vfio/iommufd: Implement VFIOIOMMUClass::query_dirty_bitmap support

ioctl(iommufd, IOMMU_HWPT_GET_DIRTY_BITMAP, arg) is the UAPI
that fetches the bitmap that tells what was dirty in an IOVA
range.

A

vfio/iommufd: Implement VFIOIOMMUClass::query_dirty_bitmap support

ioctl(iommufd, IOMMU_HWPT_GET_DIRTY_BITMAP, arg) is the UAPI
that fetches the bitmap that tells what was dirty in an IOVA
range.

A single bitmap is allocated and used across all the hwpts
sharing an IOAS which is then used in log_sync() to set Qemu
global bitmaps.

Signed-off-by: Joao Martins <joao.m.martins@oracle.com>
Reviewed-by: Cédric Le Goater <clg@redhat.com>
Reviewed-by: Eric Auger <eric.auger@redhat.com>
Reviewed-by: Zhenzhong Duan <zhenzhong.duan@intel.com>

show more ...

vfio/iommufd: Implement VFIOIOMMUClass::set_dirty_tracking support

ioctl(iommufd, IOMMU_HWPT_SET_DIRTY_TRACKING, arg) is the UAPI that
enables or disables dirty page tracking. The ioctl is used if t

vfio/iommufd: Implement VFIOIOMMUClass::set_dirty_tracking support

ioctl(iommufd, IOMMU_HWPT_SET_DIRTY_TRACKING, arg) is the UAPI that
enables or disables dirty page tracking. The ioctl is used if the hwpt
has been created with dirty tracking supported domain (stored in
hwpt::flags) and it is called on the whole list of iommu domains.

Signed-off-by: Joao Martins <joao.m.martins@oracle.com>
Reviewed-by: Zhenzhong Duan <zhenzhong.duan@intel.com>
Reviewed-by: Eric Auger <eric.auger@redhat.com>

show more ...

vfio/{iommufd,container}: Remove caps::aw_bits

Remove caps::aw_bits which requires the bcontainer::iova_ranges being
initialized after device is actually attached. Instead defer that to
.get_cap() a

vfio/{iommufd,container}: Remove caps::aw_bits

Remove caps::aw_bits which requires the bcontainer::iova_ranges being
initialized after device is actually attached. Instead defer that to
.get_cap() and call vfio_device_get_aw_bits() directly.

This is in preparation for HostIOMMUDevice::realize() being called early
during attach_device().

Suggested-by: Zhenzhong Duan <zhenzhong.duan@intel.com>
Signed-off-by: Joao Martins <joao.m.martins@oracle.com>
Reviewed-by: Cédric Le Goater <clg@redhat.com>
Reviewed-by: Eric Auger <eric.auger@redhat.com>

show more ...

vfio/iommufd: Introduce auto domain creation

There's generally two modes of operation for IOMMUFD:

1) The simple user API which intends to perform relatively simple things
with IOMMUs e.g. DPDK. Th

vfio/iommufd: Introduce auto domain creation

There's generally two modes of operation for IOMMUFD:

1) The simple user API which intends to perform relatively simple things
with IOMMUs e.g. DPDK. The process generally creates an IOAS and attaches
to VFIO and mainly performs IOAS_MAP and UNMAP.

2) The native IOMMUFD API where you have fine grained control of the
IOMMU domain and model it accordingly. This is where most new feature
are being steered to.

For dirty tracking 2) is required, as it needs to ensure that
the stage-2/parent IOMMU domain will only attach devices
that support dirty tracking (so far it is all homogeneous in x86, likely
not the case for smmuv3). Such invariant on dirty tracking provides a
useful guarantee to VMMs that will refuse incompatible device
attachments for IOMMU domains.

Dirty tracking insurance is enforced via HWPT_ALLOC, which is
responsible for creating an IOMMU domain. This is contrast to the
'simple API' where the IOMMU domain is created by IOMMUFD automatically
when it attaches to VFIO (usually referred as autodomains) but it has
the needed handling for mdevs.

To support dirty tracking with the advanced IOMMUFD API, it needs
similar logic, where IOMMU domains are created and devices attached to
compatible domains. Essentially mimicking kernel
iommufd_device_auto_get_domain(). With mdevs given there's no IOMMU domain
it falls back to IOAS attach.

The auto domain logic allows different IOMMU domains to be created when
DMA dirty tracking is not desired (and VF can provide it), and others where
it is. Here it is not used in this way given how VFIODevice migration
state is initialized after the device attachment. But such mixed mode of
IOMMU dirty tracking + device dirty tracking is an improvement that can
be added on. Keep the 'all of nothing' of type1 approach that we have
been using so far between container vs device dirty tracking.

Signed-off-by: Joao Martins <joao.m.martins@oracle.com>
Reviewed-by: Zhenzhong Duan <zhenzhong.duan@intel.com>
[ clg: Added ERRP_GUARD() in iommufd_cdev_autodomains_get() ]
Signed-off-by: Cédric Le Goater <clg@redhat.com>
Reviewed-by: Eric Auger <eric.auger@redhat.com>

show more ...

backends/iommufd: Extend iommufd_backend_get_device_info() to fetch HW capabilities

The helper will be able to fetch vendor agnostic IOMMU capabilities
supported both by hardware and software. Right

backends/iommufd: Extend iommufd_backend_get_device_info() to fetch HW capabilities

The helper will be able to fetch vendor agnostic IOMMU capabilities
supported both by hardware and software. Right now it is only iommu dirty
tracking.

Signed-off-by: Joao Martins <joao.m.martins@oracle.com>
Reviewed-by: Zhenzhong Duan <zhenzhong.duan@intel.com>
Reviewed-by: Cédric Le Goater <clg@redhat.com>
Reviewed-by: Eric Auger <eric.auger@redhat.com>

show more ...

backends: Initial support for SPDM socket support

SPDM enables authentication, attestation and key exchange to assist in
providing infrastructure security enablement. It's a standard published
by th

backends: Initial support for SPDM socket support

SPDM enables authentication, attestation and key exchange to assist in
providing infrastructure security enablement. It's a standard published
by the DMTF [1].

SPDM supports multiple transports, including PCIe DOE and MCTP.
This patch adds support to QEMU to connect to an external SPDM
instance.

SPDM support can be added to any QEMU device by exposing a
TCP socket to a SPDM server. The server can then implement the SPDM
decoding/encoding support, generally using libspdm [2].

This is similar to how the current TPM implementation works and means
that the heavy lifting of setting up certificate chains, capabilities,
measurements and complex crypto can be done outside QEMU by a well
supported and tested library.

1: https://www.dmtf.org/standards/SPDM
2: https://github.com/DMTF/libspdm

Signed-off-by: Huai-Cheng Kuo <hchkuo@avery-design.com.tw>
Signed-off-by: Chris Browy <cbrowy@avery-design.com>
Co-developed-by: Jonathan Cameron <Jonathan.cameron@huawei.com>
Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>
[ Changes by WM
- Bug fixes from testing
]
Signed-off-by: Wilfred Mallawa <wilfred.mallawa@wdc.com>
[ Changes by AF:
- Convert to be more QEMU-ified
- Move to backends as it isn't PCIe specific
]
Signed-off-by: Alistair Francis <alistair.francis@wdc.com>
Message-Id: <20240703092027.644758-3-alistair.francis@wdc.com>
Reviewed-by: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>

show more ...

backends/rng-random: Get rid of qemu_open_old()

For qemu_open_old(), osdep.h said:

> Don't introduce new usage of this function, prefer the following
> qemu_open/qemu_create that take an "Error **e

backends/rng-random: Get rid of qemu_open_old()

For qemu_open_old(), osdep.h said:

> Don't introduce new usage of this function, prefer the following
> qemu_open/qemu_create that take an "Error **errp".

So replace qemu_open_old() with qemu_open(). And considering
rng_random_opened() will lose its obvious error handling case after
removing error_setg_file_open(), add comment to remind here.

Cc: Laurent Vivier <lvivier@redhat.com>
Cc: Amit Shah <amit@kernel.org>
Signed-off-by: Zhao Liu <zhao1.liu@intel.com>
Reviewed-by: Philippe Mathieu-Daudé <philmd@linaro.org>
Reviewed-by: Michael Tokarev <mjt@tls.msk.ru>
(mjt: drop superfluous commit as suggested by philmd)
Signed-off-by: Michael Tokarev <mjt@tls.msk.ru>

show more ...

backends/iommufd: Get rid of qemu_open_old()

For qemu_open_old(), osdep.h said:

> Don't introduce new usage of this function, prefer the following
> qemu_open/qemu_create that take an "Error **errp

backends/iommufd: Get rid of qemu_open_old()

For qemu_open_old(), osdep.h said:

> Don't introduce new usage of this function, prefer the following
> qemu_open/qemu_create that take an "Error **errp".

So replace qemu_open_old() with qemu_open().

Cc: Yi Liu <yi.l.liu@intel.com>
Cc: Eric Auger <eric.auger@redhat.com>
Cc: Zhenzhong Duan <zhenzhong.duan@intel.com>
Signed-off-by: Zhao Liu <zhao1.liu@intel.com>
Reviewed-by: Philippe Mathieu-Daudé <philmd@linaro.org>
Reviewed-by: Yi Liu <yi.l.liu@intel.com>
Reviewed-by: Michael Tokarev <mjt@tls.msk.ru>
Signed-off-by: Michael Tokarev <mjt@tls.msk.ru>

show more ...

backends/hostmem-epc: Get rid of qemu_open_old()

For qemu_open_old(), osdep.h said:

> Don't introduce new usage of this function, prefer the following
> qemu_open/qemu_create that take an "Error **

backends/hostmem-epc: Get rid of qemu_open_old()

For qemu_open_old(), osdep.h said:

> Don't introduce new usage of this function, prefer the following
> qemu_open/qemu_create that take an "Error **errp".

So replace qemu_open_old() with qemu_open().

Cc: David Hildenbrand <david@redhat.com>
Cc: Igor Mammedov <imammedo@redhat.com>
Signed-off-by: Zhao Liu <zhao1.liu@intel.com>
Reviewed-by: Philippe Mathieu-Daudé <philmd@linaro.org>
Reviewed-by: Igor Mammedov <imammedo@redhat.com>
Reviewed-by: Michael Tokarev <mjt@tls.msk.ru>
Signed-off-by: Michael Tokarev <mjt@tls.msk.ru>

show more ...

hostmem: add a new memory backend based on POSIX shm_open()

shm_open() creates and opens a new POSIX shared memory object.
A POSIX shared memory object allows creating memory backend with an
associa

hostmem: add a new memory backend based on POSIX shm_open()

shm_open() creates and opens a new POSIX shared memory object.
A POSIX shared memory object allows creating memory backend with an
associated file descriptor that can be shared with external processes
(e.g. vhost-user).

The new `memory-backend-shm` can be used as an alternative when
`memory-backend-memfd` is not available (Linux only), since shm_open()
should be provided by any POSIX-compliant operating system.

This backend mimics memfd, allocating memory that is practically
anonymous. In theory shm_open() requires a name, but this is allocated
for a short time interval and shm_unlink() is called right after
shm_open(). After that, only fd is shared with external processes
(e.g., vhost-user) as if it were associated with anonymous memory.

In the future we may also allow the user to specify the name to be
passed to shm_open(), but for now we keep the backend simple, mimicking
anonymous memory such as memfd.

Acked-by: David Hildenbrand <david@redhat.com>
Acked-by: Stefan Hajnoczi <stefanha@redhat.com>
Acked-by: Markus Armbruster <armbru@redhat.com> (QAPI schema)
Signed-off-by: Stefano Garzarella <sgarzare@redhat.com>
Message-Id: <20240618100519.145853-1-sgarzare@redhat.com>
Reviewed-by: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>

show more ...

backends/iommufd: Implement HostIOMMUDeviceClass::get_cap() handler

Suggested-by: Cédric Le Goater <clg@redhat.com>
Signed-off-by: Zhenzhong Duan <zhenzhong.duan@intel.com>
Reviewed-by: Eric Auger <

backends/iommufd: Implement HostIOMMUDeviceClass::get_cap() handler

Suggested-by: Cédric Le Goater <clg@redhat.com>
Signed-off-by: Zhenzhong Duan <zhenzhong.duan@intel.com>
Reviewed-by: Eric Auger <eric.auger@redhat.com>
Reviewed-by: Michael S. Tsirkin <mst@redhat.com>

show more ...

backends/iommufd: Introduce helper function iommufd_backend_get_device_info()

Introduce a helper function iommufd_backend_get_device_info() to get
host IOMMU related information through iommufd uAPI

backends/iommufd: Introduce helper function iommufd_backend_get_device_info()

Introduce a helper function iommufd_backend_get_device_info() to get
host IOMMU related information through iommufd uAPI.

Signed-off-by: Yi Liu <yi.l.liu@intel.com>
Signed-off-by: Yi Sun <yi.y.sun@linux.intel.com>
Signed-off-by: Zhenzhong Duan <zhenzhong.duan@intel.com>
Reviewed-by: Eric Auger <eric.auger@redhat.com>
Reviewed-by: Michael S. Tsirkin <mst@redhat.com>

show more ...

backends/iommufd: Introduce TYPE_HOST_IOMMU_DEVICE_IOMMUFD[_VFIO] devices

TYPE_HOST_IOMMU_DEVICE_IOMMUFD represents a host IOMMU device under
iommufd backend. It is abstract, because it is going to

backends/iommufd: Introduce TYPE_HOST_IOMMU_DEVICE_IOMMUFD[_VFIO] devices

TYPE_HOST_IOMMU_DEVICE_IOMMUFD represents a host IOMMU device under
iommufd backend. It is abstract, because it is going to be derived
into VFIO or VDPA type'd device.

It will have its own .get_cap() implementation.

TYPE_HOST_IOMMU_DEVICE_IOMMUFD_VFIO is a sub-class of
TYPE_HOST_IOMMU_DEVICE_IOMMUFD, represents a VFIO type'd host IOMMU
device under iommufd backend. It will be created during VFIO device
attaching and passed to vIOMMU.

It will have its own .realize() implementation.

Opportunistically, add missed header to include/sysemu/iommufd.h.

Suggested-by: Cédric Le Goater <clg@redhat.com>
Signed-off-by: Yi Liu <yi.l.liu@intel.com>
Signed-off-by: Zhenzhong Duan <zhenzhong.duan@intel.com>
Reviewed-by: Eric Auger <eric.auger@redhat.com>
Reviewed-by: Michael S. Tsirkin <mst@redhat.com>

show more ...

backends: Introduce HostIOMMUDevice abstract

A HostIOMMUDevice is an abstraction for an assigned device that is protected
by a physical IOMMU (aka host IOMMU). The userspace interaction with this
ph

backends: Introduce HostIOMMUDevice abstract

A HostIOMMUDevice is an abstraction for an assigned device that is protected
by a physical IOMMU (aka host IOMMU). The userspace interaction with this
physical IOMMU can be done either through the VFIO IOMMU type 1 legacy
backend or the new iommufd backend. The assigned device can be a VFIO device
or a VDPA device. The HostIOMMUDevice is needed to interact with the host
IOMMU that protects the assigned device. It is especially useful when the
device is also protected by a virtual IOMMU as this latter use the translation
services of the physical IOMMU and is constrained by it. In that context the
HostIOMMUDevice can be passed to the virtual IOMMU to collect physical IOMMU
capabilities such as the supported address width. In the future, the virtual
IOMMU will use the HostIOMMUDevice to program the guest page tables in the
first translation stage of the physical IOMMU.

Introduce .realize() to initialize HostIOMMUDevice further after instance init.

Suggested-by: Cédric Le Goater <clg@redhat.com>
Signed-off-by: Zhenzhong Duan <zhenzhong.duan@intel.com>
Reviewed-by: Eric Auger <eric.auger@redhat.com>
Reviewed-by: Michael S. Tsirkin <mst@redhat.com>

show more ...

backends/tpm: Remove newline character in trace event

Split the 'tpm_util_show_buffer' event in two to avoid
using a newline character.

Signed-off-by: Philippe Mathieu-Daudé <philmd@linaro.org>
Ack

backends/tpm: Remove newline character in trace event

Split the 'tpm_util_show_buffer' event in two to avoid
using a newline character.

Signed-off-by: Philippe Mathieu-Daudé <philmd@linaro.org>
Acked-by: Mads Ynddal <mads@ynddal.dk>
Reviewed-by: Daniel P. Berrangé <berrange@redhat.com>
Reviewed-by: Stefan Berger <stefanb@linux.ibm.com>
Message-id: 20240606103943.79116-2-philmd@linaro.org
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>

show more ...

hostmem: simplify the code for merge and dump properties

No semantic change, just simpler control flow.

Reviewed-by: Philippe Mathieu-Daudé <philmd@linaro.org>
Signed-off-by: Paolo Bonzini <pbonzin

hostmem: simplify the code for merge and dump properties

No semantic change, just simpler control flow.

Reviewed-by: Philippe Mathieu-Daudé <philmd@linaro.org>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

show more ...

machine, hostmem: improve error messages for unsupported features

Detect early unsupported MADV_MERGEABLE and MADV_DONTDUMP, and print a clearer
error message that points to the deficiency of the ho

machine, hostmem: improve error messages for unsupported features

Detect early unsupported MADV_MERGEABLE and MADV_DONTDUMP, and print a clearer
error message that points to the deficiency of the host.

Cc: Michal Privoznik <mprivozn@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

show more ...

backends/hostmem: Report error when memory size is unaligned

If memory-backend-{file,ram} has a size that's not aligned to
underlying page size it is not only wasteful, but also may lead
to hard to

backends/hostmem: Report error when memory size is unaligned

If memory-backend-{file,ram} has a size that's not aligned to
underlying page size it is not only wasteful, but also may lead
to hard to debug behaviour. For instance, in case
memory-backend-file and hugepages, madvise() and mbind() fail.
Rightfully so, page is the smallest unit they can work with. And
even though an error is reported, the root cause it not very
clear:

qemu-system-x86_64: Couldn't set property 'dump' on 'memory-backend-file': Invalid argument

After this commit:

qemu-system-x86_64: backend 'memory-backend-file' memory size must be multiple of 2 MiB

Signed-off-by: Michal Privoznik <mprivozn@redhat.com>
Reviewed-by: Philippe Mathieu-Daudé <philmd@linaro.org>
Tested-by: Mario Casquero <mcasquer@redhat.com>
Message-ID: <b5b9f9c6bba07879fb43f3c6f496c69867ae3716.1717584048.git.mprivozn@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

show more ...

backends/iommufd: Make iommufd_backend_*() return bool

This is to follow the coding standand to return bool if 'Error **'
is used to pass error.

The changed functions include:

iommufd_backend_conn

backends/iommufd: Make iommufd_backend_*() return bool

This is to follow the coding standand to return bool if 'Error **'
is used to pass error.

The changed functions include:

iommufd_backend_connect
iommufd_backend_alloc_ioas

By this chance, simplify the functions a bit by avoiding duplicate
recordings, e.g., log through either error interface or trace, not
both.

Suggested-by: Cédric Le Goater <clg@redhat.com>
Signed-off-by: Zhenzhong Duan <zhenzhong.duan@intel.com>
Reviewed-by: Cédric Le Goater <clg@redhat.com>
Signed-off-by: Cédric Le Goater <clg@redhat.com>

show more ...

backends/cryptodev-builtin: Fix local_error leaks

It seems that this error does not need to be propagated to the upper,
directly output the error to avoid the leaks

Closes: https://gitlab.com/qemu-

backends/cryptodev-builtin: Fix local_error leaks

It seems that this error does not need to be propagated to the upper,
directly output the error to avoid the leaks

Closes: https://gitlab.com/qemu-project/qemu/-/issues/2283
Fixes: 2fda101de07 ("virtio-crypto: Support asynchronous mode")
Signed-off-by: Li Zhijian <lizhijian@fujitsu.com>
Reviewed-by: Philippe Mathieu-Daudé <philmd@linaro.org>
Reviewed-by: zhenwei pi <pizhenwei@bytedance.com>
Reviewed-by: Michael Tokarev <mjt@tls.msk.ru>
Signed-off-by: Michael Tokarev <mjt@tls.msk.ru>

show more ...

error: Drop superfluous #include "qapi/qmp/qerror.h"

Signed-off-by: Markus Armbruster <armbru@redhat.com>
Message-ID: <20240312141343.3168265-2-armbru@redhat.com>

HostMem: Add mechanism to opt in kvm guest memfd via MachineState

Add a new member "guest_memfd" to memory backends. When it's set
to true, it enables RAM_GUEST_MEMFD in ram_flags, thus private kvm

HostMem: Add mechanism to opt in kvm guest memfd via MachineState

Add a new member "guest_memfd" to memory backends. When it's set
to true, it enables RAM_GUEST_MEMFD in ram_flags, thus private kvm
guest_memfd will be allocated during RAMBlock allocation.

Memory backend's @guest_memfd is wired with @require_guest_memfd
field of MachineState. It avoid looking up the machine in phymem.c.

MachineState::require_guest_memfd is supposed to be set by any VMs
that requires KVM guest memfd as private memory, e.g., TDX VM.

Signed-off-by: Xiaoyao Li <xiaoyao.li@intel.com>
Reviewed-by: David Hildenbrand <david@redhat.com>
Message-ID: <20240320083945.991426-8-michael.roth@amd.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

show more ...

backends/cryptodev: Do not abort for invalid session ID

Instead of aborting when a session ID is invalid,
return VIRTIO_CRYPTO_INVSESS ("Invalid session id").

Reproduced using:

$ cat << EOF | qe

backends/cryptodev: Do not abort for invalid session ID

Instead of aborting when a session ID is invalid,
return VIRTIO_CRYPTO_INVSESS ("Invalid session id").

Reproduced using:

$ cat << EOF | qemu-system-i386 -display none \
-machine q35,accel=qtest -m 512M -nodefaults \
-object cryptodev-backend-builtin,id=cryptodev0 \
-device virtio-crypto-pci,id=crypto0,cryptodev=cryptodev0 \
-qtest stdio
outl 0xcf8 0x80000804
outw 0xcfc 0x06
outl 0xcf8 0x80000820
outl 0xcfc 0xe0008000
write 0x10800e 0x1 0x01
write 0xe0008016 0x1 0x01
write 0xe0008020 0x4 0x00801000
write 0xe0008028 0x4 0x00c01000
write 0xe000801c 0x1 0x01
write 0x110000 0x1 0x05
write 0x110001 0x1 0x04
write 0x108002 0x1 0x11
write 0x108008 0x1 0x48
write 0x10800c 0x1 0x01
write 0x108018 0x1 0x10
write 0x10801c 0x1 0x02
write 0x10c002 0x1 0x01
write 0xe000b005 0x1 0x00
EOF
Assertion failed: (session_id < MAX_NUM_SESSIONS && builtin->sessions[session_id]),
function cryptodev_builtin_close_session, file cryptodev-builtin.c, line 430.

Cc: qemu-stable@nongnu.org
Reported-by: Zheyu Ma <zheyuma97@gmail.com>
Resolves: https://gitlab.com/qemu-project/qemu/-/issues/2274
Signed-off-by: Philippe Mathieu-Daudé <philmd@linaro.org>
Reviewed-by: zhenwei pi <pizhenwei@bytedance.com>
Message-Id: <20240409094757.9127-1-philmd@linaro.org>

show more ...

backends/iommufd: Fix missing ERRP_GUARD() for error_prepend()

As the comment in qapi/error, passing @errp to error_prepend() requires
ERRP_GUARD():

* = Why, when and how to use ERRP_GUARD() =
*
*

backends/iommufd: Fix missing ERRP_GUARD() for error_prepend()

As the comment in qapi/error, passing @errp to error_prepend() requires
ERRP_GUARD():

* = Why, when and how to use ERRP_GUARD() =
*
* Without ERRP_GUARD(), use of the @errp parameter is restricted:
...
* - It should not be passed to error_prepend(), error_vprepend() or
* error_append_hint(), because that doesn't work with &error_fatal.
* ERRP_GUARD() lifts these restrictions.
*
* To use ERRP_GUARD(), add it right at the beginning of the function.
* @errp can then be used without worrying about the argument being
* NULL or &error_fatal.

ERRP_GUARD() could avoid the case when @errp is &error_fatal, the user
can't see this additional information, because exit() happens in
error_setg earlier than information is added [1].

The iommufd_backend_set_fd() passes @errp to error_prepend(), to avoid
the above issue, add missing ERRP_GUARD() at the beginning of this
function.

[1]: Issue description in the commit message of commit ae7c80a7bd73
("error: New macro ERRP_GUARD()").

Cc: Yi Liu <yi.l.liu@intel.com>
Cc: Eric Auger <eric.auger@redhat.com>
Cc: Zhenzhong Duan <zhenzhong.duan@intel.com>
Signed-off-by: Zhao Liu <zhao1.liu@intel.com>
Reviewed-by: Zhenzhong Duan <zhenzhong.duan@intel.com>
Reviewed-by: Eric Auger <eric.auger@redhat.com>
Message-ID: <20240311033822.3142585-3-zhao1.liu@linux.intel.com>
Signed-off-by: Thomas Huth <thuth@redhat.com>

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