[Qemu-devel] [RFC PATCH v2 0/8] s390x: Enable virtio-scsi boot from /dev/sgX

[Qemu-devel] [RFC PATCH v2 0/8] s390x: Enable virtio-scsi boot from /dev/sgX

[Eric Farman]

Today, trying to boot a guest from a SCSI LUN on s390x yields the following:

  virtio-blk               = OK
  virtio-scsi and /dev/sdX = OK
  virtio-scsi and /dev/sgX = FAIL

Example of the failing scenario:

  /usr/bin/qemu-system-s390x ...
    -device virtio-scsi-ccw,id=scsi0,devno=fe.0.0001
    -drive file=/dev/sg2,if=none,id=drive0,format=raw
    -device scsi-generic,bus=scsi0.0,channel=0,scsi-id=0,drive=drive0,id=disk0
  LOADPARM=[........]
  Using virtio-scsi.
  Using SCSI scheme.
  ..
  ! virtio-scsi:read_many: STATUS=02 RSPN=70 KEY=0b CODE=00 QLFR=06, sure !

Why do we care?  Well, libvirt converts a virtio-scsi device from the host
SCSI address (host:bus:target:lun) into the associated /dev/sgX device,
which means we can't boot from virtio-scsi and have to rely on virtio-blk
for this action.

The short version of what happens is the host block device driver rejects our
requests because the transfer lengths are too long for it to satisfy.
A virtio-scsi disk connected via scsi-generic is fine as a non-boot device
because the guest kernel is able to break up the requests for us.  So we just
need to handle this situation for the boot process.

Patches 1-3 read the max_sectors parameter for the virtio-scsi controller,
and break up the READ(10) I/Os into something that the host will accept.
If not specified, max_sectors defaults to 65535, but could look like this:

  qemu-system-s390x ...
    -device virtio-scsi-ccw,id=scsi0,devno=fe.0.0001,max_sectors=2048

Patches 4-6 read the max_io_size parameter for the virtio-scsi disk device,
and use the minimum of it and the max_sectors from the controller for breaking
up the READ(10) I/Os.  If not specified, max_io_size defaults to 2147483647
but could look like this:

  qemu-system-s390x ...
    -drive file=/dev/sda,if=none,id=drive0,format=raw ...
    -device scsi-hd,bus=scsi0.0,channel=0,scsi-id=0,
            drive=drive0,id=disk0,max_io_size=1048576

In the two examples above, the maximum parameters are equivalent due to the
controller parameter measuring 512-byte blocks, and the disk measuring bytes.

Patch 7 establishes a workable default, in case neither the controller nor
the disk have the parameters specified (and thus the overly large defaults
are taken), or if they are set to something beyond what we can boot from.

Patch 8 rebuilds the s390-ccw BIOS with this entire patch set.

Changelog:

RFC v2:
 - Dropped patch outside the pc-bios/s390-ccw/ tree
 - Added Christian's r-b to patch 1 (formerly patch 2)
 - Added EVPD Inquiry calls to retrieve Block Limits page if supported
 - Added a default if Block Limits page is not supported, or response is
   still way to big to allow boot
RFC v1:
 - https://lists.nongnu.org/archive/html/qemu-devel/2017-04/msg05121.html

Eric Farman (8):
  pc-bios/s390-ccw: Remove duplicate blk_factor adjustment
  pc-bios/s390-ccw: Move SCSI block factor to outer read
  pc-bios/s390-ccw: Break up virtio-scsi read into multiples
  pc-bios/s390-ccw: Refactor scsi_inquiry function
  pc-bios/s390-ccw: Get list of supported VPD pages
  pc-bios/s390-ccw: Get Block Limits VPD device data
  pc-bios/s390-ccw: Build a reasonable max_sectors limit
  pc-bios/s390-ccw.img: rebuild image

 pc-bios/s390-ccw.img           | Bin 26472 -> 26480 bytes
 pc-bios/s390-ccw/s390-ccw.h    |   7 ++++
 pc-bios/s390-ccw/scsi.h        |  30 +++++++++++++++
 pc-bios/s390-ccw/virtio-scsi.c |  85 +++++++++++++++++++++++++++++++++++------
 pc-bios/s390-ccw/virtio-scsi.h |   2 +
 pc-bios/s390-ccw/virtio.h      |   1 +
 6 files changed, 114 insertions(+), 11 deletions(-)

-- 
2.10.2

[Qemu-devel] [RFC PATCH v2 1/8] pc-bios/s390-ccw: Remove duplicate blk_factor adjustment

[Eric Farman]

When using virtio-scsi, we multiply the READ(10) data_size by
a block factor twice when building the I/O.  This is fine,
since it's only 1 for SCSI disks, but let's clean it up.

Signed-off-by: Eric Farman <farman@linux.vnet.ibm.com>
Reviewed-by: Christian Borntraeger <borntraeger@de.ibm.com>
---
 pc-bios/s390-ccw/virtio-scsi.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/pc-bios/s390-ccw/virtio-scsi.c b/pc-bios/s390-ccw/virtio-scsi.c
index d850a8d..69b7a93 100644
--- a/pc-bios/s390-ccw/virtio-scsi.c
+++ b/pc-bios/s390-ccw/virtio-scsi.c
@@ -154,7 +154,7 @@ static bool scsi_read_10(VDev *vdev,
     VirtioCmd read_10[] = {
         { &req, sizeof(req), VRING_DESC_F_NEXT },
         { &resp, sizeof(resp), VRING_DESC_F_WRITE | VRING_DESC_F_NEXT },
-        { data, data_size * f, VRING_DESC_F_WRITE },
+        { data, data_size, VRING_DESC_F_WRITE },
     };
 
     debug_print_int("read_10  sector", sector);
-- 
2.10.2

[Qemu-devel] [RFC PATCH v2 2/8] pc-bios/s390-ccw: Move SCSI block factor to outer read

[Eric Farman]

Simple refactoring so that the blk_factor adjustment is
moved into virtio_scsi_read_many routine, in preparation
for another change.

Signed-off-by: Eric Farman <farman@linux.vnet.ibm.com>
---
 pc-bios/s390-ccw/virtio-scsi.c | 14 ++++++++------
 1 file changed, 8 insertions(+), 6 deletions(-)

diff --git a/pc-bios/s390-ccw/virtio-scsi.c b/pc-bios/s390-ccw/virtio-scsi.c
index 69b7a93..6d070e2 100644
--- a/pc-bios/s390-ccw/virtio-scsi.c
+++ b/pc-bios/s390-ccw/virtio-scsi.c
@@ -142,14 +142,13 @@ static bool scsi_report_luns(VDev *vdev, void *data, uint32_t data_size)
 }
 
 static bool scsi_read_10(VDev *vdev,
-                         ulong sector, int sectors, void *data)
+                         ulong sector, int sectors, void *data,
+                         unsigned int data_size)
 {
-    int f = vdev->blk_factor;
-    unsigned int data_size = sectors * virtio_get_block_size() * f;
     ScsiCdbRead10 cdb = {
         .command = 0x28,
-        .lba = sector * f,
-        .xfer_length = sectors * f,
+        .lba = sector,
+        .xfer_length = sectors,
     };
     VirtioCmd read_10[] = {
         { &req, sizeof(req), VRING_DESC_F_NEXT },
@@ -255,7 +254,10 @@ static void virtio_scsi_locate_device(VDev *vdev)
 int virtio_scsi_read_many(VDev *vdev,
                           ulong sector, void *load_addr, int sec_num)
 {
-    if (!scsi_read_10(vdev, sector, sec_num, load_addr)) {
+    int f = vdev->blk_factor;
+    unsigned int data_size = sec_num * virtio_get_block_size() * f;
+
+    if (!scsi_read_10(vdev, sector * f, sec_num * f, load_addr, data_size)) {
         virtio_scsi_verify_response(&resp, "virtio-scsi:read_many");
     }
 
-- 
2.10.2

[Qemu-devel] [RFC PATCH v2 3/8] pc-bios/s390-ccw: Break up virtio-scsi read into multiples

[Eric Farman]

A virtio-scsi request that goes through the host sd driver and exceeds
the maximum transfer size is automatically broken up for us.  But the
equivalent request going to the sg driver presumes that any length
requirements have already been honored.

Let's use the max_sectors field on the virtio-scsi controller device,
and break up all requests (both sd and sg) to avoid this problem.

Signed-off-by: Eric Farman <farman@linux.vnet.ibm.com>
---
 pc-bios/s390-ccw/s390-ccw.h    |  7 +++++++
 pc-bios/s390-ccw/virtio-scsi.c | 20 +++++++++++++++-----
 2 files changed, 22 insertions(+), 5 deletions(-)

diff --git a/pc-bios/s390-ccw/s390-ccw.h b/pc-bios/s390-ccw/s390-ccw.h
index 07d8cbc..2089274 100644
--- a/pc-bios/s390-ccw/s390-ccw.h
+++ b/pc-bios/s390-ccw/s390-ccw.h
@@ -42,6 +42,13 @@ typedef unsigned long long __u64;
 #ifndef NULL
 #define NULL    0
 #endif
+#ifndef MIN
+#define MIN(a, b) (((a) < (b)) ? (a) : (b))
+#endif
+#ifndef MIN_NON_ZERO
+#define MIN_NON_ZERO(a, b) ((a) == 0 ? (b) : \
+                            ((b) == 0 ? (a) : (MIN(a, b))))
+#endif
 
 #include "cio.h"
 #include "iplb.h"
diff --git a/pc-bios/s390-ccw/virtio-scsi.c b/pc-bios/s390-ccw/virtio-scsi.c
index 6d070e2..ff65e2e 100644
--- a/pc-bios/s390-ccw/virtio-scsi.c
+++ b/pc-bios/s390-ccw/virtio-scsi.c
@@ -202,6 +202,7 @@ static void virtio_scsi_locate_device(VDev *vdev)
     debug_print_int("config.scsi.max_channel", vdev->config.scsi.max_channel);
     debug_print_int("config.scsi.max_target ", vdev->config.scsi.max_target);
     debug_print_int("config.scsi.max_lun    ", vdev->config.scsi.max_lun);
+    debug_print_int("config.scsi.max_sectors", vdev->config.scsi.max_sectors);
 
     if (vdev->scsi_device_selected) {
         sdev->channel = vdev->selected_scsi_device.channel;
@@ -254,12 +255,21 @@ static void virtio_scsi_locate_device(VDev *vdev)
 int virtio_scsi_read_many(VDev *vdev,
                           ulong sector, void *load_addr, int sec_num)
 {
+    int sector_count;
     int f = vdev->blk_factor;
-    unsigned int data_size = sec_num * virtio_get_block_size() * f;
-
-    if (!scsi_read_10(vdev, sector * f, sec_num * f, load_addr, data_size)) {
-        virtio_scsi_verify_response(&resp, "virtio-scsi:read_many");
-    }
+    unsigned int data_size;
+
+    do {
+        sector_count = MIN_NON_ZERO(sec_num, vdev->config.scsi.max_sectors);
+        data_size = sector_count * virtio_get_block_size() * f;
+        if (!scsi_read_10(vdev, sector * f, sector_count * f, load_addr,
+                          data_size)) {
+            virtio_scsi_verify_response(&resp, "virtio-scsi:read_many");
+        }
+        load_addr += data_size;
+        sector += sector_count;
+        sec_num -= sector_count;
+    } while (sec_num > 0);
 
     return 0;
 }
-- 
2.10.2

[Qemu-devel] [RFC PATCH v2 4/8] pc-bios/s390-ccw: Refactor scsi_inquiry function

[Eric Farman]

If we want to issue any of the SCSI Inquiry EVPD pages,
which we do, we could use this function to issue both types
of commands with a little bit of refactoring.

Signed-off-by: Eric Farman <farman@linux.vnet.ibm.com>
---
 pc-bios/s390-ccw/scsi.h        |  6 ++++++
 pc-bios/s390-ccw/virtio-scsi.c | 10 ++++++++--
 2 files changed, 14 insertions(+), 2 deletions(-)

diff --git a/pc-bios/s390-ccw/scsi.h b/pc-bios/s390-ccw/scsi.h
index fc830f7..83ffaef 100644
--- a/pc-bios/s390-ccw/scsi.h
+++ b/pc-bios/s390-ccw/scsi.h
@@ -26,6 +26,12 @@
 #define SCSI_SENSE_KEY_NO_SENSE                 0
 #define SCSI_SENSE_KEY_UNIT_ATTENTION           6
 
+/* SCSI Inquiry Types */
+#define SCSI_INQUIRY_STANDARD                   0x00U
+
+/* SCSI Inquiry Pages */
+#define SCSI_INQUIRY_STANDARD_NONE              0x00U
+
 union ScsiLun {
     uint64_t v64;        /* numeric shortcut                             */
     uint8_t  v8[8];      /* generic 8 bytes representation               */
diff --git a/pc-bios/s390-ccw/virtio-scsi.c b/pc-bios/s390-ccw/virtio-scsi.c
index ff65e2e..9d2e14c 100644
--- a/pc-bios/s390-ccw/virtio-scsi.c
+++ b/pc-bios/s390-ccw/virtio-scsi.c
@@ -89,10 +89,13 @@ static void vs_run(const char *title, VirtioCmd *cmd, VDev *vdev,
 
 /* SCSI protocol implementation routines */
 
-static bool scsi_inquiry(VDev *vdev, void *data, uint32_t data_size)
+static bool scsi_inquiry(VDev *vdev, uint8_t evpd, uint8_t page,
+                         void *data, uint32_t data_size)
 {
     ScsiCdbInquiry cdb = {
         .command = 0x12,
+        .b1 = evpd,
+        .b2 = page,
         .alloc_len = data_size < 65535 ? data_size : 65535,
     };
     VirtioCmd inquiry[] = {
@@ -346,7 +349,10 @@ void virtio_scsi_setup(VDev *vdev)
     }
 
     /* read and cache SCSI INQUIRY response */
-    if (!scsi_inquiry(vdev, scsi_inquiry_std_response,
+    if (!scsi_inquiry(vdev,
+                      SCSI_INQUIRY_STANDARD,
+                      SCSI_INQUIRY_STANDARD_NONE,
+                      scsi_inquiry_std_response,
                       sizeof(scsi_inquiry_std_response))) {
         virtio_scsi_verify_response(&resp, "virtio-scsi:setup:inquiry");
     }
-- 
2.10.2

[Qemu-devel] [RFC PATCH v2 5/8] pc-bios/s390-ccw: Get list of supported VPD pages

[Eric Farman]

The "Supported Pages" Inquiry EVPD page is mandatory for all SCSI devices,
and is used as a gateway for what VPD pages the device actually supports.
Let's issue this Inquiry, and dump that list with the debug facility.

Signed-off-by: Eric Farman <farman@linux.vnet.ibm.com>
---
 pc-bios/s390-ccw/scsi.h        | 10 ++++++++++
 pc-bios/s390-ccw/virtio-scsi.c | 17 +++++++++++++++++
 2 files changed, 27 insertions(+)

diff --git a/pc-bios/s390-ccw/scsi.h b/pc-bios/s390-ccw/scsi.h
index 83ffaef..803eff8 100644
--- a/pc-bios/s390-ccw/scsi.h
+++ b/pc-bios/s390-ccw/scsi.h
@@ -28,9 +28,11 @@
 
 /* SCSI Inquiry Types */
 #define SCSI_INQUIRY_STANDARD                   0x00U
+#define SCSI_INQUIRY_EVPD                       0x01U
 
 /* SCSI Inquiry Pages */
 #define SCSI_INQUIRY_STANDARD_NONE              0x00U
+#define SCSI_INQUIRY_EVPD_SUPPORTED_PAGES       0x00U
 
 union ScsiLun {
     uint64_t v64;        /* numeric shortcut                             */
@@ -77,6 +79,14 @@ struct ScsiInquiryStd {
 }  __attribute__((packed));
 typedef struct ScsiInquiryStd ScsiInquiryStd;
 
+struct ScsiInquiryEvpdPages {
+    uint8_t peripheral_qdt; /* b0, use (b0 & 0x1f) to get SCSI_INQ_RDT  */
+    uint8_t page_code;      /* b1                                       */
+    uint16_t page_length;   /* b2..b3 length = N-3                      */
+    uint8_t byte[28];       /* b4..bN Supported EVPD pages (N=31 here)  */
+}  __attribute__((packed));
+typedef struct ScsiInquiryEvpdPages ScsiInquiryEvpdPages;
+
 struct ScsiCdbInquiry {
     uint8_t command;     /* b0, == 0x12         */
     uint8_t b1;          /* b1, |= 0x01 (evpd)  */
diff --git a/pc-bios/s390-ccw/virtio-scsi.c b/pc-bios/s390-ccw/virtio-scsi.c
index 9d2e14c..e34755c 100644
--- a/pc-bios/s390-ccw/virtio-scsi.c
+++ b/pc-bios/s390-ccw/virtio-scsi.c
@@ -19,6 +19,7 @@ static VirtioScsiCmdReq req;
 static VirtioScsiCmdResp resp;
 
 static uint8_t scsi_inquiry_std_response[256];
+static ScsiInquiryEvpdPages scsi_inquiry_evpd_pages_response;
 
 static inline void vs_assert(bool term, const char **msgs)
 {
@@ -319,6 +320,8 @@ void virtio_scsi_setup(VDev *vdev)
     int retry_test_unit_ready = 3;
     uint8_t data[256];
     uint32_t data_size = sizeof(data);
+    ScsiInquiryEvpdPages *evpd = &scsi_inquiry_evpd_pages_response;
+    int i;
 
     vdev->scsi_device = &default_scsi_device;
     virtio_scsi_locate_device(vdev);
@@ -363,6 +366,20 @@ void virtio_scsi_setup(VDev *vdev)
         vdev->scsi_block_size = VIRTIO_ISO_BLOCK_SIZE;
     }
 
+    if (!scsi_inquiry(vdev,
+                      SCSI_INQUIRY_EVPD,
+                      SCSI_INQUIRY_EVPD_SUPPORTED_PAGES,
+                      evpd,
+                      sizeof(*evpd))) {
+        virtio_scsi_verify_response(&resp, "virtio-scsi:setup:supported_pages");
+    }
+
+    debug_print_int("EVPD length", evpd->page_length);
+
+    for (i = 0; i <= evpd->page_length; i++) {
+        debug_print_int("supported EVPD page", evpd->byte[i]);
+    }
+
     if (!scsi_read_capacity(vdev, data, data_size)) {
         virtio_scsi_verify_response(&resp, "virtio-scsi:setup:read_capacity");
     }
-- 
2.10.2

[Qemu-devel] [RFC PATCH v2 6/8] pc-bios/s390-ccw: Get Block Limits VPD device data

[Eric Farman]

The "Block Limits" Inquiry VPD page is optional for any SCSI device,
but if it's supported it provides a hint of the maximum I/O transfer
length for this particular device. If this page is supported by the
disk, let's issue that Inquiry and use the minimum of it and the
SCSI controller limit. That will cover this scenario:

  qemu-system-s390x ...
    -device virtio-scsi-ccw,id=scsi0,max_sectors=32768 ...
    -drive file=/dev/sda,if=none,id=drive0,format=raw ...
    -device scsi-hd,bus=scsi0.0,channel=0,scsi-id=0,
            drive=drive0,id=disk0,max_io_size=1048576

controller: 32768 sectors x 512 bytes/sector = 16777216 bytes
      disk:                                     1048576 bytes

Now that we have a limit for a virtio-scsi disk, compare that with the
limit for the virtio-scsi controller when we actually build the I/O.
The minimum of these two limits should be the one we use.

Signed-off-by: Eric Farman <farman@linux.vnet.ibm.com>
---
 pc-bios/s390-ccw/scsi.h        | 14 ++++++++++++++
 pc-bios/s390-ccw/virtio-scsi.c | 21 ++++++++++++++++++++-
 pc-bios/s390-ccw/virtio.h      |  1 +
 3 files changed, 35 insertions(+), 1 deletion(-)

diff --git a/pc-bios/s390-ccw/scsi.h b/pc-bios/s390-ccw/scsi.h
index 803eff8..fe3fd5a 100644
--- a/pc-bios/s390-ccw/scsi.h
+++ b/pc-bios/s390-ccw/scsi.h
@@ -33,6 +33,7 @@
 /* SCSI Inquiry Pages */
 #define SCSI_INQUIRY_STANDARD_NONE              0x00U
 #define SCSI_INQUIRY_EVPD_SUPPORTED_PAGES       0x00U
+#define SCSI_INQUIRY_EVPD_BLOCK_LIMITS          0xb0U
 
 union ScsiLun {
     uint64_t v64;        /* numeric shortcut                             */
@@ -87,6 +88,19 @@ struct ScsiInquiryEvpdPages {
 }  __attribute__((packed));
 typedef struct ScsiInquiryEvpdPages ScsiInquiryEvpdPages;
 
+struct ScsiInquiryEvpdBl {
+    uint8_t peripheral_qdt; /* b0, use (b0 & 0x1f) to get SCSI_INQ_RDT  */
+    uint8_t page_code;
+    uint16_t page_length;
+    uint8_t b4;
+    uint8_t b5;
+    uint16_t b6;
+    uint32_t max_transfer;  /* b8                                       */
+    uint32_t b12[7];        /* b12..b43 (defined fields)                */
+    uint32_t b44[5];        /* b44..b63 (reserved fields)               */
+}  __attribute__((packed));
+typedef struct ScsiInquiryEvpdBl ScsiInquiryEvpdBl;
+
 struct ScsiCdbInquiry {
     uint8_t command;     /* b0, == 0x12         */
     uint8_t b1;          /* b1, |= 0x01 (evpd)  */
diff --git a/pc-bios/s390-ccw/virtio-scsi.c b/pc-bios/s390-ccw/virtio-scsi.c
index e34755c..b722f25 100644
--- a/pc-bios/s390-ccw/virtio-scsi.c
+++ b/pc-bios/s390-ccw/virtio-scsi.c
@@ -20,6 +20,7 @@ static VirtioScsiCmdResp resp;
 
 static uint8_t scsi_inquiry_std_response[256];
 static ScsiInquiryEvpdPages scsi_inquiry_evpd_pages_response;
+static ScsiInquiryEvpdBl scsi_inquiry_evpd_bl_response;
 
 static inline void vs_assert(bool term, const char **msgs)
 {
@@ -262,9 +263,11 @@ int virtio_scsi_read_many(VDev *vdev,
     int sector_count;
     int f = vdev->blk_factor;
     unsigned int data_size;
+    unsigned int max_transfer = MIN_NON_ZERO(vdev->config.scsi.max_sectors,
+                                             vdev->max_transfer);
 
     do {
-        sector_count = MIN_NON_ZERO(sec_num, vdev->config.scsi.max_sectors);
+        sector_count = MIN_NON_ZERO(sec_num, max_transfer);
         data_size = sector_count * virtio_get_block_size() * f;
         if (!scsi_read_10(vdev, sector * f, sector_count * f, load_addr,
                           data_size)) {
@@ -321,6 +324,7 @@ void virtio_scsi_setup(VDev *vdev)
     uint8_t data[256];
     uint32_t data_size = sizeof(data);
     ScsiInquiryEvpdPages *evpd = &scsi_inquiry_evpd_pages_response;
+    ScsiInquiryEvpdBl *evpd_bl = &scsi_inquiry_evpd_bl_response;
     int i;
 
     vdev->scsi_device = &default_scsi_device;
@@ -378,6 +382,21 @@ void virtio_scsi_setup(VDev *vdev)
 
     for (i = 0; i <= evpd->page_length; i++) {
         debug_print_int("supported EVPD page", evpd->byte[i]);
+
+        if (evpd->byte[i] != SCSI_INQUIRY_EVPD_BLOCK_LIMITS) {
+            continue;
+        }
+
+        if (!scsi_inquiry(vdev,
+                          SCSI_INQUIRY_EVPD,
+                          SCSI_INQUIRY_EVPD_BLOCK_LIMITS,
+                          evpd_bl,
+                          sizeof(*evpd_bl))) {
+            virtio_scsi_verify_response(&resp, "virtio-scsi:setup:blocklimits");
+        }
+
+        debug_print_int("max transfer", evpd_bl->max_transfer);
+        vdev->max_transfer = evpd_bl->max_transfer;
     }
 
     if (!scsi_read_capacity(vdev, data, data_size)) {
diff --git a/pc-bios/s390-ccw/virtio.h b/pc-bios/s390-ccw/virtio.h
index 3388a42..1eaf865 100644
--- a/pc-bios/s390-ccw/virtio.h
+++ b/pc-bios/s390-ccw/virtio.h
@@ -277,6 +277,7 @@ struct VDev {
     bool scsi_device_selected;
     ScsiDevice selected_scsi_device;
     uint64_t netboot_start_addr;
+    uint32_t max_transfer;
 };
 typedef struct VDev VDev;
 
-- 
2.10.2

[Qemu-devel] [RFC PATCH v2 7/8] pc-bios/s390-ccw: Build a reasonable max_sectors limit

[Eric Farman]

Now that we've read all the possible limits that have been defined for
a virtio-scsi controller and the disk we're booting from, it's possible
that we are STILL going to exceed the limits of the host device.
For example, a "-device scsi-generic" device does not support the
Block Limits VPD page.

So, let's fallback to something that seems to work for most boot
configurations if larger values were specified (including if nothing
was explicitly specified, and we took default values).

Signed-off-by: Eric Farman <farman@linux.vnet.ibm.com>
---
 pc-bios/s390-ccw/virtio-scsi.c | 9 +++++++++
 pc-bios/s390-ccw/virtio-scsi.h | 2 ++
 2 files changed, 11 insertions(+)

diff --git a/pc-bios/s390-ccw/virtio-scsi.c b/pc-bios/s390-ccw/virtio-scsi.c
index b722f25..f61ecf0 100644
--- a/pc-bios/s390-ccw/virtio-scsi.c
+++ b/pc-bios/s390-ccw/virtio-scsi.c
@@ -399,6 +399,15 @@ void virtio_scsi_setup(VDev *vdev)
         vdev->max_transfer = evpd_bl->max_transfer;
     }
 
+    /*
+     * The host sg driver will often be unhappy with particularly large
+     * I/Os that exceed the block iovec limits.  Let's enforce something
+     * reasonable, despite what the device configuration tells us.
+     */
+
+    vdev->max_transfer = MIN_NON_ZERO(VIRTIO_SCSI_MAX_SECTORS,
+                                      vdev->max_transfer);
+
     if (!scsi_read_capacity(vdev, data, data_size)) {
         virtio_scsi_verify_response(&resp, "virtio-scsi:setup:read_capacity");
     }
diff --git a/pc-bios/s390-ccw/virtio-scsi.h b/pc-bios/s390-ccw/virtio-scsi.h
index f50b38b..4c4f4bb 100644
--- a/pc-bios/s390-ccw/virtio-scsi.h
+++ b/pc-bios/s390-ccw/virtio-scsi.h
@@ -19,6 +19,8 @@
 #define VIRTIO_SCSI_CDB_SIZE   SCSI_DEFAULT_CDB_SIZE
 #define VIRTIO_SCSI_SENSE_SIZE SCSI_DEFAULT_SENSE_SIZE
 
+#define VIRTIO_SCSI_MAX_SECTORS 2048
+
 /* command-specific response values */
 #define VIRTIO_SCSI_S_OK                     0x00
 #define VIRTIO_SCSI_S_BAD_TARGET             0x03
-- 
2.10.2

[Qemu-devel] [RFC PATCH v2 8/8] pc-bios/s390-ccw.img: rebuild image

[Eric Farman]

Contains the following commits:
- pc-bios/s390-ccw: Remove duplicate blk_factor adjustment
- pc-bios/s390-ccw: Move SCSI block factor to outer read
- pc-bios/s390-ccw: Break up virtio-scsi read into multiples
- pc-bios/s390-ccw: Refactor scsi_inquiry function
- pc-bios/s390-ccw: Get list of supported EVPD pages
- pc-bios/s390-ccw: Get Block Limits VPD device data
- pc-bios/s390-ccw: Build a reasonable max_sectors limit

Signed-off-by: Eric Farman <farman@linux.vnet.ibm.com>
---
 pc-bios/s390-ccw.img | Bin 26472 -> 26480 bytes
 1 file changed, 0 insertions(+), 0 deletions(-)

diff --git a/pc-bios/s390-ccw.img b/pc-bios/s390-ccw.img
index 0b01d49495c607b67d3f1b2359395534631deb88..5ad056400073c7e1c5e862576c76f0e674ff3c60 100644
GIT binary patch
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-- 
2.10.2

Re: [Qemu-devel] [RFC PATCH v2 0/8] s390x: Enable virtio-scsi boot from /dev/sgX

[Cornelia Huck]

On Wed, 10 May 2017 17:53:51 +0200
Eric Farman <farman@linux.vnet.ibm.com> wrote:

> Today, trying to boot a guest from a SCSI LUN on s390x yields the following:
> 
>   virtio-blk               = OK
>   virtio-scsi and /dev/sdX = OK
>   virtio-scsi and /dev/sgX = FAIL
> 
> Example of the failing scenario:
> 
>   /usr/bin/qemu-system-s390x ...
>     -device virtio-scsi-ccw,id=scsi0,devno=fe.0.0001
>     -drive file=/dev/sg2,if=none,id=drive0,format=raw
>     -device scsi-generic,bus=scsi0.0,channel=0,scsi-id=0,drive=drive0,id=disk0
>   LOADPARM=[........]
>   Using virtio-scsi.
>   Using SCSI scheme.
>   ..
>   ! virtio-scsi:read_many: STATUS=02 RSPN=70 KEY=0b CODE=00 QLFR=06, sure !
> 
> Why do we care?  Well, libvirt converts a virtio-scsi device from the host
> SCSI address (host:bus:target:lun) into the associated /dev/sgX device,
> which means we can't boot from virtio-scsi and have to rely on virtio-blk
> for this action.
> 
> The short version of what happens is the host block device driver rejects our
> requests because the transfer lengths are too long for it to satisfy.
> A virtio-scsi disk connected via scsi-generic is fine as a non-boot device
> because the guest kernel is able to break up the requests for us.  So we just
> need to handle this situation for the boot process.
> 
> Patches 1-3 read the max_sectors parameter for the virtio-scsi controller,
> and break up the READ(10) I/Os into something that the host will accept.
> If not specified, max_sectors defaults to 65535, but could look like this:
> 
>   qemu-system-s390x ...
>     -device virtio-scsi-ccw,id=scsi0,devno=fe.0.0001,max_sectors=2048
> 
> Patches 4-6 read the max_io_size parameter for the virtio-scsi disk device,
> and use the minimum of it and the max_sectors from the controller for breaking
> up the READ(10) I/Os.  If not specified, max_io_size defaults to 2147483647
> but could look like this:
> 
>   qemu-system-s390x ...
>     -drive file=/dev/sda,if=none,id=drive0,format=raw ...
>     -device scsi-hd,bus=scsi0.0,channel=0,scsi-id=0,
>             drive=drive0,id=disk0,max_io_size=1048576
> 
> In the two examples above, the maximum parameters are equivalent due to the
> controller parameter measuring 512-byte blocks, and the disk measuring bytes.
> 
> Patch 7 establishes a workable default, in case neither the controller nor
> the disk have the parameters specified (and thus the overly large defaults
> are taken), or if they are set to something beyond what we can boot from.
> 
> Patch 8 rebuilds the s390-ccw BIOS with this entire patch set.

This patch set looks reasonable to me, but I have not delved into the
scsi particulars :)

The code changes seem to be fine, so if someone with more scsi
knowledge than me could give their ok as well, I'll be happy to take
this through my s390 tree.

Re: [Qemu-devel] [RFC PATCH v2 0/8] s390x: Enable virtio-scsi boot from /dev/sgX

[Christian Borntraeger]

On 05/10/2017 05:53 PM, Eric Farman wrote:
> Today, trying to boot a guest from a SCSI LUN on s390x yields the following:
> 
>   virtio-blk               = OK
>   virtio-scsi and /dev/sdX = OK
>   virtio-scsi and /dev/sgX = FAIL
> 
> Example of the failing scenario:
> 
>   /usr/bin/qemu-system-s390x ...
>     -device virtio-scsi-ccw,id=scsi0,devno=fe.0.0001
>     -drive file=/dev/sg2,if=none,id=drive0,format=raw
>     -device scsi-generic,bus=scsi0.0,channel=0,scsi-id=0,drive=drive0,id=disk0
>   LOADPARM=[........]
>   Using virtio-scsi.
>   Using SCSI scheme.
>   ..
>   ! virtio-scsi:read_many: STATUS=02 RSPN=70 KEY=0b CODE=00 QLFR=06, sure !
> 
> Why do we care?  Well, libvirt converts a virtio-scsi device from the host
> SCSI address (host:bus:target:lun) into the associated /dev/sgX device,
> which means we can't boot from virtio-scsi and have to rely on virtio-blk
> for this action.
> 
> The short version of what happens is the host block device driver rejects our
> requests because the transfer lengths are too long for it to satisfy.
> A virtio-scsi disk connected via scsi-generic is fine as a non-boot device
> because the guest kernel is able to break up the requests for us.  So we just
> need to handle this situation for the boot process.
> 
> Patches 1-3 read the max_sectors parameter for the virtio-scsi controller,
> and break up the READ(10) I/Os into something that the host will accept.
> If not specified, max_sectors defaults to 65535, but could look like this:
> 
>   qemu-system-s390x ...
>     -device virtio-scsi-ccw,id=scsi0,devno=fe.0.0001,max_sectors=2048
> 
> Patches 4-6 read the max_io_size parameter for the virtio-scsi disk device,
> and use the minimum of it and the max_sectors from the controller for breaking
> up the READ(10) I/Os.  If not specified, max_io_size defaults to 2147483647
> but could look like this:
> 
>   qemu-system-s390x ...
>     -drive file=/dev/sda,if=none,id=drive0,format=raw ...
>     -device scsi-hd,bus=scsi0.0,channel=0,scsi-id=0,
>             drive=drive0,id=disk0,max_io_size=1048576
> 
> In the two examples above, the maximum parameters are equivalent due to the
> controller parameter measuring 512-byte blocks, and the disk measuring bytes.
> 
> Patch 7 establishes a workable default, in case neither the controller nor
> the disk have the parameters specified (and thus the overly large defaults
> are taken), or if they are set to something beyond what we can boot from.
> 
> Patch 8 rebuilds the s390-ccw BIOS with this entire patch set.
> 
> Changelog:
> 
> RFC v2:
>  - Dropped patch outside the pc-bios/s390-ccw/ tree
>  - Added Christian's r-b to patch 1 (formerly patch 2)
>  - Added EVPD Inquiry calls to retrieve Block Limits page if supported
>  - Added a default if Block Limits page is not supported, or response is
>    still way to big to allow boot
> RFC v1:
>  - https://lists.nongnu.org/archive/html/qemu-devel/2017-04/msg05121.html
> 
> Eric Farman (8):
>   pc-bios/s390-ccw: Remove duplicate blk_factor adjustment
>   pc-bios/s390-ccw: Move SCSI block factor to outer read
>   pc-bios/s390-ccw: Break up virtio-scsi read into multiples
>   pc-bios/s390-ccw: Refactor scsi_inquiry function
>   pc-bios/s390-ccw: Get list of supported VPD pages
>   pc-bios/s390-ccw: Get Block Limits VPD device data
>   pc-bios/s390-ccw: Build a reasonable max_sectors limit
>   pc-bios/s390-ccw.img: rebuild image
> 
>  pc-bios/s390-ccw.img           | Bin 26472 -> 26480 bytes
>  pc-bios/s390-ccw/s390-ccw.h    |   7 ++++
>  pc-bios/s390-ccw/scsi.h        |  30 +++++++++++++++
>  pc-bios/s390-ccw/virtio-scsi.c |  85 +++++++++++++++++++++++++++++++++++------
>  pc-bios/s390-ccw/virtio-scsi.h |   2 +
>  pc-bios/s390-ccw/virtio.h      |   1 +
>  6 files changed, 114 insertions(+), 11 deletions(-)
> 

Patch set looks good. Conny, can you apply the series?

Re: [Qemu-devel] [RFC PATCH v2 0/8] s390x: Enable virtio-scsi boot from /dev/sgX

[Cornelia Huck]

On Tue, 16 May 2017 15:44:43 +0200
Christian Borntraeger <borntraeger@de.ibm.com> wrote:

> On 05/10/2017 05:53 PM, Eric Farman wrote:
> > Today, trying to boot a guest from a SCSI LUN on s390x yields the following:
> > 
> >   virtio-blk               = OK
> >   virtio-scsi and /dev/sdX = OK
> >   virtio-scsi and /dev/sgX = FAIL
> > 
> > Example of the failing scenario:
> > 
> >   /usr/bin/qemu-system-s390x ...
> >     -device virtio-scsi-ccw,id=scsi0,devno=fe.0.0001
> >     -drive file=/dev/sg2,if=none,id=drive0,format=raw
> >     -device scsi-generic,bus=scsi0.0,channel=0,scsi-id=0,drive=drive0,id=disk0
> >   LOADPARM=[........]
> >   Using virtio-scsi.
> >   Using SCSI scheme.
> >   ..
> >   ! virtio-scsi:read_many: STATUS=02 RSPN=70 KEY=0b CODE=00 QLFR=06, sure !
> > 
> > Why do we care?  Well, libvirt converts a virtio-scsi device from the host
> > SCSI address (host:bus:target:lun) into the associated /dev/sgX device,
> > which means we can't boot from virtio-scsi and have to rely on virtio-blk
> > for this action.
> > 
> > The short version of what happens is the host block device driver rejects our
> > requests because the transfer lengths are too long for it to satisfy.
> > A virtio-scsi disk connected via scsi-generic is fine as a non-boot device
> > because the guest kernel is able to break up the requests for us.  So we just
> > need to handle this situation for the boot process.
> > 
> > Patches 1-3 read the max_sectors parameter for the virtio-scsi controller,
> > and break up the READ(10) I/Os into something that the host will accept.
> > If not specified, max_sectors defaults to 65535, but could look like this:
> > 
> >   qemu-system-s390x ...
> >     -device virtio-scsi-ccw,id=scsi0,devno=fe.0.0001,max_sectors=2048
> > 
> > Patches 4-6 read the max_io_size parameter for the virtio-scsi disk device,
> > and use the minimum of it and the max_sectors from the controller for breaking
> > up the READ(10) I/Os.  If not specified, max_io_size defaults to 2147483647
> > but could look like this:
> > 
> >   qemu-system-s390x ...
> >     -drive file=/dev/sda,if=none,id=drive0,format=raw ...
> >     -device scsi-hd,bus=scsi0.0,channel=0,scsi-id=0,
> >             drive=drive0,id=disk0,max_io_size=1048576
> > 
> > In the two examples above, the maximum parameters are equivalent due to the
> > controller parameter measuring 512-byte blocks, and the disk measuring bytes.
> > 
> > Patch 7 establishes a workable default, in case neither the controller nor
> > the disk have the parameters specified (and thus the overly large defaults
> > are taken), or if they are set to something beyond what we can boot from.
> > 
> > Patch 8 rebuilds the s390-ccw BIOS with this entire patch set.
> > 
> > Changelog:
> > 
> > RFC v2:
> >  - Dropped patch outside the pc-bios/s390-ccw/ tree
> >  - Added Christian's r-b to patch 1 (formerly patch 2)
> >  - Added EVPD Inquiry calls to retrieve Block Limits page if supported
> >  - Added a default if Block Limits page is not supported, or response is
> >    still way to big to allow boot
> > RFC v1:
> >  - https://lists.nongnu.org/archive/html/qemu-devel/2017-04/msg05121.html
> > 
> > Eric Farman (8):
> >   pc-bios/s390-ccw: Remove duplicate blk_factor adjustment
> >   pc-bios/s390-ccw: Move SCSI block factor to outer read
> >   pc-bios/s390-ccw: Break up virtio-scsi read into multiples
> >   pc-bios/s390-ccw: Refactor scsi_inquiry function
> >   pc-bios/s390-ccw: Get list of supported VPD pages
> >   pc-bios/s390-ccw: Get Block Limits VPD device data
> >   pc-bios/s390-ccw: Build a reasonable max_sectors limit
> >   pc-bios/s390-ccw.img: rebuild image
> > 
> >  pc-bios/s390-ccw.img           | Bin 26472 -> 26480 bytes
> >  pc-bios/s390-ccw/s390-ccw.h    |   7 ++++
> >  pc-bios/s390-ccw/scsi.h        |  30 +++++++++++++++
> >  pc-bios/s390-ccw/virtio-scsi.c |  85 +++++++++++++++++++++++++++++++++++------
> >  pc-bios/s390-ccw/virtio-scsi.h |   2 +
> >  pc-bios/s390-ccw/virtio.h      |   1 +
> >  6 files changed, 114 insertions(+), 11 deletions(-)
> > 
> 
> Patch set looks good. Conny, can you apply the series?
> 

I had hoped for some comments from folks more familiar with scsi...

Nevertheless, applied to s390-next.