KVM selftests for 6.11

 - Remove dead code in the memslot modification stress test.

 - Treat "branch instructions retired" as supported on all AMD Family 17h+ CPUs.

 - Print the guest pseudo-RNG seed only when it changes, to avoid spamming the
   log for tests that create lots of VMs.

 - Make the PMU counters test less flaky when counting LLC cache misses by
   doing CLFLUSH{OPT} in every loop iteration.

KVM x86 misc changes for 6.11

 - Add a global struct to consolidate tracking of host values, e.g. EFER, and
   move "shadow_phys_bits" into the structure as "maxphyaddr".

 - Add KVM_CAP_X86_APIC_BUS_CYCLES_NS to allow configuring the effective APIC
   bus frequency, because TDX.

 - Print the name of the APICv/AVIC inhibits in the relevant tracepoint.

 - Clean up KVM's handling of vendor specific emulation to consistently act on
   "compatible with Intel/AMD", versus checking for a specific vendor.

 - Misc cleanups

Add udelay() for x86 tests to allow busy waiting in the guest for a
specific duration, and to match ARM and RISC-V's udelay() in the hopes
of eventually making udelay() available on all architectures.

Get the guest's TSC frequency using KVM_GET_TSC_KHZ and expose it to all
VMs via a new global, guest_tsc_khz.  Assert that KVM_GET_TSC_KHZ returns
a valid frequency, instead of simply skipping tests, which would require
detecting which tests actually need/want udelay().  KVM hasn't returned an
error for KVM_GET_TSC_KHZ since commit cc578287e322 ("KVM: Infrastructure
for software and hardware based TSC rate scaling"), which predates KVM
selftests by 6+ years (KVM_GET_TSC_KHZ itself predates KVM selftest by 7+
years).

Note, if the GUEST_ASSERT() in udelay() somehow fires and the test doesn't
check for guest asserts, then the test will fail with a very cryptic
message.  But fixing that, e.g. by automatically handling guest asserts,
is a much larger task, and practically speaking the odds of a test afoul
of this wart are infinitesimally small.

Signed-off-by: Reinette Chatre <reinette.chatre@intel.com>
Link: https://lore.kernel.org/r/5aa86285d1c1d7fe1960e3fe490f4b22273977e6.1718214999.git.reinette.chatre@intel.com
Co-developed-by: Sean Christopherson <seanjc@google.com>
Signed-off-by: Sean Christopherson <seanjc@google.com>

Print the guest's random seed during VM creation if and only if the seed
has changed since the seed was last printed.  The vast majority of tests,
if not all tests at this point, set the seed during test initialization
and never change the seed, i.e. printing it every time a VM is created is
useless noise.

Snapshot and print the seed during early selftest init to play nice with
tests that use the kselftests harness, at the cost of printing an unused
seed for tests that change the seed during test-specific initialization,
e.g. dirty_log_perf_test.  The kselftests harness runs each testcase in a
separate process that is forked from the original process before creating
each testcase's VM, i.e. waiting until first VM creation will result in
the seed being printed by each testcase despite it never changing.  And
long term, the hope/goal is that setting the seed will be handled by the
core framework, i.e. that the dirty_log_perf_test wart will naturally go
away.

Reported-by: Yi Lai <yi1.lai@intel.com>
Reported-by: Dapeng Mi <dapeng1.mi@linux.intel.com>
Link: https://lore.kernel.org/r/20240627021756.144815-2-dapeng1.mi@linux.intel.com
Signed-off-by: Sean Christopherson <seanjc@google.com>

KVM/riscv fixes for 6.10, take #2

- Fix compilation for KVM selftests

Due to commit 2b7deea3ec7c ("Revert "kvm: selftests: move base
kvm_util.h declarations to kvm_util_base.h"") kvm selftests now
requires explicitly including ucall_common.h when needed. The commit
added the directives everywhere they were needed at the time, but, by
merge time, new places had been merged for RISC-V. Add those now to
fix RISC-V's compilation.

Fixes: dee7ea42a1eb ("Merge tag 'kvm-x86-selftests_utils-6.10' of https://github.com/kvm-x86/linux into HEAD")
Signed-off-by: Andrew Jones <ajones@ventanamicro.com>
Link: https://lore.kernel.org/r/20240603122045.323064-2-ajones@ventanamicro.com
Signed-off-by: Anup Patel <anup@brainfault.org>

Use the max mappable GPA via GuestPhysBits advertised by KVM to calculate
max_gfn. Currently some selftests (e.g. access_tracking_perf_test,
dirty_log_test...) add RAM regions close to max_gfn, so guest may access
GPA beyond its mappable range and cause infinite loop.

Adjust max_gfn in vm_compute_max_gfn() since x86 selftests already
overrides vm_compute_max_gfn() specifically to deal with goofy edge cases.

Reported-by: Yi Lai <yi1.lai@intel.com>
Signed-off-by: Tao Su <tao1.su@linux.intel.com>
Tested-by: Yi Lai <yi1.lai@intel.com>
Reviewed-by: Xiaoyao Li <xiaoyao.li@intel.com>
Link: https://lore.kernel.org/r/20240513014003.104593-1-tao1.su@linux.intel.com
[sean: tweak name, add comment and sanity check]
Signed-off-by: Sean Christopherson <seanjc@google.com>

KVM selftests treewide updates for 6.10:

 - Define _GNU_SOURCE for all selftests to fix a warning that was introduced by
   a change to kselftest_harness.h late in the 6.9 cycle, and because forcing
   every test to #define _GNU_SOURCE is painful.

 - Provide a global psuedo-RNG instance for all tests, so that library code can
   generate random, but determinstic numbers.

 - Use the global pRNG to randomly force emulation of select writes from guest
   code on x86, e.g. to help validate KVM's emulation of locked accesses.

 - Rename kvm_util_base.h back to kvm_util.h, as the weird layer of indirection
   was added purely to avoid manually #including ucall_common.h in a handful of
   locations.

 - Allocate and initialize x86's GDT, IDT, TSS, segments, and default exception
   handlers at VM creation, instead of forcing tests to manually trigger the
   related setup.

KVM selftests cleanups and fixes for 6.10:

 - Enhance the demand paging test to allow for better reporting and stressing
   of UFFD performance.

 - Convert the steal time test to generate TAP-friendly output.

 - Fix a flaky false positive in the xen_shinfo_test due to comparing elapsed
   time across two different clock domains.

 - Skip the MONITOR/MWAIT test if the host doesn't actually support MWAIT.

 - Avoid unnecessary use of "sudo" in the NX hugepage test to play nice with
   running in a minimal userspace environment.

 - Allow skipping the RSEQ test's sanity check that the vCPU was able to
   complete a reasonable number of KVM_RUNs, as the assert can fail on a
   completely valid setup.  If the test is run on a large-ish system that is
   otherwise idle, and the test isn't affined to a low-ish number of CPUs, the
   vCPU task can be repeatedly migrated to CPUs that are in deep sleep states,
   which results in the vCPU having very little net runtime before the next
   migration due to high wakeup latencies.

KVM/arm64 updates for Linux 6.10

- Move a lot of state that was previously stored on a per vcpu
  basis into a per-CPU area, because it is only pertinent to the
  host while the vcpu is loaded. This results in better state
  tracking, and a smaller vcpu structure.

- Add full handling of the ERET/ERETAA/ERETAB instructions in
  nested virtualisation. The last two instructions also require
  emulating part of the pointer authentication extension.
  As a result, the trap handling of pointer authentication has
  been greattly simplified.

- Turn the global (and not very scalable) LPI translation cache
  into a per-ITS, scalable cache, making non directly injected
  LPIs much cheaper to make visible to the vcpu.

- A batch of pKVM patches, mostly fixes and cleanups, as the
  upstreaming process seems to be resuming. Fingers crossed!

- Allocate PPIs and SGIs outside of the vcpu structure, allowing
  for smaller EL2 mapping and some flexibility in implementing
  more or less than 32 private IRQs.

- Purge stale mpidr_data if a vcpu is created after the MPIDR
  map has been created.

- Preserve vcpu-specific ID registers across a vcpu reset.

- Various minor cleanups and improvements.