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Blame SOURCES/kvm-scsi-disk-support-reporting-of-rotation-rate.patch

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From 04ab93423b97ab5bc175032e0e4e1da288840805 Mon Sep 17 00:00:00 2001
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From: John Snow <jsnow@redhat.com>
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Date: Thu, 2 Aug 2018 15:53:34 +0200
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Subject: [PATCH 1/4] scsi-disk: support reporting of rotation rate
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RH-Author: John Snow <jsnow@redhat.com>
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Message-id: <20180802155336.10347-2-jsnow@redhat.com>
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Patchwork-id: 81613
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O-Subject: [RHEL-7.6 qemu-kvm PATCH 1/3] scsi-disk: support reporting of rotation rate
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Bugzilla: 1583807
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RH-Acked-by: Daniel P. Berrange <berrange@redhat.com>
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RH-Acked-by: Laszlo Ersek <lersek@redhat.com>
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RH-Acked-by: Thomas Huth <thuth@redhat.com>
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From: "Daniel P. Berrange" <berrange@redhat.com>
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The Linux kernel will query the SCSI "Block device characteristics"
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VPD to determine the rotations per minute of the disk. If this has
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the value 1, it is taken to be an SSD and so Linux sets the
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'rotational' flag to 0 for the I/O queue and will stop using that
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disk as a source of random entropy. Other operating systems may
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also take into account rotation rate when setting up default
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behaviour.
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Mgmt apps should be able to set the rotation rate for virtualized
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block devices, based on characteristics of the host storage in use,
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so that the guest OS gets sensible behaviour out of the box. This
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patch thus adds a 'rotation-rate' parameter for 'scsi-hd' and
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'scsi-block' device types. For the latter, this parameter will be
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ignored unless the host device has TYPE_DISK.
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Signed-off-by: Daniel P. Berrange <berrange@redhat.com>
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Message-Id: <20171004114008.14849-2-berrange@redhat.com>
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Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
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(cherry picked from commit 070f80095ad5b1143b50d2faffd2b1a84292e00d)
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Signed-off-by: John Snow <jsnow@redhat.com>
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Signed-off-by: Miroslav Rezanina <mrezanin@redhat.com>
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---
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 hw/scsi/scsi-disk.c | 20 ++++++++++++++++++++
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 1 file changed, 20 insertions(+)
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diff --git a/hw/scsi/scsi-disk.c b/hw/scsi/scsi-disk.c
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index 8a8b0ab..911c7b7 100644
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--- a/hw/scsi/scsi-disk.c
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+++ b/hw/scsi/scsi-disk.c
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@@ -83,6 +83,14 @@ struct SCSIDiskState
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     char *product;
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     bool tray_open;
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     bool tray_locked;
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+    /*
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+     * 0x0000        - rotation rate not reported
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+     * 0x0001        - non-rotating medium (SSD)
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+     * 0x0002-0x0400 - reserved
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+     * 0x0401-0xffe  - rotations per minute
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+     * 0xffff        - reserved
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+     */
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+    uint16_t rotation_rate;
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 };
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 static int scsi_handle_rw_error(SCSIDiskReq *r, int error);
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@@ -565,6 +573,7 @@ static int scsi_disk_emulate_inquiry(SCSIRequest *req, uint8_t *outbuf)
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             outbuf[buflen++] = 0x83; // device identification
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             if (s->qdev.type == TYPE_DISK) {
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                 outbuf[buflen++] = 0xb0; // block limits
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+                outbuf[buflen++] = 0xb1; /* block device characteristics */
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                 outbuf[buflen++] = 0xb2; // thin provisioning
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             }
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             break;
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@@ -670,6 +679,15 @@ static int scsi_disk_emulate_inquiry(SCSIRequest *req, uint8_t *outbuf)
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             outbuf[31] = unmap_sectors & 0xff;
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             break;
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         }
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+        case 0xb1: /* block device characteristics */
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+        {
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+            buflen = 8;
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+            outbuf[4] = (s->rotation_rate >> 8) & 0xff;
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+            outbuf[5] = s->rotation_rate & 0xff;
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+            outbuf[6] = 0;
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+            outbuf[7] = 0;
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+            break;
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+        }
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         case 0xb2: /* thin provisioning */
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         {
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             buflen = 8;
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@@ -2543,6 +2561,7 @@ static Property scsi_hd_properties[] = {
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     DEFINE_PROP_HEX64("wwn", SCSIDiskState, wwn, 0),
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     DEFINE_PROP_UINT64("max_unmap_size", SCSIDiskState, max_unmap_size,
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                        DEFAULT_MAX_UNMAP_SIZE),
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+    DEFINE_PROP_UINT16("rotation_rate", SCSIDiskState, rotation_rate, 0),
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     DEFINE_BLOCK_CHS_PROPERTIES(SCSIDiskState, qdev.conf),
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     DEFINE_PROP_END_OF_LIST(),
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 };
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@@ -2619,6 +2638,7 @@ static const TypeInfo scsi_cd_info = {
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 static Property scsi_block_properties[] = {
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     DEFINE_PROP_DRIVE("drive", SCSIDiskState, qdev.conf.bs),
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     DEFINE_PROP_INT32("bootindex", SCSIDiskState, qdev.conf.bootindex, -1),
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+    DEFINE_PROP_UINT16("rotation_rate", SCSIDiskState, rotation_rate, 0),
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     DEFINE_PROP_END_OF_LIST(),
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 };
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-- 
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1.8.3.1
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