From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from bombadil.infradead.org (bombadil.infradead.org [198.137.202.133]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id 4053CCD98F2 for ; Mon, 22 Jun 2026 19:07:19 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=bombadil.20210309; h=Sender:List-Subscribe:List-Help :List-Post:List-Archive:List-Unsubscribe:List-Id:Content-Transfer-Encoding: MIME-Version:Message-Id:Date:Subject:Cc:To:From:Reply-To:Content-Type: Content-ID:Content-Description:Resent-Date:Resent-From:Resent-Sender: Resent-To:Resent-Cc:Resent-Message-ID:In-Reply-To:References:List-Owner; bh=qOVFrG/Te+BEiiQDl3ih9whA6aExlG2UyJj9/8nk5R0=; b=F6kw/Hnc9vQfertm//zteWQd1J aX/hEZgtQ04covFVu3YN8qNLeEBKJKPBhIvZzFw5tQJinDBrzP4oIKMSpwr7gxVy2CGq6AvOEvshU hkZjeOQT3tD8E9zOye6a/+V6wFVRUeMLi5ew5zM2r10MdACLpMiyrCGXBKt5PiD4EHD/E6Vcqogpi A75iPfIHDfDUi/hmEnAeK/sP1Yn/9ECTR8zM8yPEjkJr+rcq5hJpYNTejN8K7BtQB7fdLtCyINvLJ n+mXmkWkeI/e4kQe+xvX0h21Xi3x31zAlWLfz+26iEwnt85b2dndqQEIOsKF/Kxg/5Qvij2FdXCmL bbMhvbyg==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.99.1 #2 (Red Hat Linux)) id 1wbjzD-00000005Kjb-3AVr; Mon, 22 Jun 2026 19:07:11 +0000 Received: from out-186.mta0.migadu.com ([91.218.175.186]) by bombadil.infradead.org with esmtps (Exim 4.99.1 #2 (Red Hat Linux)) id 1wbjzA-00000005KiW-2djC for linux-arm-kernel@lists.infradead.org; Mon, 22 Jun 2026 19:07:10 +0000 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=1782155224; 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; bh=qOVFrG/Te+BEiiQDl3ih9whA6aExlG2UyJj9/8nk5R0=; b=RYniqaT6fK6bMzx3PMItfT0iElyVNpTiCHOLmEBQbYeohLMJKI0YyazkwTTuPCMclDKIS6 mn3AaWuFRZ8Gp/1Bev/aKBUnUpOWql6bM+Efy4g9EMt1MgYl5SxjHPc5yxrAl30RBgS/rh dEJvHafxDiqUjncYWhOqNc7X5J7KsTg= From: Fuad Tabba To: Marc Zyngier , Oliver Upton Cc: Joey Gouly , Suzuki K Poulose , Zenghui Yu , Steffen Eiden , Catalin Marinas , Will Deacon , Shuah Khan , Christoffer Dall , Victor Kamensky , linux-arm-kernel@lists.infradead.org, kvmarm@lists.linux.dev, linux-kernel@vger.kernel.org Subject: [PATCH 0/2] KVM: arm64: Fix and test MMIO sign-extending loads Date: Mon, 22 Jun 2026 20:06:59 +0100 Message-Id: <20260622190701.2039766-1-fuad.tabba@linux.dev> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Migadu-Flow: FLOW_OUT X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.9.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20260622_120708_815365_8B9CD5F9 X-CRM114-Status: UNSURE ( 8.73 ) X-CRM114-Notice: Please train this message. X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org Hi folks, A sign-extending load (LDRSB/LDRSH/LDRSW) from emulated MMIO returns a zero-extended value rather than the sign-extended one the architecture requires; vcpu_data_host_to_guest() strips the sign bits when it masks the data to the access width. If my git archeology is right, the masking dates to 2014 (b30070862edbd, big-endian support) and has been wrong ever since, but sign-extending loads from device memory are rare enough that nobody hit it. Patch 1 fixes it; patch 2 adds a selftest so it doesn't regress. Cheers, /fuad Fuad Tabba (2): KVM: arm64: Fix sign-extension of MMIO loads KVM: arm64: selftests: Add MMIO sign-extending load test arch/arm64/kvm/mmio.c | 7 +- tools/testing/selftests/kvm/Makefile.kvm | 1 + .../selftests/kvm/arm64/mmio_sign_ext.c | 133 ++++++++++++++++++ 3 files changed, 138 insertions(+), 3 deletions(-) create mode 100644 tools/testing/selftests/kvm/arm64/mmio_sign_ext.c base-commit: 8cd9520d35a6c38db6567e97dd93b1f11f185dc6 -- 2.39.5