From nobody Sun Feb 8 17:36:55 2026 Received: from out-184.mta0.migadu.com (out-184.mta0.migadu.com [91.218.175.184]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id B296B2DFF28 for ; Fri, 30 Jan 2026 02:08:23 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=91.218.175.184 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1769738905; cv=none; b=eXJHVVwVj0kEZ+vRlzFddO+b8lol0YpSjzjz93xpktxRNP4/KuBTbx/Q0sKd++03sGv6yJ7RTS47B4k47zAPC1Pg21KArnVBlOApgqPI94qipQSy0cITEP6iem7TjqmFghke0LsEa8tvs7i8LcCKsBCBz/dU//8dzY99e97pOC0= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1769738905; c=relaxed/simple; bh=aQ5VNgkHVq38PZ95gRT3ahLqlKJLdIB+3idB5ksK5Rc=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=s+44EZ2vKaFwqSl3o2VNZZjsuIiD4f5wNe4sDtOTF4v7XzRx42jh2o450G6i5yLggobuVQwE4sDJuNMwhhd7hgE8tr+q6YPyVMShux9swTe/+gpJ+Lu7Rp+ZQpr70cGkCZrMHk8oSVzr8gEy8Vx32PzB9jg1OPZghX7HqaUuhE4= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=linux.dev; spf=pass smtp.mailfrom=linux.dev; dkim=pass (1024-bit key) header.d=linux.dev header.i=@linux.dev header.b=h/ZbRrnq; arc=none smtp.client-ip=91.218.175.184 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=linux.dev Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=linux.dev Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linux.dev header.i=@linux.dev header.b="h/ZbRrnq" X-Report-Abuse: Please report any abuse attempt to abuse@migadu.com and include these headers. DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linux.dev; s=key1; t=1769738901; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=qdp+L8U+yhHpW+/9jFSxvb9uYHCqer0u894nfeOf5RA=; b=h/ZbRrnqws83vxMk/u3oiNpVlLGAFouiHQ94mBa9LI2wBmk1OcqW2DvEsHoldDiRwlFSFY +8ZycLcItA+FUwI8svBjA6izDpm85Q6UMyCjMex6IKE+0ErDL0qJjlVrh3MjDm22KQH0LW 75G/DgoRT8IA+X75Q6YtUp949QYm1WQ= From: Yosry Ahmed To: Sean Christopherson Cc: Paolo Bonzini , kvm@vger.kernel.org, linux-kernel@vger.kernel.org, Yosry Ahmed Subject: [PATCH 3/3] KVM: selftests: Add a test for L2 toggling EFER.SVME Date: Fri, 30 Jan 2026 02:07:35 +0000 Message-ID: <20260130020735.2517101-4-yosry.ahmed@linux.dev> In-Reply-To: <20260130020735.2517101-1-yosry.ahmed@linux.dev> References: <20260130020735.2517101-1-yosry.ahmed@linux.dev> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable X-Migadu-Flow: FLOW_OUT Content-Type: text/plain; charset="utf-8" Add a test to make sure that L2 toggling EFER.SVME works as intended. This is a regression test for KVM mistakenly leaving nested and tearing down nested state if L2 disables EFER.SVME, even though L1 is still using nested. Signed-off-by: Yosry Ahmed --- tools/testing/selftests/kvm/Makefile.kvm | 1 + .../kvm/x86/svm_nested_toggle_efer_svme.c | 76 +++++++++++++++++++ 2 files changed, 77 insertions(+) create mode 100644 tools/testing/selftests/kvm/x86/svm_nested_toggle_efer_= svme.c diff --git a/tools/testing/selftests/kvm/Makefile.kvm b/tools/testing/selft= ests/kvm/Makefile.kvm index 58eee0474db6a..7bd2297b5494e 100644 --- a/tools/testing/selftests/kvm/Makefile.kvm +++ b/tools/testing/selftests/kvm/Makefile.kvm @@ -112,6 +112,7 @@ TEST_GEN_PROGS_x86 +=3D x86/svm_vmcall_test TEST_GEN_PROGS_x86 +=3D x86/svm_int_ctl_test TEST_GEN_PROGS_x86 +=3D x86/svm_nested_shutdown_test TEST_GEN_PROGS_x86 +=3D x86/svm_nested_soft_inject_test +TEST_GEN_PROGS_x86 +=3D x86/svm_nested_toggle_efer_svme TEST_GEN_PROGS_x86 +=3D x86/tsc_scaling_sync TEST_GEN_PROGS_x86 +=3D x86/sync_regs_test TEST_GEN_PROGS_x86 +=3D x86/ucna_injection_test diff --git a/tools/testing/selftests/kvm/x86/svm_nested_toggle_efer_svme.c = b/tools/testing/selftests/kvm/x86/svm_nested_toggle_efer_svme.c new file mode 100644 index 0000000000000..5267fbdbf01cc --- /dev/null +++ b/tools/testing/selftests/kvm/x86/svm_nested_toggle_efer_svme.c @@ -0,0 +1,76 @@ +// SPDX-License-Identifier: GPL-2.0-only +/* + * Copyright (C) 2026, Google LLC. + */ +#include "kvm_util.h" +#include "vmx.h" +#include "svm_util.h" +#include "kselftest.h" + + +#define L2_GUEST_STACK_SIZE 64 + +static void l2_guest_code(void) +{ + unsigned long efer =3D rdmsr(MSR_EFER); + + /* generic_svm_setup() initializes EFER_SVME set for L2 */ + GUEST_ASSERT(efer & EFER_SVME); + + wrmsr(MSR_EFER, efer & ~EFER_SVME); + GUEST_ASSERT(rdmsr(MSR_EFER) =3D=3D (efer & ~EFER_SVME)); + + wrmsr(MSR_EFER, efer); + GUEST_ASSERT(rdmsr(MSR_EFER) =3D=3D efer); + + vmmcall(); +} + +static void l1_guest_code(struct svm_test_data *svm) +{ + unsigned long l2_guest_stack[L2_GUEST_STACK_SIZE]; + + generic_svm_setup(svm, l2_guest_code, + &l2_guest_stack[L2_GUEST_STACK_SIZE]); + + run_guest(svm->vmcb, svm->vmcb_gpa); + GUEST_ASSERT(svm->vmcb->control.exit_code =3D=3D SVM_EXIT_VMMCALL); + + GUEST_DONE(); +} + +int main(int argc, char *argv[]) +{ + struct kvm_vcpu *vcpu; + struct kvm_vm *vm; + vm_vaddr_t nested_gva =3D 0; + + TEST_REQUIRE(kvm_cpu_has(X86_FEATURE_SVM)); + + vm =3D vm_create_with_one_vcpu(&vcpu, l1_guest_code); + + vcpu_alloc_svm(vm, &nested_gva); + vcpu_args_set(vcpu, 1, nested_gva); + + for (;;) { + struct ucall uc; + + vcpu_run(vcpu); + TEST_ASSERT_KVM_EXIT_REASON(vcpu, KVM_EXIT_IO); + + switch (get_ucall(vcpu, &uc)) { + case UCALL_ABORT: + REPORT_GUEST_ASSERT(uc); + case UCALL_SYNC: + break; + case UCALL_DONE: + goto done; + default: + TEST_FAIL("Unknown ucall %lu", uc.cmd); + } + } + +done: + kvm_vm_free(vm); + return 0; +} --=20 2.53.0.rc1.225.gd81095ad13-goog