Pull virtio updates from Michael Tsirkin:
"Just a bunch of fixes and cleanups, mostly very simple. Several
features were merged through net-next this time around"
* tag 'for_linus' of git://git.kernel.org/pub/scm/linux/kernel/git/mst/vhost:
virtio_pci: drop kernel.h
vhost: switch to arrays of feature bits
vhost/test: add test specific macro for features
virtio: clean up features qword/dword terms
vduse: add WQ_PERCPU to alloc_workqueue users
virtio_balloon: add WQ_PERCPU to alloc_workqueue users
vdpa/pds: use %pe for ERR_PTR() in event handler registration
vhost: Fix kthread worker cgroup failure handling
virtio: vdpa: Fix reference count leak in octep_sriov_enable()
vdpa/mlx5: Fix incorrect error code reporting in query_virtqueues
virtio: fix map ops comment
virtio: fix virtqueue_set_affinity() docs
virtio: standardize Returns documentation style
virtio: fix grammar in virtio_map_ops docs
virtio: fix grammar in virtio_queue_info docs
virtio: fix whitespace in virtio_config_ops
virtio: fix typo in virtio_device_ready() comment
virtio: fix kernel-doc for mapping/free_coherent functions
virtio_vdpa: fix misleading return in void function
When discarding descriptors with IN_ORDER, we should rewind
next_avail_head otherwise it would run out of sync with
last_avail_idx. This would cause driver to report
"id X is not a head".
Fixing this by returning the number of descriptors that is used for
each buffer via vhost_get_vq_desc_n() so caller can use the value
while discarding descriptors.
Fixes: 67a873df0c ("vhost: basic in order support")
Cc: stable@vger.kernel.org
Signed-off-by: Jason Wang <jasowang@redhat.com>
Acked-by: Michael S. Tsirkin <mst@redhat.com>
Link: https://patch.msgid.link/20251120022950.10117-1-jasowang@redhat.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
Commit 8c2e6b26ff ("vhost/net: Defer TX queue re-enable until after
sendmsg") tries to defer the notification enabling by moving the logic
out of the loop after the vhost_tx_batch() when nothing new is spotted.
This caused unexpected side effects as the new logic is reused for
several other error conditions.
A previous patch reverted 8c2e6b26ff. Now, bring the performance
back up by flushing batched buffers before enabling notifications.
Reported-by: Jon Kohler <jon@nutanix.com>
Cc: stable@vger.kernel.org
Fixes: 8c2e6b26ff ("vhost/net: Defer TX queue re-enable until after sendmsg")
Signed-off-by: Jason Wang <jasowang@redhat.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
Message-Id: <20250917063045.2042-3-jasowang@redhat.com>
This reverts commit 8c2e6b26ff. It tries
to defer the notification enabling by moving the logic out of the loop
after the vhost_tx_batch() when nothing new is spotted. This will
bring side effects as the new logic would be reused for several other
error conditions.
One example is the IOTLB: when there's an IOTLB miss, get_tx_bufs()
might return -EAGAIN and exit the loop and see there's still available
buffers, so it will queue the tx work again until userspace feed the
IOTLB entry correctly. This will slowdown the tx processing and
trigger the TX watchdog in the guest as reported in
https://lkml.org/lkml/2025/9/10/1596.
To fix, revert the change. A follow up patch will bring the performance
back in a safe way.
Reported-by: Jon Kohler <jon@nutanix.com>
Cc: stable@vger.kernel.org
Fixes: 8c2e6b26ff ("vhost/net: Defer TX queue re-enable until after sendmsg")
Signed-off-by: Jason Wang <jasowang@redhat.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
Message-Id: <20250917063045.2042-2-jasowang@redhat.com>
Commit 67a873df0c ("vhost: basic in order support") pass the number
of used elem to vhost_net_rx_peek_head_len() to make sure it can
signal the used correctly before trying to do busy polling. But it
forgets to clear the count, this would cause the count run out of sync
with handle_rx() and break the busy polling.
Fixing this by passing the pointer of the count and clearing it after
the signaling the used.
Acked-by: Michael S. Tsirkin <mst@redhat.com>
Cc: stable@vger.kernel.org
Fixes: 67a873df0c ("vhost: basic in order support")
Signed-off-by: Jason Wang <jasowang@redhat.com>
Message-Id: <20250917063045.2042-1-jasowang@redhat.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
The error log in vhost_scsi_make_tport() prints the arguments in the
wrong order, producing confusing output. For example, when creating a
target with a name in WWNN format such as "fc.port1234", the log
looks like:
Emulated fc.port1234 Address: FCP, exceeds max: 64
Instead, the message should report the emulated protocol type first,
followed by the configfs name as:
Emulated FCP Address: fc.port1234, exceeds max: 64
Fix the argument order so the error log is consistent and clear.
Signed-off-by: Alok Tiwari <alok.a.tiwari@oracle.com>
Message-Id: <20250913154106.3995856-1-alok.a.tiwari@oracle.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
Reviewed-by: Stefan Hajnoczi <stefanha@redhat.com>
When operating on struct vhost_net_ubuf_ref, the following execution
sequence is theoretically possible:
CPU0 is finalizing DMA operation CPU1 is doing VHOST_NET_SET_BACKEND
// ubufs->refcount == 2
vhost_net_ubuf_put() vhost_net_ubuf_put_wait_and_free(oldubufs)
vhost_net_ubuf_put_and_wait()
vhost_net_ubuf_put()
int r = atomic_sub_return(1, &ubufs->refcount);
// r = 1
int r = atomic_sub_return(1, &ubufs->refcount);
// r = 0
wait_event(ubufs->wait, !atomic_read(&ubufs->refcount));
// no wait occurs here because condition is already true
kfree(ubufs);
if (unlikely(!r))
wake_up(&ubufs->wait); // use-after-free
This leads to use-after-free on ubufs access. This happens because CPU1
skips waiting for wake_up() when refcount is already zero.
To prevent that use a read-side RCU critical section in vhost_net_ubuf_put(),
as suggested by Hillf Danton. For this lock to take effect, free ubufs with
kfree_rcu().
Cc: stable@vger.kernel.org
Fixes: 0ad8b480d6 ("vhost: fix ref cnt checking deadlock")
Reported-by: Andrey Ryabinin <arbn@yandex-team.com>
Suggested-by: Hillf Danton <hdanton@sina.com>
Signed-off-by: Nikolay Kuratov <kniv@yandex-team.ru>
Message-Id: <20250805130917.727332-1-kniv@yandex-team.ru>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
Pull virtio updates from Michael Tsirkin:
- vhost can now support legacy threading if enabled in Kconfig
- vsock memory allocation strategies for large buffers have been
improved, reducing pressure on kmalloc
- vhost now supports the in-order feature. guest bits missed the merge
window.
- fixes, cleanups all over the place
* tag 'for_linus' of git://git.kernel.org/pub/scm/linux/kernel/git/mst/vhost: (30 commits)
vsock/virtio: Allocate nonlinear SKBs for handling large transmit buffers
vsock/virtio: Rename virtio_vsock_skb_rx_put()
vhost/vsock: Allocate nonlinear SKBs for handling large receive buffers
vsock/virtio: Move SKB allocation lower-bound check to callers
vsock/virtio: Rename virtio_vsock_alloc_skb()
vsock/virtio: Resize receive buffers so that each SKB fits in a 4K page
vsock/virtio: Move length check to callers of virtio_vsock_skb_rx_put()
vsock/virtio: Validate length in packet header before skb_put()
vhost/vsock: Avoid allocating arbitrarily-sized SKBs
vhost_net: basic in_order support
vhost: basic in order support
vhost: fail early when __vhost_add_used() fails
vhost: Reintroduce kthread API and add mode selection
vdpa: Fix IDR memory leak in VDUSE module exit
vdpa/mlx5: Fix release of uninitialized resources on error path
vhost-scsi: Fix check for inline_sg_cnt exceeding preallocated limit
virtio: virtio_dma_buf: fix missing parameter documentation
vhost: Fix typos
vhost: vringh: Remove unused functions
vhost: vringh: Remove unused iotlb functions
...
In preparation for using virtio_vsock_skb_rx_put() when populating SKBs
on the vsock TX path, rename virtio_vsock_skb_rx_put() to
virtio_vsock_skb_put().
No functional change.
Reviewed-by: Stefano Garzarella <sgarzare@redhat.com>
Signed-off-by: Will Deacon <will@kernel.org>
Message-Id: <20250717090116.11987-9-will@kernel.org>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
When receiving a packet from a guest, vhost_vsock_handle_tx_kick()
calls vhost_vsock_alloc_linear_skb() to allocate and fill an SKB with
the receive data. Unfortunately, these are always linear allocations and
can therefore result in significant pressure on kmalloc() considering
that the maximum packet size (VIRTIO_VSOCK_MAX_PKT_BUF_SIZE +
VIRTIO_VSOCK_SKB_HEADROOM) is a little over 64KiB, resulting in a 128KiB
allocation for each packet.
Rework the vsock SKB allocation so that, for sizes with page order
greater than PAGE_ALLOC_COSTLY_ORDER, a nonlinear SKB is allocated
instead with the packet header in the SKB and the receive data in the
fragments. Finally, add a debug warning if virtio_vsock_skb_rx_put() is
ever called on an SKB with a non-zero length, as this would be
destructive for the nonlinear case.
Reviewed-by: Stefano Garzarella <sgarzare@redhat.com>
Signed-off-by: Will Deacon <will@kernel.org>
Message-Id: <20250717090116.11987-8-will@kernel.org>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
virtio_vsock_alloc_linear_skb() checks that the requested size is at
least big enough for the packet header (VIRTIO_VSOCK_SKB_HEADROOM).
Of the three callers of virtio_vsock_alloc_linear_skb(), only
vhost_vsock_alloc_skb() can potentially pass a packet smaller than the
header size and, as it already has a check against the maximum packet
size, extend its bounds checking to consider the minimum packet size
and remove the check from virtio_vsock_alloc_linear_skb().
Reviewed-by: Stefano Garzarella <sgarzare@redhat.com>
Signed-off-by: Will Deacon <will@kernel.org>
Message-Id: <20250717090116.11987-7-will@kernel.org>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
In preparation for nonlinear allocations for large SKBs, rename
virtio_vsock_alloc_skb() to virtio_vsock_alloc_linear_skb() to indicate
that it returns linear SKBs unconditionally and switch all callers over
to this new interface for now.
No functional change.
Reviewed-by: Stefano Garzarella <sgarzare@redhat.com>
Signed-off-by: Will Deacon <will@kernel.org>
Message-Id: <20250717090116.11987-6-will@kernel.org>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
virtio_vsock_skb_rx_put() only calls skb_put() if the length in the
packet header is not zero even though skb_put() handles this case
gracefully.
Remove the functionally redundant check from virtio_vsock_skb_rx_put()
and, on the assumption that this is a worthwhile optimisation for
handling credit messages, augment the existing length checks in
virtio_transport_rx_work() to elide the call for zero-length payloads.
Since the callers all have the length, extend virtio_vsock_skb_rx_put()
to take it as an additional parameter rather than fish it back out of
the packet header.
Note that the vhost code already has similar logic in
vhost_vsock_alloc_skb().
Reviewed-by: Stefano Garzarella <sgarzare@redhat.com>
Signed-off-by: Will Deacon <will@kernel.org>
Message-Id: <20250717090116.11987-4-will@kernel.org>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
vhost_vsock_alloc_skb() returns NULL for packets advertising a length
larger than VIRTIO_VSOCK_MAX_PKT_BUF_SIZE in the packet header. However,
this is only checked once the SKB has been allocated and, if the length
in the packet header is zero, the SKB may not be freed immediately.
Hoist the size check before the SKB allocation so that an iovec larger
than VIRTIO_VSOCK_MAX_PKT_BUF_SIZE + the header size is rejected
outright. The subsequent check on the length field in the header can
then simply check that the allocated SKB is indeed large enough to hold
the packet.
Cc: <stable@vger.kernel.org>
Fixes: 71dc9ec9ac ("virtio/vsock: replace virtio_vsock_pkt with sk_buff")
Reviewed-by: Stefano Garzarella <sgarzare@redhat.com>
Signed-off-by: Will Deacon <will@kernel.org>
Message-Id: <20250717090116.11987-2-will@kernel.org>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
This patch introduces basic in-order support for vhost-net. By
recording the number of batched buffers in an array when calling
`vhost_add_used_and_signal_n()`, we can reduce the number of userspace
accesses. Note that the vhost-net batching logic is kept as we still
count the number of buffers there.
Testing Results:
With testpmd:
- TX: txonly mode + vhost_net with XDP_DROP on TAP shows a 17.5%
improvement, from 4.75 Mpps to 5.35 Mpps.
- RX: No obvious improvements were observed.
With virtio-ring in-order experimental code in the guest:
- TX: pktgen in the guest + XDP_DROP on TAP shows a 19% improvement,
from 5.2 Mpps to 6.2 Mpps.
- RX: pktgen on TAP with vhost_net + XDP_DROP in the guest achieves a
6.1% improvement, from 3.47 Mpps to 3.61 Mpps.
Acked-by: Jonah Palmer <jonah.palmer@oracle.com>
Acked-by: Eugenio Pérez <eperezma@redhat.com>
Signed-off-by: Jason Wang <jasowang@redhat.com>
Message-Id: <20250714084755.11921-4-jasowang@redhat.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
Tested-by: Lei Yang <leiyang@redhat.com>
This patch adds basic in order support for vhost. Two optimizations
are implemented in this patch:
1) Since driver uses descriptor in order, vhost can deduce the next
avail ring head by counting the number of descriptors that has been
used in next_avail_head. This eliminate the need to access the
available ring in vhost.
2) vhost_add_used_and_singal_n() is extended to accept the number of
batched buffers per used elem. While this increases the times of
userspace memory access but it helps to reduce the chance of
used ring access of both the driver and vhost.
Vhost-net will be the first user for this.
Acked-by: Jonah Palmer <jonah.palmer@oracle.com>
Signed-off-by: Jason Wang <jasowang@redhat.com>
Message-Id: <20250714084755.11921-3-jasowang@redhat.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
Tested-by: Lei Yang <leiyang@redhat.com>
Since commit 6e890c5d50 ("vhost: use vhost_tasks for worker threads"),
the vhost uses vhost_task and operates as a child of the
owner thread. This is required for correct CPU usage accounting,
especially when using containers.
However, this change has caused confusion for some legacy
userspace applications, and we didn't notice until it's too late.
Unfortunately, it's too late to revert - we now have userspace
depending both on old and new behaviour :(
To address the issue, reintroduce kthread mode for vhost workers and
provide a configuration to select between kthread and task worker.
- Add 'fork_owner' parameter to vhost_dev to let users select kthread
or task mode. Default mode is task mode(VHOST_FORK_OWNER_TASK).
- Reintroduce kthread mode support:
* Bring back the original vhost_worker() implementation,
and renamed to vhost_run_work_kthread_list().
* Add cgroup support for the kthread
* Introduce struct vhost_worker_ops:
- Encapsulates create / stop / wake‑up callbacks.
- vhost_worker_create() selects the proper ops according to
inherit_owner.
- Userspace configuration interface:
* New IOCTLs:
- VHOST_SET_FORK_FROM_OWNER lets userspace select task mode
(VHOST_FORK_OWNER_TASK) or kthread mode (VHOST_FORK_OWNER_KTHREAD)
- VHOST_GET_FORK_FROM_OWNER reads the current worker mode
* Expose module parameter 'fork_from_owner_default' to allow system
administrators to configure the default mode for vhost workers
* Kconfig option CONFIG_VHOST_ENABLE_FORK_OWNER_CONTROL controls whether
these IOCTLs and the parameter are available
- The VHOST_NEW_WORKER functionality requires fork_owner to be set
to true, with validation added to ensure proper configuration
This partially reverts or improves upon:
commit 6e890c5d50 ("vhost: use vhost_tasks for worker threads")
commit 1cdaafa1b8 ("vhost: replace single worker pointer with xarray")
Fixes: 6e890c5d50 ("vhost: use vhost_tasks for worker threads"),
Signed-off-by: Cindy Lu <lulu@redhat.com>
Message-Id: <20250714071333.59794-2-lulu@redhat.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
Acked-by: Jason Wang <jasowang@redhat.com>
Tested-by: Lei Yang <leiyang@redhat.com>
The condition comparing ret to VHOST_SCSI_PREALLOC_SGLS was incorrect,
as ret holds the result of kstrtouint() (typically 0 on success),
not the parsed value. Update the check to use cnt, which contains the
actual user-provided value.
prevents silently accepting values exceeding the maximum inline_sg_cnt.
Fixes: bca939d5bc ("vhost-scsi: Dynamically allocate scatterlists")
Signed-off-by: Alok Tiwari <alok.a.tiwari@oracle.com>
Reviewed-by: Mike Christie <michael.christie@oracle.com>
Reviewed-by: Stefan Hajnoczi <stefanha@redhat.com>
Message-Id: <20250628183405.3979538-1-alok.a.tiwari@oracle.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
Acked-by: Jason Wang <jasowang@redhat.com>
The functions:
vringh_abandon_kern()
vringh_abandon_user()
vringh_iov_pull_kern() and
vringh_iov_push_kern()
were all added in 2013 by
commit f87d0fbb57 ("vringh: host-side implementation of virtio rings.")
but have remained unused.
Remove them and the two helper functions they used.
Signed-off-by: Dr. David Alan Gilbert <linux@treblig.org>
Message-Id: <20250617001838.114457-3-linux@treblig.org>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
Acked-by: Eugenio Pérez <eperezma@redhat.com>
Tested-by: Lei Yang <leiyang@redhat.com>
Reviewed-by: Simon Horman <horms@kernel.org>
As part of the normal initiator side scanning the guest's scsi layer
will loop over all possible targets and send an inquiry. Since the
max number of targets for virtio-scsi is 256, this can result in 255
error messages about targets not existing if you only have a single
target. When there's more than 1 vhost-scsi device each with a single
target, then you get N * 255 log messages.
It looks like the log message was added by accident in:
commit 3f8ca2e115 ("vhost/scsi: Extract common handling code from
control queue handler")
when we added common helpers. Then in:
commit 09d7583294 ("vhost/scsi: Use common handling code in request
queue handler")
we converted the scsi command processing path to use the new
helpers so we started to see the extra log messages during scanning.
The patches were just making some code common but added the vq_err
call and I'm guessing the patch author forgot to enable the vq_err
call (vq_err is implemented by pr_debug which defaults to off). So
this patch removes the call since it's expected to hit this path
during device discovery.
Fixes: 09d7583294 ("vhost/scsi: Use common handling code in request queue handler")
Signed-off-by: Mike Christie <michael.christie@oracle.com>
Reviewed-by: Stefan Hajnoczi <stefanha@redhat.com>
Reviewed-by: Stefano Garzarella <sgarzare@redhat.com>
Message-Id: <20250611210113.10912-1-michael.christie@oracle.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
This patch corrects several minor typos and formatting issues.
Changes include:
Fixing misspellings like in comments
- "explict" -> "explicit"
- "infight" -> "inflight",
- "with generate" -> "will generate"
formatting in logs
- Correcting log formatting specifier from "%dd" to "%d"
- Adding a missing space in the sysfs emit string to prevent
misinterpreted output like "X86_64on ". changing to "X86_64 on "
- Cleaning up stray semicolons in struct definition endings
These changes improve code readability and consistency.
no functionality changes.
Signed-off-by: Alok Tiwari <alok.a.tiwari@oracle.com>
Message-Id: <20250611143932.2443796-1-alok.a.tiwari@oracle.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
Reviewed-by: Stefan Hajnoczi <stefanha@redhat.com>
Reviewed-by: Mike Christie <michael.christie@oracle.com>
Pull kvm updates from Paolo Bonzini:
"ARM:
- Host driver for GICv5, the next generation interrupt controller for
arm64, including support for interrupt routing, MSIs, interrupt
translation and wired interrupts
- Use FEAT_GCIE_LEGACY on GICv5 systems to virtualize GICv3 VMs on
GICv5 hardware, leveraging the legacy VGIC interface
- Userspace control of the 'nASSGIcap' GICv3 feature, allowing
userspace to disable support for SGIs w/o an active state on
hardware that previously advertised it unconditionally
- Map supporting endpoints with cacheable memory attributes on
systems with FEAT_S2FWB and DIC where KVM no longer needs to
perform cache maintenance on the address range
- Nested support for FEAT_RAS and FEAT_DoubleFault2, allowing the
guest hypervisor to inject external aborts into an L2 VM and take
traps of masked external aborts to the hypervisor
- Convert more system register sanitization to the config-driven
implementation
- Fixes to the visibility of EL2 registers, namely making VGICv3
system registers accessible through the VGIC device instead of the
ONE_REG vCPU ioctls
- Various cleanups and minor fixes
LoongArch:
- Add stat information for in-kernel irqchip
- Add tracepoints for CPUCFG and CSR emulation exits
- Enhance in-kernel irqchip emulation
- Various cleanups
RISC-V:
- Enable ring-based dirty memory tracking
- Improve perf kvm stat to report interrupt events
- Delegate illegal instruction trap to VS-mode
- MMU improvements related to upcoming nested virtualization
s390x
- Fixes
x86:
- Add CONFIG_KVM_IOAPIC for x86 to allow disabling support for I/O
APIC, PIC, and PIT emulation at compile time
- Share device posted IRQ code between SVM and VMX and harden it
against bugs and runtime errors
- Use vcpu_idx, not vcpu_id, for GA log tag/metadata, to make lookups
O(1) instead of O(n)
- For MMIO stale data mitigation, track whether or not a vCPU has
access to (host) MMIO based on whether the page tables have MMIO
pfns mapped; using VFIO is prone to false negatives
- Rework the MSR interception code so that the SVM and VMX APIs are
more or less identical
- Recalculate all MSR intercepts from scratch on MSR filter changes,
instead of maintaining shadow bitmaps
- Advertise support for LKGS (Load Kernel GS base), a new instruction
that's loosely related to FRED, but is supported and enumerated
independently
- Fix a user-triggerable WARN that syzkaller found by setting the
vCPU in INIT_RECEIVED state (aka wait-for-SIPI), and then putting
the vCPU into VMX Root Mode (post-VMXON). Trying to detect every
possible path leading to architecturally forbidden states is hard
and even risks breaking userspace (if it goes from valid to valid
state but passes through invalid states), so just wait until
KVM_RUN to detect that the vCPU state isn't allowed
- Add KVM_X86_DISABLE_EXITS_APERFMPERF to allow disabling
interception of APERF/MPERF reads, so that a "properly" configured
VM can access APERF/MPERF. This has many caveats (APERF/MPERF
cannot be zeroed on vCPU creation or saved/restored on suspend and
resume, or preserved over thread migration let alone VM migration)
but can be useful whenever you're interested in letting Linux
guests see the effective physical CPU frequency in /proc/cpuinfo
- Reject KVM_SET_TSC_KHZ for vm file descriptors if vCPUs have been
created, as there's no known use case for changing the default
frequency for other VM types and it goes counter to the very reason
why the ioctl was added to the vm file descriptor. And also, there
would be no way to make it work for confidential VMs with a
"secure" TSC, so kill two birds with one stone
- Dynamically allocation the shadow MMU's hashed page list, and defer
allocating the hashed list until it's actually needed (the TDP MMU
doesn't use the list)
- Extract many of KVM's helpers for accessing architectural local
APIC state to common x86 so that they can be shared by guest-side
code for Secure AVIC
- Various cleanups and fixes
x86 (Intel):
- Preserve the host's DEBUGCTL.FREEZE_IN_SMM when running the guest.
Failure to honor FREEZE_IN_SMM can leak host state into guests
- Explicitly check vmcs12.GUEST_DEBUGCTL on nested VM-Enter to
prevent L1 from running L2 with features that KVM doesn't support,
e.g. BTF
x86 (AMD):
- WARN and reject loading kvm-amd.ko instead of panicking the kernel
if the nested SVM MSRPM offsets tracker can't handle an MSR (which
is pretty much a static condition and therefore should never
happen, but still)
- Fix a variety of flaws and bugs in the AVIC device posted IRQ code
- Inhibit AVIC if a vCPU's ID is too big (relative to what hardware
supports) instead of rejecting vCPU creation
- Extend enable_ipiv module param support to SVM, by simply leaving
IsRunning clear in the vCPU's physical ID table entry
- Disable IPI virtualization, via enable_ipiv, if the CPU is affected
by erratum #1235, to allow (safely) enabling AVIC on such CPUs
- Request GA Log interrupts if and only if the target vCPU is
blocking, i.e. only if KVM needs a notification in order to wake
the vCPU
- Intercept SPEC_CTRL on AMD if the MSR shouldn't exist according to
the vCPU's CPUID model
- Accept any SNP policy that is accepted by the firmware with respect
to SMT and single-socket restrictions. An incompatible policy
doesn't put the kernel at risk in any way, so there's no reason for
KVM to care
- Drop a superfluous WBINVD (on all CPUs!) when destroying a VM and
use WBNOINVD instead of WBINVD when possible for SEV cache
maintenance
- When reclaiming memory from an SEV guest, only do cache flushes on
CPUs that have ever run a vCPU for the guest, i.e. don't flush the
caches for CPUs that can't possibly have cache lines with dirty,
encrypted data
Generic:
- Rework irqbypass to track/match producers and consumers via an
xarray instead of a linked list. Using a linked list leads to
O(n^2) insertion times, which is hugely problematic for use cases
that create large numbers of VMs. Such use cases typically don't
actually use irqbypass, but eliminating the pointless registration
is a future problem to solve as it likely requires new uAPI
- Track irqbypass's "token" as "struct eventfd_ctx *" instead of a
"void *", to avoid making a simple concept unnecessarily difficult
to understand
- Decouple device posted IRQs from VFIO device assignment, as binding
a VM to a VFIO group is not a requirement for enabling device
posted IRQs
- Clean up and document/comment the irqfd assignment code
- Disallow binding multiple irqfds to an eventfd with a priority
waiter, i.e. ensure an eventfd is bound to at most one irqfd
through the entire host, and add a selftest to verify eventfd:irqfd
bindings are globally unique
- Add a tracepoint for KVM_SET_MEMORY_ATTRIBUTES to help debug issues
related to private <=> shared memory conversions
- Drop guest_memfd's .getattr() implementation as the VFS layer will
call generic_fillattr() if inode_operations.getattr is NULL
- Fix issues with dirty ring harvesting where KVM doesn't bound the
processing of entries in any way, which allows userspace to keep
KVM in a tight loop indefinitely
- Kill off kvm_arch_{start,end}_assignment() and x86's associated
tracking, now that KVM no longer uses assigned_device_count as a
heuristic for either irqbypass usage or MDS mitigation
Selftests:
- Fix a comment typo
- Verify KVM is loaded when getting any KVM module param so that
attempting to run a selftest without kvm.ko loaded results in a
SKIP message about KVM not being loaded/enabled (versus some random
parameter not existing)
- Skip tests that hit EACCES when attempting to access a file, and
print a "Root required?" help message. In most cases, the test just
needs to be run with elevated permissions"
* tag 'for-linus' of git://git.kernel.org/pub/scm/virt/kvm/kvm: (340 commits)
Documentation: KVM: Use unordered list for pre-init VGIC registers
RISC-V: KVM: Avoid re-acquiring memslot in kvm_riscv_gstage_map()
RISC-V: KVM: Use find_vma_intersection() to search for intersecting VMAs
RISC-V: perf/kvm: Add reporting of interrupt events
RISC-V: KVM: Enable ring-based dirty memory tracking
RISC-V: KVM: Fix inclusion of Smnpm in the guest ISA bitmap
RISC-V: KVM: Delegate illegal instruction fault to VS mode
RISC-V: KVM: Pass VMID as parameter to kvm_riscv_hfence_xyz() APIs
RISC-V: KVM: Factor-out g-stage page table management
RISC-V: KVM: Add vmid field to struct kvm_riscv_hfence
RISC-V: KVM: Introduce struct kvm_gstage_mapping
RISC-V: KVM: Factor-out MMU related declarations into separate headers
RISC-V: KVM: Use ncsr_xyz() in kvm_riscv_vcpu_trap_redirect()
RISC-V: KVM: Implement kvm_arch_flush_remote_tlbs_range()
RISC-V: KVM: Don't flush TLB when PTE is unchanged
RISC-V: KVM: Replace KVM_REQ_HFENCE_GVMA_VMID_ALL with KVM_REQ_TLB_FLUSH
RISC-V: KVM: Rename and move kvm_riscv_local_tlb_sanitize()
RISC-V: KVM: Drop the return value of kvm_riscv_vcpu_aia_init()
RISC-V: KVM: Check kvm_riscv_vcpu_alloc_vector_context() return value
KVM: arm64: selftests: Add FEAT_RAS EL2 registers to get-reg-list
...
Paolo Abeni says:
====================
virtio: introduce GSO over UDP tunnel
Some virtualized deployments use UDP tunnel pervasively and are impacted
negatively by the lack of GSO support for such kind of traffic in the
virtual NIC driver.
The virtio_net specification recently introduced support for GSO over
UDP tunnel, this series updates the virtio implementation to support
such a feature.
Currently the kernel virtio support limits the feature space to 64,
while the virtio specification allows for a larger number of features.
Specifically the GSO-over-UDP-tunnel-related virtio features use bits
65-69.
The first four patches in this series rework the virtio and vhost
feature support to cope with up to 128 bits. The limit is set by
a define and could be easily raised in future, as needed.
This implementation choice is aimed at keeping the code churn as
limited as possible. For the same reason, only the virtio_net driver is
reworked to leverage the extended feature space; all other
virtio/vhost drivers are unaffected, but could be upgraded to support
the extended features space in a later time.
The last four patches bring in the actual GSO over UDP tunnel support.
As per specification, some additional fields are introduced into the
virtio net header to support the new offload. The presence of such
fields depends on the negotiated features.
New helpers are introduced to convert the UDP-tunneled skb metadata to
an extended virtio net header and vice versa. Such helpers are used by
the tun and virtio_net driver to cope with the newly supported offloads.
Tested with basic stream transfer with all the possible permutations of
host kernel/qemu/guest kernel with/without GSO over UDP tunnel support.
====================
Link: https://patch.msgid.link/cover.1751874094.git.pabeni@redhat.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
Vhost net need to know the exact virtio net hdr size to be able
to copy such header correctly. Teach it about the newly defined
UDP tunnel-related option and update the hdr size computation
accordingly.
Acked-by: Jason Wang <jasowang@redhat.com>
Signed-off-by: Paolo Abeni <pabeni@redhat.com>
Use the extended feature type for 'acked_features' and implement
two new ioctls operation allowing the user-space to set/query an
unbounded amount of features.
The actual number of processed features is limited by VIRTIO_FEATURES_MAX
and attempts to set features above such limit fail with
EOPNOTSUPP.
Note that: the legacy ioctls implicitly truncate the negotiated
features to the lower 64 bits range and the 'acked_backend_features'
field don't need conversion, as the only negotiated feature there
is in the low 64 bit range.
Acked-by: Jason Wang <jasowang@redhat.com>
Signed-off-by: Paolo Abeni <pabeni@redhat.com>
We used to do twice copy_from_iter() to copy virtio-net and packet
separately. This introduce overheads for userspace access hardening as
well as SMAP (for x86 it's stac/clac). So this patch tries to use one
copy_from_iter() to copy them once and move the virtio-net header
afterwards to reduce overheads.
Testpmd + vhost_net shows 10% improvement from 5.45Mpps to 6.0Mpps.
Signed-off-by: Jason Wang <jasowang@redhat.com>
Link: https://patch.msgid.link/20250701010352.74515-2-jasowang@redhat.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
Pass in the Linux IRQ associated with an IRQ bypass producer instead of
relying on the caller to set the field prior to registration, as there's
no benefit to relying on callers to do the right thing.
Take care to set producer->irq before __connect(), as KVM expects the IRQ
to be valid as soon as a connection is possible.
Reviewed-by: Kevin Tian <kevin.tian@intel.com>
Reviewed-by: Alex Williamson <alex.williamson@redhat.com>
Acked-by: Michael S. Tsirkin <mst@redhat.com>
Link: https://lore.kernel.org/r/20250516230734.2564775-9-seanjc@google.com
Signed-off-by: Sean Christopherson <seanjc@google.com>
Move ownership of IRQ bypass token tracking into irqbypass.ko, and
explicitly require callers to pass an eventfd_ctx structure instead of a
completely opaque token. Relying on producers and consumers to set the
token appropriately is error prone, and hiding the fact that the token must
be an eventfd_ctx pointer (for all intents and purposes) unnecessarily
obfuscates the code and makes it more brittle.
Reviewed-by: Kevin Tian <kevin.tian@intel.com>
Acked-by: Michael S. Tsirkin <mst@redhat.com>
Reviewed-by: Alex Williamson <alex.williamson@redhat.com>
Link: https://lore.kernel.org/r/20250516230734.2564775-4-seanjc@google.com
Signed-off-by: Sean Christopherson <seanjc@google.com>
Pull virtio updates from Michael Tsirkin:
- A new virtio RTC driver
- vhost scsi now logs write descriptors so migration works
- Some hardening work in virtio core
- An old spec compliance issue fixed in vhost net
- A couple of cleanups, fixes in vringh, virtio-pci, vdpa
* tag 'for_linus' of git://git.kernel.org/pub/scm/linux/kernel/git/mst/vhost:
virtio: reject shm region if length is zero
virtio_rtc: Add RTC class driver
virtio_rtc: Add Arm Generic Timer cross-timestamping
virtio_rtc: Add PTP clocks
virtio_rtc: Add module and driver core
vringh: use bvec_kmap_local
vhost: vringh: Use matching allocation type in resize_iovec()
virtio-pci: Fix result size returned for the admin command completion
vdpa/octeon_ep: Control PCI dev enabling manually
vhost-scsi: log event queue write descriptors
vhost-scsi: log control queue write descriptors
vhost-scsi: log I/O queue write descriptors
vhost-scsi: adjust vhost_scsi_get_desc() to log vring descriptors
vhost: modify vhost_log_write() for broader users
In preparation for making the kmalloc family of allocators type aware,
we need to make sure that the returned type from the allocation matches
the type of the variable being assigned. (Before, the allocator would
always return "void *", which can be implicitly cast to any pointer type.)
The assigned type is "struct kvec *", but the returned type will be
"struct iovec *". These have the same allocation size, so there is no
bug:
struct kvec {
void *iov_base; /* and that should *never* hold a userland pointer */
size_t iov_len;
};
struct iovec
{
void __user *iov_base; /* BSD uses caddr_t (1003.1g requires void *) */
__kernel_size_t iov_len; /* Must be size_t (1003.1g) */
};
Adjust the allocation type to match the assignment.
Signed-off-by: Kees Cook <kees@kernel.org>
Message-Id: <20250426062214.work.334-kees@kernel.org>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
Log write descriptors for the control queue, leveraging
vhost_scsi_get_desc() and vhost_get_vq_desc() to retrieve the array of
write descriptors to obtain the log buffer.
For Task Management Requests, similar to the I/O queue, store the log
buffer during the submission path and log it in the completion or error
handling path.
For Asynchronous Notifications, only the submission path is involved.
Suggested-by: Joao Martins <joao.m.martins@oracle.com>
Signed-off-by: Dongli Zhang <dongli.zhang@oracle.com>
Message-Id: <20250403063028.16045-8-dongli.zhang@oracle.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
Reviewed-by: Mike Christie <michael.christie@oracle.com>
Log write descriptors for the I/O queue, leveraging vhost_scsi_get_desc()
and vhost_get_vq_desc() to retrieve the array of write descriptors to
obtain the log buffer.
In addition, introduce a vhost-scsi specific function to log vring
descriptors. In this function, the 'partial' argument is set to false, and
the 'len' argument is set to 0, because vhost-scsi always logs all pages
shared by a vring descriptor. Add WARN_ON_ONCE() since vhost-scsi doesn't
support VIRTIO_F_ACCESS_PLATFORM.
The per-cmd log buffer is allocated on demand in the submission path after
VHOST_F_LOG_ALL is set. Return -ENOMEM on allocation failure, in order to
send SAM_STAT_TASK_SET_FULL to the guest.
It isn't reclaimed in the completion path. Instead, it is reclaimed when
VHOST_F_LOG_ALL is removed, or during VHOST_SCSI_SET_ENDPOINT when all
commands are destroyed.
Store the log buffer during the submission path and log it in the
completion path. Logging is also required in the error handling path of the
submission process.
Suggested-by: Joao Martins <joao.m.martins@oracle.com>
Signed-off-by: Dongli Zhang <dongli.zhang@oracle.com>
Message-Id: <20250403063028.16045-7-dongli.zhang@oracle.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
Reviewed-by: Mike Christie <michael.christie@oracle.com>
Adjust vhost_scsi_get_desc() to facilitate logging of vring descriptors.
Add new arguments to allow passing the log buffer and length to
vhost_get_vq_desc().
In addition, reset 'log_num' since vhost_get_vq_desc() may reset it only
after certain condition checks.
Suggested-by: Joao Martins <joao.m.martins@oracle.com>
Signed-off-by: Dongli Zhang <dongli.zhang@oracle.com>
Reviewed-by: Mike Christie <michael.christie@oracle.com>
Message-Id: <20250403063028.16045-6-dongli.zhang@oracle.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
Currently, the only user of vhost_log_write() is vhost-net. The 'len'
argument prevents logging of pages that are not tainted by the RX path.
Adjustments are needed since more drivers (i.e. vhost-scsi) begin using
vhost_log_write(). So far vhost-net RX path may only partially use pages
shared via the last vring descriptor. Unlike vhost-net, vhost-scsi always
logs all pages shared via vring descriptors. To accommodate this,
use (len == U64_MAX) to indicate whether the driver would log all pages of
vring descriptors, or only pages that are tainted by the driver.
In addition, removes BUG().
Suggested-by: Joao Martins <joao.m.martins@oracle.com>
Signed-off-by: Dongli Zhang <dongli.zhang@oracle.com>
Message-Id: <20250403063028.16045-5-dongli.zhang@oracle.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
In handle_tx_copy, TX batching processes packets below ~PAGE_SIZE and
batches up to 64 messages before calling sock->sendmsg.
Currently, when there are no more messages on the ring to dequeue,
handle_tx_copy re-enables kicks on the ring *before* firing off the
batch sendmsg. However, sock->sendmsg incurs a non-zero delay,
especially if it needs to wake up a thread (e.g., another vhost worker).
If the guest submits additional messages immediately after the last ring
check and disablement, it triggers an EPT_MISCONFIG vmexit to attempt to
kick the vhost worker. This may happen while the worker is still
processing the sendmsg, leading to wasteful exit(s).
This is particularly problematic for single-threaded guest submission
threads, as they must exit, wait for the exit to be processed
(potentially involving a TTWU), and then resume.
In scenarios like a constant stream of UDP messages, this results in a
sawtooth pattern where the submitter frequently vmexits, and the
vhost-net worker alternates between sleeping and waking.
A common solution is to configure vhost-net busy polling via userspace
(e.g., qemu poll-us). However, treating the sendmsg as the "busy"
period by keeping kicks disabled during the final sendmsg and
performing one additional ring check afterward provides a significant
performance improvement without any excess busy poll cycles.
If messages are found in the ring after the final sendmsg, requeue the
TX handler. This ensures fairness for the RX handler and allows
vhost_run_work_list to cond_resched() as needed.
Test Case
TX VM: taskset -c 2 iperf3 -c rx-ip-here -t 60 -p 5200 -b 0 -u -i 5
RX VM: taskset -c 2 iperf3 -s -p 5200 -D
6.12.0, each worker backed by tun interface with IFF_NAPI setup.
Note: TCP side is largely unchanged as that was copy bound
6.12.0 unpatched
EPT_MISCONFIG/second: 5411
Datagrams/second: ~382k
Interval Transfer Bitrate Lost/Total Datagrams
0.00-30.00 sec 15.5 GBytes 4.43 Gbits/sec 0/11481630 (0%) sender
6.12.0 patched
EPT_MISCONFIG/second: 58 (~93x reduction)
Datagrams/second: ~650k (~1.7x increase)
Interval Transfer Bitrate Lost/Total Datagrams
0.00-30.00 sec 26.4 GBytes 7.55 Gbits/sec 0/19554720 (0%) sender
Acked-by: Jason Wang <jasowang@redhat.com>
Signed-off-by: Jon Kohler <jon@nutanix.com>
Acked-by: Michael S. Tsirkin <mst@redhat.com>
Link: https://patch.msgid.link/20250501020428.1889162-1-jon@nutanix.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
Although the support of VIRTIO_F_ANY_LAYOUT + VIRTIO_F_VERSION_1 was
signaled by the commit 664ed90e62 ("vhost/scsi: Set
VIRTIO_F_ANY_LAYOUT + VIRTIO_F_VERSION_1 feature bits"),
vhost_scsi_send_bad_target() still assumes the response in a single
descriptor.
Similar issue in vhost_scsi_send_bad_target() has been fixed in previous
commit. In addition, similar issue for vhost_scsi_complete_cmd_work() has
been fixed by the commit 6dd88fd59d ("vhost-scsi: unbreak any layout for
response").
Fixes: 3ca51662f8 ("vhost-scsi: Add better resource allocation failure handling")
Signed-off-by: Dongli Zhang <dongli.zhang@oracle.com>
Acked-by: Jason Wang <jasowang@redhat.com>
Reviewed-by: Mike Christie <michael.christie@oracle.com>
Message-Id: <20250403063028.16045-4-dongli.zhang@oracle.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
