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2025-06-17rust: qemu_api: introduce MaybeUninit field projectionPaolo Bonzini2-0/+86
Add a macro that makes it possible to convert a MaybeUninit<> into another MaybeUninit<> for a single field within it. Furthermore, it is possible to use the resulting MaybeUninitField<> in APIs that take the parent object, such as memory_region_init_io(). This allows removing some of the undefined behavior from instance_init() functions, though this may not be the definitive implementation. Reviewed-by: Zhao Liu <zhao1.liu@intel.com> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2025-06-17pc-bios/dtb/meson: Prefer target name to be outfile, not infileBernhard Beschow1-1/+1
Makes this custom_target() usage consistent with other ones in QEMU. Fixes: 6e0dc9d2a88a ("meson: compile bundled device trees") Signed-off-by: Bernhard Beschow <shentey@gmail.com> Link: https://lore.kernel.org/r/20250610204131.2862-3-shentey@gmail.com Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2025-06-17hw: Fix type constant for DTB filesBernhard Beschow2-2/+2
Commit fcb1ad456c58 ("system/datadir: Add new type constant for DTB files") introduced a new type constant for DTB files and converted the boards with bundled device trees to use it. Convert the other boards for consistency. Fixes: fcb1ad456c58 ("system/datadir: Add new type constant for DTB files") Signed-off-by: Bernhard Beschow <shentey@gmail.com> Link: https://lore.kernel.org/r/20250610204131.2862-2-shentey@gmail.com Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2025-06-17target/i386: fix TB exit logic in gen_movl_seg() when writing to SSMark Cave-Ayland1-2/+5
Before commit e54ef98c8a ("target/i386: do not trigger IRQ shadow for LSS"), any write to SS in gen_movl_seg() would cause a TB exit. The changes introduced by this commit were intended to restrict the DISAS_EOB_INHIBIT_IRQ exit to the case where inhibit_irq is true, but missed that a DISAS_EOB_NEXT exit can still be required when writing to SS and inhibit_irq is false. Comparing the PE(s) && !VM86(s) section with the logic in x86_update_hflags(), we can see that the DISAS_EOB_NEXT exit is still required for the !CODE32 case when writing to SS in gen_movl_seg() because any change to the SS flags can affect hflags. Similarly we can see that the existing CODE32 case is still correct since a change to any of DS, ES and SS can affect hflags. Finally for the gen_op_movl_seg_real() case an explicit TB exit is not needed because the segment register selector does not affect hflags. Update the logic in gen_movl_seg() so that a write to SS with inhibit_irq set to false where PE(s) && !VM86(s) will generate a DISAS_EOB_NEXT exit along with the inline comment. This has the effect of allowing Win98SE to boot in QEMU once again. Signed-off-by: Mark Cave-Ayland <mark.cave-ayland@ilande.co.uk> Fixes: e54ef98c8a ("target/i386: do not trigger IRQ shadow for LSS") Resolves: https://gitlab.com/qemu-project/qemu/-/issues/2987 Link: https://lore.kernel.org/r/20250611130315.383151-1-mark.cave-ayland@ilande.co.uk Reviewed-by: Peter Maydell <peter.maydell@linaro.org> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2025-06-17meson: cleanup win32 library detectionPaolo Bonzini1-8/+5
As pointed out by Akihiko Odaki, all Win32 libraries in MinGW have lowercase names. This means that on (case-insensitive) Windows you can use the mixed-case names suggested by Microsoft or all-lowercase names, while on Linux you need to make them lowercase. QEMU was already using lowercase names, so there is no need to test the mixed-case name version of libSynchronization. Remove the unnecessary test and while at it make all the tests use "required: true". Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2025-06-12net/stream: skip automatic zero-init of large arrayDaniel P. Berrangé1-1/+1
The 'net_stream_send' method has a 68k byte array used for copying data between guest and host. Skip the automatic zero-init of this array to eliminate the performance overhead in the I/O hot path. The 'buf1' array will be fully initialized when reading data off the network socket. Signed-off-by: Daniel P. Berrangé <berrange@redhat.com> Reviewed-by: Stefan Hajnoczi <stefanha@redhat.com> Reviewed-by: Klaus Jensen <k.jensen@samsung.com> Reviewed-by: Harsh Prateek Bora <harshpb@linux.ibm.com> Message-id: 20250610123709.835102-32-berrange@redhat.com Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
2025-06-12net/socket: skip automatic zero-init of large arrayDaniel P. Berrangé1-1/+1
The 'net_socket_send' method has a 68k byte array used for copying data between guest and host. Skip the automatic zero-init of this array to eliminate the performance overhead in the I/O hot path. The 'buf1' array will be fully initialized when reading data off the network socket. Signed-off-by: Daniel P. Berrangé <berrange@redhat.com> Reviewed-by: Stefan Hajnoczi <stefanha@redhat.com> Reviewed-by: Klaus Jensen <k.jensen@samsung.com> Reviewed-by: Harsh Prateek Bora <harshpb@linux.ibm.com> Message-id: 20250610123709.835102-31-berrange@redhat.com Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
2025-06-12hw/ufs/lu: skip automatic zero-init of large arrayDaniel P. Berrangé1-1/+1
The 'ufs_emulate_scsi_cmd' method has a 4k byte array used for copying data from the device. Skip the automatic zero-init of this array to eliminate the performance overhead in the I/O hot path. The 'outbuf' array will be fully initialized when data is copied from the guest. Signed-off-by: Daniel P. Berrangé <berrange@redhat.com> Reviewed-by: Stefan Hajnoczi <stefanha@redhat.com> Reviewed-by: Klaus Jensen <k.jensen@samsung.com> Reviewed-by: Harsh Prateek Bora <harshpb@linux.ibm.com> Message-id: 20250610123709.835102-30-berrange@redhat.com Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
2025-06-12hw/scsi/megasas: skip automatic zero-init of large arraysDaniel P. Berrangé1-5/+2
The 'megasas_dcmd_pd_get_list' and 'megasas_dcmd_get_properties' methods have 4k structs used for copying data from the device. Skip the automatic zero-init of this array to eliminate the performance overhead in the I/O hot path. The 'info' structs are manually initialized with memset(). The compiler ought to be intelligent enough to turn the memset() into a static initialization operation, and thus not duplicate the automatic zero-init. Replacing memset() with '{}' makes it unambiguous that the arrays are statically initialized. Signed-off-by: Daniel P. Berrangé <berrange@redhat.com> Reviewed-by: Stefan Hajnoczi <stefanha@redhat.com> Reviewed-by: Klaus Jensen <k.jensen@samsung.com> Reviewed-by: Harsh Prateek Bora <harshpb@linux.ibm.com> Message-id: 20250610123709.835102-29-berrange@redhat.com Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
2025-06-12hw/scsi/lsi53c895a: skip automatic zero-init of large arrayDaniel P. Berrangé1-1/+1
The 'lsi_memcpy' method has a 4k byte array used for copying data to/from the device. Skip the automatic zero-init of this array to eliminate the performance overhead in the I/O hot path. The 'buf' array will be fully initialized when data is copied. Signed-off-by: Daniel P. Berrangé <berrange@redhat.com> Reviewed-by: Stefan Hajnoczi <stefanha@redhat.com> Reviewed-by: Klaus Jensen <k.jensen@samsung.com> Reviewed-by: Harsh Prateek Bora <harshpb@linux.ibm.com> Message-id: 20250610123709.835102-28-berrange@redhat.com Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
2025-06-12hw/usb/hcd-ohci: skip automatic zero-init of large arrayDaniel P. Berrangé1-1/+1
The 'ohci_service_iso_td' method has a 8k byte array used for copying data between guest and host. Skip the automatic zero-init of this array to eliminate the performance overhead in the I/O hot path. The 'buf' array will be fully initialized when reading data from guest memory. Signed-off-by: Daniel P. Berrangé <berrange@redhat.com> Reviewed-by: Stefan Hajnoczi <stefanha@redhat.com> Reviewed-by: Klaus Jensen <k.jensen@samsung.com> Reviewed-by: Harsh Prateek Bora <harshpb@linux.ibm.com> Message-id: 20250610123709.835102-27-berrange@redhat.com Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
2025-06-12hw/ppc/spapr_tpm_proxy: skip automatic zero-init of large arraysDaniel P. Berrangé1-2/+2
The 'tpm_execute' method has a pair of 4k arrays used for copying data between guest and host. Skip the automatic zero-init of these arrays to eliminate the performance overhead in the I/O hot path. The two arrays will be fully initialized when reading data from guest memory or reading data from the proxy FD. Signed-off-by: Daniel P. Berrangé <berrange@redhat.com> Reviewed-by: Stefan Hajnoczi <stefanha@redhat.com> Reviewed-by: Klaus Jensen <k.jensen@samsung.com> Reviewed-by: Harsh Prateek Bora <harshpb@linux.ibm.com> Message-id: 20250610123709.835102-26-berrange@redhat.com Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
2025-06-12hw/ppc/pnv_occ: skip automatic zero-init of large structDaniel P. Berrangé1-1/+1
The 'occ_model_tick' method has a 12k struct used for copying data between guest and host. Skip the automatic zero-init of this struct to eliminate the performance overhead in the I/O hot path. The 'dynamic_data' buffer will be fully initialized when reading data from the guest. Signed-off-by: Daniel P. Berrangé <berrange@redhat.com> Reviewed-by: Stefan Hajnoczi <stefanha@redhat.com> Reviewed-by: Klaus Jensen <k.jensen@samsung.com> Reviewed-by: Harsh Prateek Bora <harshpb@linux.ibm.com> Message-id: 20250610123709.835102-25-berrange@redhat.com Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
2025-06-12hw/nvme/ctrl: skip automatic zero-init of large arraysDaniel P. Berrangé1-3/+3
The 'nvme_map_sgl' method has a 256 element array used for copying data from the device. Skip the automatic zero-init of this array to eliminate the performance overhead in the I/O hot path. The 'segment' array will be fully initialized when reading data from the device. The 'nme_changed_nslist' method has a 4k byte array that is manually initialized with memset(). The compiler ought to be intelligent enough to turn the memset() into a static initialization operation, and thus not duplicate the automatic zero-init. Replacing memset() with '{}' makes it unambiguous that the array is statically initialized. Signed-off-by: Daniel P. Berrangé <berrange@redhat.com> Reviewed-by: Stefan Hajnoczi <stefanha@redhat.com> Reviewed-by: Klaus Jensen <k.jensen@samsung.com> Message-id: 20250610123709.835102-24-berrange@redhat.com Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
2025-06-12hw/net/xgamc: skip automatic zero-init of large arrayDaniel P. Berrangé1-1/+1
The 'xgmac_enet_send' method has a 8k byte array used for copying data between guest and host. Skip the automatic zero-init of this array to eliminate the performance overhead in the I/O hot path. The 'frame' buffer will be fully initialized when reading guest memory to fetch the data to send. Signed-off-by: Daniel P. Berrangé <berrange@redhat.com> Reviewed-by: Stefan Hajnoczi <stefanha@redhat.com> Message-id: 20250610123709.835102-23-berrange@redhat.com Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
2025-06-12hw/net/virtio-net: skip automatic zero-init of large arraysDaniel P. Berrangé1-3/+3
The 'virtio_net_receive_rcu' method has three arrays with VIRTQUEUE_MAX_SIZE elements, which are apprixmately 32k in size used for copying data between guest and host. Skip the automatic zero-init of these arrays to eliminate the performance overhead in the I/O hot path. The three arrays will be selectively initialized as required when processing network buffers. Signed-off-by: Daniel P. Berrangé <berrange@redhat.com> Reviewed-by: Stefan Hajnoczi <stefanha@redhat.com> Message-id: 20250610123709.835102-22-berrange@redhat.com Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
2025-06-12hw/net/tulip: skip automatic zero-init of large arrayDaniel P. Berrangé1-1/+1
The 'tulip_setup_frame' method has a 4k byte array used for copynig DMA data from the device. Skip the automatic zero-init of this array to eliminate the performance overhead in the I/O hot path. The 'buf' array will be fully initialized when reading data from the device. Signed-off-by: Daniel P. Berrangé <berrange@redhat.com> Reviewed-by: Stefan Hajnoczi <stefanha@redhat.com> Message-id: 20250610123709.835102-21-berrange@redhat.com Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
2025-06-12hw/net/rtl8139: skip automatic zero-init of large arrayDaniel P. Berrangé1-1/+1
The 'rtl8139_transmit_one' method has a 8k byte array used for copying data between guest and host. Skip the automatic zero-init of this array to eliminate the performance overhead in the I/O hot path. The 'txbuffer' will be fully initialized when reading PCI DMA buffers. Signed-off-by: Daniel P. Berrangé <berrange@redhat.com> Reviewed-by: Stefan Hajnoczi <stefanha@redhat.com> Message-id: 20250610123709.835102-20-berrange@redhat.com Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
2025-06-12hw/misc/aspeed_hace: skip automatic zero-init of large arrayDaniel P. Berrangé1-1/+1
The 'do_hash_operation' method has a 256 element iovec array used for holding pointers to data that is to be hashed. Skip the automatic zero-init of this array to eliminate the performance overhead in the I/O hot path. The 'iovec' array will be selectively initialized based on data that needs to be hashed. Signed-off-by: Daniel P. Berrangé <berrange@redhat.com> Reviewed-by: Stefan Hajnoczi <stefanha@redhat.com> Message-id: 20250610123709.835102-19-berrange@redhat.com Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
2025-06-12hw/hyperv/syndbg: skip automatic zero-init of large arrayDaniel P. Berrangé1-1/+1
The 'handle_recv_msg' method has a 4k byte array used for copying data between the network socket and guest memory. Skip the automatic zero-init of this array to eliminate the performance overhead in the I/O hot path. The 'data_buf' array will be fully initialized when data is read off the network socket. Signed-off-by: Daniel P. Berrangé <berrange@redhat.com> Reviewed-by: Stefan Hajnoczi <stefanha@redhat.com> Message-id: 20250610123709.835102-18-berrange@redhat.com Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
2025-06-12hw/display/vmware_vga: skip automatic zero-init of large structDaniel P. Berrangé1-1/+1
The 'vmsvga_fifo_run' method has a struct which is a little over 20k in size, used for holding image data for cursor changes. Skip the automatic zero-init of this struct to eliminate the performance overhead in the I/O hot path. The cursor variable will be fully initialized only when processing a cursor definition message from the guest. Signed-off-by: Daniel P. Berrangé <berrange@redhat.com> Reviewed-by: Stefan Hajnoczi <stefanha@redhat.com> Message-id: 20250610123709.835102-17-berrange@redhat.com Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
2025-06-12hw/dma/xlnx_csu_dma: skip automatic zero-init of large arrayDaniel P. Berrangé1-1/+1
The 'xlnx_csu_dma_src_notify' method has a 4k byte array used for copying DMA data. Skip the automatic zero-init of this array to eliminate the performance overhead in the I/O hot path. The 'buf' array will be fully initialized when data is copied. Signed-off-by: Daniel P. Berrangé <berrange@redhat.com> Reviewed-by: Stefan Hajnoczi <stefanha@redhat.com> Message-id: 20250610123709.835102-16-berrange@redhat.com Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
2025-06-12hw/char/sclpconsole-lm: skip automatic zero-init of large arrayDaniel P. Berrangé1-1/+1
The 'process_mdb' method has a 4k byte array used for copying data between the guest and the chardev backend. Skip the automatic zero-init of this array to eliminate the performance overhead in the I/O hot path. The 'buffer' array will be selectively initialized when data is converted between EBCDIC and ASCII. Signed-off-by: Daniel P. Berrangé <berrange@redhat.com> Reviewed-by: Stefan Hajnoczi <stefanha@redhat.com> Message-id: 20250610123709.835102-15-berrange@redhat.com Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
2025-06-12hw/audio/via-ac97: skip automatic zero-init of large arrayDaniel P. Berrangé1-1/+1
The 'out_cb' method has a 4k byte array used for copying data between the audio backend and device. Skip the automatic zero-init of this array to eliminate the performance overhead in the I/O hot path. The 'tmpbuf' array will be fully initialized when reading data from device memory. Signed-off-by: Daniel P. Berrangé <berrange@redhat.com> Reviewed-by: Stefan Hajnoczi <stefanha@redhat.com> Message-id: 20250610123709.835102-14-berrange@redhat.com Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
2025-06-12hw/audio/sb16: skip automatic zero-init of large arrayDaniel P. Berrangé1-1/+1
The 'write_audio' method has a 4k byte array used for copying data between the audio backend and device. Skip the automatic zero-init of this array to eliminate the performance overhead in the I/O hot path. The 'tmpbuf' array will be fully initialized when reading data from device memory. Signed-off-by: Daniel P. Berrangé <berrange@redhat.com> Reviewed-by: Stefan Hajnoczi <stefanha@redhat.com> Message-id: 20250610123709.835102-13-berrange@redhat.com Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
2025-06-12hw/audio/marvell_88w8618: skip automatic zero-init of large arrayDaniel P. Berrangé1-1/+1
The 'mv88w8618_audio_callback' method has a 4k byte array used for copying data between the audio backend and device. Skip the automatic zero-init of this array to eliminate the performance overhead in the I/O hot path. The 'buf' array will be fully initialized when reading data from device memory. Signed-off-by: Daniel P. Berrangé <berrange@redhat.com> Reviewed-by: Stefan Hajnoczi <stefanha@redhat.com> Message-id: 20250610123709.835102-12-berrange@redhat.com [Fixed hw/audio/gus in commit message --Stefan] Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
2025-06-12hw/audio/gus: skip automatic zero-init of large arrayDaniel P. Berrangé1-1/+1
The 'GUS_read_DMA' method has a 4k byte array used for copying data between the audio backend and device. Skip the automatic zero-init of this array to eliminate the performance overhead in the I/O hot path. The 'tmpbuf' array will be fully initialized when reading data from device memory. Signed-off-by: Daniel P. Berrangé <berrange@redhat.com> Reviewed-by: Stefan Hajnoczi <stefanha@redhat.com> Message-id: 20250610123709.835102-11-berrange@redhat.com Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
2025-06-12hw/audio/es1370: skip automatic zero-init of large arrayDaniel P. Berrangé1-1/+1
The 'es1370_transfer_audio' method has a 4k byte array used for copying data between the audio backend and device. Skip the automatic zero-init of this array to eliminate the performance overhead in the I/O hot path. The 'tmpbuf' array will be fully initialized when reading data from the audio backend and/or device memory. Signed-off-by: Daniel P. Berrangé <berrange@redhat.com> Reviewed-by: Stefan Hajnoczi <stefanha@redhat.com> Message-id: 20250610123709.835102-10-berrange@redhat.com Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
2025-06-12hw/audio/cs4231a: skip automatic zero-init of large arraysDaniel P. Berrangé1-2/+2
The 'cs_write_audio' method has a pair of byte arrays, one 4k in size and one 8k, which are used in converting audio samples. Skip the automatic zero-init of these arrays to eliminate the performance overhead in the I/O hot path. The 'tmpbuf' array will be fully initialized when reading a block of data from the guest. The 'linbuf' array will be fully initialized when converting the audio samples. Signed-off-by: Daniel P. Berrangé <berrange@redhat.com> Reviewed-by: Stefan Hajnoczi <stefanha@redhat.com> Message-id: 20250610123709.835102-9-berrange@redhat.com Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
2025-06-12hw/audio/ac97: skip automatic zero-init of large arraysDaniel P. Berrangé1-2/+2
The 'read_audio' & 'write_audio' methods have a 4k byte array used for copying data between the audio backend and device. Skip the automatic zero-init of these arrays to eliminate the performance overhead in the I/O hot path. The 'tmpbuf' array will be fully initialized when reading data from the audio backend and/or device memory. Signed-off-by: Daniel P. Berrangé <berrange@redhat.com> Reviewed-by: Stefan Hajnoczi <stefanha@redhat.com> Message-id: 20250610123709.835102-8-berrange@redhat.com Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
2025-06-12chardev/char-socket: skip automatic zero-init of large arrayDaniel P. Berrangé1-1/+1
The 'tcp_chr_read' method has a 4k byte array used for copying data between the socket and device. Skip the automatic zero-init of this array to eliminate the performance overhead in the I/O hot path. The 'buf' array will be fully initialized when reading data off the network socket. Signed-off-by: Daniel P. Berrangé <berrange@redhat.com> Reviewed-by: Stefan Hajnoczi <stefanha@redhat.com> Message-id: 20250610123709.835102-7-berrange@redhat.com Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
2025-06-12chardev/char-pty: skip automatic zero-init of large arrayDaniel P. Berrangé1-1/+1
The 'pty_chr_read' method has a 4k byte array used for copying data between the PTY and device. Skip the automatic zero-init of this array to eliminate the performance overhead in the I/O hot path. The 'buf' array will be fully initialized when reading data off the PTY. Signed-off-by: Daniel P. Berrangé <berrange@redhat.com> Reviewed-by: Stefan Hajnoczi <stefanha@redhat.com> Message-id: 20250610123709.835102-6-berrange@redhat.com Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
2025-06-12chardev/char-fd: skip automatic zero-init of large arrayDaniel P. Berrangé1-1/+1
The 'fd_chr_read' method has a 4k byte array used for copying data between the socket and device. Skip the automatic zero-init of this array to eliminate the performance overhead in the I/O hot path. The 'buf' array will be fully initialized when reading data off the network socket. Signed-off-by: Daniel P. Berrangé <berrange@redhat.com> Reviewed-by: Stefan Hajnoczi <stefanha@redhat.com> Message-id: 20250610123709.835102-5-berrange@redhat.com Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
2025-06-12block: skip automatic zero-init of large array in ioq_submitDaniel P. Berrangé1-1/+1
The 'ioq_submit' method has a struct array that is 8k in size. Skip the automatic zero-init of this array to eliminate the performance overhead in the I/O hot path. The 'iocbs' array will selectively initialized when processing the I/O data. Signed-off-by: Daniel P. Berrangé <berrange@redhat.com> Reviewed-by: Stefan Hajnoczi <stefanha@redhat.com> Message-id: 20250610123709.835102-4-berrange@redhat.com Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
2025-06-12hw/virtio/virtio: avoid cost of -ftrivial-auto-var-init in hot pathStefan Hajnoczi1-4/+4
Since commit 7ff9ff039380 ("meson: mitigate against use of uninitialize stack for exploits") the -ftrivial-auto-var-init=zero compiler option is used to zero local variables. While this reduces security risks associated with uninitialized stack data, it introduced a measurable bottleneck in the virtqueue_split_pop() and virtqueue_packed_pop() functions. These virtqueue functions are in the hot path. They are called for each element (request) that is popped from a VIRTIO device's virtqueue. Using __attribute__((uninitialized)) on large stack variables in these functions improves fio randread bs=4k iodepth=64 performance from 304k to 332k IOPS (+9%). This issue was found using perf-top(1). virtqueue_split_pop() was one of the top CPU consumers and the "annotate" feature showed that the memory zeroing instructions at the beginning of the functions were hot. Fixes: 7ff9ff039380 ("meson: mitigate against use of uninitialize stack for exploits") Cc: Daniel P. Berrangé <berrange@redhat.com> Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com> Reviewed-by: Stefan Hajnoczi <stefanha@redhat.com> Message-id: 20250610123709.835102-3-berrange@redhat.com Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
2025-06-12include/qemu/compiler: add QEMU_UNINITIALIZED attribute macroStefan Hajnoczi1-0/+20
The QEMU_UNINITIALIZED macro is to be used to skip the default compiler variable initialization done by -ftrivial-auto-var-init=zero. Use this in cases where there a method in the device I/O path (or other important hot paths), that has large variables on the stack. A rule of thumb is that "large" means a method with 4kb data in the local stack frame. Any variables which are KB in size, should be annotated with this attribute, to pre-emptively eliminate any potential overhead from the compiler zero'ing memory. Given that this turns off a security hardening feature, when using this to flag variables, it is important that the code is double-checked to ensure there is no possible use of uninitialized data in the method. Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com> Reviewed-by: Stefan Hajnoczi <stefanha@redhat.com> Signed-off-by: Daniel P. Berrangé <berrange@redhat.com> Message-id: 20250610123709.835102-2-berrange@redhat.com [DB: split off patch & rewrite guidance on when to use the annotation] Signed-off-by: Daniel P. Berrangé <berrange@redhat.com> Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
2025-06-12qga: Add tests for guest-get-load commandKonstantin Kostiuk1-0/+17
Tested-by: Dehan Meng <demeng@redhat.com> Reviewed-by: Yan Vugenfirer <yvugenfi@redhat.com> Signed-off-by: Konstantin Kostiuk <kkostiuk@redhat.com>
2025-06-12qga-win: implement a 'guest-get-load' commandKonstantin Kostiuk5-3/+205
Windows has no native equivalent API, but it would be possible to simulate it as illustrated here (BSD-3-Clause): https://github.com/giampaolo/psutil/pull/1485 Reviewed-by: Daniel P. Berrangé <berrange@redhat.com> Tested-by: Dehan Meng <demeng@redhat.com> Reviewed-by: Yan Vugenfirer <yvugenfi@redhat.com> Signed-off-by: Konstantin Kostiuk <kkostiuk@redhat.com>
2025-06-11vfio: improve VFIODeviceIOOps docsJohn Levon1-9/+43
Explicitly describe every parameter rather than summarizing. Signed-off-by: John Levon <john.levon@nutanix.com> Reviewed-by: Cédric Le Goater <clg@redhat.com> Link: https://lore.kernel.org/qemu-devel/20250611104753.1199796-1-john.levon@nutanix.com Signed-off-by: Cédric Le Goater <clg@redhat.com>
2025-06-11vfio/pci: export MSI functionsSteve Sistare2-12/+25
Export various MSI functions, renamed with a vfio_pci prefix, for use by CPR in subsequent patches. No functional change. Signed-off-by: Steve Sistare <steven.sistare@oracle.com> Reviewed-by: Cédric Le Goater <clg@redhat.com> Link: https://lore.kernel.org/qemu-devel/1749569991-25171-18-git-send-email-steven.sistare@oracle.com Signed-off-by: Cédric Le Goater <clg@redhat.com>
2025-06-11vfio/pci: vfio_notifier_cleanupSteve Sistare1-11/+17
Move event_notifier_cleanup calls to a helper vfio_notifier_cleanup. This version is trivial, and does not yet use the vdev and nr parameters. No functional change. Signed-off-by: Steve Sistare <steven.sistare@oracle.com> Reviewed-by: Cédric Le Goater <clg@redhat.com> Link: https://lore.kernel.org/qemu-devel/1749569991-25171-17-git-send-email-steven.sistare@oracle.com Signed-off-by: Cédric Le Goater <clg@redhat.com>
2025-06-11vfio/pci: vfio_notifier_init cpr parametersSteve Sistare1-12/+19
Pass vdev and nr to vfio_notifier_init, for use by CPR in a subsequent patch. No functional change. Signed-off-by: Steve Sistare <steven.sistare@oracle.com> Reviewed-by: Cédric Le Goater <clg@redhat.com> Link: https://lore.kernel.org/qemu-devel/1749569991-25171-16-git-send-email-steven.sistare@oracle.com Signed-off-by: Cédric Le Goater <clg@redhat.com>
2025-06-11vfio/pci: pass vector to virq functionsSteve Sistare1-6/+7
Pass the vector number to vfio_connect_kvm_msi_virq and vfio_remove_kvm_msi_virq, so it can be passed to their subroutines in a subsequent patch. No functional change. Signed-off-by: Steve Sistare <steven.sistare@oracle.com> Reviewed-by: Cédric Le Goater <clg@redhat.com> Link: https://lore.kernel.org/qemu-devel/1749569991-25171-15-git-send-email-steven.sistare@oracle.com Signed-off-by: Cédric Le Goater <clg@redhat.com>
2025-06-11vfio/pci: vfio_notifier_initSteve Sistare1-15/+25
Move event_notifier_init calls to a helper vfio_notifier_init. This version is trivial, but it will be expanded to support CPR in subsequent patches. No functional change. Signed-off-by: Steve Sistare <steven.sistare@oracle.com> Reviewed-by: Cédric Le Goater <clg@redhat.com> Link: https://lore.kernel.org/qemu-devel/1749569991-25171-14-git-send-email-steven.sistare@oracle.com Signed-off-by: Cédric Le Goater <clg@redhat.com>
2025-06-11vfio/pci: vfio_pci_vector_initSteve Sistare1-7/+17
Extract a subroutine vfio_pci_vector_init. No functional change. Signed-off-by: Steve Sistare <steven.sistare@oracle.com> Reviewed-by: Cédric Le Goater <clg@redhat.com> Link: https://lore.kernel.org/qemu-devel/1749569991-25171-13-git-send-email-steven.sistare@oracle.com Signed-off-by: Cédric Le Goater <clg@redhat.com>
2025-06-11vfio-pci: skip reset during cprSteve Sistare3-0/+40
Do not reset a vfio-pci device during CPR, and do not complain if the kernel's PCI config space changes for non-emulated bits between the vmstate save and load, which can happen due to ongoing interrupt activity. Signed-off-by: Steve Sistare <steven.sistare@oracle.com> Reviewed-by: Cédric Le Goater <clg@redhat.com> Link: https://lore.kernel.org/qemu-devel/1749569991-25171-12-git-send-email-steven.sistare@oracle.com Signed-off-by: Cédric Le Goater <clg@redhat.com>
2025-06-11pci: skip reset during cprSteve Sistare3-0/+14
Do not reset a vfio-pci device during CPR. Signed-off-by: Steve Sistare <steven.sistare@oracle.com> Acked-by: Michael S. Tsirkin <mst@redhat.com> Link: https://lore.kernel.org/qemu-devel/1749576403-25355-1-git-send-email-steven.sistare@oracle.com Signed-off-by: Cédric Le Goater <clg@redhat.com>
2025-06-11pci: export msix_is_pendingSteve Sistare2-1/+2
Export msix_is_pending for use by cpr. No functional change. Signed-off-by: Steve Sistare <steven.sistare@oracle.com> Acked-by: Michael S. Tsirkin <mst@redhat.com> Link: https://lore.kernel.org/qemu-devel/1749569991-25171-10-git-send-email-steven.sistare@oracle.com Signed-off-by: Cédric Le Goater <clg@redhat.com>
2025-06-11vfio/container: recover from unmap-all-vaddr failureSteve Sistare4-1/+122
If there are multiple containers and unmap-all fails for some container, we need to remap vaddr for the other containers for which unmap-all succeeded. Recover by walking all address ranges of all containers to restore the vaddr for each. Do so by invoking the vfio listener callback, and passing a new "remap" flag that tells it to restore a mapping without re-allocating new userland data structures. Signed-off-by: Steve Sistare <steven.sistare@oracle.com> Reviewed-by: Cédric Le Goater <clg@redhat.com> Link: https://lore.kernel.org/qemu-devel/1749569991-25171-9-git-send-email-steven.sistare@oracle.com Signed-off-by: Cédric Le Goater <clg@redhat.com>
2025-06-11vfio/container: mdev cpr blockerSteve Sistare3-0/+13
During CPR, after VFIO_DMA_UNMAP_FLAG_VADDR, the vaddr is temporarily invalid, so mediated devices cannot be supported. Add a blocker for them. This restriction will not apply to iommufd containers when CPR is added for them in a future patch. Signed-off-by: Steve Sistare <steven.sistare@oracle.com> Reviewed-by: Cédric Le Goater <clg@redhat.com> Link: https://lore.kernel.org/qemu-devel/1749569991-25171-8-git-send-email-steven.sistare@oracle.com [ clg: Fixed context change in VFIODevice ] Signed-off-by: Cédric Le Goater <clg@redhat.com>