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authorLibravatar Linus Torvalds <torvalds@linux-foundation.org>2023-02-21 18:24:12 -0800
committerLibravatar Linus Torvalds <torvalds@linux-foundation.org>2023-02-21 18:24:12 -0800
commit5b7c4cabbb65f5c469464da6c5f614cbd7f730f2 (patch)
treecc5c2d0a898769fd59549594fedb3ee6f84e59a0 /tools/testing/selftests/kvm/rseq_test.c
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Merge tag 'net-next-6.3' of git://git.kernel.org/pub/scm/linux/kernel/git/netdev/net-nextgrafted
Pull networking updates from Jakub Kicinski: "Core: - Add dedicated kmem_cache for typical/small skb->head, avoid having to access struct page at kfree time, and improve memory use. - Introduce sysctl to set default RPS configuration for new netdevs. - Define Netlink protocol specification format which can be used to describe messages used by each family and auto-generate parsers. Add tools for generating kernel data structures and uAPI headers. - Expose all net/core sysctls inside netns. - Remove 4s sleep in netpoll if carrier is instantly detected on boot. - Add configurable limit of MDB entries per port, and port-vlan. - Continue populating drop reasons throughout the stack. - Retire a handful of legacy Qdiscs and classifiers. Protocols: - Support IPv4 big TCP (TSO frames larger than 64kB). - Add IP_LOCAL_PORT_RANGE socket option, to control local port range on socket by socket basis. - Track and report in procfs number of MPTCP sockets used. - Support mixing IPv4 and IPv6 flows in the in-kernel MPTCP path manager. - IPv6: don't check net.ipv6.route.max_size and rely on garbage collection to free memory (similarly to IPv4). - Support Penultimate Segment Pop (PSP) flavor in SRv6 (RFC8986). - ICMP: add per-rate limit counters. - Add support for user scanning requests in ieee802154. - Remove static WEP support. - Support minimal Wi-Fi 7 Extremely High Throughput (EHT) rate reporting. - WiFi 7 EHT channel puncturing support (client & AP). BPF: - Add a rbtree data structure following the "next-gen data structure" precedent set by recently added linked list, that is, by using kfunc + kptr instead of adding a new BPF map type. - Expose XDP hints via kfuncs with initial support for RX hash and timestamp metadata. - Add BPF_F_NO_TUNNEL_KEY extension to bpf_skb_set_tunnel_key to better support decap on GRE tunnel devices not operating in collect metadata. - Improve x86 JIT's codegen for PROBE_MEM runtime error checks. - Remove the need for trace_printk_lock for bpf_trace_printk and bpf_trace_vprintk helpers. - Extend libbpf's bpf_tracing.h support for tracing arguments of kprobes/uprobes and syscall as a special case. - Significantly reduce the search time for module symbols by livepatch and BPF. - Enable cpumasks to be used as kptrs, which is useful for tracing programs tracking which tasks end up running on which CPUs in different time intervals. - Add support for BPF trampoline on s390x and riscv64. - Add capability to export the XDP features supported by the NIC. - Add __bpf_kfunc tag for marking kernel functions as kfuncs. - Add cgroup.memory=nobpf kernel parameter option to disable BPF memory accounting for container environments. Netfilter: - Remove the CLUSTERIP target. It has been marked as obsolete for years, and we still have WARN splats wrt races of the out-of-band /proc interface installed by this target. - Add 'destroy' commands to nf_tables. They are identical to the existing 'delete' commands, but do not return an error if the referenced object (set, chain, rule...) did not exist. Driver API: - Improve cpumask_local_spread() locality to help NICs set the right IRQ affinity on AMD platforms. - Separate C22 and C45 MDIO bus transactions more clearly. - Introduce new DCB table to control DSCP rewrite on egress. - Support configuration of Physical Layer Collision Avoidance (PLCA) Reconciliation Sublayer (RS) (802.3cg-2019). Modern version of shared medium Ethernet. - Support for MAC Merge layer (IEEE 802.3-2018 clause 99). Allowing preemption of low priority frames by high priority frames. - Add support for controlling MACSec offload using netlink SET. - Rework devlink instance refcounts to allow registration and de-registration under the instance lock. Split the code into multiple files, drop some of the unnecessarily granular locks and factor out common parts of netlink operation handling. - Add TX frame aggregation parameters (for USB drivers). - Add a new attr TCA_EXT_WARN_MSG to report TC (offload) warning messages with notifications for debug. - Allow offloading of UDP NEW connections via act_ct. - Add support for per action HW stats in TC. - Support hardware miss to TC action (continue processing in SW from a specific point in the action chain). - Warn if old Wireless Extension user space interface is used with modern cfg80211/mac80211 drivers. Do not support Wireless Extensions for Wi-Fi 7 devices at all. Everyone should switch to using nl80211 interface instead. - Improve the CAN bit timing configuration. Use extack to return error messages directly to user space, update the SJW handling, including the definition of a new default value that will benefit CAN-FD controllers, by increasing their oscillator tolerance. New hardware / drivers: - Ethernet: - nVidia BlueField-3 support (control traffic driver) - Ethernet support for imx93 SoCs - Motorcomm yt8531 gigabit Ethernet PHY - onsemi NCN26000 10BASE-T1S PHY (with support for PLCA) - Microchip LAN8841 PHY (incl. cable diagnostics and PTP) - Amlogic gxl MDIO mux - WiFi: - RealTek RTL8188EU (rtl8xxxu) - Qualcomm Wi-Fi 7 devices (ath12k) - CAN: - Renesas R-Car V4H Drivers: - Bluetooth: - Set Per Platform Antenna Gain (PPAG) for Intel controllers. - Ethernet NICs: - Intel (1G, igc): - support TSN / Qbv / packet scheduling features of i226 model - Intel (100G, ice): - use GNSS subsystem instead of TTY - multi-buffer XDP support - extend support for GPIO pins to E823 devices - nVidia/Mellanox: - update the shared buffer configuration on PFC commands - implement PTP adjphase function for HW offset control - TC support for Geneve and GRE with VF tunnel offload - more efficient crypto key management method - multi-port eswitch support - Netronome/Corigine: - add DCB IEEE support - support IPsec offloading for NFP3800 - Freescale/NXP (enetc): - support XDP_REDIRECT for XDP non-linear buffers - improve reconfig, avoid link flap and waiting for idle - support MAC Merge layer - Other NICs: - sfc/ef100: add basic devlink support for ef100 - ionic: rx_push mode operation (writing descriptors via MMIO) - bnxt: use the auxiliary bus abstraction for RDMA - r8169: disable ASPM and reset bus in case of tx timeout - cpsw: support QSGMII mode for J721e CPSW9G - cpts: support pulse-per-second output - ngbe: add an mdio bus driver - usbnet: optimize usbnet_bh() by avoiding unnecessary queuing - r8152: handle devices with FW with NCM support - amd-xgbe: support 10Mbps, 2.5GbE speeds and rx-adaptation - virtio-net: support multi buffer XDP - virtio/vsock: replace virtio_vsock_pkt with sk_buff - tsnep: XDP support - Ethernet high-speed switches: - nVidia/Mellanox (mlxsw): - add support for latency TLV (in FW control messages) - Microchip (sparx5): - separate explicit and implicit traffic forwarding rules, make the implicit rules always active - add support for egress DSCP rewrite - IS0 VCAP support (Ingress Classification) - IS2 VCAP filters (protos, L3 addrs, L4 ports, flags, ToS etc.) - ES2 VCAP support (Egress Access Control) - support for Per-Stream Filtering and Policing (802.1Q, 8.6.5.1) - Ethernet embedded switches: - Marvell (mv88e6xxx): - add MAB (port auth) offload support - enable PTP receive for mv88e6390 - NXP (ocelot): - support MAC Merge layer - support for the the vsc7512 internal copper phys - Microchip: - lan9303: convert to PHYLINK - lan966x: support TC flower filter statistics - lan937x: PTP support for KSZ9563/KSZ8563 and LAN937x - lan937x: support Credit Based Shaper configuration - ksz9477: support Energy Efficient Ethernet - other: - qca8k: convert to regmap read/write API, use bulk operations - rswitch: Improve TX timestamp accuracy - Intel WiFi (iwlwifi): - EHT (Wi-Fi 7) rate reporting - STEP equalizer support: transfer some STEP (connection to radio on platforms with integrated wifi) related parameters from the BIOS to the firmware. - Qualcomm 802.11ax WiFi (ath11k): - IPQ5018 support - Fine Timing Measurement (FTM) responder role support - channel 177 support - MediaTek WiFi (mt76): - per-PHY LED support - mt7996: EHT (Wi-Fi 7) support - Wireless Ethernet Dispatch (WED) reset support - switch to using page pool allocator - RealTek WiFi (rtw89): - support new version of Bluetooth co-existance - Mobile: - rmnet: support TX aggregation" * tag 'net-next-6.3' of git://git.kernel.org/pub/scm/linux/kernel/git/netdev/net-next: (1872 commits) page_pool: add a comment explaining the fragment counter usage net: ethtool: fix __ethtool_dev_mm_supported() implementation ethtool: pse-pd: Fix double word in comments xsk: add linux/vmalloc.h to xsk.c sefltests: netdevsim: wait for devlink instance after netns removal selftest: fib_tests: Always cleanup before exit net/mlx5e: Align IPsec ASO result memory to be as required by hardware net/mlx5e: TC, Set CT miss to the specific ct action instance net/mlx5e: Rename CHAIN_TO_REG to MAPPED_OBJ_TO_REG net/mlx5: Refactor tc miss handling to a single function net/mlx5: Kconfig: Make tc offload depend on tc skb extension net/sched: flower: Support hardware miss to tc action net/sched: flower: Move filter handle initialization earlier net/sched: cls_api: Support hardware miss to tc action net/sched: Rename user cookie and act cookie sfc: fix builds without CONFIG_RTC_LIB sfc: clean up some inconsistent indentings net/mlx4_en: Introduce flexible array to silence overflow warning net: lan966x: Fix possible deadlock inside PTP net/ulp: Remove redundant ->clone() test in inet_clone_ulp(). ...
Diffstat (limited to '')
-rw-r--r--tools/testing/selftests/kvm/rseq_test.c268
1 files changed, 268 insertions, 0 deletions
diff --git a/tools/testing/selftests/kvm/rseq_test.c b/tools/testing/selftests/kvm/rseq_test.c
new file mode 100644
index 000000000..f74e76d03
--- /dev/null
+++ b/tools/testing/selftests/kvm/rseq_test.c
@@ -0,0 +1,268 @@
+// SPDX-License-Identifier: GPL-2.0-only
+#define _GNU_SOURCE /* for program_invocation_short_name */
+#include <errno.h>
+#include <fcntl.h>
+#include <pthread.h>
+#include <sched.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <signal.h>
+#include <syscall.h>
+#include <sys/ioctl.h>
+#include <sys/sysinfo.h>
+#include <asm/barrier.h>
+#include <linux/atomic.h>
+#include <linux/rseq.h>
+#include <linux/unistd.h>
+
+#include "kvm_util.h"
+#include "processor.h"
+#include "test_util.h"
+
+#include "../rseq/rseq.c"
+
+/*
+ * Any bug related to task migration is likely to be timing-dependent; perform
+ * a large number of migrations to reduce the odds of a false negative.
+ */
+#define NR_TASK_MIGRATIONS 100000
+
+static pthread_t migration_thread;
+static cpu_set_t possible_mask;
+static int min_cpu, max_cpu;
+static bool done;
+
+static atomic_t seq_cnt;
+
+static void guest_code(void)
+{
+ for (;;)
+ GUEST_SYNC(0);
+}
+
+static int next_cpu(int cpu)
+{
+ /*
+ * Advance to the next CPU, skipping those that weren't in the original
+ * affinity set. Sadly, there is no CPU_SET_FOR_EACH, and cpu_set_t's
+ * data storage is considered as opaque. Note, if this task is pinned
+ * to a small set of discontigous CPUs, e.g. 2 and 1023, this loop will
+ * burn a lot cycles and the test will take longer than normal to
+ * complete.
+ */
+ do {
+ cpu++;
+ if (cpu > max_cpu) {
+ cpu = min_cpu;
+ TEST_ASSERT(CPU_ISSET(cpu, &possible_mask),
+ "Min CPU = %d must always be usable", cpu);
+ break;
+ }
+ } while (!CPU_ISSET(cpu, &possible_mask));
+
+ return cpu;
+}
+
+static void *migration_worker(void *__rseq_tid)
+{
+ pid_t rseq_tid = (pid_t)(unsigned long)__rseq_tid;
+ cpu_set_t allowed_mask;
+ int r, i, cpu;
+
+ CPU_ZERO(&allowed_mask);
+
+ for (i = 0, cpu = min_cpu; i < NR_TASK_MIGRATIONS; i++, cpu = next_cpu(cpu)) {
+ CPU_SET(cpu, &allowed_mask);
+
+ /*
+ * Bump the sequence count twice to allow the reader to detect
+ * that a migration may have occurred in between rseq and sched
+ * CPU ID reads. An odd sequence count indicates a migration
+ * is in-progress, while a completely different count indicates
+ * a migration occurred since the count was last read.
+ */
+ atomic_inc(&seq_cnt);
+
+ /*
+ * Ensure the odd count is visible while getcpu() isn't
+ * stable, i.e. while changing affinity is in-progress.
+ */
+ smp_wmb();
+ r = sched_setaffinity(rseq_tid, sizeof(allowed_mask), &allowed_mask);
+ TEST_ASSERT(!r, "sched_setaffinity failed, errno = %d (%s)",
+ errno, strerror(errno));
+ smp_wmb();
+ atomic_inc(&seq_cnt);
+
+ CPU_CLR(cpu, &allowed_mask);
+
+ /*
+ * Wait 1-10us before proceeding to the next iteration and more
+ * specifically, before bumping seq_cnt again. A delay is
+ * needed on three fronts:
+ *
+ * 1. To allow sched_setaffinity() to prompt migration before
+ * ioctl(KVM_RUN) enters the guest so that TIF_NOTIFY_RESUME
+ * (or TIF_NEED_RESCHED, which indirectly leads to handling
+ * NOTIFY_RESUME) is handled in KVM context.
+ *
+ * If NOTIFY_RESUME/NEED_RESCHED is set after KVM enters
+ * the guest, the guest will trigger a IO/MMIO exit all the
+ * way to userspace and the TIF flags will be handled by
+ * the generic "exit to userspace" logic, not by KVM. The
+ * exit to userspace is necessary to give the test a chance
+ * to check the rseq CPU ID (see #2).
+ *
+ * Alternatively, guest_code() could include an instruction
+ * to trigger an exit that is handled by KVM, but any such
+ * exit requires architecture specific code.
+ *
+ * 2. To let ioctl(KVM_RUN) make its way back to the test
+ * before the next round of migration. The test's check on
+ * the rseq CPU ID must wait for migration to complete in
+ * order to avoid false positive, thus any kernel rseq bug
+ * will be missed if the next migration starts before the
+ * check completes.
+ *
+ * 3. To ensure the read-side makes efficient forward progress,
+ * e.g. if getcpu() involves a syscall. Stalling the read-side
+ * means the test will spend more time waiting for getcpu()
+ * to stabilize and less time trying to hit the timing-dependent
+ * bug.
+ *
+ * Because any bug in this area is likely to be timing-dependent,
+ * run with a range of delays at 1us intervals from 1us to 10us
+ * as a best effort to avoid tuning the test to the point where
+ * it can hit _only_ the original bug and not detect future
+ * regressions.
+ *
+ * The original bug can reproduce with a delay up to ~500us on
+ * x86-64, but starts to require more iterations to reproduce
+ * as the delay creeps above ~10us, and the average runtime of
+ * each iteration obviously increases as well. Cap the delay
+ * at 10us to keep test runtime reasonable while minimizing
+ * potential coverage loss.
+ *
+ * The lower bound for reproducing the bug is likely below 1us,
+ * e.g. failures occur on x86-64 with nanosleep(0), but at that
+ * point the overhead of the syscall likely dominates the delay.
+ * Use usleep() for simplicity and to avoid unnecessary kernel
+ * dependencies.
+ */
+ usleep((i % 10) + 1);
+ }
+ done = true;
+ return NULL;
+}
+
+static void calc_min_max_cpu(void)
+{
+ int i, cnt, nproc;
+
+ TEST_REQUIRE(CPU_COUNT(&possible_mask) >= 2);
+
+ /*
+ * CPU_SET doesn't provide a FOR_EACH helper, get the min/max CPU that
+ * this task is affined to in order to reduce the time spent querying
+ * unusable CPUs, e.g. if this task is pinned to a small percentage of
+ * total CPUs.
+ */
+ nproc = get_nprocs_conf();
+ min_cpu = -1;
+ max_cpu = -1;
+ cnt = 0;
+
+ for (i = 0; i < nproc; i++) {
+ if (!CPU_ISSET(i, &possible_mask))
+ continue;
+ if (min_cpu == -1)
+ min_cpu = i;
+ max_cpu = i;
+ cnt++;
+ }
+
+ __TEST_REQUIRE(cnt >= 2,
+ "Only one usable CPU, task migration not possible");
+}
+
+int main(int argc, char *argv[])
+{
+ int r, i, snapshot;
+ struct kvm_vm *vm;
+ struct kvm_vcpu *vcpu;
+ u32 cpu, rseq_cpu;
+
+ r = sched_getaffinity(0, sizeof(possible_mask), &possible_mask);
+ TEST_ASSERT(!r, "sched_getaffinity failed, errno = %d (%s)", errno,
+ strerror(errno));
+
+ calc_min_max_cpu();
+
+ r = rseq_register_current_thread();
+ TEST_ASSERT(!r, "rseq_register_current_thread failed, errno = %d (%s)",
+ errno, strerror(errno));
+
+ /*
+ * Create and run a dummy VM that immediately exits to userspace via
+ * GUEST_SYNC, while concurrently migrating the process by setting its
+ * CPU affinity.
+ */
+ vm = vm_create_with_one_vcpu(&vcpu, guest_code);
+
+ pthread_create(&migration_thread, NULL, migration_worker,
+ (void *)(unsigned long)syscall(SYS_gettid));
+
+ for (i = 0; !done; i++) {
+ vcpu_run(vcpu);
+ TEST_ASSERT(get_ucall(vcpu, NULL) == UCALL_SYNC,
+ "Guest failed?");
+
+ /*
+ * Verify rseq's CPU matches sched's CPU. Ensure migration
+ * doesn't occur between getcpu() and reading the rseq cpu_id
+ * by rereading both if the sequence count changes, or if the
+ * count is odd (migration in-progress).
+ */
+ do {
+ /*
+ * Drop bit 0 to force a mismatch if the count is odd,
+ * i.e. if a migration is in-progress.
+ */
+ snapshot = atomic_read(&seq_cnt) & ~1;
+
+ /*
+ * Ensure calling getcpu() and reading rseq.cpu_id complete
+ * in a single "no migration" window, i.e. are not reordered
+ * across the seq_cnt reads.
+ */
+ smp_rmb();
+ r = sys_getcpu(&cpu, NULL);
+ TEST_ASSERT(!r, "getcpu failed, errno = %d (%s)",
+ errno, strerror(errno));
+ rseq_cpu = rseq_current_cpu_raw();
+ smp_rmb();
+ } while (snapshot != atomic_read(&seq_cnt));
+
+ TEST_ASSERT(rseq_cpu == cpu,
+ "rseq CPU = %d, sched CPU = %d\n", rseq_cpu, cpu);
+ }
+
+ /*
+ * Sanity check that the test was able to enter the guest a reasonable
+ * number of times, e.g. didn't get stalled too often/long waiting for
+ * getcpu() to stabilize. A 2:1 migration:KVM_RUN ratio is a fairly
+ * conservative ratio on x86-64, which can do _more_ KVM_RUNs than
+ * migrations given the 1us+ delay in the migration task.
+ */
+ TEST_ASSERT(i > (NR_TASK_MIGRATIONS / 2),
+ "Only performed %d KVM_RUNs, task stalled too much?\n", i);
+
+ pthread_join(migration_thread, NULL);
+
+ kvm_vm_free(vm);
+
+ rseq_unregister_current_thread();
+
+ return 0;
+}