From nobody Tue Aug 25 10:46:55 2026 Received: from foss.arm.com (foss.arm.com [217.140.110.172]) by smtp.subspace.kernel.org (Postfix) with ESMTP id 5B3DB3F12EE; Wed, 8 Jul 2026 15:22:45 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=217.140.110.172 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1783524166; cv=none; b=eXgX3pk4TADtSdBinaGBsCSdB+i8OEAtTm0AXJfWiP0cOWmAySMjHAJd7HVcY73nDpxuWvGT/sZwhUQzUvHwmOaX9vJXYDhSw2XpAvuP6BWjyXg2OHeriLc92jHHhJC3Kv3ZFvNVE3MoGihefVoI9sfji2ovSj0E231RWR9rxCk= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1783524166; c=relaxed/simple; bh=apzV4oh9O1P2YQMbrmGXEcX+PtvV3tL6P8GVOtdu8z8=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=CgWj9UX2+2tFR0sIwVF4lFCqMvqTWtA9bvliKKhWVm2XYGbYwKSfT3UzBjDs28Q+I42qLw2rJQ7xqBgLnAhFXuZPQxmV0VoDf2+x1yDUXIHf/ITYduAyXsRTLv765K0cwXT4G11l7swkDOkozTVpoKEnlCdg985cMIk8gNBvPoA= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=arm.com; spf=pass smtp.mailfrom=arm.com; dkim=pass (1024-bit key) header.d=arm.com header.i=@arm.com header.b=IyvYvGxN; arc=none smtp.client-ip=217.140.110.172 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=arm.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=arm.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=arm.com header.i=@arm.com header.b="IyvYvGxN" Received: from usa-sjc-imap-foss1.foss.arm.com (unknown [10.121.207.14]) by usa-sjc-mx-foss1.foss.arm.com (Postfix) with ESMTP id 60F781E2F; Wed, 8 Jul 2026 08:22:40 -0700 (PDT) Received: from LeoBrasDK.cambridge.arm.com (LeoBrasDK.cambridge.arm.com [10.2.212.21]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id 5D54F3F66F; Wed, 8 Jul 2026 08:22:42 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=simple/simple; d=arm.com; s=foss; t=1783524164; bh=apzV4oh9O1P2YQMbrmGXEcX+PtvV3tL6P8GVOtdu8z8=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=IyvYvGxNwcS151RrtXbzKfeaWjMCXoY0gD2nfEQcsrmOlrSFdl3L2UAvz0M6SuZl8 58cBb9rMEyxvcXgkGXD9Jb2UUJtkiv59F4v2eILqk0xmUky3zd0Nzjq35lSy2hvQPK 3TJmSQMjfPYxq26YeVlZ+IVGmt1nwL+HBMmquHak= From: Leonardo Bras To: Paolo Bonzini , Shuah Khan , Sean Christopherson , David Matlack , Leonardo Bras , Ackerley Tng , Marc Zyngier , Oliver Upton , Wu Fei , Claudio Imbrenda , Steffen Eiden Cc: kvm@vger.kernel.org, linux-kselftest@vger.kernel.org, linux-kernel@vger.kernel.org Subject: [RFC PATCH v3 2/3] KVM: selftests: Check dirty-ring size before enabling Date: Wed, 8 Jul 2026 16:22:27 +0100 Message-ID: <20260708152232.2568907-3-leo.bras@arm.com> X-Mailer: git-send-email 2.55.0 In-Reply-To: <20260708152232.2568907-1-leo.bras@arm.com> References: <20260708152232.2568907-1-leo.bras@arm.com> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 X-Developer-Signature: v=1; a=openpgp-sha256; l=2030; i=leo.bras@arm.com; h=from:subject; bh=apzV4oh9O1P2YQMbrmGXEcX+PtvV3tL6P8GVOtdu8z8=; b=owGbwMvMwCX2pizjszvTwvWMp9WSGLL8spUunj7kcfogr9fZqwuOCB/yszf20uAUdCjaelV4w u4YifiYjlIWBjEuBlkxRRbZR/NX8XyfknHkyo8FMHNYmUCGMHBxCsBEnk5k+Ct499RVxb7iLfvr nV//eGcv1VZ6dM+qJ3pOIn8Dmd8pOtxmZOjrk9zwbY46T9wPF85El1cp295XRh/acqaW533cJin 9RFYA X-Developer-Key: i=leo.bras@arm.com; a=openpgp; fpr=36E6C95AE0F111CC5B6F4D2E688C33F8A0C5B0C5 Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset="utf-8" As of today, trying to enable dirty-ring with a size bigger than the maximum will return an "argument list too long" error. Change vm_enable_dirty_ring() to get the maximum size, then compare it to the desired size before enabling. If the value is invalid, print a more precise error message. Signed-off-by: Leonardo Bras --- tools/testing/selftests/kvm/lib/kvm_util.c | 19 +++++++++++++++---- 1 file changed, 15 insertions(+), 4 deletions(-) diff --git a/tools/testing/selftests/kvm/lib/kvm_util.c b/tools/testing/sel= ftests/kvm/lib/kvm_util.c index 195f3fdae1e3..4ae27ad9f947 100644 --- a/tools/testing/selftests/kvm/lib/kvm_util.c +++ b/tools/testing/selftests/kvm/lib/kvm_util.c @@ -160,24 +160,35 @@ unsigned int kvm_check_cap(long cap) ret =3D __kvm_ioctl(kvm_fd, KVM_CHECK_EXTENSION, (void *)cap); TEST_ASSERT(ret >=3D 0, KVM_IOCTL_ERROR(KVM_CHECK_EXTENSION, ret)); =20 kvm_free_fd(kvm_fd); =20 return (unsigned int)ret; } =20 void vm_enable_dirty_ring(struct kvm_vm *vm, u32 ring_size) { - if (vm_check_cap(vm, KVM_CAP_DIRTY_LOG_RING_ACQ_REL)) - vm_enable_cap(vm, KVM_CAP_DIRTY_LOG_RING_ACQ_REL, ring_size); - else - vm_enable_cap(vm, KVM_CAP_DIRTY_LOG_RING, ring_size); + long cap =3D KVM_CAP_DIRTY_LOG_RING_ACQ_REL; + int max_size =3D vm_check_cap(vm, cap); + + if (!max_size) { + cap =3D KVM_CAP_DIRTY_LOG_RING; + max_size =3D vm_check_cap(vm, cap); + } + + TEST_ASSERT(max_size > 0, "Dirty-ring not supported in this kernel\n"); + TEST_ASSERT(ring_size <=3D max_size && is_power_of_2(ring_size), + "Invalid dirty-ring size: Should be a power of two " + "<=3D %lu entries\n", + max_size / sizeof(struct kvm_dirty_gfn)); + + vm_enable_cap(vm, cap, ring_size); vm->dirty_ring_size =3D ring_size; } =20 static void vm_open(struct kvm_vm *vm) { vm->kvm_fd =3D _open_kvm_dev_path_or_exit(O_RDWR); =20 TEST_REQUIRE(kvm_has_cap(KVM_CAP_IMMEDIATE_EXIT)); =20 vm->fd =3D __kvm_ioctl(vm->kvm_fd, KVM_CREATE_VM, (void *)vm->type); --=20 2.55.0