KVM SEV changes for 7.2

 - Don't advertise support for unusuable VM types, and account for VM types
   that are disabled by firmware, e.g. to mitigate security vulnerabilities.

 - Rewrite the SEV {en,de}crypt debug ioctls as they were riddle with bugs and
   unnecessarily complicated, and add comprehensive tests.

 - Clean up and deduplicate the SEV page pinning code.

 - Fix minor goofs related to writing back CPUID information after firmware
   rejects a CPUID page for an SNP vCPU.

Add BIT_ULL(35) (CpuidUserDis) to the valid mask in hwcr_msr_test, now that
KVM accepts writes to this bit when the guest CPUID advertises
CpuidUserDis.

Signed-off-by: Jim Mattson <jmattson@google.com>
Link: https://patch.msgid.link/20260527174347.2356165-6-jmattson@google.com
Signed-off-by: Sean Christopherson <seanjc@google.com>

Add a test that exercises nested page fault injection during L2
execution. L2 executes I/O string instructions (OUTSB/INSB) that access
memory restricted in L1's nested page tables (NPT/EPT), triggering a
nested page fault that L0 must inject to L1.

The test supports both AMD SVM (NPF) and Intel VMX (EPT violation) and
verifies that:
  - The exit reason is an NPF/EPT violation
  - The access type and permission bits are correct
  - The faulting GPA is correct

Three test cases are implemented:
  - Unmap the final data page (final translation fault, OUTSB read)
  - Unmap a PT page (page walk fault, OUTSB read)
  - Write-protect the final data page (protection violation, INSB write)
  - Write-protect a PT page (protection violation on A/D update, OUTSB
    read)

Signed-off-by: Kevin Cheng <chengkev@google.com>
[sean: name it nested_tdp_fault_test, consolidate asserts]
Link: https://patch.msgid.link/20260522232701.3671446-6-seanjc@google.com
Signed-off-by: Sean Christopherson <seanjc@google.com>

Add #defines for all known EFLAGS bit, e.g. so that tests can use things
like EFLAGS.TF to validate single-stepping behavior.  Opportunistically
use X86_EFLAGS_FIXED instead of an open-coded equivalent when stuffing
initial vCPU state.

No functional change intended.

Link: https://patch.msgid.link/20260515222638.1949982-9-seanjc@google.com
Signed-off-by: Sean Christopherson <seanjc@google.com>

Add a selftest to verify KVM's handling of {de,en}crypt debug ioctls,
specifically focusing on edge cases around the chunk (16 bytes) and page
(4096) sizes, where KVM had multiple bugs.  E.g. KVM would fail to handle
small sizes that aren't naturally aligned and sized, would buffer overflow
if the destination was unaligned but the source was not, etc.

Attempt to strike a balance between an exhaustive test and a reasonable
runtime.  On a system with both SEV and SEV-ES support, the current runtime
is under 45 seconds.  Which isn't great, but it's tolerable, and it's not
obvious which of the combinations are "better" than the others.

Link: https://patch.msgid.link/20260501203537.2120074-3-seanjc@google.com
Signed-off-by: Sean Christopherson <seanjc@google.com>

Replace all variations of "paddr" variables in KVM selftests with "gpa",
with the exception of the ELF structures, as those fields are not specific
to guest virtual addresses, to complete the conversion from vm_paddr_t to
gpa_t.

No functional change intended.

Link: https://patch.msgid.link/20260420212004.3938325-20-seanjc@google.com
Signed-off-by: Sean Christopherson <seanjc@google.com>

In x86's nested TDP APIs, use the appropriate gpa_t typedef and rename
variables from nested_paddr to l2_gpa to match KVM x86's nomenclature.

No functional change intended.

Link: https://patch.msgid.link/20260420212004.3938325-19-seanjc@google.com
Signed-off-by: Sean Christopherson <seanjc@google.com>

Use gpa_t instead of u64 for obvious declarations of GPA variables.

No functional change intended.

Link: https://patch.msgid.link/20260420212004.3938325-18-seanjc@google.com
Signed-off-by: Sean Christopherson <seanjc@google.com>

Replace all variations of "vaddr" variables in KVM selftests with "gva",
with the exception of the ELF structures, as those fields are not specific
to guest virtual addresses, to complete the conversion from vm_vaddr_t to
gva_t.

Opportunistically use gva_t instead of u64 for relevant variables, and
fixup indentation as appropriate.

No functional change intended.

Link: https://patch.msgid.link/20260420212004.3938325-17-seanjc@google.com
Signed-off-by: Sean Christopherson <seanjc@google.com>

Use u8 instead of uint8_t to make the KVM selftests code more concise
and more similar to the kernel (since selftests are primarily developed
by kernel developers).

This commit was generated with the following command:

  git ls-files tools/testing/selftests/kvm | xargs sed -i 's/uint8_t/u8/g'

Then by manually adjusting whitespace to make checkpatch.pl happy.

No functional change intended.

Signed-off-by: David Matlack <dmatlack@google.com>
Link: https://patch.msgid.link/20260420212004.3938325-11-seanjc@google.com
Signed-off-by: Sean Christopherson <seanjc@google.com>