KVM: selftests: Annotate guest ucall, printf, and assert helpers with __printf()

Annotate guest printf helpers with __printf() so that the compiler will
warn about incorrect formatting at compile time (see git log for how easy
it is to screw up with the formatting).

Suggested-by: Maxim Levitsky <mlevitsk@redhat.com>
Link: https://lore.kernel.org/r/20231129224916.532431-5-seanjc@google.com
Signed-off-by: Sean Christopherson <seanjc@google.com>

KVM: selftests: Add GUEST_SYNC[1-6] macros for synchronizing more data

Add GUEST_SYNC[1-6]() so that tests can pass the maximum amount of
information supported via ucall(), without needing to resort to shared
memory.

Signed-off-by: Sean Christopherson <seanjc@google.com>
Message-Id: <20231027182217.3615211-31-seanjc@google.com>
Reviewed-by: Fuad Tabba <tabba@google.com>
Tested-by: Fuad Tabba <tabba@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

KVM: selftests: Remove obsolete and incorrect test case metadata

Delete inaccurate descriptions and obsolete metadata for test cases.
It adds zero value, and has a non-zero chance of becoming stale and
misleading in the future. No functional changes intended.

Suggested-by: Sean Christopherson <seanjc@google.com>
Signed-off-by: Like Xu <likexu@tencent.com>
Link: https://lore.kernel.org/r/20230914094803.94661-1-likexu@tencent.com
Signed-off-by: Sean Christopherson <seanjc@google.com>

KVM: selftests: Use GUEST_FAIL() in ARM's arch timer helpers

Use GUEST_FAIL() in ARM's arch timer helpers now that printf-based
guest asserts are the default (and only) style of guest asserts, and
say goodbye to the GUEST_ASSERT_1() alias.

Link: https://lore.kernel.org/r/20230729003643.1053367-35-seanjc@google.com
Signed-off-by: Sean Christopherson <seanjc@google.com>

KVM: selftests: Rip out old, param-based guest assert macros

Drop the param-based guest assert macros and enable the printf versions
for all selftests. Note! This change can affect tests even if they
don't use directly use guest asserts! E.g. via library code, or due to
the compiler making different optimization decisions.

Link: https://lore.kernel.org/r/20230729003643.1053367-33-seanjc@google.com
Signed-off-by: Sean Christopherson <seanjc@google.com>

KVM: selftests: Add arch ucall.h and inline simple arch hooks

Add an architecture specific ucall.h and inline the simple arch hooks,
e.g. the init hook for everything except ARM, and the actual "do ucall"
hook for everything except x86 (which should be simple, but temporarily
isn't due to carrying a workaround).

Having a per-arch ucall header will allow adding a #define for the
expected KVM exit reason for a ucall that is colocated (for everything
except x86) with the ucall itself.

Reviewed-by: Andrew Jones <ajones@ventanamicro.com>
Link: https://lore.kernel.org/r/20230731203026.1192091-2-seanjc@google.com
Signed-off-by: Sean Christopherson <seanjc@google.com>

KVM: selftests: Add formatted guest assert support in ucall framework

Add printf-based GUEST_ASSERT macros and accompanying host-side support to
provide an assert-specific versions of GUEST_PRINTF(). To make it easier
to parse assert messages, for humans and bots alike, preserve/use the same
layout as host asserts, e.g. in the example below, the reported expression,
file, line number, and message are from the guest assertion, not the host
reporting of the assertion.

The call stack still captures the host reporting, but capturing the guest
stack is a less pressing concern, i.e. can be done in the future, and an
optimal solution would capture *both* the host and guest stacks, i.e.
capturing the host stack isn't an outright bug.

Running soft int test
==== Test Assertion Failure ====
x86_64/svm_nested_soft_inject_test.c:39: regs->rip != (unsigned long)l2_guest_code_int
pid=214104 tid=214104 errno=4 - Interrupted system call
1 0x0000000000401b35: run_test at svm_nested_soft_inject_test.c:191
2 0x00000000004017d2: main at svm_nested_soft_inject_test.c:212
3 0x0000000000415b03: __libc_start_call_main at libc-start.o:?
4 0x000000000041714f: __libc_start_main_impl at ??:?
5 0x0000000000401660: _start at ??:?
Expected IRQ at RIP 0x401e50, received IRQ at 0x401e50

Don't bother sharing code between ucall_assert() and ucall_fmt(), as
forwarding the variable arguments would either require using macros or
building a va_list, i.e. would make the code less readable and/or require
just as much copy+paste code anyways.

Gate the new macros with a flag so that tests can more or less be switched
over one-by-one. The slow conversion won't be perfect, e.g. library code
won't pick up the flag, but the only asserts in library code are of the
vanilla GUEST_ASSERT() variety, i.e. don't print out variables.

Add a temporary alias to GUEST_ASSERT_1() to fudge around ARM's
arch_timer.h header using GUEST_ASSERT_1(), thus thwarting any attempt to
convert tests one-by-one.

Link: https://lore.kernel.org/r/20230729003643.1053367-9-seanjc@google.com
Signed-off-by: Sean Christopherson <seanjc@google.com>

KVM: selftests: Add string formatting options to ucall

Add more flexibility to guest debugging and testing by adding
GUEST_PRINTF() and GUEST_ASSERT_FMT() to the ucall framework.

Add a sized buffer to the ucall structure to hold the formatted string,
i.e. to allow the guest to easily resolve the string, and thus avoid the
ugly pattern of the host side having to make assumptions about the desired
format, as well as having to pass around a large number of parameters.

The buffer size was chosen to accommodate most use cases, and based on
similar usage. E.g. printf() uses the same size buffer in
arch/x86/boot/printf.c. And 1KiB ought to be enough for anybody.

Signed-off-by: Aaron Lewis <aaronlewis@google.com>
[sean: massage changelog, wrap macro param in ()]
Link: https://lore.kernel.org/r/20230729003643.1053367-8-seanjc@google.com
Signed-off-by: Sean Christopherson <seanjc@google.com>

KVM: selftests: Add additional pages to the guest to accommodate ucall

Add additional pages to the guest to account for the number of pages
the ucall headers need. The only reason things worked before is the
ucall headers are fairly small. If they were ever to increase in
size the guest could run out of memory.

This is done in preparation for adding string formatting options to
the guest through the ucall framework which increases the size of
the ucall headers.

Fixes: 426729b2cf2e ("KVM: selftests: Add ucall pool based implementation")
Signed-off-by: Aaron Lewis <aaronlewis@google.com>
Link: https://lore.kernel.org/r/20230729003643.1053367-7-seanjc@google.com
Signed-off-by: Sean Christopherson <seanjc@google.com>

KVM: arm64: selftests: Enable single-step without a "full" ucall()

Add a new ucall hook, GUEST_UCALL_NONE(), to allow tests to make ucalls
without allocating a ucall struct, and use it to enable single-step
in ARM's debug-exceptions test. Like the disable single-step path, the
enabling path also needs to ensure that no exclusive access sequences are
attempted after enabling single-step, as the exclusive monitor is cleared
on ERET from the debug exception taken to EL2.

The test currently "works" because clear_bit() isn't actually an atomic
operation... yet.

Signed-off-by: Sean Christopherson <seanjc@google.com>
Message-Id: <20221119013450.2643007-4-seanjc@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

KVM: selftests: Add ucall pool based implementation

To play nice with guests whose stack memory is encrypted, e.g. AMD SEV,
introduce a new "ucall pool" implementation that passes the ucall struct
via dedicated memory (which can be mapped shared, a.k.a. as plain text).

Because not all architectures have access to the vCPU index in the guest,
use a bitmap with atomic accesses to track which entries in the pool are
free/used. A list+lock could also work in theory, but synchronizing the
individual pointers to the guest would be a mess.

Note, there's no need to rewalk the bitmap to ensure success. If all
vCPUs are simply allocating, success is guaranteed because there are
enough entries for all vCPUs. If one or more vCPUs are freeing and then
reallocating, success is guaranteed because vCPUs _always_ walk the
bitmap from 0=>N; if vCPU frees an entry and then wins a race to
re-allocate, then either it will consume the entry it just freed (bit is
the first free bit), or the losing vCPU is guaranteed to see the freed
bit (winner consumes an earlier bit, which the loser hasn't yet visited).

Reviewed-by: Andrew Jones <andrew.jones@linux.dev>
Signed-off-by: Peter Gonda <pgonda@google.com>
Co-developed-by: Sean Christopherson <seanjc@google.com>
Signed-off-by: Sean Christopherson <seanjc@google.com>
Link: https://lore.kernel.org/r/20221006003409.649993-8-seanjc@google.com

KVM: selftests: Drop now-unnecessary ucall_uninit()

Drop ucall_uninit() and ucall_arch_uninit() now that ARM doesn't modify
the host's copy of ucall_exit_mmio_addr, i.e. now that there's no need to
reset the pointer before potentially creating a new VM. The few calls to
ucall_uninit() are all immediately followed by kvm_vm_free(), and that is
likely always going to hold true, i.e. it's extremely unlikely a test
will want to effectively disable ucall in the middle of a test.

Reviewed-by: Andrew Jones <andrew.jones@linux.dev>
Tested-by: Peter Gonda <pgonda@google.com>
Signed-off-by: Sean Christopherson <seanjc@google.com>
Link: https://lore.kernel.org/r/20221006003409.649993-7-seanjc@google.com

KVM: selftests: Automatically do init_ucall() for non-barebones VMs

Do init_ucall() automatically during VM creation to kill two (three?)
birds with one stone.

First, initializing ucall immediately after VM creations allows forcing
aarch64's MMIO ucall address to immediately follow memslot0. This is
still somewhat fragile as tests could clobber the MMIO address with a
new memslot, but it's safe-ish since tests have to be conversative when
accounting for memslot0. And this can be hardened in the future by
creating a read-only memslot for the MMIO page (KVM ARM exits with MMIO
if the guest writes to a read-only memslot). Add a TODO to document that
selftests can and should use a memslot for the ucall MMIO (doing so
requires yet more rework because tests assumes thay can use all memslots
except memslot0).

Second, initializing ucall for all VMs prepares for making ucall
initialization meaningful on all architectures. aarch64 is currently the
only arch that needs to do any setup, but that will change in the future
by switching to a pool-based implementation (instead of the current
stack-based approach).

Lastly, defining the ucall MMIO address from common code will simplify
switching all architectures (except s390) to a common MMIO-based ucall
implementation (if there's ever sufficient motivation to do so).

Cc: Oliver Upton <oliver.upton@linux.dev>
Reviewed-by: Andrew Jones <andrew.jones@linux.dev>
Tested-by: Peter Gonda <pgonda@google.com>
Signed-off-by: Sean Christopherson <seanjc@google.com>
Link: https://lore.kernel.org/r/20221006003409.649993-4-seanjc@google.com

KVM: selftests: Consolidate boilerplate code in get_ucall()

Consolidate the actual copying of a ucall struct from guest=>host into
the common get_ucall(). Return a host virtual address instead of a guest
virtual address even though the addr_gva2hva() part could be moved to
get_ucall() too. Conceptually, get_ucall() is invoked from the host and
should return a host virtual address (and returning NULL for "nothing to
see here" is far superior to returning 0).

Use pointer shenanigans instead of an unnecessary bounce buffer when the
caller of get_ucall() provides a valid pointer.

Reviewed-by: Andrew Jones <andrew.jones@linux.dev>
Tested-by: Peter Gonda <pgonda@google.com>
Signed-off-by: Sean Christopherson <seanjc@google.com>
Link: https://lore.kernel.org/r/20221006003409.649993-3-seanjc@google.com

KVM: selftests: Consolidate common code for populating ucall struct

Make ucall() a common helper that populates struct ucall, and only calls
into arch code to make the actually call out to userspace.

Rename all arch-specific helpers to make it clear they're arch-specific,
and to avoid collisions with common helpers (one more on its way...)

Add WRITE_ONCE() to stores in ucall() code (as already done to aarch64
code in commit 9e2f6498efbb ("selftests: KVM: Handle compiler
optimizations in ucall")) to prevent clang optimizations breaking ucalls.

Cc: Colton Lewis <coltonlewis@google.com>
Reviewed-by: Andrew Jones <andrew.jones@linux.dev>
Tested-by: Peter Gonda <pgonda@google.com>
Signed-off-by: Sean Christopherson <seanjc@google.com>
Link: https://lore.kernel.org/r/20221006003409.649993-2-seanjc@google.com

KVM: selftests: Fix filename reporting in guest asserts

Fix filename reporting in guest asserts by ensuring the GUEST_ASSERT
macro records __FILE__ and substituting REPORT_GUEST_ASSERT for many
repetitive calls to TEST_FAIL.

Previously filename was reported by using __FILE__ directly in the
selftest, wrongly assuming it would always be the same as where the
assertion failed.

Signed-off-by: Colton Lewis <coltonlewis@google.com>
Reported-by: Ricardo Koller <ricarkol@google.com>
Fixes: 4e18bccc2e5544f0be28fc1c4e6be47a469d6c60
Link: https://lore.kernel.org/r/20220615193116.806312-5-coltonlewis@google.com
[sean: convert more TEST_FAIL => REPORT_GUEST_ASSERT instances]
Signed-off-by: Sean Christopherson <seanjc@google.com>

KVM: selftests: Write REPORT_GUEST_ASSERT macros to pair with GUEST_ASSERT

Write REPORT_GUEST_ASSERT macros to pair with GUEST_ASSERT to abstract
and make consistent all guest assertion reporting. Every report
includes an explanatory string, a filename, and a line number.

Signed-off-by: Colton Lewis <coltonlewis@google.com>
Reviewed-by: Andrew Jones <drjones@redhat.com>
Link: https://lore.kernel.org/r/20220615193116.806312-4-coltonlewis@google.com
Signed-off-by: Sean Christopherson <seanjc@google.com>

KVM: selftests: Increase UCALL_MAX_ARGS to 7

Increase UCALL_MAX_ARGS to 7 to allow GUEST_ASSERT_4 to pass 3 builtin
ucall arguments specified in guest_assert_builtin_args plus 4
user-specified arguments.

Signed-off-by: Colton Lewis <coltonlewis@google.com>
Reviewed-by: Andrew Jones <drjones@redhat.com>
Link: https://lore.kernel.org/r/20220615193116.806312-3-coltonlewis@google.com
Signed-off-by: Sean Christopherson <seanjc@google.com>

KVM: selftests: enumerate GUEST_ASSERT arguments

Enumerate GUEST_ASSERT arguments to avoid magic indices to ucall.args.

Signed-off-by: Colton Lewis <coltonlewis@google.com>
Reviewed-by: Andrew Jones <drjones@redhat.com>
Link: https://lore.kernel.org/r/20220615193116.806312-2-coltonlewis@google.com
Signed-off-by: Sean Christopherson <seanjc@google.com>

KVM: selftests: Purge vm+vcpu_id == vcpu silliness

Take a vCPU directly instead of a VM+vcpu pair in all vCPU-scoped helpers
and ioctls.

Signed-off-by: Sean Christopherson <seanjc@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

kvm: selftests: move ucall declarations into ucall_common.h

Now that core kvm_util declarations have special home in
kvm_util_base.h, move ucall-related declarations out into a separate
header.

Signed-off-by: Michael Roth <michael.roth@amd.com>
Message-Id: <20211210164620.11636-3-michael.roth@amd.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>