From nobody Sat Apr 11 13:34:51 2026 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 vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id E1F5EC67871 for ; Thu, 27 Oct 2022 09:59:14 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S234975AbiJ0J7N (ORCPT ); Thu, 27 Oct 2022 05:59:13 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:39396 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S234610AbiJ0J6U (ORCPT ); Thu, 27 Oct 2022 05:58:20 -0400 Received: from linux.microsoft.com (linux.microsoft.com [13.77.154.182]) by lindbergh.monkeyblade.net (Postfix) with ESMTP id B6426186DE; Thu, 27 Oct 2022 02:58:08 -0700 (PDT) Received: from anrayabh-desk.corp.microsoft.com (unknown [167.220.238.193]) by linux.microsoft.com (Postfix) with ESMTPSA id A92F3210DC4A; Thu, 27 Oct 2022 02:58:03 -0700 (PDT) DKIM-Filter: OpenDKIM Filter v2.11.0 linux.microsoft.com A92F3210DC4A DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linux.microsoft.com; s=default; t=1666864688; bh=jZZ6qM4jUHM2tL93sOCGMRdtlaB9Zvma95PgYX3k+/8=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=Or5dRUFbmQppKY2ubGZ3DaOOE7D2DWgjIkzD9tFR4HwPXfrK/ZNOV8XfCzbPksEzj WhHFyxyqHJbnrhPRze4TbVrIgwbosQbfJ7iVnN1tpQjGz3XO1xEBG9zkOgfzVZQOPl qUgjCvi+xZ6UfCrxrAc+vDgUI3KNcH630oQFXYqU= From: Anirudh Rayabharam To: kys@microsoft.com, haiyangz@microsoft.com, sthemmin@microsoft.com, wei.liu@kernel.org, decui@microsoft.com, tglx@linutronix.de, mingo@redhat.com, bp@alien8.de, dave.hansen@linux.intel.com, x86@kernel.org, hpa@zytor.com, daniel.lezcano@linaro.org, Arnd Bergmann , linux-hyperv@vger.kernel.org, linux-kernel@vger.kernel.org, linux-arch@vger.kernel.org Cc: stanislav.kinsburskiy@gmail.com, Anirudh Rayabharam , kumarpraveen@linux.microsoft.com, mail@anirudhrb.com Subject: [PATCH v2 2/2] x86/hyperv: fix invalid writes to MSRs during root partition kexec Date: Thu, 27 Oct 2022 15:27:29 +0530 Message-Id: <20221027095729.1676394-3-anrayabh@linux.microsoft.com> X-Mailer: git-send-email 2.34.1 In-Reply-To: <20221027095729.1676394-1-anrayabh@linux.microsoft.com> References: <20221027095729.1676394-1-anrayabh@linux.microsoft.com> MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Type: text/plain; charset="utf-8" hv_cleanup resets the hypercall page by setting the MSR to 0. However, the root partition is not allowed to write to the GPA bits of the MSR. Instead, it uses the hypercall page provided by the MSR. Similar is the case with the reference TSC MSR. Clear only the enable bit instead of zeroing the entire MSR to make the code valid for root partition too. Signed-off-by: Anirudh Rayabharam Reviewed-by: Michael Kelley --- arch/x86/hyperv/hv_init.c | 11 +++++++---- 1 file changed, 7 insertions(+), 4 deletions(-) diff --git a/arch/x86/hyperv/hv_init.c b/arch/x86/hyperv/hv_init.c index 29774126e931..80fdfff9266c 100644 --- a/arch/x86/hyperv/hv_init.c +++ b/arch/x86/hyperv/hv_init.c @@ -537,6 +537,7 @@ void __init hyperv_init(void) void hyperv_cleanup(void) { union hv_x64_msr_hypercall_contents hypercall_msr; + union hv_reference_tsc_msr tsc_msr; =20 unregister_syscore_ops(&hv_syscore_ops); =20 @@ -552,12 +553,14 @@ void hyperv_cleanup(void) hv_hypercall_pg =3D NULL; =20 /* Reset the hypercall page */ - hypercall_msr.as_uint64 =3D 0; - wrmsrl(HV_X64_MSR_HYPERCALL, hypercall_msr.as_uint64); + hypercall_msr.as_uint64 =3D hv_get_register(HV_X64_MSR_HYPERCALL); + hypercall_msr.enable =3D 0; + hv_set_register(HV_X64_MSR_HYPERCALL, hypercall_msr.as_uint64); =20 /* Reset the TSC page */ - hypercall_msr.as_uint64 =3D 0; - wrmsrl(HV_X64_MSR_REFERENCE_TSC, hypercall_msr.as_uint64); + tsc_msr.as_uint64 =3D hv_get_register(HV_X64_MSR_REFERENCE_TSC); + tsc_msr.enable =3D 0; + hv_set_register(HV_X64_MSR_REFERENCE_TSC, tsc_msr.as_uint64); } =20 void hyperv_report_panic(struct pt_regs *regs, long err, bool in_die) --=20 2.34.1