kernel/tools/testing/selftests/kvm/lib/userfaultfd_util.c, branch linux-rolling-stable

KVM: selftests: Fix spelling mistake "UFFDIO_CONINUE" -> "UFFDIO_CONTINUE"

2025-02-28T17:12:52Z

There is a spelling mistake in a PER_PAGE_DEBUG debug message. Fix it. Signed-off-by: Colin Ian King Link: https://lore.kernel.org/r/20250227220819.656780-1-colin.i.king@gmail.com Signed-off-by: Sean Christopherson

Merge tag 'kvm-x86-selftests_utils-6.10' of https://github.com/kvm-x86/linux into HEAD

2024-05-12T07:18:11Z

KVM selftests treewide updates for 6.10: - Define _GNU_SOURCE for all selftests to fix a warning that was introduced by a change to kselftest_harness.h late in the 6.9 cycle, and because forcing every test to #define _GNU_SOURCE is painful. - Provide a global psuedo-RNG instance for all tests, so that library code can generate random, but determinstic numbers. - Use the global pRNG to randomly force emulation of select writes from guest code on x86, e.g. to help validate KVM's emulation of locked accesses. - Rename kvm_util_base.h back to kvm_util.h, as the weird layer of indirection was added purely to avoid manually #including ucall_common.h in a handful of locations. - Allocate and initialize x86's GDT, IDT, TSS, segments, and default exception handlers at VM creation, instead of forcing tests to manually trigger the related setup.

KVM: selftests: Define _GNU_SOURCE for all selftests code

2024-04-29T19:49:10Z

Define _GNU_SOURCE is the base CFLAGS instead of relying on selftests to manually #define _GNU_SOURCE, which is repetitive and error prone. E.g. kselftest_harness.h requires _GNU_SOURCE for asprintf(), but if a selftest includes kvm_test_harness.h after stdio.h, the include guards result in the effective version of stdio.h consumed by kvm_test_harness.h not defining asprintf(): In file included from x86_64/fix_hypercall_test.c:12: In file included from include/kvm_test_harness.h:11: ../kselftest_harness.h:1169:2: error: call to undeclared function 'asprintf'; ISO C99 and later do not support implicit function declarations [-Wimplicit-function-declaration] 1169 | asprintf(&test_name, "%s%s%s.%s", f->name, | ^ When including the rseq selftest's "library" code, #undef _GNU_SOURCE so that rseq.c controls whether or not it wants to build with _GNU_SOURCE. Reported-by: Muhammad Usama Anjum Acked-by: Claudio Imbrenda Acked-by: Oliver Upton Acked-by: Anup Patel Reviewed-by: Muhammad Usama Anjum Link: https://lore.kernel.org/r/20240423190308.2883084-1-seanjc@google.com Signed-off-by: Sean Christopherson

KVM: selftests: Use EPOLL in userfaultfd_util reader threads

2024-04-09T21:30:14Z

With multiple reader threads POLLing a single UFFD, the demand paging test suffers from the thundering herd problem: performance degrades as the number of reader threads is increased. Solve this issue [1] by switching the the polling mechanism to EPOLL + EPOLLEXCLUSIVE. Also, change the error-handling convention of uffd_handler_thread_fn. Instead of just printing errors and returning early from the polling loop, check for them via TEST_ASSERT(). "return NULL" is reserved for a successful exit from uffd_handler_thread_fn, i.e. one triggered by a write to the exit pipe. Performance samples generated by the command in [2] are given below. Num Reader Threads, Paging Rate (POLL), Paging Rate (EPOLL) 1 249k 185k 2 201k 235k 4 186k 155k 16 150k 217k 32 89k 198k [1] Single-vCPU performance does suffer somewhat. [2] ./demand_paging_test -u MINOR -s shmem -v 4 -o -r Signed-off-by: Anish Moorthy Acked-by: James Houghton Link: https://lore.kernel.org/r/20240215235405.368539-13-amoorthy@google.com Signed-off-by: Sean Christopherson

KVM: selftests: Allow many vCPUs and reader threads per UFFD in demand paging test

2024-04-09T21:28:53Z

At the moment, demand_paging_test does not support profiling/testing multiple vCPU threads concurrently faulting on a single uffd because (a) "-u" (run test in userfaultfd mode) creates a uffd for each vCPU's region, so that each uffd services a single vCPU thread. (b) "-u -o" (userfaultfd mode + overlapped vCPU memory accesses) simply doesn't work: the test tries to register the same memory to multiple uffds, causing an error. Add support for many vcpus per uffd by (1) Keeping "-u" behavior unchanged. (2) Making "-u -a" create a single uffd for all of guest memory. (3) Making "-u -o" implicitly pass "-a", solving the problem in (b). In cases (2) and (3) all vCPU threads fault on a single uffd. With potentially multiple vCPUs per UFFD, it makes sense to allow configuring the number of reader threads per UFFD as well: add the "-r" flag to do so. Signed-off-by: Anish Moorthy Acked-by: James Houghton Link: https://lore.kernel.org/r/20240215235405.368539-12-amoorthy@google.com [sean: fix kernel style violations, use calloc() for arrays] Signed-off-by: Sean Christopherson

KVM: selftests: Remove redundant newlines

2024-01-29T16:39:14Z

TEST_* functions append their own newline. Remove newlines from TEST_* callsites to avoid extra newlines in output. Signed-off-by: Andrew Jones Link: https://lore.kernel.org/r/20231206170241.82801-8-ajones@ventanamicro.com Signed-off-by: Sean Christopherson

KVM: selftests: Allow dumping per-vcpu info for uffd threads

2023-05-31T21:05:15Z

There's one PER_VCPU_DEBUG in per-vcpu uffd threads but it's never hit. Trigger that when quit in normal ways (kick pollfd[1]), meanwhile fix the number of nanosec calculation. Signed-off-by: Peter Xu Reviewed-by: James Houghton Link: https://lore.kernel.org/r/20230427201112.2164776-3-peterx@redhat.com Signed-off-by: Sean Christopherson

Merge tag 'kvmarm-6.2' of https://git.kernel.org/pub/scm/linux/kernel/git/kvmarm/kvmarm into HEAD

2022-12-09T08:12:12Z

KVM/arm64 updates for 6.2 - Enable the per-vcpu dirty-ring tracking mechanism, together with an option to keep the good old dirty log around for pages that are dirtied by something other than a vcpu. - Switch to the relaxed parallel fault handling, using RCU to delay page table reclaim and giving better performance under load. - Relax the MTE ABI, allowing a VMM to use the MAP_SHARED mapping option, which multi-process VMMs such as crosvm rely on. - Merge the pKVM shadow vcpu state tracking that allows the hypervisor to have its own view of a vcpu, keeping that state private. - Add support for the PMUv3p5 architecture revision, bringing support for 64bit counters on systems that support it, and fix the no-quite-compliant CHAIN-ed counter support for the machines that actually exist out there. - Fix a handful of minor issues around 52bit VA/PA support (64kB pages only) as a prefix of the oncoming support for 4kB and 16kB pages. - Add/Enable/Fix a bunch of selftests covering memslots, breakpoints, stage-2 faults and access tracking. You name it, we got it, we probably broke it. - Pick a small set of documentation and spelling fixes, because no good merge window would be complete without those. As a side effect, this tag also drags: - The 'kvmarm-fixes-6.1-3' tag as a dependency to the dirty-ring series - A shared branch with the arm64 tree that repaints all the system registers to match the ARM ARM's naming, and resulting in interesting conflicts

KVM: selftests: Add a userfaultfd library

2022-11-10T19:10:27Z

Move the generic userfaultfd code out of demand_paging_test.c into a common library, userfaultfd_util. This library consists of a setup and a stop function. The setup function starts a thread for handling page faults using the handler callback function. This setup returns a uffd_desc object which is then used in the stop function (to wait and destroy the threads). Reviewed-by: Oliver Upton Reviewed-by: Ben Gardon Signed-off-by: Ricardo Koller Signed-off-by: Marc Zyngier Link: https://lore.kernel.org/r/20221017195834.2295901-2-ricarkol@google.com