On Thu, 11 Dec 2025, Jiaqi Yan wrote:
> CONFIGs seem alright to me. Do you boot kernel with cmdline options like "default_hugepagesz=1G hugepagesz=1G hugepages=64", or dynamically set up
> huge pages via "echo 64 > /sys/kernel/mm/hugepages/hugepages-1048576kB/nr_hugepages"?
Neither of these. When I do the test is skipped:
# echo 64 > /sys/kernel/mm/hugepages/hugepages-1048576kB/nr_hugepages
# ./arm64/sea_to_user
Random seed: 0x6b8b4567
# Mapped 0x40000 pages: gva=0x80000000 to gpa=0xff80000000
# Before EINJect: data=0xbaadcafe
# EINJ_GVA=0x81234bad, einj_gpa=0xff81234bad, einj_hva=0xffff41234bad,
einj_hpa=0x80241234bad
ok 1 # SKIP EINJ module probably not loaded?sh: line 1:
/sys/kernel/debug/apei/einj/error_type: No such file or directory
Bail out! Failed to write EINJ entry: No such file or directory (2)
# 1 skipped test(s) detected. Consider enabling relevant config options to
improve coverage.
# Planned tests != run tests (0 != 1)
# Totals: pass:0 fail:0 xfail:0 xpass:0 skip:1 error:0
Note: it's net/ only bits and doesn't include changes, which shoulf be
merged separately and are posted separately. The full branch for
convenience is at [1], and the patch is here:
https://lore.kernel.org/io-uring/7486ab32e99be1f614b3ef8d0e9bc77015b173f7.1…
Many modern NICs support configurable receive buffer lengths, and zcrx and
memory providers can use buffers larger than 4K/PAGE_SIZE on x86 to improve
performance. When paired with hw-gro larger rx buffer sizes can drastically
reduce the number of buffers traversing the stack and save a lot of processing
time. It also allows to give to users larger contiguous chunks of data. The
idea was first floated around by Saeed during netdev conf 2024 and was
asked about by a few folks.
Single stream benchmarks showed up to ~30% CPU util improvement.
E.g. comparison for 4K vs 32K buffers using a 200Gbit NIC:
packets=23987040 (MB=2745098), rps=199559 (MB/s=22837)
CPU %usr %nice %sys %iowait %irq %soft %idle
0 1.53 0.00 27.78 2.72 1.31 66.45 0.22
packets=24078368 (MB=2755550), rps=200319 (MB/s=22924)
CPU %usr %nice %sys %iowait %irq %soft %idle
0 0.69 0.00 8.26 31.65 1.83 57.00 0.57
This series adds net infrastructure for memory providers configuring
the size and implements it for bnxt. It's an opt-in feature for drivers,
they should advertise support for the parameter in the qops and must check
if the hardware supports the given size. It's limited to memory providers
as it drastically simplifies implementation. It doesn't affect the fast
path zcrx uAPI, and the sizes is defined in zcrx terms, which allows it
to be flexible and adjusted in the future, see Patch 8 for details.
A liburing example can be found at [2]
full branch:
[1] https://github.com/isilence/linux.git zcrx/large-buffers-v7
Liburing example:
[2] https://github.com/isilence/liburing.git zcrx/rx-buf-len
v7: - Add xa_destroy
- Rebase
v6: - Update docs and add a selftest
v5: https://lore.kernel.org/netdev/cover.1760440268.git.asml.silence@gmail.com/
- Remove all unnecessary bits like configuration via netlink, and
multi-stage queue configuration.
v4: https://lore.kernel.org/all/cover.1760364551.git.asml.silence@gmail.com/
- Update fbnic qops
- Propagate max buf len for hns3
- Use configured buf size in __bnxt_alloc_rx_netmem
- Minor stylistic changes
v3: https://lore.kernel.org/all/cover.1755499375.git.asml.silence@gmail.com/
- Rebased, excluded zcrx specific patches
- Set agg_size_fac to 1 on warning
v2: https://lore.kernel.org/all/cover.1754657711.git.asml.silence@gmail.com/
- Add MAX_PAGE_ORDER check on pp init
- Applied comments rewording
- Adjust pp.max_len based on order
- Patch up mlx5 queue callbacks after rebase
- Minor ->queue_mgmt_ops refactoring
- Rebased to account for both fill level and agg_size_fac
- Pass providers buf length in struct pp_memory_provider_params and
apply it in __netdev_queue_confi().
- Use ->supported_ring_params to validate drivers support of set
qcfg parameters.
Jakub Kicinski (1):
eth: bnxt: adjust the fill level of agg queues with larger buffers
Pavel Begunkov (8):
net: page pool: xa init with destroy on pp init
net: page_pool: sanitise allocation order
net: memzero mp params when closing a queue
net: let pp memory provider to specify rx buf len
eth: bnxt: store rx buffer size per queue
eth: bnxt: allow providers to set rx buf size
io_uring/zcrx: document area chunking parameter
selftests: iou-zcrx: test large chunk sizes
Documentation/networking/iou-zcrx.rst | 20 +++
drivers/net/ethernet/broadcom/bnxt/bnxt.c | 118 ++++++++++++++----
drivers/net/ethernet/broadcom/bnxt/bnxt.h | 2 +
drivers/net/ethernet/broadcom/bnxt/bnxt_xdp.c | 6 +-
drivers/net/ethernet/broadcom/bnxt/bnxt_xdp.h | 2 +-
include/net/netdev_queues.h | 9 ++
include/net/page_pool/types.h | 1 +
net/core/netdev_rx_queue.c | 14 ++-
net/core/page_pool.c | 4 +
.../selftests/drivers/net/hw/iou-zcrx.c | 72 +++++++++--
.../selftests/drivers/net/hw/iou-zcrx.py | 37 ++++++
11 files changed, 236 insertions(+), 49 deletions(-)
--
2.52.0
Problem
=======
When host APEI is unable to claim a synchronous external abort (SEA)
during guest abort, today KVM directly injects an asynchronous SError
into the VCPU then resumes it. The injected SError usually results in
unpleasant guest kernel panic.
One of the major situation of guest SEA is when VCPU consumes recoverable
uncorrected memory error (UER), which is not uncommon at all in modern
datacenter servers with large amounts of physical memory. Although SError
and guest panic is sufficient to stop the propagation of corrupted memory,
there is room to recover from an UER in a more graceful manner.
Proposed Solution
=================
The idea is, we can replay the SEA to the faulting VCPU. If the memory
error consumption or the fault that cause SEA is not from guest kernel,
the blast radius can be limited to the poison-consuming guest process,
while the VM can keep running.
In addition, instead of doing under the hood without involving userspace,
there are benefits to redirect the SEA to VMM:
- VM customers care about the disruptions caused by memory errors, and
VMM usually has the responsibility to start the process of notifying
the customers of memory error events in their VMs. For example some
cloud provider emits a critical log in their observability UI [1], and
provides a playbook for customers on how to mitigate disruptions to
their workloads.
- VMM can protect future memory error consumption by unmapping the poisoned
pages from stage-2 page table with KVM userfault [2], or by splitting the
memslot that contains the poisoned pages.
- VMM can keep track of SEA events in the VM. When VMM thinks the status
on the host or the VM is bad enough, e.g. number of distinct SEAs
exceeds a threshold, it can restart the VM on another healthy host.
- Behavior parity with x86 architecture. When machine check exception
(MCE) is caused by VCPU, kernel or KVM signals userspace SIGBUS to
let VMM either recover from the MCE, or terminate itself with VM.
The prior RFC proposes to implement SIGBUS on arm64 as well, but
Marc preferred KVM exit over signal [3]. However, implementation
aside, returning SEA to VMM is on par with returning MCE to VMM.
Once SEA is redirected to VMM, among other actions, VMM is encouraged
to inject external aborts into the faulting VCPU.
New UAPIs
=========
This patchset introduces following userspace-visible changes to empower
VMM to control what happens for SEA on guest memory:
- KVM_CAP_ARM_SEA_TO_USER. While taking SEA, if userspace has enabled
this new capability at VM creation, and the SEA is not owned by kernel
allocated memory, instead of injecting SError, return KVM_EXIT_ARM_SEA
to userspace.
- KVM_EXIT_ARM_SEA. This is the VM exit reason VMM gets. The details
about the SEA is provided in arm_sea as much as possible, including
sanitized ESR value at EL2, faulting guest virtual and physical
addresses if available.
* From v3 [4]
- Rebased on commit 3a8660878839 ("Linux 6.18-rc1").
- In selftest, print a message if GVA or GPA expects to be valid.
* From v2 [5]:
- Rebased on "[PATCH] KVM: arm64: nv: Handle SEAs due to VNCR redirection" [6]
and kvmarm/next commit 7b8346bd9fce6 ("KVM: arm64: Don't attempt vLPI
mappings when vPE allocation is disabled")
- Took the host_owns_sea implementation from Oliver [7, 8].
- Excluded the guest SEA injection patches.
- Updated selftest.
* From v1 [9]:
- Rebased on commit 4d62121ce9b5 ("KVM: arm64: vgic-debug: Avoid
dereferencing NULL ITE pointer").
- Sanitize ESR_EL2 before reporting it to userspace.
- Do not do KVM_EXIT_ARM_SEA when SEA is caused by memory allocated to
stage-2 translation table.
[1] https://cloud.google.com/solutions/sap/docs/manage-host-errors
[2] https://lore.kernel.org/kvm/20250109204929.1106563-1-jthoughton@google.com
[3] https://lore.kernel.org/kvm/86pljbqqh0.wl-maz@kernel.org
[4] https://lore.kernel.org/kvmarm/20250731205844.1346839-1-jiaqiyan@google.com
[5] https://lore.kernel.org/kvm/20250604050902.3944054-1-jiaqiyan@google.com
[6] https://lore.kernel.org/kvmarm/20250729182342.3281742-1-oliver.upton@linux.…
[7] https://lore.kernel.org/kvm/aHFohmTb9qR_JG1E@linux.dev
[8] https://lore.kernel.org/kvm/aHK-DPufhLy5Dtuk@linux.dev
[9] https://lore.kernel.org/kvm/20250505161412.1926643-1-jiaqiyan@google.com
Jiaqi Yan (3):
KVM: arm64: VM exit to userspace to handle SEA
KVM: selftests: Test for KVM_EXIT_ARM_SEA
Documentation: kvm: new UAPI for handling SEA
Documentation/virt/kvm/api.rst | 61 ++++
arch/arm64/include/asm/kvm_host.h | 2 +
arch/arm64/kvm/arm.c | 5 +
arch/arm64/kvm/mmu.c | 68 +++-
include/uapi/linux/kvm.h | 10 +
tools/arch/arm64/include/asm/esr.h | 2 +
tools/testing/selftests/kvm/Makefile.kvm | 1 +
.../testing/selftests/kvm/arm64/sea_to_user.c | 331 ++++++++++++++++++
tools/testing/selftests/kvm/lib/kvm_util.c | 1 +
9 files changed, 480 insertions(+), 1 deletion(-)
create mode 100644 tools/testing/selftests/kvm/arm64/sea_to_user.c
--
2.51.0.760.g7b8bcc2412-goog
The resctrl selftest currently exhibits several failures on Hygon CPUs
due to missing vendor detection and edge-case handling specific to
Hygon's architecture.
This patch series addresses three distinct issues:
1. Missing CPU vendor detection, causing the test to fail with
"# Can not get vendor info..." on Hygon CPUs.
2. A division-by-zero crash in SNC detection on Hygon CPUs.
3. Incorrect handling of non-contiguous CBM support on Hygon CPUs.
These changes enable resctrl selftest to run successfully on
Hygon CPUs that support Platform QoS features.
Changelog:
v3:
- Patch 1:
1. Update the return types of detect_vendor() and get_vendor() from
'int' to 'unsigned int' to align with their usage as bitmask values
and to prevent potentially risky type conversions (Fenghua).
2. Split the code changes of "define CPU vendor IDs as bits to match
usage" from original patch 1 into a separate patch (this patch,
suggested by Fenghua and Reinette).
3. Introduce the flag 'initialized' to simplify the get_vendor() ->
detect_vendor() logic (Reinette).
- Patch 2 (original patch 1):
1. Move the code changes of "define CPU vendor IDs as bits to match
usage" into patch 1.
- Patch 3 (original patch 2):
1. Fix a nit of code comment for affected platforms (Fenghua).
2. Add Reviewed-by: Fenghua Yu <fenghuay(a)nvidia.com>.
- Patch 4 (original patch 3):
1. Fix a nit to avoid calling get_vendor() twice (Fenghua).
2. Add Reviewed-by: Fenghua Yu <fenghuay(a)nvidia.com>.
v2:
- Patch 1: switch all of the vendor id bitmasks to use BIT() (Reinette)
- Patch 2: add Reviewed-by: Reinette Chatre <reinette.chatre(a)intel.com>
- Patch 3: add Reviewed-by: Reinette Chatre <reinette.chatre(a)intel.com>
add a maintainer note to highlight it is not a candidate for
backport (Reinette)
Xiaochen Shen (4):
selftests/resctrl: Define CPU vendor IDs as bits to match usage
selftests/resctrl: Add CPU vendor detection for Hygon
selftests/resctrl: Fix a division by zero error on Hygon
selftests/resctrl: Fix non-contiguous CBM check for Hygon
tools/testing/selftests/resctrl/cat_test.c | 6 ++--
tools/testing/selftests/resctrl/resctrl.h | 8 ++++--
.../testing/selftests/resctrl/resctrl_tests.c | 28 +++++++++++++------
tools/testing/selftests/resctrl/resctrlfs.c | 10 +++++++
4 files changed, 39 insertions(+), 13 deletions(-)
--
2.47.3
This is a follow-up series of [1]. It tries to fix a possible UAF in the
fops of cros_ec_chardev after the underlying protocol device has gone by
using revocable.
The 1st patch introduces the revocable which is an implementation of ideas
from the talk [2].
The 2nd and 3rd patches add test cases for revocable in Kunit and selftest.
The 4th patch converts existing protocol devices to resource providers
of cros_ec_device.
The 5th - 7th are PoC patches for showing the use case of "Replace file
operations" below.
---
I came out with 2 possible usages of revocable.
1. Use primitive APIs
Use the primitive APIs of revocable directly.
The file operations make sure the resources are available when using them.
This is what the series original proposed[3][4]. Even though it has the
finest grain for accessing the resources, it makes the user code verbose.
Per feedback from the community, I'm looking for some subsystem level
helpers so that user code can be simlper.
2. Replace file operations
Replace filp->f_op to revocable-aware warppers.
The warppers make sure the resources are available in the file operations.
The user code needs to provide a callback .try_access() to tell the wrappers
where/how to *save* the pointers of resources.
Known drawback:
- The warppers reserve the resources for all file operations even if they
might be unused.
- The user code still needs to be revocable-aware.
- The whole file operation becomes a SRCU read-side critical section. Are
there any functions can't be called in the critical section? If there is,
the file operations may not be awared of that.
See 5th - 7th patches for an example usage.
[1] https://lore.kernel.org/chrome-platform/20250721044456.2736300-6-tzungbi@ke…
[2] https://lpc.events/event/17/contributions/1627/
[3] https://lore.kernel.org/chrome-platform/20250912081718.3827390-5-tzungbi@ke…
[4] https://lore.kernel.org/chrome-platform/20250912081718.3827390-6-tzungbi@ke…
v5:
- Rebase onto next-20251015.
- Add more context about the PoC.
- Support multiple revocable providers in the PoC.
v4: https://lore.kernel.org/chrome-platform/20250923075302.591026-1-tzungbi@ker…
- Rebase onto next-20250922.
- Remove the 5th patch from v3.
- Add fops replacement PoC in 5th - 7th patches.
v3: https://lore.kernel.org/chrome-platform/20250912081718.3827390-1-tzungbi@ke…
- Rebase onto https://lore.kernel.org/chrome-platform/20250828083601.856083-1-tzungbi@ker…
and next-20250912.
- The 4th patch changed accordingly.
v2: https://lore.kernel.org/chrome-platform/20250820081645.847919-1-tzungbi@ker…
- Rename "ref_proxy" -> "revocable".
- Add test cases in Kunit and selftest.
v1: https://lore.kernel.org/chrome-platform/20250814091020.1302888-1-tzungbi@ke…
Tzung-Bi Shih (7):
revocable: Revocable resource management
revocable: Add Kunit test cases
selftests: revocable: Add kselftest cases
platform/chrome: Protect cros_ec_device lifecycle with revocable
revocable: Add fops replacement
char: misc: Leverage revocable fops replacement
platform/chrome: cros_ec_chardev: Secure cros_ec_device via revocable
.../driver-api/driver-model/index.rst | 1 +
.../driver-api/driver-model/revocable.rst | 87 +++++++
MAINTAINERS | 9 +
drivers/base/Kconfig | 8 +
drivers/base/Makefile | 5 +-
drivers/base/revocable.c | 233 ++++++++++++++++++
drivers/base/revocable_test.c | 110 +++++++++
drivers/char/misc.c | 8 +
drivers/platform/chrome/cros_ec.c | 5 +
drivers/platform/chrome/cros_ec_chardev.c | 22 +-
fs/Makefile | 2 +-
fs/fs_revocable.c | 154 ++++++++++++
include/linux/fs.h | 2 +
include/linux/fs_revocable.h | 21 ++
include/linux/miscdevice.h | 4 +
include/linux/platform_data/cros_ec_proto.h | 4 +
include/linux/revocable.h | 53 ++++
tools/testing/selftests/Makefile | 1 +
.../selftests/drivers/base/revocable/Makefile | 7 +
.../drivers/base/revocable/revocable_test.c | 116 +++++++++
.../drivers/base/revocable/test-revocable.sh | 39 +++
.../base/revocable/test_modules/Makefile | 10 +
.../revocable/test_modules/revocable_test.c | 188 ++++++++++++++
23 files changed, 1086 insertions(+), 3 deletions(-)
create mode 100644 Documentation/driver-api/driver-model/revocable.rst
create mode 100644 drivers/base/revocable.c
create mode 100644 drivers/base/revocable_test.c
create mode 100644 fs/fs_revocable.c
create mode 100644 include/linux/fs_revocable.h
create mode 100644 include/linux/revocable.h
create mode 100644 tools/testing/selftests/drivers/base/revocable/Makefile
create mode 100644 tools/testing/selftests/drivers/base/revocable/revocable_test.c
create mode 100755 tools/testing/selftests/drivers/base/revocable/test-revocable.sh
create mode 100644 tools/testing/selftests/drivers/base/revocable/test_modules/Makefile
create mode 100644 tools/testing/selftests/drivers/base/revocable/test_modules/revocable_test.c
--
2.51.0.788.g6d19910ace-goog
The get_hw_info uses a smaller user buffer on purpose to check how
the kernel updates only the fields that fit in the buffer. The test
created a custom smaller struct for this, but the helper function later
treats the buffer as struct iommu_test_hw_info. This makes the compiler
warn about a possible out-of-bounds access (-Warray-bounds).
This keeps the test behavior the same and removes the warning.
Signed-off-by: Kathara Sasikumar <katharasasikumar007(a)gmail.com>
---
tools/testing/selftests/iommu/iommufd.c | 4 +---
1 file changed, 1 insertion(+), 3 deletions(-)
diff --git a/tools/testing/selftests/iommu/iommufd.c b/tools/testing/selftests/iommu/iommufd.c
index 10e051b6f592..f6aceb65313f 100644
--- a/tools/testing/selftests/iommu/iommufd.c
+++ b/tools/testing/selftests/iommu/iommufd.c
@@ -755,9 +755,7 @@ TEST_F(iommufd_ioas, get_hw_info)
struct iommu_test_hw_info info;
uint64_t trailing_bytes;
} buffer_larger;
- struct iommu_test_hw_info_buffer_smaller {
- __u32 flags;
- } buffer_smaller;
+ struct iommu_test_hw_info buffer_smaller;
if (self->device_id) {
uint8_t max_pasid = 0;
--
2.51.0