From nobody Sun Jul 26 11:07:39 2026 Delivered-To: importer@patchew.org Authentication-Results: mx.zohomail.com; dkim=pass; spf=pass (zohomail.com: domain of gnu.org designates 209.51.188.17 as permitted sender) smtp.mailfrom=qemu-devel-bounces+importer=patchew.org@nongnu.org; dmarc=pass(p=quarantine dis=none) header.from=redhat.com ARC-Seal: i=1; a=rsa-sha256; t=1782908544; cv=none; d=zohomail.com; s=zohoarc; b=RhUKjsfZ0E0CZyJRLpC368oOA7DQKtNoxGUWNOonn1b/zrwsrE0rV5sSjVu6uOwAg+bHlvhAB7ZMJAVJquQdZaBtlllkcQ2qsfIAZnGLjkzFadgLcZfN3A/89OXHDXzDbKmoo0acFc/W2XV48rONkLuh0Nb+7Qdq0Azh63OW7lI= ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=zohomail.com; s=zohoarc; t=1782908544; h=Content-Type:Content-Transfer-Encoding:Cc:Cc:Date:Date:From:From:List-Subscribe:List-Post:List-Id:List-Archive:List-Help:List-Unsubscribe:MIME-Version:Message-ID:Sender:Subject:Subject:To:To:Message-Id:Reply-To; bh=yeOIfhuA4RPtJKlJYeZDFX68YuNf/Zw9w1HH1eJpJkM=; b=iuJsj5rL19nUW3sPAisQkThAZkwYonI+HhpjU6A/pc3jIfXsv22yh02DCP5ALthIV2mYm/48zqedbDOLB6kDtQbao12ZNevAJkAe27oxRY/nKnuXtsZ/7qPrJH9XKwpGwWVzZGFu7AQl7rPqo3n76ApQsORyTl2U3kCllwkHQ9I= ARC-Authentication-Results: i=1; mx.zohomail.com; dkim=pass; spf=pass (zohomail.com: domain of gnu.org designates 209.51.188.17 as permitted sender) smtp.mailfrom=qemu-devel-bounces+importer=patchew.org@nongnu.org; dmarc=pass header.from= (p=quarantine dis=none) Return-Path: Received: from lists1p.gnu.org (lists1p.gnu.org [209.51.188.17]) by mx.zohomail.com with SMTPS id 1782908544299449.1256006350835; Wed, 1 Jul 2026 05:22:24 -0700 (PDT) Received: from localhost ([::1] helo=lists1p.gnu.org) by lists1p.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1wetws-0007Zm-K6; Wed, 01 Jul 2026 08:21:50 -0400 Received: from eggs.gnu.org ([2001:470:142:3::10]) by lists1p.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1wetwq-0007ZH-RS for qemu-devel@nongnu.org; Wed, 01 Jul 2026 08:21:48 -0400 Received: from us-smtp-delivery-124.mimecast.com ([170.10.133.124]) by eggs.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1wetwp-0006GV-AB for qemu-devel@nongnu.org; Wed, 01 Jul 2026 08:21:48 -0400 Received: from mx-prod-mc-08.mail-002.prod.us-west-2.aws.redhat.com (ec2-35-165-154-97.us-west-2.compute.amazonaws.com [35.165.154.97]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.3, cipher=TLS_AES_256_GCM_SHA384) id us-mta-144-H-tEf-4QPxyatpl6KnUYvA-1; Wed, 01 Jul 2026 08:21:44 -0400 Received: from mx-prod-int-10.mail-002.prod.us-west-2.aws.redhat.com (mx-prod-int-10.mail-002.prod.us-west-2.aws.redhat.com [10.30.177.95]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (2048 bits) server-digest SHA256) (No client certificate requested) by mx-prod-mc-08.mail-002.prod.us-west-2.aws.redhat.com (Postfix) with ESMTPS id 94C14188E6C0; Wed, 1 Jul 2026 12:21:43 +0000 (UTC) Received: from localhost (unknown [10.44.22.3]) by mx-prod-int-10.mail-002.prod.us-west-2.aws.redhat.com (Postfix) with ESMTP id 23F271686; Wed, 1 Jul 2026 12:21:41 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1782908506; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: content-transfer-encoding:content-transfer-encoding; bh=yeOIfhuA4RPtJKlJYeZDFX68YuNf/Zw9w1HH1eJpJkM=; b=VWWsByaIg8zkcQOJwdLA6nRSuBiZULNDNm7z6PK7LTsBNpbcJGkN1vLsLoSwQAjIm5EGF9 vP3hjjCidrBtXzymwIB1TS/qUjpF2CnLglPpN2fkb4eWmGwZdRJ6Dg0ufnOvfU7uHjAoWP sE35JckWNrN/Zku+Ahl8psoSDW5UgjM= X-MC-Unique: H-tEf-4QPxyatpl6KnUYvA-1 X-Mimecast-MFC-AGG-ID: H-tEf-4QPxyatpl6KnUYvA_1782908503 From: marcandre.lureau@redhat.com To: qemu-devel@nongnu.org Cc: vkuznets@redhat.com, =?UTF-8?q?Marc-Andr=C3=A9=20Lureau?= , Paolo Bonzini , Zhao Liu , Pierrick Bouvier Subject: [PATCH] docs/hyperv: fix misleading hv-crash shutdown description Date: Wed, 1 Jul 2026 16:21:35 +0400 Message-ID: <20260701122135.3168729-1-marcandre.lureau@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: quoted-printable X-Scanned-By: MIMEDefang 3.6 on 10.30.177.95 Received-SPF: pass (zohomail.com: domain of gnu.org designates 209.51.188.17 as permitted sender) client-ip=209.51.188.17; envelope-from=qemu-devel-bounces+importer=patchew.org@nongnu.org; helo=lists1p.gnu.org; Received-SPF: pass client-ip=170.10.133.124; envelope-from=marcandre.lureau@redhat.com; helo=us-smtp-delivery-124.mimecast.com X-Spam_score_int: -24 X-Spam_score: -2.5 X-Spam_bar: -- X-Spam_report: (-2.5 / 5.0 requ) BAYES_00=-1.9, DKIMWL_WL_HIGH=-0.445, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, DKIM_VALID_EF=-0.1, RCVD_IN_DNSWL_NONE=-0.0001, RCVD_IN_MSPIKE_H4=0.001, RCVD_IN_MSPIKE_WL=0.001, SPF_HELO_PASS=-0.001, SPF_PASS=-0.001 autolearn=ham autolearn_force=no X-Spam_action: no action X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: qemu development List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: qemu-devel-bounces+importer=patchew.org@nongnu.org Sender: qemu-devel-bounces+importer=patchew.org@nongnu.org X-ZohoMail-DKIM: pass (identity @redhat.com) X-ZM-MESSAGEID: 1782908546053158500 From: Marc-Andr=C3=A9 Lureau The documentation stated that writing to HV_X64_MSR_CRASH_CTL unconditionally causes the guest to shutdown. In reality, it triggers qemu_system_guest_panicked() via KVM_SYSTEM_EVENT_CRASH and the resulting action depends on the generic panic action policy (-action panic=3D...), which defaults to shutdown. Signed-off-by: Marc-Andr=C3=A9 Lureau Reviewed-by: Vitaly Kuznetsov --- docs/system/i386/hyperv.rst | 12 ++++++++---- 1 file changed, 8 insertions(+), 4 deletions(-) diff --git a/docs/system/i386/hyperv.rst b/docs/system/i386/hyperv.rst index 1c1de77feb6..e1babffb0f9 100644 --- a/docs/system/i386/hyperv.rst +++ b/docs/system/i386/hyperv.rst @@ -71,8 +71,11 @@ Existing enlightenments by the guest when it crashes, HV_X64_MSR_CRASH_P0..HV_X64_MSR_CRASH_P5 M= SRs contain additional crash information. This information is outputted in Q= EMU log and through QAPI. - Note: unlike under genuine Hyper-V, write to HV_X64_MSR_CRASH_CTL causes= guest - to shutdown. This effectively blocks crash dump generation by Windows. + Note: unlike under genuine Hyper-V, write to HV_X64_MSR_CRASH_CTL trigge= rs + ``qemu_system_guest_panicked()`` via ``KVM_SYSTEM_EVENT_CRASH`` and the + resulting action depends on the ``-action panic=3D...`` policy (default: + ``shutdown``). With the default action, this effectively blocks crash du= mp + generation by Windows. =20 ``hv-time`` Enables two Hyper-V-specific clocksources available to the guest: MSR-ba= sed @@ -304,8 +307,9 @@ currently implemented Hyper-V enlightenments with the f= ollowing exceptions: ``hv-version-id-snumber`` can be left unchanged, guests are not supposed= to behave differently when different Hyper-V version is presented to them. - ``hv-crash`` must only be enabled if the crash information is consumed v= ia - QAPI by higher levels of the virtualization stack. Enabling this feature - effectively prevents Windows from creating dumps upon crashes. + QAPI by higher levels of the virtualization stack. With the default + ``-action panic=3Dshutdown`` policy, enabling this feature effectively + prevents Windows from creating dumps upon crashes. - ``hv-reenlightenment`` can only be used on hardware which supports TSC scaling or when guest migration is not needed. - ``hv-spinlocks`` should be set to e.g. 0xfff when host CPUs are overcomm= ited --=20 2.54.0