hv_hvcrash_ctxt_save() in arch/x86/hyperv/hv_crash.c currently saves
segment registers via a general-purpose register (%eax). Update the
code to save segment registers (cs, ss, ds, es, fs, gs) directly to
the crash context memory using movw. This avoids unnecessary use of
a general-purpose register, making the code simpler and more efficient.
The size of the corresponding object file improves as follows:
text data bss dec hex filename
4167 176 200 4543 11bf hv_crash-old.o
4151 176 200 4527 11af hv_crash-new.o
No functional change occurs to the saved context contents; this is
purely a code-quality improvement.
Signed-off-by: Uros Bizjak <ubizjak@gmail.com>
Cc: K. Y. Srinivasan <kys@microsoft.com>
Cc: Haiyang Zhang <haiyangz@microsoft.com>
Cc: Wei Liu <wei.liu@kernel.org>
Cc: Dexuan Cui <decui@microsoft.com>
Cc: Long Li <longli@microsoft.com>
Cc: Thomas Gleixner <tglx@kernel.org>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Dave Hansen <dave.hansen@linux.intel.com>
Cc: H. Peter Anvin <hpa@zytor.com>
Signed-off-by: Wei Liu <wei.liu@kernel.org>
hv_crash_c_entry() is a C function that is entered without a stack,
and this is only allowed for functions that have the __naked attribute,
which informs the compiler that it must not emit the usual prologue and
epilogue or emit any other kind of instrumentation that relies on a
stack frame.
So split up the function, and set the __naked attribute on the initial
part that sets up the stack, GDT, IDT and other pieces that are needed
for ordinary C execution. Given that function calls are not permitted
either, use the existing long return coded in an asm() block to call the
second part of the function, which is an ordinary function that is
permitted to call other functions as usual.
Reviewed-by: Andrew Cooper <andrew.cooper3@citrix.com> # asm parts, not hv parts
Reviewed-by: Mukesh Rathor <mrathor@linux.microsoft.com>
Acked-by: Uros Bizjak <ubizjak@gmail.com>
Cc: Wei Liu <wei.liu@kernel.org>
Cc: linux-hyperv@vger.kernel.org
Fixes: 94212d3461 ("x86/hyperv: Implement hypervisor RAM collection into vmcore")
Signed-off-by: Ard Biesheuvel <ardb@kernel.org>
Signed-off-by: Wei Liu <wei.liu@kernel.org>
This converts some of the visually simpler cases that have been split
over multiple lines. I only did the ones that are easy to verify the
resulting diff by having just that final GFP_KERNEL argument on the next
line.
Somebody should probably do a proper coccinelle script for this, but for
me the trivial script actually resulted in an assertion failure in the
middle of the script. I probably had made it a bit _too_ trivial.
So after fighting that far a while I decided to just do some of the
syntactically simpler cases with variations of the previous 'sed'
scripts.
The more syntactically complex multi-line cases would mostly really want
whitespace cleanup anyway.
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This was done entirely with mindless brute force, using
git grep -l '\<k[vmz]*alloc_objs*(.*, GFP_KERNEL)' |
xargs sed -i 's/\(alloc_objs*(.*\), GFP_KERNEL)/\1)/'
to convert the new alloc_obj() users that had a simple GFP_KERNEL
argument to just drop that argument.
Note that due to the extreme simplicity of the scripting, any slightly
more complex cases spread over multiple lines would not be triggered:
they definitely exist, but this covers the vast bulk of the cases, and
the resulting diff is also then easier to check automatically.
For the same reason the 'flex' versions will be done as a separate
conversion.
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This is the result of running the Coccinelle script from
scripts/coccinelle/api/kmalloc_objs.cocci. The script is designed to
avoid scalar types (which need careful case-by-case checking), and
instead replace kmalloc-family calls that allocate struct or union
object instances:
Single allocations: kmalloc(sizeof(TYPE), ...)
are replaced with: kmalloc_obj(TYPE, ...)
Array allocations: kmalloc_array(COUNT, sizeof(TYPE), ...)
are replaced with: kmalloc_objs(TYPE, COUNT, ...)
Flex array allocations: kmalloc(struct_size(PTR, FAM, COUNT), ...)
are replaced with: kmalloc_flex(*PTR, FAM, COUNT, ...)
(where TYPE may also be *VAR)
The resulting allocations no longer return "void *", instead returning
"TYPE *".
Signed-off-by: Kees Cook <kees@kernel.org>
Pull Hyper-V updates from Wei Liu:
- Debugfs support for MSHV statistics (Nuno Das Neves)
- Support for the integrated scheduler (Stanislav Kinsburskii)
- Various fixes for MSHV memory management and hypervisor status
handling (Stanislav Kinsburskii)
- Expose more capabilities and flags for MSHV partition management
(Anatol Belski, Muminul Islam, Magnus Kulke)
- Miscellaneous fixes to improve code quality and stability (Carlos
López, Ethan Nelson-Moore, Li RongQing, Michael Kelley, Mukesh
Rathor, Purna Pavan Chandra Aekkaladevi, Stanislav Kinsburskii, Uros
Bizjak)
- PREEMPT_RT fixes for vmbus interrupts (Jan Kiszka)
* tag 'hyperv-next-signed-20260218' of git://git.kernel.org/pub/scm/linux/kernel/git/hyperv/linux: (34 commits)
mshv: Handle insufficient root memory hypervisor statuses
mshv: Handle insufficient contiguous memory hypervisor status
mshv: Introduce hv_deposit_memory helper functions
mshv: Introduce hv_result_needs_memory() helper function
mshv: Add SMT_ENABLED_GUEST partition creation flag
mshv: Add nested virtualization creation flag
Drivers: hv: vmbus: Simplify allocation of vmbus_evt
mshv: expose the scrub partition hypercall
mshv: Add support for integrated scheduler
mshv: Use try_cmpxchg() instead of cmpxchg()
x86/hyperv: Fix error pointer dereference
x86/hyperv: Reserve 3 interrupt vectors used exclusively by MSHV
Drivers: hv: vmbus: Use kthread for vmbus interrupts on PREEMPT_RT
x86/hyperv: Remove ASM_CALL_CONSTRAINT with VMMCALL insn
x86/hyperv: Use savesegment() instead of inline asm() to save segment registers
mshv: fix SRCU protection in irqfd resampler ack handler
mshv: make field names descriptive in a header struct
x86/hyperv: Update comment in hyperv_cleanup()
mshv: clear eventfd counter on irqfd shutdown
x86/hyperv: Use memremap()/memunmap() instead of ioremap_cache()/iounmap()
...
The function idle_thread_get() can return an error pointer and is not
checked for it. Add check for error pointer.
Detected by Smatch:
arch/x86/hyperv/hv_vtl.c:126 hv_vtl_bringup_vcpu() error:
'idle' dereferencing possible ERR_PTR()
Fixes: 2b4b90e053 ("x86/hyperv: Use per cpu initial stack for vtl context")
Signed-off-by: Ethan Tidmore <ethantidmore06@gmail.com>
Signed-off-by: Wei Liu <wei.liu@kernel.org>
Pull x86 paravirt updates from Borislav Petkov:
- A nice cleanup to the paravirt code containing a unification of the
paravirt clock interface, taming the include hell by splitting the
pv_ops structure and removing of a bunch of obsolete code (Juergen
Gross)
* tag 'x86_paravirt_for_v7.0_rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (23 commits)
x86/paravirt: Use XOR r32,r32 to clear register in pv_vcpu_is_preempted()
x86/paravirt: Remove trailing semicolons from alternative asm templates
x86/pvlocks: Move paravirt spinlock functions into own header
x86/paravirt: Specify pv_ops array in paravirt macros
x86/paravirt: Allow pv-calls outside paravirt.h
objtool: Allow multiple pv_ops arrays
x86/xen: Drop xen_mmu_ops
x86/xen: Drop xen_cpu_ops
x86/xen: Drop xen_irq_ops
x86/paravirt: Move pv_native_*() prototypes to paravirt.c
x86/paravirt: Introduce new paravirt-base.h header
x86/paravirt: Move paravirt_sched_clock() related code into tsc.c
x86/paravirt: Use common code for paravirt_steal_clock()
riscv/paravirt: Use common code for paravirt_steal_clock()
loongarch/paravirt: Use common code for paravirt_steal_clock()
arm64/paravirt: Use common code for paravirt_steal_clock()
arm/paravirt: Use common code for paravirt_steal_clock()
sched: Move clock related paravirt code to kernel/sched
paravirt: Remove asm/paravirt_api_clock.h
x86/paravirt: Move thunk macros to paravirt_types.h
...
The comment in hyperv_cleanup() became out-of-date as a result of
commit c8ed081264 ("x86/hyperv: Use direct call to hypercall-page").
Update the comment. No code or functional change.
Signed-off-by: Michael Kelley <mhklinux@outlook.com>
Signed-off-by: Wei Liu <wei.liu@kernel.org>
When running with a paravisor and SEV-SNP, the GHCB page is provided
by the paravisor instead of being allocated by Linux. The provided page
is normal memory, but is outside of the physical address space seen by
Linux. As such it cannot be accessed via the kernel's direct map, and
must be explicitly mapped to a kernel virtual address.
Current code uses ioremap_cache() and iounmap() to map and unmap the page.
These functions are for use on I/O address space that may not behave as
normal memory, so they generate or expect addresses with the __iomem
attribute. For normal memory, the preferred functions are memremap() and
memunmap(), which operate similarly but without __iomem.
At the time of the original work on CoCo VMs on Hyper-V, memremap() did not
support creating a decrypted mapping, so ioremap_cache() was used instead,
since I/O address space is always mapped decrypted. memremap() has since
been enhanced to allow decrypted mappings, so replace ioremap_cache() with
memremap() when mapping the GHCB page. Similarly, replace iounmap() with
memunmap(). As a side benefit, the replacement cleans up 'sparse' warnings
about __iomem mismatches.
The replacement is done to use the correct functions as long-term goodness
and to clean up the sparse warnings. No runtime bugs are fixed.
Reported-by: kernel test robot <lkp@intel.com>
Closes: https://lore.kernel.org/oe-kbuild-all/202311111925.iPGGJik4-lkp@intel.com/
Signed-off-by: Michael Kelley <mhklinux@outlook.com>
Signed-off-by: Wei Liu <wei.liu@kernel.org>
hv_root_crash_init() is not setting up the hypervisor crash collection
for baremetal cases because when it's called, hypervisor page is not
setup.
Fix is simple, just move the crash init call after the hypercall
page setup.
Signed-off-by: Mukesh Rathor <mrathor@linux.microsoft.com>
Signed-off-by: Wei Liu <wei.liu@kernel.org>
CI testing found this build failure:
arch/x86/hyperv/hv_crash.c:631:9: error: ‘smp_ops’ undeclared (first use in this function)
And I bisected it back to the initial commit that enabled this feature:
77c860d2db is the first bad commit
commit 77c860d2db (HEAD)
Author: Mukesh Rathor <mrathor@linux.microsoft.com>
Date: Mon Oct 6 15:42:08 2025 -0700
x86/hyperv: Enable build of hypervisor crashdump collection files
Hyperv should probably be limited to SMP kernels, as nobody
appears to be testing it on UP kernels.
Until then, fix the smp_ops assumption. Build tested only.
Fixes: 77c860d2db ("x86/hyperv: Enable build of hypervisor crashdump collection files")
Cc: Mukesh Rathor <mrathor@linux.microsoft.com>
Cc: Wei Liu <wei.liu@kernel.org>
Cc: linux-kernel@vger.kernel.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Commit 7bfe3b8ea6 ("Drivers: hv: Introduce mshv_vtl driver") added a
new generated header file for the offsets into the mshv_vtl_cpu_context
structure to be used by the low-level assembly code. But it didn't add
the .gitignore file to go with it, so 'git status' and friends will
mention it.
Let's add the gitignore file before somebody thinks that generated
header should be committed.
Fixes: 7bfe3b8ea6 ("Drivers: hv: Introduce mshv_vtl driver")
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Pull hyperv updates from Wei Liu:
- Enhancements to Linux as the root partition for Microsoft Hypervisor:
- Support a new mode called L1VH, which allows Linux to drive the
hypervisor running the Azure Host directly
- Support for MSHV crash dump collection
- Allow Linux's memory management subsystem to better manage guest
memory regions
- Fix issues that prevented a clean shutdown of the whole system on
bare metal and nested configurations
- ARM64 support for the MSHV driver
- Various other bug fixes and cleanups
- Add support for Confidential VMBus for Linux guest on Hyper-V
- Secure AVIC support for Linux guests on Hyper-V
- Add the mshv_vtl driver to allow Linux to run as the secure kernel in
a higher virtual trust level for Hyper-V
* tag 'hyperv-next-signed-20251207' of git://git.kernel.org/pub/scm/linux/kernel/git/hyperv/linux: (58 commits)
mshv: Cleanly shutdown root partition with MSHV
mshv: Use reboot notifier to configure sleep state
mshv: Add definitions for MSHV sleep state configuration
mshv: Add support for movable memory regions
mshv: Add refcount and locking to mem regions
mshv: Fix huge page handling in memory region traversal
mshv: Move region management to mshv_regions.c
mshv: Centralize guest memory region destruction
mshv: Refactor and rename memory region handling functions
mshv: adjust interrupt control structure for ARM64
Drivers: hv: use kmalloc_array() instead of kmalloc()
mshv: Add ioctl for self targeted passthrough hvcalls
Drivers: hv: Introduce mshv_vtl driver
Drivers: hv: Export some symbols for mshv_vtl
static_call: allow using STATIC_CALL_TRAMP_STR() from assembly
mshv: Extend create partition ioctl to support cpu features
mshv: Allow mappings that overlap in uaddr
mshv: Fix create memory region overlap check
mshv: add WQ_PERCPU to alloc_workqueue users
Drivers: hv: Use kmalloc_array() instead of kmalloc()
...
Provide an interface for Virtual Machine Monitor like OpenVMM and its
use as OpenHCL paravisor to control VTL0 (Virtual trust Level).
Expose devices and support IOCTLs for features like VTL creation,
VTL0 memory management, context switch, making hypercalls,
mapping VTL0 address space to VTL2 userspace, getting new VMBus
messages and channel events in VTL2 etc.
Co-developed-by: Roman Kisel <romank@linux.microsoft.com>
Signed-off-by: Roman Kisel <romank@linux.microsoft.com>
Co-developed-by: Saurabh Sengar <ssengar@linux.microsoft.com>
Signed-off-by: Saurabh Sengar <ssengar@linux.microsoft.com>
Reviewed-by: Michael Kelley <mhklinux@outlook.com>
Signed-off-by: Naman Jain <namjain@linux.microsoft.com>
Signed-off-by: Wei Liu <wei.liu@kernel.org>
Enable build of the new files introduced in the earlier commits and add
call to do the setup during boot.
Signed-off-by: Mukesh Rathor <mrathor@linux.microsoft.com>
[ wei: fix build ]
Signed-off-by: Wei Liu <wei.liu@kernel.org>
Introduce a new file to implement collection of hypervisor RAM into the
vmcore collected by linux. By default, the hypervisor RAM is locked, ie,
protected via hw page table. Hyper-V implements a disable hypercall which
essentially devirtualizes the system on the fly. This mechanism makes the
hypervisor RAM accessible to linux. Because the hypervisor RAM is already
mapped into linux address space (as reserved RAM), it is automatically
collected into the vmcore without extra work. More details of the
implementation are available in the file prologue.
Signed-off-by: Mukesh Rathor <mrathor@linux.microsoft.com>
Signed-off-by: Wei Liu <wei.liu@kernel.org>
Uros BizjakandWei Liu
Ard BiesheuvelandWei Liu
Linus Torvalds
Kees Cook
Ethan TidmoreandWei Liu
Michael KelleyandWei Liu
Mukesh RandWei Liu
Ingo Molnar
Juergen GrossandBorislav Petkov (AMD)
Praveen K PaladuguandWei Liu
Naman JainandWei Liu