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

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>

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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
v

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

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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

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

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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

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

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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

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

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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

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

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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>
Signe

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>

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selftests: kvm: replace ternary operator with min()

Fix the following coccicheck warnings:

tools/testing/selftests/kvm/lib/s390x/ucall.c:25:15-17: WARNING
opportunity for min()
tools/testing/selfte

selftests: kvm: replace ternary operator with min()

Fix the following coccicheck warnings:

tools/testing/selftests/kvm/lib/s390x/ucall.c:25:15-17: WARNING
opportunity for min()
tools/testing/selftests/kvm/lib/x86_64/ucall.c:27:15-17: WARNING
opportunity for min()
tools/testing/selftests/kvm/lib/riscv/ucall.c:56:15-17: WARNING
opportunity for min()
tools/testing/selftests/kvm/lib/aarch64/ucall.c:82:15-17: WARNING
opportunity for min()
tools/testing/selftests/kvm/lib/aarch64/ucall.c:55:20-21: WARNING
opportunity for min()

min() is defined in tools/include/linux/kernel.h.

Signed-off-by: Guo Zhengkui <guozhengkui@vivo.com>
Acked-by: Claudio Imbrenda <imbrenda@linux.ibm.com>
Acked-by: Anup Patel <anup@brainfault.org>
Message-Id: <20220511120621.36956-1-guozhengkui@vivo.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

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selftests: kvm: Clear uc so UCALL_NONE is being properly reported

Ensure the out value 'uc' in get_ucall() is properly reporting
UCALL_NONE if the call fails. The return value will be correctly
rep

selftests: kvm: Clear uc so UCALL_NONE is being properly reported

Ensure the out value 'uc' in get_ucall() is properly reporting
UCALL_NONE if the call fails. The return value will be correctly
reported, however, the out parameter 'uc' will not be. Clear the struct
to ensure the correct value is being reported in the out parameter.

Signed-off-by: Aaron Lewis <aaronlewis@google.com>
Reviewed-by: Andrew Jones <drjones@redhat.com>
Reviewed-by: Alexander Graf <graf@amazon.com>
Message-Id: <20201012194716.3950330-3-aaronlewis@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

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KVM: selftests: Implement ucall() for s390x

On s390x, we can neither exit via PIO nor MMIO, but have to use an
instruction like DIAGNOSE. Now that ucall() is implemented, we can
use it in the sync_r

KVM: selftests: Implement ucall() for s390x

On s390x, we can neither exit via PIO nor MMIO, but have to use an
instruction like DIAGNOSE. Now that ucall() is implemented, we can
use it in the sync_reg_test on s390x, too.

Reviewed-by: Andrew Jones <drjones@redhat.com>
Signed-off-by: Thomas Huth <thuth@redhat.com>
Link: https://lore.kernel.org/r/20190731151525.17156-3-thuth@redhat.com
Signed-off-by: Christian Borntraeger <borntraeger@de.ibm.com>

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selftests: kvm: Clear uc so UCALL_NONE is being properly reported

Ensure the out value 'uc' in get_ucall() is properly reporting
UCALL_NONE if the call fails. The return value will be c

selftests: kvm: Clear uc so UCALL_NONE is being properly reported

Ensure the out value 'uc' in get_ucall() is properly reporting
UCALL_NONE if the call fails. The return value will be correctly
reported, however, the out parameter 'uc' will not be. Clear the struct
to ensure the correct value is being reported in the out parameter.

Signed-off-by: Aaron Lewis <aaronlewis@google.com>
Reviewed-by: Andrew Jones <drjones@redhat.com>
Reviewed-by: Alexander Graf <graf@amazon.com>
Message-Id: <20201012194716.3950330-3-aaronlewis@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

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KVM: selftests: Implement ucall() for s390x

On s390x, we can neither exit via PIO nor MMIO, but have to use an
instruction like DIAGNOSE. Now that ucall() is implemented, we can
use

KVM: selftests: Implement ucall() for s390x

On s390x, we can neither exit via PIO nor MMIO, but have to use an
instruction like DIAGNOSE. Now that ucall() is implemented, we can
use it in the sync_reg_test on s390x, too.

Reviewed-by: Andrew Jones <drjones@redhat.com>
Signed-off-by: Thomas Huth <thuth@redhat.com>
Link: https://lore.kernel.org/r/20190731151525.17156-3-thuth@redhat.com
Signed-off-by: Christian Borntraeger <borntraeger@de.ibm.com>

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