When running nested, these hypercalls must be sent to the L0 hypervisor
or VMBus will fail.

Remove hv_do_nested_hypercall() and hv_do_fast_nested_hypercall8()
altogether and open-code these cases, since there are only 2 and all
they do is add the nested bit.

Signed-off-by: Nuno Das Neves <nunodasneves@linux.microsoft.com>
Reviewed-by: Roman Kisel <romank@linux.microsoft.com>
Reviewed-by: Michael Kelley <mhklinux@outlook.com>
Link: https://lore.kernel.org/r/1752261532-7225-2-git-send-email-nunodasneves@linux.microsoft.com
Signed-off-by: Wei Liu <wei.liu@kernel.org>
Message-ID: <1752261532-7225-2-git-send-email-nunodasneves@linux.microsoft.com>

Fix below warning in Hyper-V drivers that comes when kernel is compiled
with W=1 option. Include export.h in driver files to fix it.
* warning: EXPORT_SYMBOL() is used, but #include <linux/export.h>
is missing

Signed-off-by: Naman Jain <namjain@linux.microsoft.com>
Reviewed-by: Nuno Das Neves <nunodasneves@linux.microsoft.com>
Reviewed-by: Saurabh Sengar <ssengar@linux.microsoft.com>
Link: https://lore.kernel.org/r/20250611100459.92900-2-namjain@linux.microsoft.com
Signed-off-by: Wei Liu <wei.liu@kernel.org>
Message-ID: <20250611100459.92900-2-namjain@linux.microsoft.com>

__is_defined(HYPERVISOR_CALLBACK_VECTOR) would return 1, only if
HYPERVISOR_CALLBACK_VECTOR macro is defined as 1. However its value is
0xf3 and this leads to __is_defined() returning 0. The expectation
was to just check whether this MACRO is defined or not and get 1 if
it's defined. Replace __is_defined with #ifdef blocks instead to
fix it.

Fixes: 1dc5df133b98 ("Drivers: hv: vmbus: Get the IRQ number from DeviceTree")
Cc: stable@kernel.org
Signed-off-by: Naman Jain <namjain@linux.microsoft.com>
Reviewed-by: Roman Kisel <romank@linux.microsoft.com>
Link: https://lore.kernel.org/r/20250707084322.1763-1-namjain@linux.microsoft.com
Signed-off-by: Wei Liu <wei.liu@kernel.org>
Message-ID: <20250707084322.1763-1-namjain@linux.microsoft.com>

Commit 96959283a58d ("Drivers: hv: Always select CONFIG_SYSFB
for Hyper-V guests") selects CONFIG_SYSFB for Hyper-V guests
so that screen_info is available to the VMBus driver to get
the location of the framebuffer in Generation 2 VMs. However,
if CONFIG_HYPERV is enabled but CONFIG_EFI is not, a kernel
link error results in ARM64 builds because screen_info is
provided by the EFI firmware interface. While configuring
an ARM64 Hyper-V guest without EFI isn't useful since EFI is
required to boot, the configuration is still possible and
the link error should be prevented.

Fix this by making the selection of CONFIG_SYSFB conditional
on CONFIG_EFI being defined. For Generation 1 VMs on x86/x64,
which don't use EFI, the additional condition is OK because
such VMs get the framebuffer information via a mechanism
that doesn't use screen_info.

Fixes: 96959283a58d ("Drivers: hv: Always select CONFIG_SYSFB for Hyper-V guests")
Reported-by: Arnd Bergmann <arnd@arndb.de>
Closes: https://lore.kernel.org/linux-hyperv/20250610091810.2638058-1-arnd@kernel.org/
Reported-by: kernel test robot <lkp@intel.com>
Closes: https://lore.kernel.org/oe-kbuild-all/202506080820.1wmkQufc-lkp@intel.com/
Signed-off-by: Michael Kelley <mhklinux@outlook.com>
Link: https://lore.kernel.org/stable/20250613230059.380483-1-mhklinux%40outlook.com
Reviewed-by: Roman Kisel <romank@linux.microsoft.com>
Link: https://lore.kernel.org/r/20250613230059.380483-1-mhklinux@outlook.com
Signed-off-by: Wei Liu <wei.liu@kernel.org>
Message-ID: <20250613230059.380483-1-mhklinux@outlook.com>

Pull hyperv updates from Wei Liu:

 - Support for Virtual Trust Level (VTL) on arm64 (Roman Kisel)

 - Fixes for Hyper-V UIO driver (Long Li)

 - Fixes for Hyper-V PCI driver (Michael Kelley)

 - Select CONFIG_SYSFB for Hyper-V guests (Michael Kelley)

 - Documentation updates for Hyper-V VMBus (Michael Kelley)

 - Enhance logging for hv_kvp_daemon (Shradha Gupta)

* tag 'hyperv-next-signed-20250602' of git://git.kernel.org/pub/scm/linux/kernel/git/hyperv/linux: (23 commits)
  Drivers: hv: Always select CONFIG_SYSFB for Hyper-V guests
  Drivers: hv: vmbus: Add comments about races with "channels" sysfs dir
  Documentation: hyperv: Update VMBus doc with new features and info
  PCI: hv: Remove unnecessary flex array in struct pci_packet
  Drivers: hv: Remove hv_alloc/free_* helpers
  Drivers: hv: Use kzalloc for panic page allocation
  uio_hv_generic: Align ring size to system page
  uio_hv_generic: Use correct size for interrupt and monitor pages
  Drivers: hv: Allocate interrupt and monitor pages aligned to system page boundary
  arch/x86: Provide the CPU number in the wakeup AP callback
  x86/hyperv: Fix APIC ID and VP index confusion in hv_snp_boot_ap()
  PCI: hv: Get vPCI MSI IRQ domain from DeviceTree
  ACPI: irq: Introduce acpi_get_gsi_dispatcher()
  Drivers: hv: vmbus: Introduce hv_get_vmbus_root_device()
  Drivers: hv: vmbus: Get the IRQ number from DeviceTree
  dt-bindings: microsoft,vmbus: Add interrupt and DMA coherence properties
  arm64, x86: hyperv: Report the VTL the system boots in
  arm64: hyperv: Initialize the Virtual Trust Level field
  Drivers: hv: Provide arch-neutral implementation of get_vtl()
  Drivers: hv: Enable VTL mode for arm64
  ...

Pull driver core updates from Greg KH:
 "Here are the driver core / kernfs changes for 6.16-rc1.

  Not a huge number of changes this development cycle, here's the
  summary of what is included in here:

   - kernfs locking tweaks, pushing some global locks down into a per-fs
     image lock

   - rust driver core and pci device bindings added for new features.

   - sysfs const work for bin_attributes.

     The final churn of switching away from and removing the
     transitional struct members, "read_new", "write_new" and
     "bin_attrs_new" will come after the merge window to avoid
     unnecesary merge conflicts.

   - auxbus device creation helpers added

   - fauxbus fix for creating sysfs files after the probe completed
     properly

   - other tiny updates for driver core things.

  All of these have been in linux-next for over a week with no reported
  issues"

* tag 'driver-core-6.16-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/driver-core/driver-core:
  kernfs: Relax constraint in draining guard
  Documentation: embargoed-hardware-issues.rst: Remove myself
  drivers: hv: fix up const issue with vmbus_chan_bin_attrs
  firmware_loader: use SHA-256 library API instead of crypto_shash API
  docs: debugfs: do not recommend debugfs_remove_recursive
  PM: wakeup: Do not expose 4 device wakeup source APIs
  kernfs: switch global kernfs_rename_lock to per-fs lock
  kernfs: switch global kernfs_idr_lock to per-fs lock
  driver core: auxiliary bus: Fix IS_ERR() vs NULL mixup in __devm_auxiliary_device_create()
  sysfs: constify attribute_group::bin_attrs
  sysfs: constify bin_attribute argument of bin_attribute::read/write()
  software node: Correct a OOB check in software_node_get_reference_args()
  devres: simplify devm_kstrdup() using devm_kmemdup()
  platform: replace magic number with macro PLATFORM_DEVID_NONE
  component: do not try to unbind unbound components
  driver core: auxiliary bus: add device creation helpers
  driver core: faux: Add sysfs groups after probing

The Hyper-V host provides guest VMs with a range of MMIO addresses
that guest VMBus drivers can use. The VMBus driver in Linux manages
that MMIO space, and allocates portions to drivers upon request. As
part of managing that MMIO space in a Generation 2 VM, the VMBus
driver must reserve the portion of the MMIO space that Hyper-V has
designated for the synthetic frame buffer, and not allocate this
space to VMBus drivers other than graphics framebuffer drivers. The
synthetic frame buffer MMIO area is described by the screen_info data
structure that is passed to the Linux kernel at boot time, so the
VMBus driver must access screen_info for Generation 2 VMs. (In
Generation 1 VMs, the framebuffer MMIO space is communicated to
the guest via a PCI pseudo-device, and access to screen_info is
not needed.)

In commit a07b50d80ab6 ("hyperv: avoid dependency on screen_info")
the VMBus driver's access to screen_info is restricted to when
CONFIG_SYSFB is enabled. CONFIG_SYSFB is typically enabled in kernels
built for Hyper-V by virtue of having at least one of CONFIG_FB_EFI,
CONFIG_FB_VESA, or CONFIG_SYSFB_SIMPLEFB enabled, so the restriction
doesn't usually affect anything. But it's valid to have none of these
enabled, in which case CONFIG_SYSFB is not enabled, and the VMBus driver
is unable to properly reserve the framebuffer MMIO space for graphics
framebuffer drivers. The framebuffer MMIO space may be assigned to
some other VMBus driver, with undefined results. As an example, if
a VM is using a PCI pass-thru NVMe controller to host the OS disk,
the PCI NVMe controller is probed before any graphics devices, and the
NVMe controller is assigned a portion of the framebuffer MMIO space.
Hyper-V reports an error to Linux during the probe, and the OS disk
fails to get setup. Then Linux fails to boot in the VM.

Fix this by having CONFIG_HYPERV always select SYSFB. Then the
VMBus driver in a Gen 2 VM can always reserve the MMIO space for the
graphics framebuffer driver, and prevent the undefined behavior. But
don't select SYSFB when building for HYPERV_VTL_MODE as VTLs other
than VTL 0 don't have a framebuffer and aren't subject to the issue.
Adding SYSFB in such cases is harmless, but would increase the image
size for no purpose.

Fixes: a07b50d80ab6 ("hyperv: avoid dependency on screen_info")
Signed-off-by: Michael Kelley <mhklinux@outlook.com>
Reviewed-by: Saurabh Sengar <ssengar@linux.microsoft.com>
Link: https://lore.kernel.org/stable/20250520040143.6964-1-mhklinux%40outlook.com
Link: https://lore.kernel.org/r/20250520040143.6964-1-mhklinux@outlook.com
Signed-off-by: Wei Liu <wei.liu@kernel.org>
Message-ID: <20250520040143.6964-1-mhklinux@outlook.com>

The VMBus driver code has some inherent races in the creation of the
"channels" sysfs subdirectory and its per-channel numbered subdirectories.
These races have not generally been recognized or understood. Add some
comments to call them out. No code changes.

Signed-off-by: Michael Kelley <mhklinux@outlook.com>
Link: https://lore.kernel.org/r/20250514225508.52629-1-mhklinux@outlook.com
Signed-off-by: Wei Liu <wei.liu@kernel.org>
Message-ID: <20250514225508.52629-1-mhklinux@outlook.com>

There are no users for those functions, remove them.

Signed-off-by: Long Li <longli@microsoft.com>
Reviewed-by: Michael Kelley <mhklinux@outlook.com>
Link: https://lore.kernel.org/r/1746492997-4599-6-git-send-email-longli@linuxonhyperv.com
Signed-off-by: Wei Liu <wei.liu@kernel.org>
Message-ID: <1746492997-4599-6-git-send-email-longli@linuxonhyperv.com>

To prepare for removal of hv_alloc_* and hv_free* functions, use
kzalloc/kfree directly for panic reporting page.

Signed-off-by: Long Li <longli@microsoft.com>
Reviewed-by: Michael Kelley <mhklinux@outlook.com>
Link: https://lore.kernel.org/r/1746492997-4599-5-git-send-email-longli@linuxonhyperv.com
Signed-off-by: Wei Liu <wei.liu@kernel.org>
Message-ID: <1746492997-4599-5-git-send-email-longli@linuxonhyperv.com>