Implement KVM selftests support for powerpc (Book3S-64).

ucalls are implemented with an unsupported PAPR hcall number which will
always cause KVM to exit to userspace.

Virtual memory is implemented for the radix MMU, and only a base page
size is supported (both 4K and 64K).

Guest interrupts are taken in real-mode, so require a page allocated at
gRA 0x0. Interrupt entry is complicated because gVA:gRA is not 1:1
mapped (like the kernel is), so the MMU can not just be switched on and
off.

This patch series also changes the following types as done in other
selftests. These changes are squashed in this main patch as discussed
here [1]:
- Use u64 instead of uint64_t
- Use s64 instead of int64_t
- Use u32 instead of uint32_t
- Use u8 instead of uint8_t
- Replace u64 gpa, u64 gva|vaddr with gpa_t and gva_t
- Adopt to the new page table allocator APIs
- Start the guest at the entry point and not the descriptor in case of
  elfv1

[1]: https://lore.kernel.org/linuxppc-dev/cover.1781093720.git.ritesh.list@gmail.com/
[Rebased to latest mainline tree, "cc" to clobber list, fix the
size calculation in kvm_arch_vm_post_create()]

Co-developed-by: Ritesh Harjani (IBM) <ritesh.list@gmail.com>
Signed-off-by: Nicholas Piggin <npiggin@gmail.com>
Link: https://lore.kernel.org/linuxppc-dev/cover.1781093720.git.ritesh.list@gmail.com/
Tested-by: Anushree Mathur <anushree.mathur@linux.ibm.com>
Signed-off-by: Ritesh Harjani (IBM) <ritesh.list@gmail.com>
Reviewed-by: Gautam Menghani <gautam@linux.ibm.com>
Tested-by: Gautam Menghani <gautam@linux.ibm.com>
Acked-by: Madhavan Srinivasan <maddy@linux.ibm.com>
Link: https://patch.msgid.link/062570e96982a9a1a82e95c7ed0a3458321fd569.1791280439.git.ritesh.list@gmail.com
Signed-off-by: Sean Christopherson <seanjc@google.com>

Forcefully override ARCH from x86_64 to x86 to handle the scenario where
the user specifies ARCH=x86_64 on the command line.

Fixes: 9af04539d474 ("KVM: selftests: Override ARCH for x86_64 instead of using ARCH_DIR")
Cc: stable@vger.kernel.org
Reported-by: David Matlack <dmatlack@google.com>
Closes: https://lore.kernel.org/all/20250724213130.3374922-1-dmatlack@google.com
Link: https://lore.kernel.org/r/20251007223057.368082-1-seanjc@google.com
Signed-off-by: Sean Christopherson <seanjc@google.com>

Some common KVM test cases are supported on LoongArch now as following:
  coalesced_io_test
  demand_paging_test
  dirty_log_perf_test
  dirty_log_test
  guest_print_test
  hardware_disable_test
  kvm_binary_stats_test
  kvm_create_max_vcpus
  kvm_page_table_test
  memslot_modification_stress_test
  memslot_perf_test
  set_memory_region_test

And other test cases are not supported by LoongArch such as rseq_test,
since it is not supported on LoongArch physical machine either.

Signed-off-by: Bibo Mao <maobibo@loongson.cn>
Signed-off-by: Huacai Chen <chenhuacai@loongson.cn>

Now that KVM selftests uses the kernel's canonical arch paths, directly
override ARCH to 'x86' when targeting x86_64 instead of defining ARCH_DIR
to redirect to appropriate paths.  ARCH_DIR was originally added to deal
with KVM selftests using the target triple ARCH for directories, e.g.
s390x and aarch64; keeping it around just to deal with the one-off alias
from x86_64=>x86 is unnecessary and confusing.

Note, even when selftests are built from the top-level Makefile, ARCH is
scoped to KVM's makefiles, i.e. overriding ARCH won't trip up some other
selftests that (somehow) expects x86_64 and can't work with x86.

Reviewed-by: Muhammad Usama Anjum <usama.anjum@collabora.com>
Link: https://lore.kernel.org/r/20241128005547.4077116-17-seanjc@google.com
Signed-off-by: Sean Christopherson <seanjc@google.com>

Use the kernel's canonical $(ARCH) paths instead of the raw target triple
for KVM selftests directories.  KVM selftests are quite nearly the only
place in the entire kernel that using the target triple for directories,
tools/testing/selftests/drivers/s390x being the lone holdout.

Using the kernel's preferred nomenclature eliminates the minor, but
annoying, friction of having to translate to KVM's selftests directories,
e.g. for pattern matching, opening files, running selftests, etc.

Opportunsitically delete file comments that reference the full path of the
file, as they are obviously prone to becoming stale, and serve no known
purpose.

Reviewed-by: Muhammad Usama Anjum <usama.anjum@collabora.com>
Acked-by: Claudio Imbrenda <imbrenda@linux.ibm.com>
Acked-by: Andrew Jones <ajones@ventanamicro.com>
Link: https://lore.kernel.org/r/20241128005547.4077116-16-seanjc@google.com
Signed-off-by: Sean Christopherson <seanjc@google.com>

Provide empty targets for KVM selftests if the target architecture is
unsupported to make it obvious which architectures are supported, and so
that various side effects don't fail and/or do weird things, e.g. as is,
"mkdir -p $(sort $(dir $(TEST_GEN_PROGS)))" fails due to a missing operand,
and conversely, "$(shell mkdir -p $(sort $(OUTPUT)/$(ARCH_DIR) ..." will
create an empty, useless directory for the unsupported architecture.

Move the guts of the Makefile to Makefile.kvm so that it's easier to see
that the if-statement effectively guards all of KVM selftests.

Reported-by: Muhammad Usama Anjum <usama.anjum@collabora.com>
Acked-by: Muhammad Usama Anjum <usama.anjum@collabora.com>
Acked-by: Andrew Jones <ajones@ventanamicro.com>
Link: https://lore.kernel.org/r/20241128005547.4077116-15-seanjc@google.com
Signed-off-by: Sean Christopherson <seanjc@google.com>

Enable the mmu_stress_test on arm64.  The intent was to enable the test
across all architectures when it was first added, but a few goofs made it
unrunnable on !x86.  Now that those goofs are fixed, at least for arm64,
enable the test.

Cc: Oliver Upton <oliver.upton@linux.dev>
Cc: Marc Zyngier <maz@kernel.org>
Reviewed-by: James Houghton <jthoughton@google.com>
Reviewed-by: Andrew Jones <ajones@ventanamicro.com>
Link: https://lore.kernel.org/r/20241128005547.4077116-10-seanjc@google.com
Signed-off-by: Sean Christopherson <seanjc@google.com>

Rename max_guest_memory_test to mmu_stress_test so that the name isn't
horribly misleading when future changes extend the test to verify things
like mprotect() interactions, and because the test is useful even when its
configured to populate far less than the maximum amount of guest memory.

Reviewed-by: James Houghton <jthoughton@google.com>
Reviewed-by: Andrew Jones <ajones@ventanamicro.com>
Link: https://lore.kernel.org/r/20241128005547.4077116-6-seanjc@google.com
Signed-off-by: Sean Christopherson <seanjc@google.com>

KVM/arm64 changes for 6.13, part #1

 - Support for stage-1 permission indirection (FEAT_S1PIE) and
   permission overlays (FEAT_S1POE), including nested virt + the
   emulated page table walker

 - Introduce PSCI SYSTEM_OFF2 support to KVM + client driver. This call
   was introduced in PSCIv1.3 as a mechanism to request hibernation,
   similar to the S4 state in ACPI

 - Explicitly trap + hide FEAT_MPAM (QoS controls) from KVM guests. As
   part of it, introduce trivial initialization of the host's MPAM
   context so KVM can use the corresponding traps

 - PMU support under nested virtualization, honoring the guest
   hypervisor's trap configuration and event filtering when running a
   nested guest

 - Fixes to vgic ITS serialization where stale device/interrupt table
   entries are not zeroed when the mapping is invalidated by the VM

 - Avoid emulated MMIO completion if userspace has requested synchronous
   external abort injection

 - Various fixes and cleanups affecting pKVM, vCPU initialization, and
   selftests

- Drop obsolete references to PPC970 KVM, which was removed 10 years ago.

- Fix incorrect references to non-existing ioctls

- List registers supported by KVM_GET/SET_ONE_REG on s390

- Use rST internal links

- Reorganize the introduction to the API document