From 51c8629ca55d0b6e51faffcddfc5e3b10898fc5c Mon Sep 17 00:00:00 2001

From: Paolo Bonzini <pbonzini@redhat.com>

Date: Thu, 20 Dec 2018 12:30:58 +0000

Subject: [PATCH 3/8] hw/scsi: add VPD Block Limits emulation

RH-Author: Paolo Bonzini <pbonzini@redhat.com>

Message-id: <20181220123103.29579-4-pbonzini@redhat.com>

Patchwork-id: 83713

O-Subject: [PATCH 3/8] hw/scsi: add VPD Block Limits emulation

Bugzilla: 1639957

RH-Acked-by: Stefan Hajnoczi <stefanha@redhat.com>

RH-Acked-by: Kevin Wolf <kwolf@redhat.com>

RH-Acked-by: Laurent Vivier <lvivier@redhat.com>

From: Daniel Henrique Barboza <danielhb413@gmail.com>

The VPD Block Limits Inquiry page is optional, allowing SCSI devices

to not implement it. This is the case for devices like the MegaRAID

SAS 9361-8i and Microsemi PM8069.

In case of SCSI passthrough, the response of this request is used by

the QEMU SCSI layer to set the max_io_sectors that the guest

device will support, based on the value of the max_sectors_kb that

the device has set in the host at that time. Without this response,

the guest kernel is free to assume any value of max_io_sectors

for the SCSI device. If this value is greater than the value from

the host, SCSI Sense errors will occur because the guest will send

read/write requests that are larger than the underlying host device

is configured to support. An example of this behavior can be seen

in [1].

A workaround is to set the max_sectors_kb host value back in the guest

kernel (a process that can be automated using rc.local startup scripts

and the like), but this has several drawbacks:

- it can be troublesome if the guest has many passthrough devices that

needs this tuning;

- if a change in max_sectors_kb is made in the host side, manual change

in the guests will also be required;

- during an OS install it is difficult, and sometimes not possible, to

go to a terminal and change the max_sectors_kb prior to the installation.

This means that the disk can't be used during the install process. The

easiest alternative here is to roll back to scsi-hd, install the guest

and then go back to SCSI passthrough when the installation is done and

max_sectors_kb can be set.

An easier way would be to QEMU handle the absence of the Block Limits

VPD device response, setting max_io_sectors accordingly and allowing

the guest to use the device without the hassle.

This patch adds emulation of the Block Limits VPD response for

SCSI passthrough devices of type TYPE_DISK that doesn't support

it. The following changes were made:

- scsi_handle_inquiry_reply will now check the available VPD

pages from the Inquiry EVPD reply. In case the device does not

- a new function called scsi_generic_set_vpd_bl_emulation,

that is called during device realize,  was created to set a

new flag 'needs_vpd_bl_emulation' of the device. This function

retrieves the Inquiry EVPD response of the device to check for

VPD BL support.

- scsi_handle_inquiry_reply will now check the available VPD

pages from the Inquiry EVPD reply in case the device needs

VPD BL emulation, adding the Block Limits page (0xb0) to

the list. This will make the guest kernel aware of the

support that we're now providing by emulation.

- a new function scsi_emulate_block_limits creates the

emulated Block Limits response. This function is called

inside scsi_read_complete in case the device requires

Block Limits VPD emulation and we detected a SCSI Sense

error in the VPD Block Limits reply that was issued

from the guest kernel to the device. This error is

expected: we're reporting support from our side, but

the device isn't aware of it.

With this patch, the guest now queries the Block Limits

page during the device configuration because it is being

advertised in the Supported Pages response. It will either

receive the Block Limits page from the hardware, if it supports

it, or will receive an emulated response from QEMU. At any rate,

the guest now has the information to set the max_sectors_kb

parameter accordingly, sparing the user of SCSI sense errors

that would happen without the emulated response and in the

absence of Block Limits support from the hardware.

[1] https://bugzilla.redhat.com/show_bug.cgi?id=1566195

Fixes: https://bugzilla.redhat.com/show_bug.cgi?id=1566195

Reported-by: Dac Nguyen <dacng@us.ibm.com>

Signed-off-by: Daniel Henrique Barboza <danielhb413@gmail.com>

Message-Id: <20180627172432.11120-4-danielhb413@gmail.com>

Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

(cherry picked from commit a71c775b24ebc664129eb1d9b4c360590353efd5)

Signed-off-by: Danilo C. L. de Paula <ddepaula@redhat.com>

---

 hw/scsi/scsi-disk.c    |   2 +-

 hw/scsi/scsi-generic.c | 132 +++++++++++++++++++++++++++++++++++++++++++++----

 include/hw/scsi/scsi.h |   3 +-

 3 files changed, 125 insertions(+), 12 deletions(-)

diff --git a/hw/scsi/scsi-disk.c b/hw/scsi/scsi-disk.c

index ea86849..b3d53ec 100644

--- a/hw/scsi/scsi-disk.c

+++ b/hw/scsi/scsi-disk.c

@@ -2646,7 +2646,7 @@ static void scsi_block_realize(SCSIDevice *dev, Error **errp)

     s->features |= (1 << SCSI_DISK_F_NO_REMOVABLE_DEVOPS);

     scsi_realize(&s->qdev, errp);

-    scsi_generic_read_device_identification(&s->qdev);

+    scsi_generic_read_device_inquiry(&s->qdev);

 }

 typedef struct SCSIBlockReq {

diff --git a/hw/scsi/scsi-generic.c b/hw/scsi/scsi-generic.c

index c6307a8..4266003 100644

--- a/hw/scsi/scsi-generic.c

+++ b/hw/scsi/scsi-generic.c

@@ -145,6 +145,8 @@ static int execute_command(BlockBackend *blk,

 static void scsi_handle_inquiry_reply(SCSIGenericReq *r, SCSIDevice *s)

 {

+    uint8_t page, page_len;

+

     /*

      *  EVPD set to zero returns the standard INQUIRY data.

      *

@@ -168,22 +170,57 @@ static void scsi_handle_inquiry_reply(SCSIGenericReq *r, SCSIDevice *s)

             s->scsi_version = r->buf[2];

         }

     }

-    if (s->type == TYPE_DISK && r->req.cmd.buf[2] == 0xb0) {

-        uint32_t max_transfer =

-            blk_get_max_transfer(s->conf.blk) / s->blocksize;

-        assert(max_transfer);

-        stl_be_p(&r->buf[8], max_transfer);

-        /* Also take care of the opt xfer len. */

-        stl_be_p(&r->buf[12],

-                 MIN_NON_ZERO(max_transfer, ldl_be_p(&r->buf[12])));

+    if (s->type == TYPE_DISK && (r->req.cmd.buf[1] & 0x01)) {

+        page = r->req.cmd.buf[2];

+        if (page == 0xb0) {

+            uint32_t max_transfer =

+                blk_get_max_transfer(s->conf.blk) / s->blocksize;

+

+            assert(max_transfer);

+            stl_be_p(&r->buf[8], max_transfer);

+            /* Also take care of the opt xfer len. */

+            stl_be_p(&r->buf[12],

+                    MIN_NON_ZERO(max_transfer, ldl_be_p(&r->buf[12])));

+        } else if (page == 0x00 && s->needs_vpd_bl_emulation) {

+            /*

+             * Now we're capable of supplying the VPD Block Limits

+             * response if the hardware can't. Add it in the INQUIRY

+             * Supported VPD pages response in case we are using the

+             * emulation for this device.

+             *

+             * This way, the guest kernel will be aware of the support

+             * and will use it to proper setup the SCSI device.

+             */

+            page_len = r->buf[3];

+            r->buf[page_len + 4] = 0xb0;

+            r->buf[3] = ++page_len;

+        }

     }

 }

+static int scsi_emulate_block_limits(SCSIGenericReq *r)

+{

+    r->buflen = scsi_disk_emulate_vpd_page(&r->req, r->buf);

+    r->io_header.sb_len_wr = 0;

+

+    /*

+    * We have valid contents in the reply buffer but the

+    * io_header can report a sense error coming from

+    * the hardware in scsi_command_complete_noio. Clean

+    * up the io_header to avoid reporting it.

+    */

+    r->io_header.driver_status = 0;

+    r->io_header.status = 0;

+

+    return r->buflen;

+}

+

 static void scsi_read_complete(void * opaque, int ret)

 {

     SCSIGenericReq *r = (SCSIGenericReq *)opaque;

     SCSIDevice *s = r->req.dev;

+    SCSISense sense;

     int len;

     assert(r->req.aiocb != NULL);

@@ -200,6 +237,27 @@ static void scsi_read_complete(void * opaque, int ret)

     DPRINTF("Data ready tag=0x%x len=%d\n", r->req.tag, len);

     r->len = -1;

+

+    /*

+     * Check if this is a VPD Block Limits request that

+     * resulted in sense error but would need emulation.

+     * In this case, emulate a valid VPD response.

+     */

+    if (s->needs_vpd_bl_emulation) {

+        int is_vpd_bl = r->req.cmd.buf[0] == INQUIRY &&

+                         r->req.cmd.buf[1] & 0x01 &&

+                         r->req.cmd.buf[2] == 0xb0;

+

+        if (is_vpd_bl && sg_io_sense_from_errno(-ret, &r->io_header, &sense)) {

+            len = scsi_emulate_block_limits(r);

+            /*

+             * No need to let scsi_read_complete go on and handle an

+             * INQUIRY VPD BL request we created manually.

+             */

+            goto req_complete;

+        }

+    }

+

     if (len == 0) {

         scsi_command_complete_noio(r, 0);

         goto done;

@@ -234,6 +292,8 @@ static void scsi_read_complete(void * opaque, int ret)

     if (r->req.cmd.buf[0] == INQUIRY) {

         scsi_handle_inquiry_reply(r, s);

     }

+

+req_complete:

     scsi_req_data(&r->req, len);

     scsi_req_unref(&r->req);

@@ -435,7 +495,49 @@ int scsi_SG_IO_FROM_DEV(BlockBackend *blk, uint8_t *cmd, uint8_t cmd_size,

     return 0;

 }

-void scsi_generic_read_device_identification(SCSIDevice *s)

+/*

+ * Executes an INQUIRY request with EVPD set to retrieve the

+ * available VPD pages of the device. If the device does

+ * not support the Block Limits page (page 0xb0), set

+ * the needs_vpd_bl_emulation flag for future use.

+ */

+static void scsi_generic_set_vpd_bl_emulation(SCSIDevice *s)

+{

+    uint8_t cmd[6];

+    uint8_t buf[250];

+    uint8_t page_len;

+    int ret, i;

+

+    memset(cmd, 0, sizeof(cmd));

+    memset(buf, 0, sizeof(buf));

+    cmd[0] = INQUIRY;

+    cmd[1] = 1;

+    cmd[2] = 0x00;

+    cmd[4] = sizeof(buf);

+

+    ret = scsi_SG_IO_FROM_DEV(s->conf.blk, cmd, sizeof(cmd),

+                              buf, sizeof(buf));

+    if (ret < 0) {

+        /*

+         * Do not assume anything if we can't retrieve the

+         * INQUIRY response to assert the VPD Block Limits

+         * support.

+         */

+        s->needs_vpd_bl_emulation = false;

+        return;

+    }

+

+    page_len = buf[3];

+    for (i = 4; i < page_len + 4; i++) {

+        if (buf[i] == 0xb0) {

+            s->needs_vpd_bl_emulation = false;

+            return;

+        }

+    }

+    s->needs_vpd_bl_emulation = true;

+}

+

+static void scsi_generic_read_device_identification(SCSIDevice *s)

 {

     uint8_t cmd[6];

     uint8_t buf[250];

@@ -480,6 +582,16 @@ void scsi_generic_read_device_identification(SCSIDevice *s)

     }

 }

+void scsi_generic_read_device_inquiry(SCSIDevice *s)

+{

+    scsi_generic_read_device_identification(s);

+    if (s->type == TYPE_DISK) {

+        scsi_generic_set_vpd_bl_emulation(s);

+    } else {

+        s->needs_vpd_bl_emulation = false;

+    }

+}

+

 static int get_stream_blocksize(BlockBackend *blk)

 {

     uint8_t cmd[6];

@@ -581,7 +693,7 @@ static void scsi_generic_realize(SCSIDevice *s, Error **errp)

     /* Only used by scsi-block, but initialize it nevertheless to be clean.  */

     s->default_scsi_version = -1;

-    scsi_generic_read_device_identification(s);

+    scsi_generic_read_device_inquiry(s);

 }

 const SCSIReqOps scsi_generic_req_ops = {

diff --git a/include/hw/scsi/scsi.h b/include/hw/scsi/scsi.h

index b6e05c4..ee3a411 100644

--- a/include/hw/scsi/scsi.h

+++ b/include/hw/scsi/scsi.h

@@ -87,6 +87,7 @@ struct SCSIDevice

     uint64_t port_wwn;

     int scsi_version;

     int default_scsi_version;

+    bool needs_vpd_bl_emulation;

 };

 extern const VMStateDescription vmstate_scsi_device;

@@ -186,7 +187,7 @@ void scsi_device_purge_requests(SCSIDevice *sdev, SCSISense sense);

 void scsi_device_set_ua(SCSIDevice *sdev, SCSISense sense);

 void scsi_device_report_change(SCSIDevice *dev, SCSISense sense);

 void scsi_device_unit_attention_reported(SCSIDevice *dev);

-void scsi_generic_read_device_identification(SCSIDevice *dev);

+void scsi_generic_read_device_inquiry(SCSIDevice *dev);

 int scsi_device_get_sense(SCSIDevice *dev, uint8_t *buf, int len, bool fixed);

 int scsi_disk_emulate_vpd_page(SCSIRequest *req, uint8_t *outbuf);

 int scsi_SG_IO_FROM_DEV(BlockBackend *blk, uint8_t *cmd, uint8_t cmd_size,

-- 

1.8.3.1