From 9e2f6498efbbc880d7caa7935839e682b64fe5a6 Mon Sep 17 00:00:00 2001 From: Raghavendra Rao Ananta Date: Wed, 15 Jun 2022 18:57:06 +0000 Subject: selftests: KVM: Handle compiler optimizations in ucall The selftests, when built with newer versions of clang, is found to have over optimized guests' ucall() function, and eliminating the stores for uc.cmd (perhaps due to no immediate readers). This resulted in the userspace side always reading a value of '0', and causing multiple test failures. As a result, prevent the compiler from optimizing the stores in ucall() with WRITE_ONCE(). Suggested-by: Ricardo Koller Suggested-by: Reiji Watanabe Signed-off-by: Raghavendra Rao Ananta Message-Id: <20220615185706.1099208-1-rananta@google.com> Reviewed-by: Andrew Jones Signed-off-by: Paolo Bonzini --- tools/testing/selftests/kvm/lib/aarch64/ucall.c | 9 ++++----- 1 file changed, 4 insertions(+), 5 deletions(-) (limited to 'tools/testing/selftests/kvm') diff --git a/tools/testing/selftests/kvm/lib/aarch64/ucall.c b/tools/testing/selftests/kvm/lib/aarch64/ucall.c index e0b0164e9af8..be1d9728c4ce 100644 --- a/tools/testing/selftests/kvm/lib/aarch64/ucall.c +++ b/tools/testing/selftests/kvm/lib/aarch64/ucall.c @@ -73,20 +73,19 @@ void ucall_uninit(struct kvm_vm *vm) void ucall(uint64_t cmd, int nargs, ...) { - struct ucall uc = { - .cmd = cmd, - }; + struct ucall uc = {}; va_list va; int i; + WRITE_ONCE(uc.cmd, cmd); nargs = nargs <= UCALL_MAX_ARGS ? nargs : UCALL_MAX_ARGS; va_start(va, nargs); for (i = 0; i < nargs; ++i) - uc.args[i] = va_arg(va, uint64_t); + WRITE_ONCE(uc.args[i], va_arg(va, uint64_t)); va_end(va); - *ucall_exit_mmio_addr = (vm_vaddr_t)&uc; + WRITE_ONCE(*ucall_exit_mmio_addr, (vm_vaddr_t)&uc); } uint64_t get_ucall(struct kvm_vm *vm, uint32_t vcpu_id, struct ucall *uc) -- cgit v1.2.3-59-g8ed1b