Add ACPI SPCR table test case for ARM when SPCR was off.
Signed-off-by: Li Chen <chenl311@chinatelecom.cn>
Message-Id: <20250528105404.457729-3-me@linux.beauty>
Reviewed-by: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
The ACPI SPCR (Serial Port Console Redirection) table allows firmware
to specify a preferred serial console device to the operating system.
On ARM64 systems, Linux by default respects this table: even if the
kernel command line does not include a hardware serial console (e.g.,
"console=ttyAMA0"), the kernel still register the serial device
referenced by SPCR as a printk console.
While this behavior is standard-compliant, it can lead to situations
where guest console behavior is influenced by platform firmware rather
than user-specified configuration. To make guest console behavior more
predictable and under user control, this patch introduces a machine
option to explicitly disable SPCR table exposure:
-machine spcr=off
By default, the option is enabled (spcr=on), preserving existing
behavior. When disabled, QEMU will omit the SPCR table from the guest's
ACPI namespace, ensuring that only consoles explicitly declared in the
kernel command line are registered.
Signed-off-by: Li Chen <chenl311@chinatelecom.cn>
Reviewed-by: Bibo Mao <maobibo@loongson.cn>
Acked-by: Michael S. Tsirkin <mst@redhat.com>
Reviewed-by: Gavin Shan <gshan@redhat.com>
Reviewed-by: Sunil V L <sunilvl@ventanamicro.com>
Message-Id: <20250528105404.457729-2-me@linux.beauty>
Reviewed-by: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
The variable `oldval` was incorrectly declared as a 32-bit `uint32_t`.
This could lead to truncation and incorrect behavior where the upper
read-only 32 bits are significant.
Fix the type of `oldval` to match the return type of `ldq_le_p()`.
Cc: qemu-stable@nongnu.org
Fixes: d29a09ca68 ("hw/i386: Introduce AMD IOMMU")
Signed-off-by: Ethan Milon <ethan.milon@eviden.com>
Message-Id: <20250617150427.20585-9-alejandro.j.jimenez@oracle.com>
Reviewed-by: Vasant Hegde <vasant.hegde@amd.com>
Reviewed-by: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
No functional change.
Signed-off-by: Alejandro Jimenez <alejandro.j.jimenez@oracle.com>
Reviewed-by: Vasant Hegde <vasant.hegde@amd.com>
Message-Id: <20250617150427.20585-8-alejandro.j.jimenez@oracle.com>
Reviewed-by: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
Correctly calculate the Device Table size using the format encoded in the
Device Table Base Address Register (MMIO Offset 0000h).
Cc: qemu-stable@nongnu.org
Fixes: d29a09ca68 ("hw/i386: Introduce AMD IOMMU")
Signed-off-by: Alejandro Jimenez <alejandro.j.jimenez@oracle.com>
Reviewed-by: Vasant Hegde <vasant.hegde@amd.com>
Message-Id: <20250617150427.20585-7-alejandro.j.jimenez@oracle.com>
Reviewed-by: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
Fix an off-by-one error in the definition of AMDVI_IR_PHYS_ADDR_MASK. The
current definition masks off the most significant bit of the Interrupt Table
Root ptr i.e. it only generates a mask with bits [50:6] set. See the AMD I/O
Virtualization Technology (IOMMU) Specification for the Interrupt Table
Root Pointer[51:6] field in the Device Table Entry format.
Cc: qemu-stable@nongnu.org
Fixes: b44159fe00 ("x86_iommu/amd: Add interrupt remap support when VAPIC is not enabled")
Signed-off-by: Alejandro Jimenez <alejandro.j.jimenez@oracle.com>
Reviewed-by: Vasant Hegde <vasant.hegde@amd.com>
Message-Id: <20250617150427.20585-6-alejandro.j.jimenez@oracle.com>
Reviewed-by: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
Address various issues with definitions of the MMIO registers e.g. for the
Device Table Address Register, the size mask currently encompasses reserved
bits [11:9], so change it to only extract the bits [8:0] encoding size.
Convert masks to use GENMASK64 for consistency, and make unrelated
definitions independent.
Cc: qemu-stable@nongnu.org
Fixes: d29a09ca68 ("hw/i386: Introduce AMD IOMMU")
Signed-off-by: Alejandro Jimenez <alejandro.j.jimenez@oracle.com>
Reviewed-by: Vasant Hegde <vasant.hegde@amd.com>
Message-Id: <20250617150427.20585-5-alejandro.j.jimenez@oracle.com>
Reviewed-by: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
The DTE validation method verifies that all bits in reserved DTE fields are
unset. Update them according to the latest definition available in AMD I/O
Virtualization Technology (IOMMU) Specification - Section 2.2.2.1 Device
Table Entry Format. Remove the magic numbers and use a macro helper to
generate bitmasks covering the specified ranges for better legibility.
Note that some reserved fields specify that events are generated when they
contain non-zero bits, or checks are skipped under certain configurations.
This change only updates the reserved masks, checks for special conditions
are not yet implemented.
Cc: qemu-stable@nongnu.org
Signed-off-by: Alejandro Jimenez <alejandro.j.jimenez@oracle.com>
Reviewed-by: Vasant Hegde <vasant.hegde@amd.com>
Message-Id: <20250617150427.20585-4-alejandro.j.jimenez@oracle.com>
Reviewed-by: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
The DeviceID bits are extracted using an incorrect offset in the call to
amdvi_iotlb_remove_page(). This field is read (correctly) earlier, so use
the value already retrieved for devid.
Cc: qemu-stable@nongnu.org
Fixes: d29a09ca68 ("hw/i386: Introduce AMD IOMMU")
Signed-off-by: Alejandro Jimenez <alejandro.j.jimenez@oracle.com>
Reviewed-by: Vasant Hegde <vasant.hegde@amd.com>
Message-Id: <20250617150427.20585-3-alejandro.j.jimenez@oracle.com>
Reviewed-by: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
The definitions encoding the maximum Virtual, Physical, and Guest Virtual
Address sizes supported by the IOMMU are using incorrect offsets i.e. the
VASize and GVASize offsets are switched. The value in the GVAsize field is
also modified, since it was incorrectly encoded.
Cc: qemu-stable@nongnu.org
Fixes: d29a09ca68 ("hw/i386: Introduce AMD IOMMU")
Co-developed-by: Ethan MILON <ethan.milon@eviden.com>
Signed-off-by: Ethan MILON <ethan.milon@eviden.com>
Signed-off-by: Alejandro Jimenez <alejandro.j.jimenez@oracle.com>
Message-Id: <20250617150427.20585-2-alejandro.j.jimenez@oracle.com>
Reviewed-by: Vasant Hegde <vasant.hegde@amd.com>
Reviewed-by: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
This leak was detected by the valgrind.
The crs_range_merge() function unconditionally allocated a GPtrArray
'even when range->len was zero, causing an early return without freeing
the allocated array. This resulted in a memory leak when an empty range
was processed.
Instead of moving the allocation after the check (as previously attempted),
use g_autoptr for automatic cleanup. This ensures the array is freed even
on early returns, and also removes the need for the explicit free at the
end of the function.
Signed-off-by: Li Zhijian <lizhijian@fujitsu.com>
Message-Id: <20250613085110.111204-1-lizhijian@fujitsu.com>
Reviewed-by: Daniel P. Berrangé <berrange@redhat.com>
Reviewed-by: Ani Sinha <anisinha@redhat.com>
Reviewed-by: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
Remove stale allowed tables for LoongArch virt machine.
Signed-off-by: Bibo Mao <maobibo@loongson.cn>
Message-Id: <20250612090321.3416594-6-maobibo@loongson.cn>
Reviewed-by: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
The acpi table data is filled for LoongArch virt machine with the
following command:
tests/data/acpi/rebuild-expected-aml.sh
Signed-off-by: Bibo Mao <maobibo@loongson.cn>
Message-Id: <20250612090321.3416594-5-maobibo@loongson.cn>
Reviewed-by: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
Update the list of supported architectures to include LoongArch.
Signed-off-by: Bibo Mao <maobibo@loongson.cn>
Message-Id: <20250612090321.3416594-4-maobibo@loongson.cn>
Reviewed-by: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
Add basic ACPI table test case for LoongArch, including cpu topology,
numa memory, memory hotplug and oem-id test cases.
Signed-off-by: Bibo Mao <maobibo@loongson.cn>
Message-Id: <20250612090321.3416594-3-maobibo@loongson.cn>
Reviewed-by: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
Add empty acpi table for LoongArch virt machine, it is only empty
file and there is no data in these files.
Signed-off-by: Bibo Mao <maobibo@loongson.cn>
Message-Id: <20250612090321.3416594-2-maobibo@loongson.cn>
Reviewed-by: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
If we have a server running disk requests that is for whatever reason
hanging or not able to process any more IO requests but still has some
in-flight requests previously issued by the guest OS, QEMU will still
try to drain the vring before shutting down even if it was explicitly
asked to do a "force shutdown" via SIGTERM or QMP quit. This is not
useful since the guest is no longer running at this point since it was
killed by QEMU earlier in the process. At this point, we don't care
about whatever in-flight IO it might have pending, we just want QEMU
to shut down.
Add an option called "skip-get-vring-base-on-force-shutdown" to allow
SIGTERM/QMP quit() to actually act like a "force shutdown" at least
for vhost-user-blk devices since those require the drain operation
to shut down gracefully unlike, for example, network devices.
Signed-off-by: Daniil Tatianin <d-tatianin@yandex-team.ru>
Message-Id: <20250609212547.2859224-4-d-tatianin@yandex-team.ru>
Acked-by: Raphael Norwitz <raphael@enfabrica.net>
Reviewed-by: Vladimir Sementsov-Ogievskiy <vsementsov@yandex-team.ru>
Reviewed-by: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
This adds an ability to skip GET_VRING_BASE during device stop entirely,
and thus the expensive drain operation that this call entails as well,
which may be useful during a non-graceful shutdown in case the guest
operating system hangs or refuses to react to a previously requested
ACPI shutdown for whatever reason.
Signed-off-by: Daniil Tatianin <d-tatianin@yandex-team.ru>
Message-Id: <20250609212547.2859224-3-d-tatianin@yandex-team.ru>
Reviewed-by: Vladimir Sementsov-Ogievskiy <vsementsov@yandex-team.ru>
Reviewed-by: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
This can be useful for devices that might take too long to shut down
gracefully, but may have a way to shutdown quickly otherwise if needed
or explicitly requested by a force shutdown.
For now we only consider SIGTERM or the QMP quit() command a force
shutdown, since those bypass the guest entirely and are equivalent to
pulling the power plug.
Signed-off-by: Daniil Tatianin <d-tatianin@yandex-team.ru>
Message-Id: <20250609212547.2859224-2-d-tatianin@yandex-team.ru>
Reviewed-by: Vladimir Sementsov-Ogievskiy <vsementsov@yandex-team.ru>
Reviewed-by: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
When we unplug a vhost device, we end up calling vhost_dev_cleanup()
where we do a memory_listener_unregister().
This memory_listener_unregister() call will end up disconnecting the
listener from the address space through listener_del_address_space().
In that process, we effectively communicate the removal of all memory
regions from that listener, resulting in region_del() + commit()
callbacks getting triggered.
So in case of vhost, we end up calling vhost_commit() with no remaining
memory slots (0).
In vhost_commit() we end up overwriting the global variables
used_memslots / used_shared_memslots, used for detecting the number
of free memslots. With used_memslots / used_shared_memslots set to 0
by vhost_commit() during device removal, we'll later assume that the
other vhost devices still have plenty of memslots left when calling
vhost_get_free_memslots().
Let's fix it by simply removing the global variables and depending
only on the actual per-device count.
Easy to reproduce by adding two vhost-user devices to a VM and then
hot-unplugging one of them.
While at it, detect unexpected underflows in vhost_get_free_memslots()
and issue a warning.
Reported-by: yuanminghao <yuanmh12@chinatelecom.cn>
Link: https://lore.kernel.org/qemu-devel/20241121060755.164310-1-yuanmh12@chinatelecom.cn/
Fixes: 2ce68e4cf5 ("vhost: add vhost_has_free_slot() interface")
Cc: Igor Mammedov <imammedo@redhat.com>
Cc: Michael S. Tsirkin <mst@redhat.com>
Cc: Stefano Garzarella <sgarzare@redhat.com>
Signed-off-by: David Hildenbrand <david@redhat.com>
Message-Id: <20250603111336.1858888-1-david@redhat.com>
Reviewed-by: Igor Mammedov <imammedo@redhat.com>
Reviewed-by: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
By default, virtio-net limits the hash types that will be advertised to
the guest so that all hash types are covered by the offloading
capability the client provides. This change allows to override this
behavior and to advertise hash types that require user-space hash
calculation by specifying "on" for the corresponding properties.
Signed-off-by: Akihiko Odaki <akihiko.odaki@daynix.com>
Message-Id: <20250530-vdpa-v1-6-5af4109b1c19@daynix.com>
Reviewed-by: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
It is no longer used.
Signed-off-by: Akihiko Odaki <akihiko.odaki@daynix.com>
Message-Id: <20250530-vdpa-v1-5-5af4109b1c19@daynix.com>
Reviewed-by: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
Retrieve peer hashing capability instead of hardcoding.
Signed-off-by: Akihiko Odaki <akihiko.odaki@daynix.com>
Message-Id: <20250530-vdpa-v1-4-5af4109b1c19@daynix.com>
Reviewed-by: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
Move virtio_net_get_features() to the later part of the file so that
it can call other functions.
Signed-off-by: Akihiko Odaki <akihiko.odaki@daynix.com>
Message-Id: <20250530-vdpa-v1-3-5af4109b1c19@daynix.com>
Reviewed-by: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
Report hashing capability so that virtio-net can deliver the correct
capability information to the guest.
Signed-off-by: Akihiko Odaki <akihiko.odaki@daynix.com>
Message-Id: <20250530-vdpa-v1-2-5af4109b1c19@daynix.com>
Reviewed-by: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
DEFINE_PROP_ON_OFF_AUTO_BIT64() corresponds to DEFINE_PROP_ON_OFF_AUTO()
as DEFINE_PROP_BIT64() corresponds to DEFINE_PROP_BOOL(). The difference
is that DEFINE_PROP_ON_OFF_AUTO_BIT64() exposes OnOffAuto instead of
bool.
Signed-off-by: Akihiko Odaki <akihiko.odaki@daynix.com>
Message-Id: <20250530-vdpa-v1-1-5af4109b1c19@daynix.com>
Reviewed-by: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
tcg: Use uintptr_t in tcg_malloc implementation
linux-user: Hold the fd-trans lock across fork
linux-user: Implement fchmodat2 syscall
linux-user: Check for EFAULT failure in nanosleep
linux-user: Use qemu_set_cloexec() to mark pidfd as FD_CLOEXEC
linux-user/gen-vdso: Handle fseek() failure
linux-user/gen-vdso: Don't read off the end of buf[]
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Merge tag 'pull-tcg-20250711' of https://gitlab.com/rth7680/qemu into staging
fpu: Process float_muladd_negate_result after rounding
tcg: Use uintptr_t in tcg_malloc implementation
linux-user: Hold the fd-trans lock across fork
linux-user: Implement fchmodat2 syscall
linux-user: Check for EFAULT failure in nanosleep
linux-user: Use qemu_set_cloexec() to mark pidfd as FD_CLOEXEC
linux-user/gen-vdso: Handle fseek() failure
linux-user/gen-vdso: Don't read off the end of buf[]
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* tag 'pull-tcg-20250711' of https://gitlab.com/rth7680/qemu:
linux-user: Use qemu_set_cloexec() to mark pidfd as FD_CLOEXEC
tcg: Use uintptr_t in tcg_malloc implementation
linux-user: Hold the fd-trans lock across fork
linux-user/mips/o32: Drop sa_restorer functionality
linux-user/gen-vdso: Don't read off the end of buf[]
linux-user/gen-vdso: Handle fseek() failure
linux-user: Check for EFAULT failure in nanosleep
linux-user: Implement fchmodat2 syscall
fpu: Process float_muladd_negate_result after rounding
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
* New board type max78000fthr
* Enable use of CXL on Arm 'virt' board
* Some more tidyup of ID register handling
* Refactor AT insns and PMU regs into separate source files
* Don't enforce NSE,NS check for EL3->EL3 returns
* hw/arm/fsl-imx8mp: Wire VIRQ and VFIQ
* Allow nested-virtualization with KVM on the 'virt' board
* system/qdev: Remove pointless NULL check in qdev_device_add_from_qdict
* hw/arm/virt-acpi-build: Don't create ITS id mappings by default
* target/arm: Remove unused helper_sme2_luti4_4b
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Merge tag 'pull-target-arm-20250711' of https://gitlab.com/pm215/qemu into staging
target-arm queue:
* New board type max78000fthr
* Enable use of CXL on Arm 'virt' board
* Some more tidyup of ID register handling
* Refactor AT insns and PMU regs into separate source files
* Don't enforce NSE,NS check for EL3->EL3 returns
* hw/arm/fsl-imx8mp: Wire VIRQ and VFIQ
* Allow nested-virtualization with KVM on the 'virt' board
* system/qdev: Remove pointless NULL check in qdev_device_add_from_qdict
* hw/arm/virt-acpi-build: Don't create ITS id mappings by default
* target/arm: Remove unused helper_sme2_luti4_4b
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# gpg: Signature made Fri 11 Jul 2025 09:29:46 EDT
# gpg: using RSA key E1A5C593CD419DE28E8315CF3C2525ED14360CDE
# gpg: issuer "peter.maydell@linaro.org"
# gpg: Good signature from "Peter Maydell <peter.maydell@linaro.org>" [full]
# gpg: aka "Peter Maydell <pmaydell@gmail.com>" [full]
# gpg: aka "Peter Maydell <pmaydell@chiark.greenend.org.uk>" [full]
# gpg: aka "Peter Maydell <peter@archaic.org.uk>" [unknown]
# Primary key fingerprint: E1A5 C593 CD41 9DE2 8E83 15CF 3C25 25ED 1436 0CDE
* tag 'pull-target-arm-20250711' of https://gitlab.com/pm215/qemu: (36 commits)
tests/functional: Add a test for the MAX78000 arm machine
docs/system: arm: Add max78000 board description
target/arm: Remove helper_sme2_luti4_4b
hw/arm/virt-acpi-build: Don't create ITS id mappings by default
system/qdev: Remove pointless NULL check in qdev_device_add_from_qdict
hw/arm/virt: Allow virt extensions with KVM
hw/arm/arm_gicv3_kvm: Add a migration blocker with kvm nested virt
target/arm: Enable feature ARM_FEATURE_EL2 if EL2 is supported
target/arm/kvm: Add helper to detect EL2 when using KVM
hw/arm: Allow setting KVM vGIC maintenance IRQ
hw/arm/fsl-imx8mp: Wire VIRQ and VFIQ
target/arm: Don't enforce NSE,NS check for EL3->EL3 returns
target/arm: Split out performance monitor regs to cpregs-pmu.c
target/arm: Split out AT insns to tcg/cpregs-at.c
target/arm: Drop stub for define_tlb_insn_regs
arm/kvm: shorten one overly long line
arm/cpu: store clidr into the idregs array
arm/cpu: fix trailing ',' for SET_IDREG
arm/cpu: store id_aa64afr{0,1} into the idregs array
arm/cpu: store id_afr0 into the idregs array
...
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
* Link s390-ccw.img statically
* Fix broken bamboo functional test
* s390x code cleanups and refactorings
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Merge tag 'pull-request-2025-07-11' of https://gitlab.com/thuth/qemu into staging
* s390x: Allow to select different entries when booting via pxelinux.cfg
* Link s390-ccw.img statically
* Fix broken bamboo functional test
* s390x code cleanups and refactorings
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# gpg: Signature made Fri 11 Jul 2025 05:32:29 EDT
# gpg: using RSA key 27B88847EEE0250118F3EAB92ED9D774FE702DB5
# gpg: issuer "thuth@redhat.com"
# gpg: Good signature from "Thomas Huth <th.huth@gmx.de>" [full]
# gpg: aka "Thomas Huth <thuth@redhat.com>" [full]
# gpg: aka "Thomas Huth <huth@tuxfamily.org>" [full]
# gpg: aka "Thomas Huth <th.huth@posteo.de>" [unknown]
# Primary key fingerprint: 27B8 8847 EEE0 2501 18F3 EAB9 2ED9 D774 FE70 2DB5
* tag 'pull-request-2025-07-11' of https://gitlab.com/thuth/qemu:
target/s390x: Have s390_cpu_halt() not return anything
target/s390x: Expose s390_count_running_cpus() method
target/s390x: Remove unused s390_cpu_[un]halt() user stubs
tests/functional/test_ppc_bamboo: Replace broken link with working assets
tests/functional: Add dependency to the keymap_targets
pc-bios: Update the s390 bios images with the pxelinux.cfg loadparm changes
pc-bios/s390-ccw: link statically
tests/functional: Add a test for s390x pxelinux.cfg network booting
pc-bios/s390-ccw: Add a boot menu for booting via pxelinux.cfg
pc-bios/s390-ccw: Make get_boot_index() from menu.c global
pc-bios/s390-ccw: Allow up to 31 entries for pxelinux.cfg
pc-bios/s390-ccw: Allow to select a different pxelinux.cfg entry via loadparm
hw/s390x/s390-pci-bus.c: Use g_assert_not_reached() in functions taking an ett
target/s390x/tcg: Use vaddr in s390_probe_access()
target/s390x/kvm: Use vaddr in find/insert_hw_breakpoint()
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
In the linux-user do_fork() function we try to set the FD_CLOEXEC
flag on a pidfd like this:
fcntl(pid_fd, F_SETFD, fcntl(pid_fd, F_GETFL) | FD_CLOEXEC);
This has two problems:
(1) it doesn't check errors, which Coverity complains about
(2) we use F_GETFL when we mean F_GETFD
Deal with both of these problems by using qemu_set_cloexec() instead.
That function will assert() if the fcntls fail, which is fine (we are
inside fork_start()/fork_end() so we know nothing can mess around
with our file descriptors here, and we just got this one from
pidfd_open()).
(As we are touching the if() statement here, we correct the
indentation.)
Coverity: CID 1508111
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Reviewed-by: Daniel P. Berrangé <berrange@redhat.com>
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
Message-ID: <20250711141217.1429412-1-peter.maydell@linaro.org>
Avoid ubsan failure with clang-20,
tcg.h:715:19: runtime error: applying non-zero offset 64 to null pointer
by not using pointers.
Acked-by: Ilya Leoshkevich <iii@linux.ibm.com>
Reviewed-by: Philippe Mathieu-Daudé <philmd@linaro.org>
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
Recent patch [1] renames the save_live_complete_precopy handler to
save_complete, as the machine is not live in most cases when this
handler is executed. The same is true also for
save_live_complete_precopy_thread, therefore this patch removes the
"live" keyword from the handler itself and related types to keep the
naming unified.
In contrast to save_complete, this handler is only executed at the end
of precopy, therefore the "precopy" keyword is retained.
[1]: https://lore.kernel.org/all/20250613140801.474264-7-peterx@redhat.com/
Cc: Alex Williamson <alex.williamson@redhat.com>
Cc: Cédric Le Goater <clg@redhat.com>
Signed-off-by: Juraj Marcin <jmarcin@redhat.com>
Link: https://lore.kernel.org/r/20250626085235.294690-1-jmarcin@redhat.com
Signed-off-by: Peter Xu <peterx@redhat.com>
Signed-off-by: Fabiano Rosas <farosas@suse.de>
Add the latency distribution too for blocktime, using order-of-two buckets.
It accounts for all the faults, from either vCPU or non-vCPU threads. With
prior rework, it's very easy to achieve by adding an array to account for
faults in each buckets.
Sample output for HMP (while for QMP it's simply an array):
Postcopy Latency Distribution:
[ 1 us - 2 us ]: 0
[ 2 us - 4 us ]: 0
[ 4 us - 8 us ]: 1
[ 8 us - 16 us ]: 2
[ 16 us - 32 us ]: 2
[ 32 us - 64 us ]: 3
[ 64 us - 128 us ]: 10169
[ 128 us - 256 us ]: 50151
[ 256 us - 512 us ]: 12876
[ 512 us - 1 ms ]: 97
[ 1 ms - 2 ms ]: 42
[ 2 ms - 4 ms ]: 44
[ 4 ms - 8 ms ]: 93
[ 8 ms - 16 ms ]: 138
[ 16 ms - 32 ms ]: 0
[ 32 ms - 65 ms ]: 0
[ 65 ms - 131 ms ]: 0
[ 131 ms - 262 ms ]: 0
[ 262 ms - 524 ms ]: 0
[ 524 ms - 1 sec ]: 0
[ 1 sec - 2 sec ]: 0
[ 2 sec - 4 sec ]: 0
[ 4 sec - 8 sec ]: 0
[ 8 sec - 16 sec ]: 0
Cc: Markus Armbruster <armbru@redhat.com>
Acked-by: Dr. David Alan Gilbert <dave@treblig.org>
Reviewed-by: Fabiano Rosas <farosas@suse.de>
Link: https://lore.kernel.org/r/20250613141217.474825-15-peterx@redhat.com
Signed-off-by: Peter Xu <peterx@redhat.com>
Signed-off-by: Fabiano Rosas <farosas@suse.de>
When used to report page fault latencies, the blocktime feature can be
almost useless when KVM async page fault is enabled, because in most cases
such remote fault will kickoff async page faults, then it's not trackable
from blocktime layer.
After all these recent rewrites to blocktime layer, it's finally so easy to
also support tracking non-vCPU faults. It'll be even faster if we could
always index fault records with TIDs, unfortunately we need to maintain the
blocktime API which report things in vCPU indexes.
Of course this can work not only for kworkers, but also any guest accesses
that may reach a missing page, for example, very likely when in the QEMU
main thread too (and all other threads whenever applicable).
In this case, we don't care about "how long the threads are blocked", but
we only care about "how long the fault will be resolved".
Cc: Markus Armbruster <armbru@redhat.com>
Cc: Dr. David Alan Gilbert <dave@treblig.org>
Reviewed-by: Fabiano Rosas <farosas@suse.de>
Tested-by: Mario Casquero <mcasquer@redhat.com>
Link: https://lore.kernel.org/r/20250613141217.474825-14-peterx@redhat.com
Signed-off-by: Peter Xu <peterx@redhat.com>
Signed-off-by: Fabiano Rosas <farosas@suse.de>
Currently, the postcopy blocktime feature maintains vCPU fault information
using an array (vcpu_addr[]). It has two issues.
Issue 1: Performance Concern
============================
The old algorithm was almost OK and fast on inserts, except that the lookup
is slow and won't scale if there are a lot of vCPUs: when a page is copied
during postcopy, mark_postcopy_blocktime_end() will walk the whole array
trying to find which vCPUs are blocked by the address. So it needs
constant O(N) walk for each page resolution.
Alexey (the author of postcopy blocktime) mentioned the perf issue and how
to optimize it in a piece of comment in the page resolution path. The
comment was (interestingly..) not complete, but it's relatively clear what
he wanted to say about this perf issue.
Issue 2: Wrong Accounting on re-entrancies
==========================================
People might think that each vCPU should only and always get one fault at a
time, so that when the blocktime layer captured one fault on one vCPU, we
should never see another fault message on this vCPU.
It's almost correct, except in some extreme rare cases.
Case 1: it's possible the fault thread processes the userfaultfd messages
too fast so it can see >1 messages on one vCPU before the previous one was
resolved.
Case 2: it's theoretically also possible one vCPU can get even more than
one message on the same fault address if a fault is retried by the
kernel (e.g., handle_userfault() got interrupted before page resolution).
As this info might be important, instead of using commit message, I put
more details into the code as comment, when introducing an array
maintaining concurrent faults on one vCPU. Please refer to the comments
for details on both cases, especially case 1 which can be tricky.
Case 1 sounds rare, but it can be easily reproduced locally for me when we
run blocktime together with the migration-test on the vanilla postcopy.
New Design
==========
This patch should do almost what Alexey mentioned, but slightly
differently: instead of having an array to maintain vCPU fault addresses,
for each of the fault message we push a message into a hash, indexed by the
fault address.
With the hash, it can replace the old two structs: both the vcpu_addr[]
array, and also the array to store the start time of the fault. However
due to above we need one more counter array to account concurrent faults on
the same vCPU - that should even be needed in the old code, it's just that
the old code was buggy and it will blindly overwrite an existing
entry.. now we'll start to really track everything.
The hash structure might be more efficient than tree to maintain such
addr->(cpu, fault_time) information, so that the insert() and lookup()
paths should ideally both be ~O(1). After all, we do not need to sort.
Here we need to do one remove() though after the lookup(). It could be
slow but only if many vCPUs faulted exactly on the same address (so when
the list of cpu entries is long), which should be unlikely. Even with that,
it's still a worst case O(N) (consider 400 vCPUs faulted on the same
address and how likely is it..) rather than a constant O(N) complexity.
When at it, touch up the tracepoints to make them slightly more useful.
One tracepoint is added when walking all the fault entries.
Reviewed-by: Fabiano Rosas <farosas@suse.de>
Link: https://lore.kernel.org/r/20250613141217.474825-13-peterx@redhat.com
Signed-off-by: Peter Xu <peterx@redhat.com>
Signed-off-by: Fabiano Rosas <farosas@suse.de>
The variable vcpu_total_blocktime isn't easy to follow. In reality, it
wants to capture the case where all vCPUs are stopped, and now there will
be some vCPUs starts running.
The name now starts to conflict with vcpu_blocktime_total[], meanwhile it's
actually not necessary to have the variable at all: since nobody is
touching smp_cpus_down except ourselves, we can safely do the calculation
at the end before decrementing smp_cpus_down.
Hopefully this makes the logic easier to read, side benefit is we drop one
temp var.
Reviewed-by: Fabiano Rosas <farosas@suse.de>
Link: https://lore.kernel.org/r/20250613141217.474825-12-peterx@redhat.com
Signed-off-by: Peter Xu <peterx@redhat.com>
Signed-off-by: Fabiano Rosas <farosas@suse.de>
Looking up the vCPU index for each fault can be expensive when there're
hundreds of vCPUs. Provide a cache for tid->vcpu instead with a hash
table, then lookup from there.
When at it, add another counter to record how many non-vCPU faults it gets.
For example, the main thread can also access a guest page that was missing.
These kind of faults are not accounted by blocktime so far.
Reviewed-by: Fabiano Rosas <farosas@suse.de>
Link: https://lore.kernel.org/r/20250613141217.474825-11-peterx@redhat.com
Signed-off-by: Peter Xu <peterx@redhat.com>
Signed-off-by: Fabiano Rosas <farosas@suse.de>
Before this patch, the blocktime context can be created very early, because
postcopy_ram_supported_by_host() <- migrate_caps_check() can happen during
migration object init.
The trick here is the blocktime context needs system vCPU information,
which seems to be possible to change after that point. I didn't verify it,
but it doesn't sound right.
Now move it out and initialize the context only when postcopy listen
starts. That is already during a migration so it should be guaranteed the
vCPU topology can never change on both sides.
While at it, assert that the ctx isn't created instead this time; the old
"if" trick isn't needed when we're sure it will only happen once now.
Reviewed-by: Fabiano Rosas <farosas@suse.de>
Link: https://lore.kernel.org/r/20250613141217.474825-10-peterx@redhat.com
Signed-off-by: Peter Xu <peterx@redhat.com>
Signed-off-by: Fabiano Rosas <farosas@suse.de>
Blocktime so far only cares about the time one vcpu (or the whole system)
got blocked. It would be also be helpful if it can also report the latency
of page requests, which could be very sensitive during postcopy.
Blocktime itself is sometimes not very important, especially when one
thinks about KVM async PF support, which means vCPUs are literally almost
not blocked at all because the guest OS is smart enough to switch to
another task when a remote fault is needed.
However, latency is still sensitive and important because even if the guest
vCPU is running on threads that do not need a remote fault, the workload
that accesses some missing page is still affected.
Add two entries to the report, showing how long it takes to resolve a
remote fault. Mention in the QAPI doc that this is not the real average
fault latency, but only the ones that was requested for a remote fault.
Unwrap get_vcpu_blocktime_list() so we don't need to walk the list twice,
meanwhile add the entry checks in qtests for all postcopy tests.
Cc: Markus Armbruster <armbru@redhat.com>
Cc: Dr. David Alan Gilbert <dave@treblig.org>
Reviewed-by: Fabiano Rosas <farosas@suse.de>
Tested-by: Mario Casquero <mcasquer@redhat.com>
Link: https://lore.kernel.org/r/20250613141217.474825-9-peterx@redhat.com
Signed-off-by: Peter Xu <peterx@redhat.com>
Signed-off-by: Fabiano Rosas <farosas@suse.de>
Add a field to count how many remote faults one vCPU has taken. So far
it's still not used, but will be soon.
Reviewed-by: Fabiano Rosas <farosas@suse.de>
Link: https://lore.kernel.org/r/20250613141217.474825-8-peterx@redhat.com
Signed-off-by: Peter Xu <peterx@redhat.com>
Signed-off-by: Fabiano Rosas <farosas@suse.de>
With 64-bit fields, it is trivial. The caution is when exposing any values
in QMP, it was still declared with milliseconds (ms). Hence it's needed to
do the convertion when exporting the values to existing QMP queries.
Reviewed-by: Fabiano Rosas <farosas@suse.de>
Link: https://lore.kernel.org/r/20250613141217.474825-7-peterx@redhat.com
Signed-off-by: Peter Xu <peterx@redhat.com>
Signed-off-by: Fabiano Rosas <farosas@suse.de>
Now with 64bits, the offseting using start_time is not needed anymore,
because the array can always remember the whole timestamp.
Then drop the unused parameter in get_low_time_offset() altogether.
Reviewed-by: Fabiano Rosas <farosas@suse.de>
Link: https://lore.kernel.org/r/20250613141217.474825-6-peterx@redhat.com
Signed-off-by: Peter Xu <peterx@redhat.com>
Signed-off-by: Fabiano Rosas <farosas@suse.de>
I am guessing it was used to be 32bits because of the atomic ops. Now all
the atomic ops are gone and we're protected by a mutex instead, it's ok we
can switch to 64 bits.
Reasons to move over:
- Allow further patches to change the unit from ms to us: with postcopy
preempt mode, we're really into hundreds of microseconds level on
blocktime. We'd better be able to trap those.
- This also paves way for some other tricks that the original version
used to avoid overflows, e.g., start_time was almost only useful before
to make sure the sampled timestamp won't overflow a 32-bit field.
- This prepares further reports on top of existing data collected,
e.g. average page fault latencies. When average operation is taken into
account, milliseconds are simply too coarse grained.
When at it:
- Rename page_fault_vcpu_time to vcpu_blocktime_start.
- Rename vcpu_blocktime to vcpu_blocktime_total.
- Touch up the trace-events to not dump blocktime ctx pointer
Reviewed-by: Fabiano Rosas <farosas@suse.de>
Link: https://lore.kernel.org/r/20250613141217.474825-5-peterx@redhat.com
Signed-off-by: Peter Xu <peterx@redhat.com>
Signed-off-by: Fabiano Rosas <farosas@suse.de>
The postcopy blocktime feature was tricky that it used quite some atomic
operations over quite a few arrays and vars, without explaining how that
would be thread safe. The thread safety here is about concurrency between
the fault thread and the fault resolution threads, possible to access the
same chunk of data. All these atomic ops can be expensive too before
knowing clearly how it works.
OTOH, postcopy has one page_request_mutex used to serialize the received
bitmap updates. So far it's ok - we don't yet have a lot of threads
contending the lock. It might change after multifd will be supported, but
that's a separate story. What is important is, with that mutex, it's
pretty lightweight to move all the blocktime maintenance into the mutex
critical section. It's because the blocktime layer is lightweighted:
almost "remember which vcpu faulted on which address", and "ok we get some
fault resolved, calculate how long it takes". It's also an optional
feature for now (but I have thought of changing that, maybe in the future).
Let's push the blocktime layer into the mutex, so that it's always
thread-safe even without any atomic ops.
To achieve that, I'll need to add a tid parameter on fault path so that
it'll start to pass the faulted thread ID into deeper the stack, but not
too deep. When at it, add a comment for the shared fault handler (for
example, vhost-user devices running with postcopy), to mention a TODO. One
reason it might not be trivial is that vhost-user's userfaultfds should be
opened by vhost-user process, so it's pretty hard to control making sure
the TID feature will be around. It wasn't supported before, so keep it
like that for now.
Now we should be as ease when everything is protected by a mutex that we
always take anyway.
One side effect: we can finally remove one ramblock_recv_bitmap_test() in
mark_postcopy_blocktime_begin(), which was pretty weird and which also
includes a weird (but maybe necessary.. but maybe not?) operation to inject
a blocktime entry then quickly erase it.. When we're with the mutex, and
when we make sure it's invoked after checking the receive bitmap, it's not
needed anymore. Instead, we assert.
As another side effect, this paves way for removing all atomic ops in all
the mem accesses in blocktime layer.
Note that we need a stub for mark_postcopy_blocktime_begin() for Windows
builds.
Reviewed-by: Fabiano Rosas <farosas@suse.de>
Link: https://lore.kernel.org/r/20250613141217.474825-3-peterx@redhat.com
Signed-off-by: Peter Xu <peterx@redhat.com>
Signed-off-by: Fabiano Rosas <farosas@suse.de>
This is a follow up on the other commit "migration/ram: avoid to do log
clear in the last round" but for postcopy.
https://lore.kernel.org/r/20250514115827.3216082-1-yanfei.xu@bytedance.com
I can observe more than 10% reduction of average page fault latency during
postcopy phase with this optimization:
Before: 268.00us (+-1.87%)
After: 232.67us (+-2.01%)
The test was done with a 16GB VM with 80 vCPUs, running a workload that
busy random writes to 13GB memory.
Cc: Yanfei Xu <yanfei.xu@bytedance.com>
Reviewed-by: Fabiano Rosas <farosas@suse.de>
Link: https://lore.kernel.org/r/20250613140801.474264-12-peterx@redhat.com
Signed-off-by: Peter Xu <peterx@redhat.com>
Signed-off-by: Fabiano Rosas <farosas@suse.de>
There're a few things off here in that logic, rewrite it. When at it, add
rich comment to explain each of the decisions.
Since this is very sensitive path for migration, below are the list of
things changed with their reasonings.
(1) Exact pending size is only needed for precopy not postcopy
Fundamentally it's because "exact" version only does one more deep
sync to fetch the pending results, while in postcopy's case it's
never going to sync anything more than estimate as the VM on source
is stopped.
(2) Do _not_ rely on threshold_size anymore to decide whether postcopy
should complete
threshold_size was calculated from the expected downtime and
bandwidth only during precopy as an efficient way to decide when to
switchover. It's not sensible to rely on threshold_size in postcopy.
For precopy, if switchover is decided, the migration will complete
soon. It's not true for postcopy. Logically speaking, postcopy
should only complete the migration if all pending data is flushed.
Here it used to work because save_complete() used to implicitly
contain save_live_iterate() when there's pending size.
Even if that looks benign, having RAMs to be migrated in postcopy's
save_complete() has other bad side effects:
(a) Since save_complete() needs to be run once at a time, it means
when moving RAM there's no way moving other things (rather than
round-robin iterating the vmstate handlers like what we do with
ITERABLE phase). Not an immediate concern, but it may stop working
in the future when there're more than one iterables (e.g. vfio
postcopy).
(b) postcopy recovery, unfortunately, only works during ITERABLE
phase. IOW, if src QEMU moves RAM during postcopy's save_complete()
and network failed, then it'll crash both QEMUs... OTOH if it failed
during iteration it'll still be recoverable. IOW, this change should
further reduce the window QEMU split brain and crash in extreme cases.
If we enable the ram_save_complete() tracepoints, we'll see this
before this patch:
1267959@1748381938.294066:ram_save_complete dirty=9627, done=0
1267959@1748381938.308884:ram_save_complete dirty=0, done=1
It means in this migration there're 9627 pages migrated at complete()
of postcopy phase.
After this change, all the postcopy RAM should be migrated in iterable
phase, rather than save_complete():
1267959@1748381938.294066:ram_save_complete dirty=0, done=0
1267959@1748381938.308884:ram_save_complete dirty=0, done=1
(3) Adjust when to decide to switch to postcopy
This shouldn't be super important, the movement makes sure there's
only one in_postcopy check, then we are clear on what we do with the
two completely differnt use cases (precopy v.s. postcopy).
(4) Trivial touch up on threshold_size comparision
Which changes:
"(!pending_size || pending_size < s->threshold_size)"
into:
"(pending_size <= s->threshold_size)"
Reviewed-by: Juraj Marcin <jmarcin@redhat.com>
Reviewed-by: Fabiano Rosas <farosas@suse.de>
Link: https://lore.kernel.org/r/20250613140801.474264-11-peterx@redhat.com
Signed-off-by: Peter Xu <peterx@redhat.com>
Signed-off-by: Fabiano Rosas <farosas@suse.de>
