kernel/linux.git/tools/testing/selftests/kvm, branch v6.12.80

KVM: selftests: Add -U_FORTIFY_SOURCE to avoid some unpredictable test failures

2026-02-11T12:40:18+00:00

[ Upstream commit e396a74222654486d6ab45dca5d0c54c408b8b91 ] Some distributions (such as Ubuntu) configure GCC so that _FORTIFY_SOURCE is automatically enabled at -O1 or above. This results in some fortified version of definitions of standard library functions are included. While linker resolves the symbols, the fortified versions might override the definitions in lib/string_override.c and reference to those PLT entries in GLIBC. This is not a problem for the code in host, but it is a disaster for the guest code. E.g., if build and run x86/nested_emulation_test on Ubuntu 24.04 will encounter a L1 #PF due to memset() reference to __memset_chk@plt. The option -fno-builtin-memset is not helpful here, because those fortified versions are not built-in but some definitions which are included by header, they are for different intentions. In order to eliminate the unpredictable behaviors may vary depending on the linker and platform, add the "-U_FORTIFY_SOURCE" into CFLAGS to prevent from introducing the fortified definitions. Signed-off-by: Zhiquan Li Link: https://patch.msgid.link/20260122053551.548229-1-zhiquan_li@163.com Fixes: 6b6f71484bf4 ("KVM: selftests: Implement memcmp(), memcpy(), and memset() for guest use") Cc: stable@vger.kernel.org [sean: tag for stable] Signed-off-by: Sean Christopherson [ Makefile.kvm -> Makefile ] Signed-off-by: Sasha Levin Signed-off-by: Greg Kroah-Hartman

KVM: selftests: use X86_MEMTYPE_WB instead of VMX_BASIC_MEM_TYPE_WB

2024-11-08T10:57:12+00:00

In 08a7d2525511 ("tools arch x86: Sync the msr-index.h copy with the kernel sources"), VMX_BASIC_MEM_TYPE_WB was removed. Use X86_MEMTYPE_WB instead. Fixes: 08a7d2525511 ("tools arch x86: Sync the msr-index.h copy with the kernel sources") Signed-off-by: John Sperbeck Message-ID: <20241106034031.503291-1-jsperbeck@google.com> Signed-off-by: Paolo Bonzini

KVM: selftests: Don't force -march=x86-64-v2 if it's unsupported

2024-11-05T05:10:48+00:00

Force -march=x86-64-v2 to avoid SSE/AVX instructions if and only if the uarch definition is supported by the compiler, e.g. gcc 7.5 only supports x86-64. Fixes: 9a400068a158 ("KVM: selftests: x86: Avoid using SSE/AVX instructions") Cc: Vitaly Kuznetsov Reviewed-and-tested-by: Vitaly Kuznetsov Link: https://lore.kernel.org/r/20241031045333.1209195-1-seanjc@google.com Signed-off-by: Sean Christopherson

KVM: selftests: Disable strict aliasing

2024-11-05T05:10:47+00:00

Disable strict aliasing, as has been done in the kernel proper for decades (literally since before git history) to fix issues where gcc will optimize away loads in code that looks 100% correct, but is _technically_ undefined behavior, and thus can be thrown away by the compiler. E.g. arm64's vPMU counter access test casts a uint64_t (unsigned long) pointer to a u64 (unsigned long long) pointer when setting PMCR.N via u64p_replace_bits(), which gcc-13 detects and optimizes away, i.e. ignores the result and uses the original PMCR. The issue is most easily observed by making set_pmcr_n() noinline and wrapping the call with printf(), e.g. sans comments, for this code: printf("orig = %lx, next = %lx, want = %lu\n", pmcr_orig, pmcr, pmcr_n); set_pmcr_n(&pmcr, pmcr_n); printf("orig = %lx, next = %lx, want = %lu\n", pmcr_orig, pmcr, pmcr_n); gcc-13 generates: 0000000000401c90 : 401c90: f9400002 ldr x2, [x0] 401c94: b3751022 bfi x2, x1, #11, #5 401c98: f9000002 str x2, [x0] 401c9c: d65f03c0 ret 0000000000402660 : 402724: aa1403e3 mov x3, x20 402728: aa1503e2 mov x2, x21 40272c: aa1603e0 mov x0, x22 402730: aa1503e1 mov x1, x21 402734: 940060ff bl 41ab30 <_IO_printf> 402738: aa1403e1 mov x1, x20 40273c: 910183e0 add x0, sp, #0x60 402740: 97fffd54 bl 401c90 402744: aa1403e3 mov x3, x20 402748: aa1503e2 mov x2, x21 40274c: aa1503e1 mov x1, x21 402750: aa1603e0 mov x0, x22 402754: 940060f7 bl 41ab30 <_IO_printf> with the value stored in [sp + 0x60] ignored by both printf() above and in the test proper, resulting in a false failure due to vcpu_set_reg() simply storing the original value, not the intended value. $ ./vpmu_counter_access Random seed: 0x6b8b4567 orig = 3040, next = 3040, want = 0 orig = 3040, next = 3040, want = 0 ==== Test Assertion Failure ==== aarch64/vpmu_counter_access.c:505: pmcr_n == get_pmcr_n(pmcr) pid=71578 tid=71578 errno=9 - Bad file descriptor 1 0x400673: run_access_test at vpmu_counter_access.c:522 2 (inlined by) main at vpmu_counter_access.c:643 3 0x4132d7: __libc_start_call_main at libc-start.o:0 4 0x413653: __libc_start_main at ??:0 5 0x40106f: _start at ??:0 Failed to update PMCR.N to 0 (received: 6) Somewhat bizarrely, gcc-11 also exhibits the same behavior, but only if set_pmcr_n() is marked noinline, whereas gcc-13 fails even if set_pmcr_n() is inlined in its sole caller. Cc: stable@vger.kernel.org Link: https://gcc.gnu.org/bugzilla/show_bug.cgi?id=116912 Signed-off-by: Sean Christopherson

KVM: selftests: fix unintentional noop test in guest_memfd_test.c

2024-11-05T05:10:28+00:00

The loop in test_create_guest_memfd_invalid() that is supposed to test that nothing is accepted as a valid flag to KVM_CREATE_GUEST_MEMFD was initializing `flag` as 0 instead of BIT(0). This caused the loop to immediately exit instead of iterating over BIT(0), BIT(1), ... . Fixes: 8a89efd43423 ("KVM: selftests: Add basic selftest for guest_memfd()") Signed-off-by: Patrick Roy Reviewed-by: James Gowans Reviewed-by: Muhammad Usama Anjum Link: https://lore.kernel.org/r/20241024095956.3668818-1-roypat@amazon.co.uk Signed-off-by: Sean Christopherson

KVM: selftests: memslot_perf_test: increase guest sync timeout

2024-11-05T05:04:10+00:00

When memslot_perf_test is run nested, first iteration of test_memslot_rw_loop testcase, sometimes takes more than 2 seconds due to build of shadow page tables. Following iterations are fast. To be on the safe side, bump the timeout to 10 seconds. Signed-off-by: Maxim Levitsky Tested-by: Liam Merwick Reviewed-by: Liam Merwick Link: https://lore.kernel.org/r/20241004220153.287459-1-mlevitsk@redhat.com Signed-off-by: Sean Christopherson

KVM: selftests: Fix build on on non-x86 architectures

2024-10-21T22:49:33+00:00

Commit 9a400068a158 ("KVM: selftests: x86: Avoid using SSE/AVX instructions") unconditionally added -march=x86-64-v2 to the CFLAGS used to build the KVM selftests which does not work on non-x86 architectures: cc1: error: unknown value ‘x86-64-v2’ for ‘-march’ Fix this by making the addition of this x86 specific command line flag conditional on building for x86. Fixes: 9a400068a158 ("KVM: selftests: x86: Avoid using SSE/AVX instructions") Signed-off-by: Mark Brown Signed-off-by: Linus Torvalds

Merge tag 'kvmarm-fixes-6.12-2' of git://git.kernel.org/pub/scm/linux/kernel/git/kvmarm/kvmarm into HEAD

2024-10-20T16:10:56+00:00

KVM/arm64 fixes for 6.12, take #2 - Fix the guest view of the ID registers, making the relevant fields writable from userspace (affecting ID_AA64DFR0_EL1 and ID_AA64PFR1_EL1) - Correcly expose S1PIE to guests, fixing a regression introduced in 6.12-rc1 with the S1POE support - Fix the recycling of stage-2 shadow MMUs by tracking the context (are we allowed to block or not) as well as the recycling state - Address a couple of issues with the vgic when userspace misconfigures the emulation, resulting in various splats. Headaches courtesy of our Syzkaller friends

KVM: selftests: Fix out-of-bounds reads in CPUID test's array lookups

2024-10-20T16:10:44+00:00

When looking for a "mangled", i.e. dynamic, CPUID entry, terminate the walk based on the number of array _entries_, not the size in bytes of the array. Iterating based on the total size of the array can result in false passes, e.g. if the random data beyond the array happens to match a CPUID entry's function and index. Fixes: fb18d053b7f8 ("selftest: kvm: x86: test KVM_GET_CPUID2 and guest visible CPUIDs against KVM_GET_SUPPORTED_CPUID") Signed-off-by: Sean Christopherson Reviewed-by: Vitaly Kuznetsov Message-ID: <20241003234337.273364-2-seanjc@google.com> Signed-off-by: Paolo Bonzini

KVM: selftests: x86: Avoid using SSE/AVX instructions

2024-10-20T16:10:27+00:00

Some distros switched gcc to '-march=x86-64-v3' by default and while it's hard to find a CPU which doesn't support it today, many KVM selftests fail with ==== Test Assertion Failure ==== lib/x86_64/processor.c:570: Unhandled exception in guest pid=72747 tid=72747 errno=4 - Interrupted system call Unhandled exception '0x6' at guest RIP '0x4104f7' The failure is easy to reproduce elsewhere with $ make clean && CFLAGS='-march=x86-64-v3' make -j && ./x86_64/kvm_pv_test The root cause of the problem seems to be that with '-march=x86-64-v3' GCC uses AVX* instructions (VMOVQ in the example above) and without prior XSETBV() in the guest this results in #UD. It is certainly possible to add it there, e.g. the following saves the day as well: Signed-off-by: Vitaly Kuznetsov Message-ID: <20240920154422.2890096-1-vkuznets@redhat.com> Signed-off-by: Paolo Bonzini