computing platforms need special treatment in the
early startup phase vs. CPUID and APCI ID readouts.
The change makes cc_vendor global and provides stub accessors in case
that CONFIG_ARCH_HAS_CC_PLATFORM is not set.
This was merged from the x86/cc branch in anticipation of further
parallel bringup commits which require access to cc_vendor. Due to
late discoveries of fundamental issue with those patches these
commits never happened.
The merge commit is unfortunately in the middle of the APIC commits
so unraveling it would have required a rebase or revert. As the
parallel bringup seems to be well on its way for 6.5 this would be
just pointless churn. As the commit does not contain any functional
change it's not a risk to keep it.
* tag 'x86-apic-2023-04-24' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
x86/ioapic: Don't return 0 from arch_dynirq_lower_bound()
x86/apic: Fix atomic update of offset in reserve_eilvt_offset()
x86/coco: Export cc_vendor
x86/smpboot: Reference count on smpboot_setup_warm_reset_vector()
x86/smpboot: Remove initial_gs
x86/smpboot: Remove early_gdt_descr on 64-bit
x86/smpboot: Remove initial_stack on 64-bit
x86/apic/x2apic: Allow CPU cluster_mask to be populated in parallel
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git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip
Pull x86 paravirt updates from Borislav Petkov:
- Convert a couple of paravirt callbacks to asm to prevent
'-fzero-call-used-regs' builds from zeroing live registers because
paravirt hides the CALLs from the compiler so latter doesn't know
there's a CALL in the first place
- Merge two paravirt callbacks into one, as their functionality is
identical
* tag 'x86_paravirt_for_v6.4_rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
x86/paravirt: Convert simple paravirt functions to asm
x86/paravirt: Merge activate_mm() and dup_mmap() callbacks
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git://git.kernel.org/pub/scm/linux/kernel/git/xen/tip
Pull xen fixes from Juergen Gross:
- fix build warning
- avoid concurrent accesses to the Xen PV console ring page
* tag 'for-linus-6.3-rc4-tag' of git://git.kernel.org/pub/scm/linux/kernel/git/xen/tip:
x86/PVH: avoid 32-bit build warning when obtaining VGA console info
hvc/xen: prevent concurrent accesses to the shared ring
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Mark reported that the ORC unwinder incorrectly marks an unwind as
reliable when the unwind terminates prematurely in the dark corners of
return_to_handler() due to lack of information about the next frame.
The problem is UNWIND_HINT_EMPTY is used in two different situations:
1) The end of the kernel stack unwind before hitting user entry, boot
code, or fork entry
2) A blind spot in ORC coverage where the unwinder has to bail due to
lack of information about the next frame
The ORC unwinder has no way to tell the difference between the two.
When it encounters an undefined stack state with 'end=1', it blindly
marks the stack reliable, which can break the livepatch consistency
model.
Fix it by splitting UNWIND_HINT_EMPTY into UNWIND_HINT_UNDEFINED and
UNWIND_HINT_END_OF_STACK.
Reported-by: Mark Rutland <mark.rutland@arm.com>
Signed-off-by: Josh Poimboeuf <jpoimboe@kernel.org>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Acked-by: Steven Rostedt (Google) <rostedt@goodmis.org>
Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://lore.kernel.org/r/fd6212c8b450d3564b855e1cb48404d6277b4d9f.1677683419.git.jpoimboe@kernel.org
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In the commit referenced below I failed to pay attention to this code
also being buildable as 32-bit. Adjust the type of "ret" - there's no
real need for it to be wider than 32 bits.
Fixes: 934ef33ee75c ("x86/PVH: obtain VGA console info in Dom0")
Reported-by: kernel test robot <lkp@intel.com>
Signed-off-by: Jan Beulich <jbeulich@suse.com>
Reviewed-by: Juergen Gross <jgross@suse.com>
Link: https://lore.kernel.org/r/2d2193ff-670b-0a27-e12d-2c5c4c121c79@suse.com
Signed-off-by: Juergen Gross <jgross@suse.com>
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In order to facilitate parallel startup, start to eliminate some of the
global variables passing information to CPUs in the startup path.
However, start by introducing one more: smpboot_control. For now this
merely holds the CPU# of the CPU which is coming up. Each CPU can then
find its own per-cpu data, and everything else it needs can be found
from there, allowing the other global variables to be removed.
First to be removed is initial_stack. Each CPU can load %rsp from its
current_task->thread.sp instead. That is already set up with the correct
idle thread for APs. Set up the .sp field in INIT_THREAD on x86 so that
the BSP also finds a suitable stack pointer in the static per-cpu data
when coming up on first boot.
On resume from S3, the CPU needs a temporary stack because its idle task
is already active. Instead of setting initial_stack, the sleep code can
simply set its own current->thread.sp to point to the temporary stack.
Nobody else cares about ->thread.sp for a thread which is currently on
a CPU, because the true value is actually in the %rsp register. Which
is restored with the rest of the CPU context in do_suspend_lowlevel().
Signed-off-by: Brian Gerst <brgerst@gmail.com>
Signed-off-by: David Woodhouse <dwmw@amazon.co.uk>
Signed-off-by: Usama Arif <usama.arif@bytedance.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Tested-by: Usama Arif <usama.arif@bytedance.com>
Tested-by: Guilherme G. Piccoli <gpiccoli@igalia.com>
Reviewed-by: David Woodhouse <dwmw@amazon.co.uk>
Link: https://lore.kernel.org/r/20230316222109.1940300-7-usama.arif@bytedance.com
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git://git.kernel.org/pub/scm/linux/kernel/git/xen/tip
Pull xen fixes from Juergen Gross:
- cleanup for xen time handling
- enable the VGA console in a Xen PVH dom0
- cleanup in the xenfs driver
* tag 'for-linus-6.3-rc3-tag' of git://git.kernel.org/pub/scm/linux/kernel/git/xen/tip:
xen: remove unnecessary (void*) conversions
x86/PVH: obtain VGA console info in Dom0
x86/xen/time: cleanup xen_tsc_safe_clocksource
xen: update arch/x86/include/asm/xen/cpuid.h
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A new platform-op was added to Xen to allow obtaining the same VGA
console information PV Dom0 is handed. Invoke the new function and have
the output data processed by xen_init_vga().
Signed-off-by: Jan Beulich <jbeulich@suse.com>
Reviewed-by: Juergen Gross <jgross@suse.com>
Link: https://lore.kernel.org/r/8f315e92-7bda-c124-71cc-478ab9c5e610@suse.com
Signed-off-by: Juergen Gross <jgross@suse.com>
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The two paravirt callbacks .mmu.activate_mm() and .mmu.dup_mmap() are
sharing the same implementations in all cases: for Xen PV guests they
are pinning the PGD of the new mm_struct, and for all other cases they
are a NOP.
In the end, both callbacks are meant to register an address space with
the underlying hypervisor, so there needs to be only a single callback
for that purpose.
So merge them to a common callback .mmu.enter_mmap() (in contrast to the
corresponding already existing .mmu.exit_mmap()).
As the first parameter of the old callbacks isn't used, drop it from the
replacement one.
[ bp: Remove last occurrence of paravirt_activate_mm() in
asm/mmu_context.h ]
Signed-off-by: Juergen Gross <jgross@suse.com>
Signed-off-by: Borislav Petkov (AMD) <bp@alien8.de>
Reviewed-by: Boris Ostrovsky <boris.ostrovsky@oracle.com>
Reviewed-by: Srivatsa S. Bhat (VMware) <srivatsa@csail.mit.edu>
Link: https://lore.kernel.org/r/20230207075902.7539-1-jgross@suse.com
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Modifies xen_tsc_safe_clocksource() to use newly defined constants from
arch/x86/include/asm/xen/cpuid.h. This replaces a numeric value with
XEN_CPUID_TSC_MODE_NEVER_EMULATE, and deletes a comment that is now self
explanatory.
There should be no change in the function's behavior.
Signed-off-by: Krister Johansen <kjlx@templeofstupid.com>
Reviewed-by: Juergen Gross <jgross@suse.com>
Link: https://lore.kernel.org/r/a69ca370fecf85d312d2db633d9438ace2af6e5b.1677038165.git.kjlx@templeofstupid.com
Signed-off-by: Juergen Gross <jgross@suse.com>
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git://git.kernel.org/pub/scm/linux/kernel/git/xen/tip
Pull xen updates from Juergen Gross:
- help deprecate the /proc/xen files by making the related information
available via sysfs
- mark the Xen variants of play_dead "noreturn"
- support a shared Xen platform interrupt
- several small cleanups and fixes
* tag 'for-linus-6.3-rc1-tag' of git://git.kernel.org/pub/scm/linux/kernel/git/xen/tip:
xen: sysfs: make kobj_type structure constant
x86/Xen: drop leftover VM-assist uses
xen: Replace one-element array with flexible-array member
xen/grant-dma-iommu: Implement a dummy probe_device() callback
xen/pvcalls-back: fix permanently masked event channel
xen: Allow platform PCI interrupt to be shared
x86/xen/time: prefer tsc as clocksource when it is invariant
x86/xen: mark xen_pv_play_dead() as __noreturn
x86/xen: don't let xen_pv_play_dead() return
drivers/xen/hypervisor: Expose Xen SIF flags to userspace
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git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip
Pull x86 cpuid updates from Borislav Petkov:
- Cache the AMD debug registers in per-CPU variables to avoid MSR
writes where possible, when supporting a debug registers swap feature
for SEV-ES guests
- Add support for AMD's version of eIBRS called Automatic IBRS which is
a set-and-forget control of indirect branch restriction speculation
resources on privilege change
- Add support for a new x86 instruction - LKGS - Load kernel GS which
is part of the FRED infrastructure
- Reset SPEC_CTRL upon init to accomodate use cases like kexec which
rediscover
- Other smaller fixes and cleanups
* tag 'x86_cpu_for_v6.3_rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
x86/amd: Cache debug register values in percpu variables
KVM: x86: Propagate the AMD Automatic IBRS feature to the guest
x86/cpu: Support AMD Automatic IBRS
x86/cpu, kvm: Add the SMM_CTL MSR not present feature
x86/cpu, kvm: Add the Null Selector Clears Base feature
x86/cpu, kvm: Move X86_FEATURE_LFENCE_RDTSC to its native leaf
x86/cpu, kvm: Add the NO_NESTED_DATA_BP feature
KVM: x86: Move open-coded CPUID leaf 0x80000021 EAX bit propagation code
x86/cpu, kvm: Add support for CPUID_80000021_EAX
x86/gsseg: Add the new <asm/gsseg.h> header to <asm/asm-prototypes.h>
x86/gsseg: Use the LKGS instruction if available for load_gs_index()
x86/gsseg: Move load_gs_index() to its own new header file
x86/gsseg: Make asm_load_gs_index() take an u16
x86/opcode: Add the LKGS instruction to x86-opcode-map
x86/cpufeature: Add the CPU feature bit for LKGS
x86/bugs: Reset speculation control settings on init
x86/cpu: Remove redundant extern x86_read_arch_cap_msr()
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Both the 4Gb-segments and the PAE-extended-CR3 one are applicable to
32-bit guests only. The PAE-extended-CR3 use, furthermore, was redundant
with the PAE_MODE ELF note anyway.
Signed-off-by: Jan Beulich <jbeulich@suse.com>
Reviewed-by: Juergen Gross <jgross@suse.com>
Link: https://lore.kernel.org/r/215515af-cfb9-3237-03ba-3312e3fa0d34@suse.com
Signed-off-by: Juergen Gross <jgross@suse.com>
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Kvm elects to use tsc instead of kvm-clock when it can detect that the
TSC is invariant.
(As of commit 7539b174aef4 ("x86: kvmguest: use TSC clocksource if
invariant TSC is exposed")).
Notable cloud vendors[1] and performance engineers[2] recommend that Xen
users preferentially select tsc over xen-clocksource due the performance
penalty incurred by the latter. These articles are persuasive and
tailored to specific use cases. In order to understand the tradeoffs
around this choice more fully, this author had to reference the
documented[3] complexities around the Xen configuration, as well as the
kernel's clocksource selection algorithm. Many users may not attempt
this to correctly configure the right clock source in their guest.
The approach taken in the kvm-clock module spares users this confusion,
where possible.
Both the Intel SDM[4] and the Xen tsc documentation explain that marking
a tsc as invariant means that it should be considered stable by the OS
and is elibile to be used as a wall clock source.
In order to obtain better out-of-the-box performance, and reduce the
need for user tuning, follow kvm's approach and decrease the xen clock
rating so that tsc is preferable, if it is invariant, stable, and the
tsc will never be emulated.
[1] https://aws.amazon.com/premiumsupport/knowledge-center/manage-ec2-linux-clock-source/
[2] https://www.brendangregg.com/blog/2021-09-26/the-speed-of-time.html
[3] https://xenbits.xen.org/docs/unstable/man/xen-tscmode.7.html
[4] Intel 64 and IA-32 Architectures Sofware Developer's Manual Volume
3b: System Programming Guide, Part 2, Section 17.17.1, Invariant TSC
Signed-off-by: Krister Johansen <kjlx@templeofstupid.com>
Code-reviewed-by: David Reaver <me@davidreaver.com>
Reviewed-by: Juergen Gross <jgross@suse.com>
Link: https://lore.kernel.org/r/20221216162118.GB2633@templeofstupid.com
Signed-off-by: Juergen Gross <jgross@suse.com>
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Mark xen_pv_play_dead() and related to that xen_cpu_bringup_again()
as "__noreturn".
Signed-off-by: Juergen Gross <jgross@suse.com>
Reviewed-by: Boris Ostrovsky <boris.ostrovsky@oracle.com>
Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://lore.kernel.org/r/20221125063248.30256-3-jgross@suse.com
Signed-off-by: Juergen Gross <jgross@suse.com>
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A function called via the paravirt play_dead() hook should not return
to the caller.
xen_pv_play_dead() has a problem in this regard, as it currently will
return in case an offlined cpu is brought to life again. This can be
changed only by doing basically a longjmp() to cpu_bringup_and_idle(),
as the hypercall for bringing down the cpu will just return when the
cpu is coming up again. Just re-initializing the cpu isn't possible,
as the Xen hypervisor will deny that operation.
So introduce xen_cpu_bringup_again() resetting the stack and calling
cpu_bringup_and_idle(), which can be called after HYPERVISOR_vcpu_op()
in xen_pv_play_dead().
Signed-off-by: Juergen Gross <jgross@suse.com>
Reviewed-by: Boris Ostrovsky <boris.ostrovsky@oracle.com>
Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://lore.kernel.org/r/20221125063248.30256-2-jgross@suse.com
Signed-off-by: Juergen Gross <jgross@suse.com>
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In order to use sched_clock() from noinstr code, mark it and all it's
implenentations noinstr.
The whole pvclock thing (used by KVM/Xen) is a bit of a pain,
since it calls out to watchdogs, create a
pvclock_clocksource_read_nowd() variant doesn't do that and can be
noinstr.
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Link: https://lore.kernel.org/r/20230126151323.702003578@infradead.org
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Pick up fixes before merging another batch of cpuidle updates.
Signed-off-by: Ingo Molnar <mingo@kernel.org>
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objtool found a few cases where this code called out into instrumented
code:
vmlinux.o: warning: objtool: acpi_idle_enter_s2idle+0xde: call to wbinvd() leaves .noinstr.text section
vmlinux.o: warning: objtool: default_idle+0x4: call to arch_safe_halt() leaves .noinstr.text section
vmlinux.o: warning: objtool: xen_safe_halt+0xa: call to HYPERVISOR_sched_op.constprop.0() leaves .noinstr.text section
Solve this by:
- marking arch_safe_halt(), wbinvd(), native_wbinvd() and
HYPERVISOR_sched_op() as __always_inline().
- Explicitly uninlining xen_safe_halt() and pv_native_wbinvd() [they were
already uninlined by the compiler on use as function pointers] and
annotating them as 'noinstr'.
- Annotating pv_native_safe_halt() as 'noinstr'.
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Tested-by: Tony Lindgren <tony@atomide.com>
Tested-by: Ulf Hansson <ulf.hansson@linaro.org>
Reviewed-by: Srivatsa S. Bhat (VMware) <srivatsa@csail.mit.edu>
Reviewed-by: Juergen Gross <jgross@suse.com>
Acked-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Acked-by: Frederic Weisbecker <frederic@kernel.org>
Link: https://lore.kernel.org/r/20230112195541.171918174@infradead.org
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The LKGS instruction atomically loads a segment descriptor into the
%gs descriptor registers, *except* that %gs.base is unchanged, and the
base is instead loaded into MSR_IA32_KERNEL_GS_BASE, which is exactly
what we want this function to do.
Signed-off-by: H. Peter Anvin (Intel) <hpa@zytor.com>
Signed-off-by: Xin Li <xin3.li@intel.com>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Acked-by: Peter Zijlstra <peterz@infradead.org>
Link: https://lore.kernel.org/r/20230112072032.35626-6-xin3.li@intel.com
Cc: Andy Lutomirski <luto@kernel.org>
Cc: Dave Hansen <dave.hansen@linux.intel.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
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git://git.kernel.org/pub/scm/linux/kernel/git/xen/tip
Pull xen fixes from Juergen Gross:
- two cleanup patches
- a fix of a memory leak in the Xen pvfront driver
- a fix of a locking issue in the Xen hypervisor console driver
* tag 'for-linus-6.2-rc4-tag' of git://git.kernel.org/pub/scm/linux/kernel/git/xen/tip:
xen/pvcalls: free active map buffer on pvcalls_front_free_map
hvc/xen: lock console list traversal
x86/xen: Remove the unused function p2m_index()
xen: make remove callback of xen driver void returned
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The function p2m_index is defined in the p2m.c file, but not called
elsewhere, so remove this unused function.
arch/x86/xen/p2m.c:137:24: warning: unused function 'p2m_index'.
Link: https://bugzilla.openanolis.cn/show_bug.cgi?id=3557
Reported-by: Abaci Robot <abaci@linux.alibaba.com>
Signed-off-by: Jiapeng Chong <jiapeng.chong@linux.alibaba.com>
Reviewed-by: Juergen Gross <jgross@suse.com>
Link: https://lore.kernel.org/r/20230105090141.36248-1-jiapeng.chong@linux.alibaba.com
Signed-off-by: Juergen Gross <jgross@suse.com>
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git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip
Pull x86 core updates from Borislav Petkov:
- Add the call depth tracking mitigation for Retbleed which has been
long in the making. It is a lighterweight software-only fix for
Skylake-based cores where enabling IBRS is a big hammer and causes a
significant performance impact.
What it basically does is, it aligns all kernel functions to 16 bytes
boundary and adds a 16-byte padding before the function, objtool
collects all functions' locations and when the mitigation gets
applied, it patches a call accounting thunk which is used to track
the call depth of the stack at any time.
When that call depth reaches a magical, microarchitecture-specific
value for the Return Stack Buffer, the code stuffs that RSB and
avoids its underflow which could otherwise lead to the Intel variant
of Retbleed.
This software-only solution brings a lot of the lost performance
back, as benchmarks suggest:
https://lore.kernel.org/all/20220915111039.092790446@infradead.org/
That page above also contains a lot more detailed explanation of the
whole mechanism
- Implement a new control flow integrity scheme called FineIBT which is
based on the software kCFI implementation and uses hardware IBT
support where present to annotate and track indirect branches using a
hash to validate them
- Other misc fixes and cleanups
* tag 'x86_core_for_v6.2' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (80 commits)
x86/paravirt: Use common macro for creating simple asm paravirt functions
x86/paravirt: Remove clobber bitmask from .parainstructions
x86/debug: Include percpu.h in debugreg.h to get DECLARE_PER_CPU() et al
x86/cpufeatures: Move X86_FEATURE_CALL_DEPTH from bit 18 to bit 19 of word 11, to leave space for WIP X86_FEATURE_SGX_EDECCSSA bit
x86/Kconfig: Enable kernel IBT by default
x86,pm: Force out-of-line memcpy()
objtool: Fix weak hole vs prefix symbol
objtool: Optimize elf_dirty_reloc_sym()
x86/cfi: Add boot time hash randomization
x86/cfi: Boot time selection of CFI scheme
x86/ibt: Implement FineIBT
objtool: Add --cfi to generate the .cfi_sites section
x86: Add prefix symbols for function padding
objtool: Add option to generate prefix symbols
objtool: Avoid O(bloody terrible) behaviour -- an ode to libelf
objtool: Slice up elf_create_section_symbol()
kallsyms: Revert "Take callthunks into account"
x86: Unconfuse CONFIG_ and X86_FEATURE_ namespaces
x86/retpoline: Fix crash printing warning
x86/paravirt: Fix a !PARAVIRT build warning
...
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git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip
Pull x86 boot updates from Borislav Petkov:
"A of early boot cleanups and fixes.
- Do some spring cleaning to the compressed boot code by moving the
EFI mixed-mode code to a separate compilation unit, the AMD memory
encryption early code where it belongs and fixing up build
dependencies. Make the deprecated EFI handover protocol optional
with the goal of removing it at some point (Ard Biesheuvel)
- Skip realmode init code on Xen PV guests as it is not needed there
- Remove an old 32-bit PIC code compiler workaround"
* tag 'x86_boot_for_v6.2' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
x86/boot: Remove x86_32 PIC using %ebx workaround
x86/boot: Skip realmode init code when running as Xen PV guest
x86/efi: Make the deprecated EFI handover protocol optional
x86/boot/compressed: Only build mem_encrypt.S if AMD_MEM_ENCRYPT=y
x86/boot/compressed: Adhere to calling convention in get_sev_encryption_bit()
x86/boot/compressed: Move startup32_check_sev_cbit() out of head_64.S
x86/boot/compressed: Move startup32_check_sev_cbit() into .text
x86/boot/compressed: Move startup32_load_idt() out of head_64.S
x86/boot/compressed: Move startup32_load_idt() into .text section
x86/boot/compressed: Pull global variable reference into startup32_load_idt()
x86/boot/compressed: Avoid touching ECX in startup32_set_idt_entry()
x86/boot/compressed: Simplify IDT/GDT preserve/restore in the EFI thunk
x86/boot/compressed, efi: Merge multiple definitions of image_offset into one
x86/boot/compressed: Move efi32_pe_entry() out of head_64.S
x86/boot/compressed: Move efi32_entry out of head_64.S
x86/boot/compressed: Move efi32_pe_entry into .text section
x86/boot/compressed: Move bootargs parsing out of 32-bit startup code
x86/boot/compressed: Move 32-bit entrypoint code into .text section
x86/boot/compressed: Rename efi_thunk_64.S to efi-mixed.S
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git://git.kernel.org/pub/scm/linux/kernel/git/crng/random
Pull random number generator updates from Jason Donenfeld:
- Replace prandom_u32_max() and various open-coded variants of it,
there is now a new family of functions that uses fast rejection
sampling to choose properly uniformly random numbers within an
interval:
get_random_u32_below(ceil) - [0, ceil)
get_random_u32_above(floor) - (floor, U32_MAX]
get_random_u32_inclusive(floor, ceil) - [floor, ceil]
Coccinelle was used to convert all current users of
prandom_u32_max(), as well as many open-coded patterns, resulting in
improvements throughout the tree.
I'll have a "late" 6.1-rc1 pull for you that removes the now unused
prandom_u32_max() function, just in case any other trees add a new
use case of it that needs to converted. According to linux-next,
there may be two trivial cases of prandom_u32_max() reintroductions
that are fixable with a 's/.../.../'. So I'll have for you a final
conversion patch doing that alongside the removal patch during the
second week.
This is a treewide change that touches many files throughout.
- More consistent use of get_random_canary().
- Updates to comments, documentation, tests, headers, and
simplification in configuration.
- The arch_get_random*_early() abstraction was only used by arm64 and
wasn't entirely useful, so this has been replaced by code that works
in all relevant contexts.
- The kernel will use and manage random seeds in non-volatile EFI
variables, refreshing a variable with a fresh seed when the RNG is
initialized. The RNG GUID namespace is then hidden from efivarfs to
prevent accidental leakage.
These changes are split into random.c infrastructure code used in the
EFI subsystem, in this pull request, and related support inside of
EFISTUB, in Ard's EFI tree. These are co-dependent for full
functionality, but the order of merging doesn't matter.
- Part of the infrastructure added for the EFI support is also used for
an improvement to the way vsprintf initializes its siphash key,
replacing an sleep loop wart.
- The hardware RNG framework now always calls its correct random.c
input function, add_hwgenerator_randomness(), rather than sometimes
going through helpers better suited for other cases.
- The add_latent_entropy() function has long been called from the fork
handler, but is a no-op when the latent entropy gcc plugin isn't
used, which is fine for the purposes of latent entropy.
But it was missing out on the cycle counter that was also being mixed
in beside the latent entropy variable. So now, if the latent entropy
gcc plugin isn't enabled, add_latent_entropy() will expand to a call
to add_device_randomness(NULL, 0), which adds a cycle counter,
without the absent latent entropy variable.
- The RNG is now reseeded from a delayed worker, rather than on demand
when used. Always running from a worker allows it to make use of the
CPU RNG on platforms like S390x, whose instructions are too slow to
do so from interrupts. It also has the effect of adding in new inputs
more frequently with more regularity, amounting to a long term
transcript of random values. Plus, it helps a bit with the upcoming
vDSO implementation (which isn't yet ready for 6.2).
- The jitter entropy algorithm now tries to execute on many different
CPUs, round-robining, in hopes of hitting even more memory latencies
and other unpredictable effects. It also will mix in a cycle counter
when the entropy timer fires, in addition to being mixed in from the
main loop, to account more explicitly for fluctuations in that timer
firing. And the state it touches is now kept within the same cache
line, so that it's assured that the different execution contexts will
cause latencies.
* tag 'random-6.2-rc1-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/crng/random: (23 commits)
random: include <linux/once.h> in the right header
random: align entropy_timer_state to cache line
random: mix in cycle counter when jitter timer fires
random: spread out jitter callback to different CPUs
random: remove extraneous period and add a missing one in comments
efi: random: refresh non-volatile random seed when RNG is initialized
vsprintf: initialize siphash key using notifier
random: add back async readiness notifier
random: reseed in delayed work rather than on-demand
random: always mix cycle counter in add_latent_entropy()
hw_random: use add_hwgenerator_randomness() for early entropy
random: modernize documentation comment on get_random_bytes()
random: adjust comment to account for removed function
random: remove early archrandom abstraction
random: use random.trust_{bootloader,cpu} command line option only
stackprotector: actually use get_random_canary()
stackprotector: move get_random_canary() into stackprotector.h
treewide: use get_random_u32_inclusive() when possible
treewide: use get_random_u32_{above,below}() instead of manual loop
treewide: use get_random_u32_below() instead of deprecated function
...
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git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip
Pull misc x86 updates from Thomas Gleixner:
"Updates for miscellaneous x86 areas:
- Reserve a new boot loader type for barebox which is usally used on
ARM and MIPS, but can also be utilized as EFI payload on x86 to
provide watchdog-supervised boot up.
- Consolidate the native and compat 32bit signal handling code and
split the 64bit version out into a separate source file
- Switch the ESPFIX random usage to get_random_long()"
* tag 'x86-misc-2022-12-10' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
x86/espfix: Use get_random_long() rather than archrandom
x86/signal/64: Move 64-bit signal code to its own file
x86/signal/32: Merge native and compat 32-bit signal code
x86/signal: Add ABI prefixes to frame setup functions
x86/signal: Merge get_sigframe()
x86: Remove __USER32_DS
signal/compat: Remove compat_sigset_t override
x86/signal: Remove sigset_t parameter from frame setup functions
x86/signal: Remove sig parameter from frame setup functions
Documentation/x86/boot: Reserve type_of_loader=13 for barebox
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In xen_init_lock_cpu(), the @name has allocated new string by kasprintf(),
if bind_ipi_to_irqhandler() fails, it should be freed, otherwise may lead
to a memory leak issue, fix it.
Fixes: 2d9e1e2f58b5 ("xen: implement Xen-specific spinlocks")
Signed-off-by: Xiu Jianfeng <xiujianfeng@huawei.com>
Reviewed-by: Juergen Gross <jgross@suse.com>
Link: https://lore.kernel.org/r/20221123155858.11382-3-xiujianfeng@huawei.com
Signed-off-by: Juergen Gross <jgross@suse.com>
|
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These local variables @{resched|pmu|callfunc...}_name saves the new
string allocated by kasprintf(), and when bind_{v}ipi_to_irqhandler()
fails, it goes to the @fail tag, and calls xen_smp_intr_free{_pv}() to
free resource, however the new string is not saved, which cause a memory
leak issue. fix it.
Fixes: 9702785a747a ("i386: move xen")
Signed-off-by: Xiu Jianfeng <xiujianfeng@huawei.com>
Reviewed-by: Juergen Gross <jgross@suse.com>
Link: https://lore.kernel.org/r/20221123155858.11382-2-xiujianfeng@huawei.com
Signed-off-by: Juergen Gross <jgross@suse.com>
|
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When running as a Xen PV guest there is no need for setting up the
realmode trampoline, as realmode isn't supported in this environment.
Trying to setup the trampoline has been proven to be problematic in
some cases, especially when trying to debug early boot problems with
Xen requiring to keep the EFI boot-services memory mapped (some
firmware variants seem to claim basically all memory below 1Mb for boot
services).
Introduce new x86_platform_ops operations for that purpose, which can
be set to a NOP by the Xen PV specific kernel boot code.
[ bp: s/call_init_real_mode/do_init_real_mode/ ]
Fixes: 084ee1c641a0 ("x86, realmode: Relocator for realmode code")
Suggested-by: H. Peter Anvin <hpa@zytor.com>
Signed-off-by: Juergen Gross <jgross@suse.com>
Signed-off-by: Borislav Petkov <bp@suse.de>
Link: https://lore.kernel.org/r/20221123114523.3467-1-jgross@suse.com
|
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Resolve conflicts between these commits in arch/x86/kernel/asm-offsets.c:
# upstream:
debc5a1ec0d1 ("KVM: x86: use a separate asm-offsets.c file")
# retbleed work in x86/core:
5d8213864ade ("x86/retbleed: Add SKL return thunk")
... and these commits in include/linux/bpf.h:
# upstram:
18acb7fac22f ("bpf: Revert ("Fix dispatcher patchable function entry to 5 bytes nop")")
# x86/core commits:
931ab63664f0 ("x86/ibt: Implement FineIBT")
bea75b33895f ("x86/Kconfig: Introduce function padding")
The latter two modify BPF_DISPATCHER_ATTRIBUTES(), which was removed upstream.
Conflicts:
arch/x86/kernel/asm-offsets.c
include/linux/bpf.h
Signed-off-by: Ingo Molnar <mingo@kernel.org>
|
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This has nothing to do with random.c and everything to do with stack
protectors. Yes, it uses randomness. But many things use randomness.
random.h and random.c are concerned with the generation of randomness,
not with each and every use. So move this function into the more
specific stackprotector.h file where it belongs.
Acked-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Jason A. Donenfeld <Jason@zx2c4.com>
|
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git://git.kernel.org/pub/scm/linux/kernel/git/xen/tip
Pull xen fixes from Juergen Gross:
"Two trivial cleanups, and three simple fixes"
* tag 'for-linus-6.1-rc6-tag' of git://git.kernel.org/pub/scm/linux/kernel/git/xen/tip:
xen/platform-pci: use define instead of literal number
xen/platform-pci: add missing free_irq() in error path
xen-pciback: Allow setting PCI_MSIX_FLAGS_MASKALL too
xen/pcpu: fix possible memory leak in register_pcpu()
x86/xen: Use kstrtobool() instead of strtobool()
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strtobool() is the same as kstrtobool().
However, the latter is more used within the kernel.
In order to remove strtobool() and slightly simplify kstrtox.h, switch to
the other function name.
While at it, include the corresponding header file (<linux/kstrtox.h>)
Signed-off-by: Christophe JAILLET <christophe.jaillet@wanadoo.fr>
Reviewed-by: Boris Ostrovsky <boris.ostrovsky@oracle.com>
Link: https://lore.kernel.org/r/e91af3c8708af38b1c57e0a2d7eb9765dda0e963.1667336095.git.christophe.jaillet@wanadoo.fr
Signed-off-by: Juergen Gross <jgross@suse.com>
|
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git://git.kernel.org/pub/scm/linux/kernel/git/xen/tip
Pull xen fixes from Juergen Gross:
"One fix for silencing a smatch warning, and a small cleanup patch"
* tag 'for-linus-6.1-rc4-tag' of git://git.kernel.org/pub/scm/linux/kernel/git/xen/tip:
x86/xen: simplify sysenter and syscall setup
x86/xen: silence smatch warning in pmu_msr_chk_emulated()
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xen_enable_sysenter() and xen_enable_syscall() can be simplified a lot.
While at it, switch to use cpu_feature_enabled() instead of
boot_cpu_has().
Signed-off-by: Juergen Gross <jgross@suse.com>
|
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Commit 8714f7bcd3c2 ("xen/pv: add fault recovery control to pmu msr
accesses") introduced code resulting in a warning issued by the smatch
static checker, claiming to use an uninitialized variable.
This is a false positive, but work around the warning nevertheless.
Fixes: 8714f7bcd3c2 ("xen/pv: add fault recovery control to pmu msr accesses")
Reported-by: Dan Carpenter <dan.carpenter@oracle.com>
Signed-off-by: Juergen Gross <jgross@suse.com>
|
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Replace all users with the equivalent __USER_DS, which will make merging
native and compat code simpler.
Signed-off-by: Brian Gerst <brgerst@gmail.com>
Signed-off-by: Borislav Petkov <bp@suse.de>
Acked-by: "Eric W. Biederman" <ebiederm@xmission.com>
Link: https://lore.kernel.org/r/20220606203802.158958-5-brgerst@gmail.com
Signed-off-by: Borislav Petkov <bp@suse.de>
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|
The only place where switch_to_new_gdt() is required is early boot to
switch from the early GDT to the direct GDT. Any other invocation is
completely redundant because it does not change anything.
Secondary CPUs come out of the ASM code with GDT and GSBASE correctly set
up. The same is true for XEN_PV.
Remove all the voodoo invocations which are left overs from the ancient
past, rename the function to switch_gdt_and_percpu_base() and mark it init.
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://lore.kernel.org/r/20220915111143.198076128@infradead.org
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git://git.kernel.org/pub/scm/linux/kernel/git/xen/tip
Pull xen updates from Juergen Gross:
- Some minor typo fixes
- A fix of the Xen pcifront driver for supporting the device model to
run in a Linux stub domain
- A cleanup of the pcifront driver
- A series to enable grant-based virtio with Xen on x86
- A cleanup of Xen PV guests to distinguish between safe and faulting
MSR accesses
- Two fixes of the Xen gntdev driver
- Two fixes of the new xen grant DMA driver
* tag 'for-linus-6.1-rc1-tag' of git://git.kernel.org/pub/scm/linux/kernel/git/xen/tip:
xen: Kconfig: Fix spelling mistake "Maxmium" -> "Maximum"
xen/pv: support selecting safe/unsafe msr accesses
xen/pv: refactor msr access functions to support safe and unsafe accesses
xen/pv: fix vendor checks for pmu emulation
xen/pv: add fault recovery control to pmu msr accesses
xen/virtio: enable grant based virtio on x86
xen/virtio: use dom0 as default backend for CONFIG_XEN_VIRTIO_FORCE_GRANT
xen/virtio: restructure xen grant dma setup
xen/pcifront: move xenstore config scanning into sub-function
xen/gntdev: Accommodate VMA splitting
xen/gntdev: Prevent leaking grants
xen/virtio: Fix potential deadlock when accessing xen_grant_dma_devices
xen/virtio: Fix n_pages calculation in xen_grant_dma_map(unmap)_page()
xen/xenbus: Fix spelling mistake "hardward" -> "hardware"
xen-pcifront: Handle missed Connected state
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Instead of always doing the safe variants for reading and writing MSRs
in Xen PV guests, make the behavior controllable via Kconfig option
and a boot parameter.
The default will be the current behavior, which is to always use the
safe variant.
Signed-off-by: Juergen Gross <jgross@suse.com>
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Refactor and rename xen_read_msr_safe() and xen_write_msr_safe() to
support both cases of MSR accesses, safe ones and potentially GP-fault
generating ones.
This will prepare to no longer swallow GPs silently in xen_read_msr()
and xen_write_msr().
Signed-off-by: Juergen Gross <jgross@suse.com>
Reviewed-by: Jan Beulich <jbeulich@suse.com>
Signed-off-by: Juergen Gross <jgross@suse.com>
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The CPU vendor checks for pmu emulation are rather limited today, as
the assumption seems to be that only Intel and AMD are existing and/or
supported vendors.
Fix that by handling Centaur and Zhaoxin CPUs the same way as Intel,
and Hygon the same way as AMD.
While at it fix the return type of is_intel_pmu_msr().
Suggested-by: Jan Beulich <jbeulich@suse.com>
Signed-off-by: Juergen Gross <jgross@suse.com>
Reviewed-by: Jan Beulich <jbeulich@suse.com>
Signed-off-by: Juergen Gross <jgross@suse.com>
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Today pmu_msr_read() and pmu_msr_write() fall back to the safe variants
of read/write MSR in case the MSR access isn't emulated via Xen. Allow
the caller to select that faults should not be recovered from by passing
NULL for the error pointer.
Restructure the code to make it more readable.
Signed-off-by: Juergen Gross <jgross@suse.com>
Reviewed-by: Jan Beulich <jbeulich@suse.com>
Signed-off-by: Juergen Gross <jgross@suse.com>
|
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Pull bitmap updates from Yury Norov:
- Fix unsigned comparison to -1 in CPUMAP_FILE_MAX_BYTES (Phil Auld)
- cleanup nr_cpu_ids vs nr_cpumask_bits mess (me)
This series cleans that mess and adds new config FORCE_NR_CPUS that
allows to optimize cpumask subsystem if the number of CPUs is known
at compile-time.
- optimize find_bit() functions (me)
Reworks find_bit() functions based on new FIND_{FIRST,NEXT}_BIT()
macros.
- add find_nth_bit() (me)
Adds find_nth_bit(), which is ~70 times faster than bitcounting with
for_each() loop:
for_each_set_bit(bit, mask, size)
if (n-- == 0)
return bit;
Also adds bitmap_weight_and() to let people replace this pattern:
tmp = bitmap_alloc(nbits);
bitmap_and(tmp, map1, map2, nbits);
weight = bitmap_weight(tmp, nbits);
bitmap_free(tmp);
with a single bitmap_weight_and() call.
- repair cpumask_check() (me)
After switching cpumask to use nr_cpu_ids, cpumask_check() started
generating many false-positive warnings. This series fixes it.
- Add for_each_cpu_andnot() and for_each_cpu_andnot() (Valentin
Schneider)
Extends the API with one more function and applies it in sched/core.
* tag 'bitmap-6.1-rc1' of https://github.com/norov/linux: (28 commits)
sched/core: Merge cpumask_andnot()+for_each_cpu() into for_each_cpu_andnot()
lib/test_cpumask: Add for_each_cpu_and(not) tests
cpumask: Introduce for_each_cpu_andnot()
lib/find_bit: Introduce find_next_andnot_bit()
cpumask: fix checking valid cpu range
lib/bitmap: add tests for for_each() loops
lib/find: optimize for_each() macros
lib/bitmap: introduce for_each_set_bit_wrap() macro
lib/find_bit: add find_next{,_and}_bit_wrap
cpumask: switch for_each_cpu{,_not} to use for_each_bit()
net: fix cpu_max_bits_warn() usage in netif_attrmask_next{,_and}
cpumask: add cpumask_nth_{,and,andnot}
lib/bitmap: remove bitmap_ord_to_pos
lib/bitmap: add tests for find_nth_bit()
lib: add find_nth{,_and,_andnot}_bit()
lib/bitmap: add bitmap_weight_and()
lib/bitmap: don't call __bitmap_weight() in kernel code
tools: sync find_bit() implementation
lib/find_bit: optimize find_next_bit() functions
lib/find_bit: create find_first_zero_bit_le()
...
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Use an x86-specific virtio_check_mem_acc_cb() for Xen in order to setup
the correct DMA ops.
Signed-off-by: Juergen Gross <jgross@suse.com>
Reviewed-by: Oleksandr Tyshchenko <oleksandr_tyshchenko@epam.com> # common code
Reviewed-by: Boris Ostrovsky <boris.ostrovsky@oracle.com>
Signed-off-by: Juergen Gross <jgross@suse.com>
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Clang produces a false positive when building with CONFIG_FORTIFY_SOURCE=y
and CONFIG_UBSAN_BOUNDS=y when operating on an array with a dynamic
offset. Work around this by using a direct assignment of an empty
instance. Avoids this warning:
../include/linux/fortify-string.h:309:4: warning: call to __write_overflow_field declared with 'warn
ing' attribute: detected write beyond size of field (1st parameter); maybe use struct_group()? [-Wat
tribute-warning]
__write_overflow_field(p_size_field, size);
^
which was isolated to the memset() call in xen_load_idt().
Note that this looks very much like another bug that was worked around:
https://github.com/ClangBuiltLinux/linux/issues/1592
Cc: Juergen Gross <jgross@suse.com>
Cc: Boris Ostrovsky <boris.ostrovsky@oracle.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Dave Hansen <dave.hansen@linux.intel.com>
Cc: x86@kernel.org
Cc: "H. Peter Anvin" <hpa@zytor.com>
Cc: xen-devel@lists.xenproject.org
Reviewed-by: Boris Ostrovsky <boris.ostrovsky@oracle.com>
Link: https://lore.kernel.org/lkml/41527d69-e8ab-3f86-ff37-6b298c01d5bc@oracle.com
Signed-off-by: Kees Cook <keescook@chromium.org>
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In preparation to support compile-time nr_cpu_ids, add a setter for
the variable.
This is a no-op for all arches.
Signed-off-by: Yury Norov <yury.norov@gmail.com>
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Implement support for the HVMOP_set_evtchn_upcall_vector hypercall in
order to set the per-vCPU event channel vector callback on Linux and
use it in preference of HVM_PARAM_CALLBACK_IRQ.
If the per-VCPU vector setup is successful on BSP, use this method
for the APs. If not, fallback to the global vector-type callback.
Also register callback_irq at per-vCPU event channel setup to trick
toolstack to think the domain is enlightened.
Suggested-by: "Roger Pau Monné" <roger.pau@citrix.com>
Signed-off-by: Jane Malalane <jane.malalane@citrix.com>
Reviewed-by: Boris Ostrovsky <boris.ostrovsky@oracle.com>
Link: https://lore.kernel.org/r/20220729070416.23306-1-jane.malalane@citrix.com
Signed-off-by: Juergen Gross <jgross@suse.com>
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Commit fa1f57421e0b ("xen/virtio: Enable restricted memory access using
Xen grant mappings") introduced a new requirement for using virtio
devices: the backend now needs to support the VIRTIO_F_ACCESS_PLATFORM
feature.
This is an undue requirement for non-PV guests, as those can be operated
with existing backends without any problem, as long as those backends
are running in dom0.
Per default allow virtio devices without grant support for non-PV
guests.
On Arm require VIRTIO_F_ACCESS_PLATFORM for devices having been listed
in the device tree to use grants.
Add a new config item to always force use of grants for virtio.
Fixes: fa1f57421e0b ("xen/virtio: Enable restricted memory access using Xen grant mappings")
Reported-by: Viresh Kumar <viresh.kumar@linaro.org>
Signed-off-by: Juergen Gross <jgross@suse.com>
Reviewed-by: Oleksandr Tyshchenko <oleksandr_tyshchenko@epam.com>
Tested-by: Oleksandr Tyshchenko <oleksandr_tyshchenko@epam.com> # Arm64 guest using Xen
Reviewed-by: Stefano Stabellini <sstabellini@kernel.org>
Link: https://lore.kernel.org/r/20220622063838.8854-4-jgross@suse.com
Signed-off-by: Juergen Gross <jgross@suse.com>
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