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Merge in the recent paravirt changes to resolve conflicts caused
by objtool annotations.
Conflicts:
arch/x86/xen/xen-asm.S
Signed-off-by: Ingo Molnar <mingo@kernel.org>
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There is no reason to have this as a seperate function for a single caller.
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Kees Cook <keescook@chromium.org>
Link: https://lore.kernel.org/r/20210210002513.382806685@linutronix.de
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To avoid include recursion hell move the do_softirq_own_stack() related
content into a generic asm header and include it from all places in arch/
which need the prototype.
This allows architectures to provide an inline implementation of
do_softirq_own_stack() without introducing a lot of #ifdeffery all over the
place.
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Kees Cook <keescook@chromium.org>
Link: https://lore.kernel.org/r/20210210002513.289960691@linutronix.de
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To prepare for inlining do_softirq_own_stack() replace
__ARCH_HAS_DO_SOFTIRQ with a Kconfig switch and select it in the affected
architectures.
This allows in the next step to move the function prototype and the inline
stub into a seperate asm-generic header file which is required to avoid
include recursion.
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Kees Cook <keescook@chromium.org>
Link: https://lore.kernel.org/r/20210210002513.181713427@linutronix.de
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Now that all invocations of irq_exit_rcu() happen on the irq stack, turn on
CONFIG_HAVE_IRQ_EXIT_ON_IRQ_STACK which causes the core code to invoke
__do_softirq() directly without going through do_softirq_own_stack().
That means do_softirq_own_stack() is only invoked from task context which
means it can't be on the irq stack. Remove the conditional from
run_softirq_on_irqstack_cond() and rename the function accordingly.
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Kees Cook <keescook@chromium.org>
Link: https://lore.kernel.org/r/20210210002513.068033456@linutronix.de
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Use the new inline stack switching and remove the old ASM indirect call
implementation.
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Kees Cook <keescook@chromium.org>
Link: https://lore.kernel.org/r/20210210002512.972714001@linutronix.de
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To avoid yet another macro implementation reuse the existing
run_sysvec_on_irqstack_cond() and move the set_irq_regs() handling into the
called function. Makes the code even simpler.
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Kees Cook <keescook@chromium.org>
Link: https://lore.kernel.org/r/20210210002512.869753106@linutronix.de
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Convert device interrupts to inline stack switching by replacing the
existing macro implementation with the new inline version. Tweak the
function signature of the actual handler function to have the vector
argument as u32. That allows the inline macro to avoid extra intermediates
and lets the compiler be smarter about the whole thing.
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Kees Cook <keescook@chromium.org>
Link: https://lore.kernel.org/r/20210210002512.769728139@linutronix.de
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To inline the stack switching and to prepare for enabling
CONFIG_HAVE_IRQ_EXIT_ON_IRQ_STACK provide a macro template for system
vectors and device interrupts and convert the system vectors over to it.
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Kees Cook <keescook@chromium.org>
Link: https://lore.kernel.org/r/20210210002512.676197354@linutronix.de
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The effort to make the ASM entry code slim and unified moved the irq stack
switching out of the low level ASM code so that the whole return from
interrupt work and state handling can be done in C and the ASM code just
handles the low level details of entry and exit.
This ended up being a suboptimal implementation for various reasons
(including tooling). The main pain points are:
- The indirect call which is expensive thanks to retpoline
- The inability to stay on the irq stack for softirq processing on return
from interrupt
- The fact that the stack switching code ends up being an easy to target
exploit gadget.
Prepare for inlining the stack switching logic into the C entry points by
providing a ASM macro which contains the guts of the switching mechanism:
1) Store RSP at the top of the irq stack
2) Switch RSP to the irq stack
3) Invoke code
4) Pop the original RSP back
Document the unholy asm() logic while at it to reduce the amount of head
scratching required a half year from now.
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Kees Cook <keescook@chromium.org>
Link: https://lore.kernel.org/r/20210210002512.578371068@linutronix.de
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sysvec_spurious_apic_interrupt() calls into the handling body of
__spurious_interrupt() which is not obvious as that function is declared
inside the DEFINE_IDTENTRY_IRQ(spurious_interrupt) macro.
As __spurious_interrupt() is currently always inlined this ends up with two
copies of the same code for no reason.
Split the handling function out and invoke it from both entry points.
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Kees Cook <keescook@chromium.org>
Link: https://lore.kernel.org/r/20210210002512.469379641@linutronix.de
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The per CPU hardirq_stack_ptr contains the pointer to the irq stack in the
form that it is ready to be assigned to [ER]SP so that the first push ends
up on the top entry of the stack.
But the stack switching on 64 bit has the following rules:
1) Store the current stack pointer (RSP) in the top most stack entry
to allow the unwinder to link back to the previous stack
2) Set RSP to the top most stack entry
3) Invoke functions on the irq stack
4) Pop RSP from the top most stack entry (stored in #1) so it's back
to the original stack.
That requires all stack switching code to decrement the stored pointer by 8
in order to be able to store the current RSP and then set RSP to that
location. That's a pointless exercise.
Do the -8 adjustment right when storing the pointer and make the data type
a void pointer to avoid confusion vs. the struct irq_stack data type which
is on 64bit only used to declare the backing store. Move the definition
next to the inuse flag so they likely end up in the same cache
line. Sticking them into a struct to enforce it is a seperate change.
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Kees Cook <keescook@chromium.org>
Link: https://lore.kernel.org/r/20210210002512.354260928@linutronix.de
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The recursion protection for hard interrupt stacks is an unsigned int per
CPU variable initialized to -1 named __irq_count.
The irq stack switching is only done when the variable is -1, which creates
worse code than just checking for 0. When the stack switching happens it
uses this_cpu_add/sub(1), but there is no reason to do so. It simply can
use straight writes. This is a historical leftover from the low level ASM
code which used inc and jz to make a decision.
Rename it to hardirq_stack_inuse, make it a bool and use plain stores.
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Kees Cook <keescook@chromium.org>
Link: https://lore.kernel.org/r/20210210002512.228830141@linutronix.de
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Embracing a callout into instrumentation_begin() / instrumentation_begin()
does not really make sense. Make the latter instrumentation_end().
Fixes: 2f6474e4636b ("x86/entry: Switch XEN/PV hypercall entry to IDTENTRY")
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Kees Cook <keescook@chromium.org>
Cc: stable@vger.kernel.org
Link: https://lore.kernel.org/r/20210210002512.106502464@linutronix.de
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to base the irq stack modifications on.
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Currently REG_SP_INDIRECT is unused but means (%rsp + offset),
change it to mean (%rsp) + offset.
The reason is that we're going to swizzle stack in the middle of a C
function with non-trivial stack footprint. This means that when the
unwinder finds the ToS, it needs to dereference it (%rsp) and then add
the offset to the next frame, resulting in: (%rsp) + offset
This is somewhat unfortunate, since REG_BP_INDIRECT is used (by DRAP)
and thus needs to retain the current (%rbp + offset).
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Miroslav Benes <mbenes@suse.cz>
Acked-by: Josh Poimboeuf <jpoimboe@redhat.com>
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POPF is a rather expensive operation, so don't use it for restoring
irq flags. Instead, test whether interrupts are enabled in the flags
parameter and enable interrupts via STI in that case.
This results in the restore_fl paravirt op to be no longer needed.
Suggested-by: Andy Lutomirski <luto@kernel.org>
Signed-off-by: Juergen Gross <jgross@suse.com>
Signed-off-by: Borislav Petkov <bp@suse.de>
Link: https://lkml.kernel.org/r/20210120135555.32594-7-jgross@suse.com
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USERGS_SYSRET64 is used to return from a syscall via SYSRET, but
a Xen PV guest will nevertheless use the IRET hypercall, as there
is no sysret PV hypercall defined.
So instead of testing all the prerequisites for doing a sysret and
then mangling the stack for Xen PV again for doing an iret just use
the iret exit from the beginning.
This can easily be done via an ALTERNATIVE like it is done for the
sysenter compat case already.
It should be noted that this drops the optimization in Xen for not
restoring a few registers when returning to user mode, but it seems
as if the saved instructions in the kernel more than compensate for
this drop (a kernel build in a Xen PV guest was slightly faster with
this patch applied).
While at it remove the stale sysret32 remnants.
Signed-off-by: Juergen Gross <jgross@suse.com>
Signed-off-by: Borislav Petkov <bp@suse.de>
Link: https://lkml.kernel.org/r/20210120135555.32594-6-jgross@suse.com
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SWAPGS is used only for interrupts coming from user mode or for
returning to user mode. So there is no reason to use the PARAVIRT
framework, as it can easily be replaced by an ALTERNATIVE depending
on X86_FEATURE_XENPV.
There are several instances using the PV-aware SWAPGS macro in paths
which are never executed in a Xen PV guest. Replace those with the
plain swapgs instruction. For SWAPGS_UNSAFE_STACK the same applies.
Signed-off-by: Juergen Gross <jgross@suse.com>
Signed-off-by: Borislav Petkov <bp@suse.de>
Reviewed-by: Borislav Petkov <bp@suse.de>
Reviewed-by: Thomas Gleixner <tglx@linutronix.de>
Acked-by: Andy Lutomirski <luto@kernel.org>
Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://lkml.kernel.org/r/20210120135555.32594-5-jgross@suse.com
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Xen PV guests don't use IST. For double fault interrupts, switch to
the same model as NMI.
Correct a typo in a comment while copying it.
Signed-off-by: Juergen Gross <jgross@suse.com>
Signed-off-by: Borislav Petkov <bp@suse.de>
Reviewed-by: Thomas Gleixner <tglx@linutronix.de>
Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://lkml.kernel.org/r/20210120135555.32594-4-jgross@suse.com
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Xen PV guests don't use IST. For machine check interrupts, switch to the
same model as debug interrupts.
Signed-off-by: Juergen Gross <jgross@suse.com>
Signed-off-by: Borislav Petkov <bp@suse.de>
Reviewed-by: Thomas Gleixner <tglx@linutronix.de>
Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://lkml.kernel.org/r/20210120135555.32594-3-jgross@suse.com
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git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip
Pull syscall entry fixes from Borislav Petkov:
- For syscall user dispatch, separate prctl operation from syscall
redirection range specification before the API has been made official
in 5.11.
- Ensure tasks using the generic syscall code do trap after returning
from a syscall when single-stepping is requested.
* tag 'core_urgent_for_v5.11_rc7' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
entry: Use different define for selector variable in SUD
entry: Ensure trap after single-step on system call return
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git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip
Pull x86 fixes from Borislav Petkov:
"I hope this is the last batch of x86/urgent updates for this round:
- Remove superfluous EFI PGD range checks which lead to those
assertions failing with certain kernel configs and LLVM.
- Disable setting breakpoints on facilities involved in #DB exception
handling to avoid infinite loops.
- Add extra serialization to non-serializing MSRs (IA32_TSC_DEADLINE
and x2 APIC MSRs) to adhere to SDM's recommendation and avoid any
theoretical issues.
- Re-add the EPB MSR reading on turbostat so that it works on older
kernels which don't have the corresponding EPB sysfs file.
- Add Alder Lake to the list of CPUs which support split lock.
- Fix %dr6 register handling in order to be able to set watchpoints
with gdb again.
- Disable CET instrumentation in the kernel so that gcc doesn't add
ENDBR64 to kernel code and thus confuse tracing"
* tag 'x86_urgent_for_v5.11_rc7' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
x86/efi: Remove EFI PGD build time checks
x86/debug: Prevent data breakpoints on cpu_dr7
x86/debug: Prevent data breakpoints on __per_cpu_offset
x86/apic: Add extra serialization for non-serializing MSRs
tools/power/turbostat: Fallback to an MSR read for EPB
x86/split_lock: Enable the split lock feature on another Alder Lake CPU
x86/debug: Fix DR6 handling
x86/build: Disable CET instrumentation in the kernel
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git://git.kernel.org/pub/scm/linux/kernel/git/masahiroy/linux-kbuild
Pull Kbuild fixes from Masahiro Yamada:
- Use the 'python3' command to invoke python scripts because some
distributions do not provide the 'python' command any more.
- Clean-up and update documents
- Use pkg-config to search libcrypto
- Fix duplicated debug flags
- Ignore some more stubs in scripts/kallsyms.c
* tag 'kbuild-fixes-v5.11-2' of git://git.kernel.org/pub/scm/linux/kernel/git/masahiroy/linux-kbuild:
kallsyms: fix nonconverging kallsyms table with lld
kbuild: fix duplicated flags in DEBUG_CFLAGS
scripts/clang-tools: switch explicitly to Python 3
kbuild: remove PYTHON variable
Documentation/llvm: Add a section about supported architectures
Revert "checkpatch: add check for keyword 'boolean' in Kconfig definitions"
scripts: use pkg-config to locate libcrypto
kconfig: mconf: fix HOSTCC call
doc: gcc-plugins: update gcc-plugins.rst
kbuild: simplify GCC_PLUGINS enablement in dummy-tools/gcc
Documentation/Kbuild: Remove references to gcc-plugin.sh
scripts: switch explicitly to Python 3
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git://git.kernel.org/pub/scm/linux/kernel/git/riscv/linux
Pull RISC-V fixes from Palmer Dabbelt:
"A handful of fixes for this week:
- A fix to avoid evalating the VA twice in virt_addr_valid, which
fixes some WARNs under DEBUG_VIRTUAL.
- Two fixes related to STRICT_KERNEL_RWX: one that fixes some
permissions when strict is disabled, and one to fix some alignment
issues when strict is enabled.
- A fix to disallow the selection of MAXPHYSMEM_2GB on RV32, which
isn't valid any more but may still show up in some oldconfigs.
We still have the HiFive Unleashed ethernet phy reset regression, so
there will likely be something coming next week"
* tag 'riscv-for-linus-5.11-rc7' of git://git.kernel.org/pub/scm/linux/kernel/git/riscv/linux:
RISC-V: Define MAXPHYSMEM_1GB only for RV32
riscv: Align on L1_CACHE_BYTES when STRICT_KERNEL_RWX
RISC-V: Fix .init section permission update
riscv: virt_addr_valid must check the address belongs to linear mapping
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git://git.kernel.org/pub/scm/linux/kernel/git/powerpc/linux
Pull powerpc fixes from Michael Ellerman:
- A fix for a change we made to __kernel_sigtramp_rt64() which confused
glibc's backtrace logic, and also changed the semantics of that
symbol, which was arguably an ABI break.
- A fix for a stack overwrite in our VSX instruction emulation.
- A couple of fixes for the Makefile logic in the new C VDSO.
Thanks to Masahiro Yamada, Naveen N. Rao, Raoni Fassina Firmino, and
Ravi Bangoria.
* tag 'powerpc-5.11-7' of git://git.kernel.org/pub/scm/linux/kernel/git/powerpc/linux:
powerpc/64/signal: Fix regression in __kernel_sigtramp_rt64() semantics
powerpc/vdso64: remove meaningless vgettimeofday.o build rule
powerpc/vdso: fix unnecessary rebuilds of vgettimeofday.o
powerpc/sstep: Fix array out of bound warning
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Pull ARM fixes from Russell King:
- Fix latent bug with DC21285 (Footbridge PCI bridge) configuration
accessors that affects GCC >= 4.9.2
- Fix misplaced tegra_uart_config in decompressor
- Ensure signal page contents are initialised
- Fix kexec oops
* tag 'for-linus' of git://git.armlinux.org.uk/~rmk/linux-arm:
ARM: kexec: fix oops after TLB are invalidated
ARM: ensure the signal page contains defined contents
ARM: 9043/1: tegra: Fix misplaced tegra_uart_config in decompressor
ARM: footbridge: fix dc21285 PCI configuration accessors
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With CONFIG_X86_5LEVEL, CONFIG_UBSAN and CONFIG_UBSAN_UNSIGNED_OVERFLOW
enabled, clang fails the build with
x86_64-linux-ld: arch/x86/platform/efi/efi_64.o: in function `efi_sync_low_kernel_mappings':
efi_64.c:(.text+0x22c): undefined reference to `__compiletime_assert_354'
which happens due to -fsanitize=unsigned-integer-overflow being enabled:
-fsanitize=unsigned-integer-overflow: Unsigned integer overflow, where
the result of an unsigned integer computation cannot be represented
in its type. Unlike signed integer overflow, this is not undefined
behavior, but it is often unintentional. This sanitizer does not check
for lossy implicit conversions performed before such a computation
(see -fsanitize=implicit-conversion).
and that fires when the (intentional) EFI_VA_START/END defines overflow
an unsigned long, leading to the assertion expressions not getting
optimized away (on GCC they do)...
However, those checks are superfluous: the runtime services mapping
code already makes sure the ranges don't overshoot EFI_VA_END as the
EFI mapping range is hardcoded. On each runtime services call, it is
switched to the EFI-specific PGD and even if mappings manage to escape
that last PGD, this won't remain unnoticed for long.
So rip them out.
See https://github.com/ClangBuiltLinux/linux/issues/256 for more info.
Reported-by: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Borislav Petkov <bp@suse.de>
Reviewed-by: Nathan Chancellor <nathan@kernel.org>
Acked-by: Ard Biesheuvel <ardb@kernel.org>
Tested-by: Nick Desaulniers <ndesaulniers@google.com>
Tested-by: Nathan Chancellor <nathan@kernel.org>
Link: http://lkml.kernel.org/r/20210107223424.4135538-1-arnd@kernel.org
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Commit 299155244770 ("entry: Drop usage of TIF flags in the generic syscall
code") introduced a bug on architectures using the generic syscall entry
code, in which processes stopped by PTRACE_SYSCALL do not trap on syscall
return after receiving a TIF_SINGLESTEP.
The reason is that the meaning of TIF_SINGLESTEP flag is overloaded to
cause the trap after a system call is executed, but since the above commit,
the syscall call handler only checks for the SYSCALL_WORK flags on the exit
work.
Split the meaning of TIF_SINGLESTEP such that it only means single-step
mode, and create a new type of SYSCALL_WORK to request a trap immediately
after a syscall in single-step mode. In the current implementation, the
SYSCALL_WORK flag shadows the TIF_SINGLESTEP flag for simplicity.
Update x86 to flip this bit when a tracer enables single stepping.
Fixes: 299155244770 ("entry: Drop usage of TIF flags in the generic syscall code")
Suggested-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Gabriel Krisman Bertazi <krisman@collabora.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Tested-by: Kyle Huey <me@kylehuey.com>
Link: https://lore.kernel.org/r/87h7mtc9pr.fsf_-_@collabora.com
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local_db_save() is called at the start of exc_debug_kernel(), reads DR7 and
disables breakpoints to prevent recursion.
When running in a guest (X86_FEATURE_HYPERVISOR), local_db_save() reads the
per-cpu variable cpu_dr7 to check whether a breakpoint is active or not
before it accesses DR7.
A data breakpoint on cpu_dr7 therefore results in infinite #DB recursion.
Disallow data breakpoints on cpu_dr7 to prevent that.
Fixes: 84b6a3491567a("x86/entry: Optimize local_db_save() for virt")
Signed-off-by: Lai Jiangshan <laijs@linux.alibaba.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Cc: stable@vger.kernel.org
Link: https://lore.kernel.org/r/20210204152708.21308-2-jiangshanlai@gmail.com
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When FSGSBASE is enabled, paranoid_entry() fetches the per-CPU GSBASE value
via __per_cpu_offset or pcpu_unit_offsets.
When a data breakpoint is set on __per_cpu_offset[cpu] (read-write
operation), the specific CPU will be stuck in an infinite #DB loop.
RCU will try to send an NMI to the specific CPU, but it is not working
either since NMI also relies on paranoid_entry(). Which means it's
undebuggable.
Fixes: eaad981291ee3("x86/entry/64: Introduce the FIND_PERCPU_BASE macro")
Signed-off-by: Lai Jiangshan <laijs@linux.alibaba.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Cc: stable@vger.kernel.org
Link: https://lore.kernel.org/r/20210204152708.21308-1-jiangshanlai@gmail.com
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Pull KVM fixes from Paolo Bonzini:
"x86 has lots of small bugfixes, mostly one liners. It's quite late in
5.11-rc but none of them are related to this merge window; it's just
bugs coming in at the wrong time.
Of note among the others is "KVM: x86: Allow guests to see
MSR_IA32_TSX_CTRL even if tsx=off" that fixes a live migration failure
seen on distros that hadn't switched to tsx=off right away.
ARM:
- Avoid clobbering extra registers on initialisation"
[ Sean Christopherson notes that commit 943dea8af21b ("KVM: x86: Update
emulator context mode if SYSENTER xfers to 64-bit mode") should have
had authorship credited to Jonny Barker, not to him. - Linus ]
* tag 'for-linus' of git://git.kernel.org/pub/scm/virt/kvm/kvm:
KVM: x86: Set so called 'reserved CR3 bits in LM mask' at vCPU reset
KVM: x86/mmu: Fix TDP MMU zap collapsible SPTEs
KVM: x86: cleanup CR3 reserved bits checks
KVM: SVM: Treat SVM as unsupported when running as an SEV guest
KVM: x86: Update emulator context mode if SYSENTER xfers to 64-bit mode
KVM: x86: Supplement __cr4_reserved_bits() with X86_FEATURE_PCID check
KVM/x86: assign hva with the right value to vm_munmap the pages
KVM: x86: Allow guests to see MSR_IA32_TSX_CTRL even if tsx=off
Fix unsynchronized access to sev members through svm_register_enc_region
KVM: Documentation: Fix documentation for nested.
KVM: x86: fix CPUID entries returned by KVM_GET_CPUID2 ioctl
KVM: arm64: Don't clobber x4 in __do_hyp_init
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Giancarlo Ferrari reports the following oops while trying to use kexec:
Unable to handle kernel paging request at virtual address 80112f38
pgd = fd7ef03e
[80112f38] *pgd=0001141e(bad)
Internal error: Oops: 80d [#1] PREEMPT SMP ARM
...
This is caused by machine_kexec() trying to set the kernel text to be
read/write, so it can poke values into the relocation code before
copying it - and an interrupt occuring which changes the page tables.
The subsequent writes then hit read-only sections that trigger a
data abort resulting in the above oops.
Fix this by copying the relocation code, and then writing the variables
into the destination, thereby avoiding the need to make the kernel text
read/write.
Reported-by: Giancarlo Ferrari <giancarlo.ferrari89@gmail.com>
Tested-by: Giancarlo Ferrari <giancarlo.ferrari89@gmail.com>
Signed-off-by: Russell King <rmk+kernel@armlinux.org.uk>
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Ensure that the signal page contains our poison instruction to increase
the protection against ROP attacks and also contains well defined
contents.
Acked-by: Will Deacon <will@kernel.org>
Signed-off-by: Russell King <rmk+kernel@armlinux.org.uk>
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Jan Kiszka reported that the x2apic_wrmsr_fence() function uses a plain
MFENCE while the Intel SDM (10.12.3 MSR Access in x2APIC Mode) calls for
MFENCE; LFENCE.
Short summary: we have special MSRs that have weaker ordering than all
the rest. Add fencing consistent with current SDM recommendations.
This is not known to cause any issues in practice, only in theory.
Longer story below:
The reason the kernel uses a different semantic is that the SDM changed
(roughly in late 2017). The SDM changed because folks at Intel were
auditing all of the recommended fences in the SDM and realized that the
x2apic fences were insufficient.
Why was the pain MFENCE judged insufficient?
WRMSR itself is normally a serializing instruction. No fences are needed
because the instruction itself serializes everything.
But, there are explicit exceptions for this serializing behavior written
into the WRMSR instruction documentation for two classes of MSRs:
IA32_TSC_DEADLINE and the X2APIC MSRs.
Back to x2apic: WRMSR is *not* serializing in this specific case.
But why is MFENCE insufficient? MFENCE makes writes visible, but
only affects load/store instructions. WRMSR is unfortunately not a
load/store instruction and is unaffected by MFENCE. This means that a
non-serializing WRMSR could be reordered by the CPU to execute before
the writes made visible by the MFENCE have even occurred in the first
place.
This means that an x2apic IPI could theoretically be triggered before
there is any (visible) data to process.
Does this affect anything in practice? I honestly don't know. It seems
quite possible that by the time an interrupt gets to consume the (not
yet) MFENCE'd data, it has become visible, mostly by accident.
To be safe, add the SDM-recommended fences for all x2apic WRMSRs.
This also leaves open the question of the _other_ weakly-ordered WRMSR:
MSR_IA32_TSC_DEADLINE. While it has the same ordering architecture as
the x2APIC MSRs, it seems substantially less likely to be a problem in
practice. While writes to the in-memory Local Vector Table (LVT) might
theoretically be reordered with respect to a weakly-ordered WRMSR like
TSC_DEADLINE, the SDM has this to say:
In x2APIC mode, the WRMSR instruction is used to write to the LVT
entry. The processor ensures the ordering of this write and any
subsequent WRMSR to the deadline; no fencing is required.
But, that might still leave xAPIC exposed. The safest thing to do for
now is to add the extra, recommended LFENCE.
[ bp: Massage commit message, fix typos, drop accidentally added
newline to tools/arch/x86/include/asm/barrier.h. ]
Reported-by: Jan Kiszka <jan.kiszka@siemens.com>
Signed-off-by: Dave Hansen <dave.hansen@linux.intel.com>
Signed-off-by: Borislav Petkov <bp@suse.de>
Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Acked-by: Thomas Gleixner <tglx@linutronix.de>
Cc: <stable@vger.kernel.org>
Link: https://lkml.kernel.org/r/20200305174708.F77040DD@viggo.jf.intel.com
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This reverts commit bde9cfa3afe4324ec251e4af80ebf9b7afaf7afe.
Changing the first memory page type from E820_TYPE_RESERVED to
E820_TYPE_RAM makes it a part of "System RAM" resource rather than a
reserved resource and this in turn causes devmem_is_allowed() to treat
is as area that can be accessed but it is filled with zeroes instead of
the actual data as previously.
The change in /dev/mem output causes lilo to fail as was reported at
slakware users forum, and probably other legacy applications will
experience similar problems.
Link: https://www.linuxquestions.org/questions/slackware-14/slackware-current-lilo-vesa-warnings-after-recent-updates-4175689617/#post6214439
Signed-off-by: Mike Rapoport <rppt@linux.ibm.com>
Cc: stable@kernel.org
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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Set cr3_lm_rsvd_bits, which is effectively an invalid GPA mask, at vCPU
reset. The reserved bits check needs to be done even if userspace never
configures the guest's CPUID model.
Cc: stable@vger.kernel.org
Fixes: 0107973a80ad ("KVM: x86: Introduce cr3_lm_rsvd_bits in kvm_vcpu_arch")
Signed-off-by: Sean Christopherson <seanjc@google.com>
Message-Id: <20210204000117.3303214-2-seanjc@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
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There is a bug in the TDP MMU function to zap SPTEs which could be
replaced with a larger mapping which prevents the function from doing
anything. Fix this by correctly zapping the last level SPTEs.
Cc: stable@vger.kernel.org
Fixes: 14881998566d ("kvm: x86/mmu: Support disabling dirty logging for the tdp MMU")
Signed-off-by: Ben Gardon <bgardon@google.com>
Message-Id: <20210202185734.1680553-11-bgardon@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
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git://git.kernel.org/pub/scm/linux/kernel/git/rw/uml
Pull UML fixes from Richard Weinberger:
- Make sure to set a default console, otherwise ttynull is selected
- Revert initial ARCH_HAS_SET_MEMORY support, this needs more work
- Fix a regression due to ubd refactoring
- Various small fixes
* tag 'for-linus-5.11-rc7' of git://git.kernel.org/pub/scm/linux/kernel/git/rw/uml:
um: time: fix initialization in time-travel mode
um: fix os_idle_sleep() to not hang
Revert "um: support some of ARCH_HAS_SET_MEMORY"
Revert "um: allocate a guard page to helper threads"
um: virtio: free vu_dev only with the contained struct device
um: kmsg_dumper: always dump when not tty console
um: stdio_console: Make preferred console
um: return error from ioremap()
um: ubd: fix command line handling of ubd
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git://git.kernel.org/pub/scm/linux/kernel/git/arm64/linux
Pull arm64 fixes from Catalin Marinas:
"Fix the arm64 linear map range detection for tagged addresses and
replace the bitwise operations with subtract (virt_addr_valid(),
__is_lm_address(), __lm_to_phys())"
* tag 'arm64-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/arm64/linux:
arm64: Use simpler arithmetics for the linear map macros
arm64: Do not pass tagged addresses to __is_lm_address()
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git://git.kernel.org/pub/scm/linux/kernel/git/soc/soc
Pull ARM SoC fixes from Arnd Bergmann:
"The code fixes in this round are all for the Texas Instruments OMAP
platform, addressing several regressions related to the ti-sysc
interconnect changes that was merged in linux-5.11 and one recently
introduced RCU usage warning.
Tero Kristo updates his maintainer file entries as he is changing to a
new employer.
The other changes are for devicetree files across eight different
platforms:
TI OMAP:
- multiple gpio related one-line fixes
Allwinner/sunxi:
- ARM: dts: sun7i: a20: bananapro: Fix ethernet phy-mode
- soc: sunxi: mbus: Remove DE2 display engine compatibles
NXP lpc32xx:
- ARM: dts: lpc32xx: Revert set default clock rate of HCLK PLL
STMicroelectronics stm32
- multiple minor fixes for DHCOM/DHCOR boards
NXP Layerscape:
- Fix DCFG address range on LS1046A SoC
Amlogic meson:
- fix reboot issue on odroid C4
- revert an ethernet change that caused a regression
- meson-g12: Set FL-adj property value
Rockchip:
- multiple minor fixes on 64-bit rockchip machines
Qualcomm:
- Regression fixes for Lenovo Yoga touchpad and for interconnect
configuration
- Boot fixes for 'LPASS' clock configuration on two machines"
* tag 'arm-soc-fixes-v5.11-3' of git://git.kernel.org/pub/scm/linux/kernel/git/soc/soc: (31 commits)
ARM: dts: lpc32xx: Revert set default clock rate of HCLK PLL
ARM: dts: sun7i: a20: bananapro: Fix ethernet phy-mode
arm64: dts: ls1046a: fix dcfg address range
soc: sunxi: mbus: Remove DE2 display engine compatibles
arm64: dts: meson: switch TFLASH_VDD_EN pin to open drain on Odroid-C4
Revert "arm64: dts: amlogic: add missing ethernet reset ID"
arm64: dts: rockchip: Disable display for NanoPi R2S
ARM: dts: omap4-droid4: Fix lost keypad slide interrupts for droid4
arm64: dts: rockchip: remove interrupt-names property from rk3399 vdec node
drivers: bus: simple-pm-bus: Fix compatibility with simple-bus for auxdata
ARM: OMAP2+: Fix booting for am335x after moving to simple-pm-bus
ARM: OMAP2+: Fix suspcious RCU usage splats for omap_enter_idle_coupled
ARM: dts: stm32: Fix GPIO hog flags on DHCOM DRC02
ARM: dts: stm32: Fix GPIO hog flags on DHCOM PicoITX
ARM: dts: stm32: Fix GPIO hog names on DHCOM
ARM: dts: stm32: Disable optional TSC2004 on DRC02 board
ARM: dts: stm32: Disable WP on DHCOM uSD slot
ARM: dts: stm32: Connect card-detect signal on DHCOM
ARM: dts: stm32: Fix polarity of the DH DRC02 uSD card detect
arm64: dts: qcom: sdm845: Reserve LPASS clocks in gcc
...
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git://git.kernel.org/pub/scm/linux/kernel/git/sunxi/linux into arm/fixes
One fix for a phy-mode ethernet issue, and one to fix the display output on
SoCs with the Display Engine 2
* tag 'sunxi-fixes-for-5.11-2' of git://git.kernel.org/pub/scm/linux/kernel/git/sunxi/linux:
ARM: dts: sun7i: a20: bananapro: Fix ethernet phy-mode
soc: sunxi: mbus: Remove DE2 display engine compatibles
Link: https://lore.kernel.org/r/f8298059-f9ca-43b4-9e29-35bc0e0c9b15.lettre@localhost
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
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This reverts commit c17e9377aa81664d94b4f2102559fcf2a01ec8e7.
The lpc32xx clock driver is not able to actually change the PLL rate as
this would require reparenting ARM_CLK, DDRAM_CLK, PERIPH_CLK to SYSCLK,
then stop the PLL, update the register, restart the PLL and wait for the
PLL to lock and finally reparent ARM_CLK, DDRAM_CLK, PERIPH_CLK to HCLK
PLL.
Currently, the HCLK driver simply updates the registers but this has no
real effect and all the clock rate calculation end up being wrong. This is
especially annoying for the peripheral (e.g. UARTs, I2C, SPI).
Signed-off-by: Alexandre Belloni <alexandre.belloni@bootlin.com>
Tested-by: Gregory CLEMENT <gregory.clement@bootlin.com>
Link: https://lore.kernel.org/r/20210203090320.GA3760268@piout.net'
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
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BPi Pro needs TX and RX delay for Gbit to work reliable and avoid high
packet loss rates. The realtek phy driver overrides the settings of the
pull ups for the delays, so fix this for BananaPro.
Fix the phy-mode description to correctly reflect this so that the
implementation doesn't reconfigure the delays incorrectly. This
happened with commit bbc4d71d6354 ("net: phy: realtek: fix rtl8211e
rx/tx delay config").
Fixes: 10662a33dcd9 ("ARM: dts: sun7i: Add dts file for Bananapro board")
Signed-off-by: Hermann Lauer <Hermann.Lauer@uni-heidelberg.de>
Signed-off-by: Maxime Ripard <maxime@cerno.tech>
Link: https://lore.kernel.org/r/20210128111842.GA11919@lemon.iwr.uni-heidelberg.de
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If not in long mode, the low bits of CR3 are reserved but not enforced to
be zero, so remove those checks. If in long mode, however, the MBZ bits
extend down to the highest physical address bit of the guest, excluding
the encryption bit.
Make the checks consistent with the above, and match them between
nested_vmcb_checks and KVM_SET_SREGS.
Cc: stable@vger.kernel.org
Fixes: 761e41693465 ("KVM: nSVM: Check that MBZ bits in CR3 and CR4 are not set on vmrun of nested guests")
Fixes: a780a3ea6282 ("KVM: X86: Fix reserved bits check for MOV to CR3")
Reviewed-by: Sean Christopherson <seanjc@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
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Don't let KVM load when running as an SEV guest, regardless of what
CPUID says. Memory is encrypted with a key that is not accessible to
the host (L0), thus it's impossible for L0 to emulate SVM, e.g. it'll
see garbage when reading the VMCB.
Technically, KVM could decrypt all memory that needs to be accessible to
the L0 and use shadow paging so that L0 does not need to shadow NPT, but
exposing such information to L0 largely defeats the purpose of running as
an SEV guest. This can always be revisited if someone comes up with a
use case for running VMs inside SEV guests.
Note, VMLOAD, VMRUN, etc... will also #GP on GPAs with C-bit set, i.e. KVM
is doomed even if the SEV guest is debuggable and the hypervisor is willing
to decrypt the VMCB. This may or may not be fixed on CPUs that have the
SVME_ADDR_CHK fix.
Cc: stable@vger.kernel.org
Signed-off-by: Sean Christopherson <seanjc@google.com>
Message-Id: <20210202212017.2486595-1-seanjc@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
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MAXPHYSMEM_1GB option was added for RV32 because RV32 only supports 1GB
of maximum physical memory. This lead to few compilation errors reported
by kernel test robot which created the following configuration combination
which are not useful but can be configured.
1. MAXPHYSMEM_1GB & RV64
2, MAXPHYSMEM_2GB & RV32
Fix this by restricting MAXPHYSMEM_1GB for RV32 and MAXPHYSMEM_2GB only for
RV64.
Fixes: e557793799c5 ("RISC-V: Fix maximum allowed phsyical memory for RV32")
Cc: stable@vger.kernel.org
Reported-by: Randy Dunlap <rdunlap@infradead.org>
Acked-by: Randy Dunlap <rdunlap@infradead.org>
Tested-by: Geert Uytterhoeven <geert@linux-m68k.org>
Signed-off-by: Atish Patra <atish.patra@wdc.com>
Signed-off-by: Palmer Dabbelt <palmerdabbelt@google.com>
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Allows the sections to be aligned on smaller boundaries and
therefore results in a smaller kernel image size.
Signed-off-by: Sebastien Van Cauwenberghe <svancau@gmail.com>
Reviewed-by: Atish Patra <atish.patra@wdc.com>
Signed-off-by: Palmer Dabbelt <palmerdabbelt@google.com>
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.init section permission should only updated to non-execute if
STRICT_KERNEL_RWX is enabled. Otherwise, this will lead to a kernel hang.
Fixes: 19a00869028f ("RISC-V: Protect all kernel sections including init early")
Cc: stable@vger.kernel.org
Suggested-by: Geert Uytterhoeven <geert@linux-m68k.org>
Reported-by: Geert Uytterhoeven <geert@linux-m68k.org>
Signed-off-by: Atish Patra <atish.patra@wdc.com>
Reviewed-by: Atish Patra <atish.patra@wdc.com>
Signed-off-by: Palmer Dabbelt <palmerdabbelt@google.com>
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virt_addr_valid macro checks that a virtual address is valid, ie that
the address belongs to the linear mapping and that the corresponding
physical page exists.
Add the missing check that ensures the virtual address belongs to the
linear mapping, otherwise __virt_to_phys, when compiled with
CONFIG_DEBUG_VIRTUAL enabled, raises a WARN that is interpreted as a
kernel bug by syzbot.
Signed-off-by: Alexandre Ghiti <alex@ghiti.fr>
Reviewed-by: Atish Patra <atish.patra@wdc.com>
Signed-off-by: Palmer Dabbelt <palmerdabbelt@google.com>
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