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Mon, 23 Nov 2020 06:52:05 -0500 Received: from mimecast-mx01.redhat.com (mimecast-mx01.redhat.com [209.132.183.4]) (Using TLS) by relay.mimecast.com with ESMTP id us-mta-252-z4WwDO8pPuqJa85PEj2F-Q-1; Mon, 23 Nov 2020 06:52:00 -0500 Received: from smtp.corp.redhat.com (int-mx08.intmail.prod.int.phx2.redhat.com [10.5.11.23]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx01.redhat.com (Postfix) with ESMTPS id B08DA5214; Mon, 23 Nov 2020 11:51:59 +0000 (UTC) Received: from thuth.com (ovpn-113-17.ams2.redhat.com [10.36.113.17]) by smtp.corp.redhat.com (Postfix) with ESMTP id D6C1F1A4D0; Mon, 23 Nov 2020 11:51:58 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1606132322; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:content-type:content-type:in-reply-to:in-reply-to: references:references; bh=3zlGE35tI2Q12+CZkH8qEKiDmM9/O3H1mobcJoSl7VU=; b=guKgEbGrXWNXDkfPU/DIkzzBnRrL66r8wBC+1Oiakuzidz+So7KKM/ieoHAKrhzCMLGmlI VuXHbZxTl3E2QSO8CsilAMy7Gm70oWhDYW2ZaCCFzPekdichnHqvW7wtVL3N96dSFt5nAi Pwl5aHXrLsqTBp9eb15EZ6qmt6sE/MY= X-MC-Unique: z4WwDO8pPuqJa85PEj2F-Q-1 From: Thomas Huth To: qemu-devel@nongnu.org, Peter Maydell Subject: [PULL 1/3] pc-bios: s390x: Ensure Read IPL memory is clean Date: Mon, 23 Nov 2020 12:51:53 +0100 Message-Id: <20201123115155.232335-2-thuth@redhat.com> In-Reply-To: <20201123115155.232335-1-thuth@redhat.com> References: <20201123115155.232335-1-thuth@redhat.com> X-Scanned-By: MIMEDefang 2.84 on 10.5.11.23 Authentication-Results: relay.mimecast.com; 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charset="utf-8" From: Eric Farman If, for example, we boot off a virtio device and chreipl to a vfio-ccw device, the space at lowcore will be non-zero. We build a Read IPL CCW at address zero, but it will have leftover PSW data that will conflict with the Format-0 CCW being generated: 0x0: 00080000 80010000 ------ Ccw0.cda -- Ccw0.chainData -- Reserved bits The data address will be overwritten with the correct value (0x0), but the apparent data chain bit will cause subsequent memory to be used as the target of the data store, which may not be where we expect (0x0). Clear out this space when we boot from DASD, so that we know it exists exactly as we expect. Signed-off-by: Eric Farman Reviewed-by: Jason J. Herne Reviewed-by: Janosch Frank Acked-by: Christian Borntraeger Acked-by: Cornelia Huck Message-Id: <20201120160117.59366-2-farman@linux.ibm.com> Signed-off-by: Thomas Huth --- pc-bios/s390-ccw/dasd-ipl.c | 3 +++ 1 file changed, 3 insertions(+) diff --git a/pc-bios/s390-ccw/dasd-ipl.c b/pc-bios/s390-ccw/dasd-ipl.c index 0fc879bb8e..71cbae2f16 100644 --- a/pc-bios/s390-ccw/dasd-ipl.c +++ b/pc-bios/s390-ccw/dasd-ipl.c @@ -100,6 +100,9 @@ static void make_readipl(void) { Ccw0 *ccwIplRead =3D (Ccw0 *)0x00; =20 + /* Clear out any existing data */ + memset(ccwIplRead, 0, sizeof(Ccw0)); + /* Create Read IPL ccw at address 0 */ ccwIplRead->cmd_code =3D CCW_CMD_READ_IPL; ccwIplRead->cda =3D 0x00; /* Read into address 0x00 in main memory */ --=20 2.18.4