kernel/linux.git/tools/testing/selftests/kvm/Makefile, 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: 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 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

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

Merge tag 'kvm-x86-generic-6.12' of https://github.com/kvm-x86/linux into HEAD

2024-09-17T15:38:22+00:00

KVK generic changes for 6.12: - Fix a bug that results in KVM prematurely exiting to userspace for coalesced MMIO/PIO in many cases, clean up the related code, and add a testcase. - Fix a bug in kvm_clear_guest() where it would trigger a buffer overflow _if_ the gpa+len crosses a page boundary, which thankfully is guaranteed to not happen in the current code base. Add WARNs in more helpers that read/write guest memory to detect similar bugs.

Merge tag 'kvm-s390-next-6.12-1' of https://git.kernel.org/pub/scm/linux/kernel/git/kvms390/linux into HEAD

2024-09-17T15:37:03+00:00

* New ucontrol selftest * Inline assembly touchups

Merge branch kvm-arm64/selftests-6.12 into kvmarm-master/next

2024-09-12T07:37:20+00:00

* kvm-arm64/selftests-6.12: : . : KVM/arm64 selftest updates for 6.12 : : - Check for a bunch of timer emulation corner cases (COlton Lewis) : . KVM: arm64: selftests: Add arch_timer_edge_cases selftest KVM: arm64: selftests: Ensure pending interrupts are handled in arch_timer test Signed-off-by: Marc Zyngier

KVM: arm64: selftests: Add arch_timer_edge_cases selftest

2024-08-30T08:04:16+00:00

Add a new arch_timer_edge_cases selftests that validates: * timers above the max TVAL value * timers in the past * moving counters ahead and behind pending timers * reprograming timers * timers fired multiple times * masking/unmasking using the timer control mask These are intentionally unusual scenarios to stress compliance with the arm architecture. Co-developed-by: Ricardo Koller Signed-off-by: Ricardo Koller Signed-off-by: Colton Lewis Link: https://lore.kernel.org/r/20240823175836.2798235-3-coltonlewis@google.com Signed-off-by: Marc Zyngier

KVM: selftests: Add a test for coalesced MMIO (and PIO on x86)

2024-08-30T02:38:33+00:00

Add a test to verify that KVM correctly exits (or not) when a vCPU's coalesced I/O ring is full (or isn't). Iterate over all legal starting points in the ring (with an empty ring), and verify that KVM doesn't exit until the ring is full. Opportunistically verify that KVM exits immediately on non-coalesced I/O, either because the MMIO/PIO region was never registered, or because a previous region was unregistered. This is a regression test for a KVM bug where KVM would prematurely exit due to bad math resulting in a false positive if the first entry in the ring was before the halfway mark. See commit 92f6d4130497 ("KVM: Fix coalesced_mmio_has_room() to avoid premature userspace exit"). Enable the test for x86, arm64, and risc-v, i.e. all architectures except s390, which doesn't have MMIO. On x86, which has both MMIO and PIO, interleave MMIO and PIO into the same ring, as KVM shouldn't exit until a non-coalesced I/O is encountered, regardless of whether the ring is filled with MMIO, PIO, or both. Lastly, wrap the coalesced I/O ring in a structure to prepare for a potential future where KVM supports multiple ring buffers beyond KVM's "default" built-in buffer. Link: https://lore.kernel.org/all/20240820133333.1724191-1-ilstam@amazon.com Cc: Ilias Stamatis Cc: Marc Zyngier Cc: Oliver Upton Cc: Anup Patel Link: https://lore.kernel.org/r/20240828181446.652474-2-seanjc@google.com Signed-off-by: Sean Christopherson