src/patches/suse-2.6.27.25/patches.xen/xen-blkif-protocol-fallback-hack

   1 Subject: 32-on-64 blkif protocol negotiation fallback for old guests.
   2 From: kraxel@suse.de
   3 References: 244055
   4 Patch-mainline: never.
   5
   6 See the comment below.  Oh well.
   7
   8 ---
   9  drivers/xen/blkback/xenbus.c |   10 +--
  10  drivers/xen/blktap/xenbus.c  |   10 +--
  11  drivers/xen/core/Makefile    |    2
  12  drivers/xen/core/domctl.c    |  133 +++++++++++++++++++++++++++++++++++++++++++
  13  drivers/xen/core/domctl.h    |    2
  14  5 files changed, 148 insertions(+), 9 deletions(-)
  15
  16 Index: head-2008-09-15/drivers/xen/blkback/xenbus.c
  17 ===================================================================
  18 --- head-2008-09-15.orig/drivers/xen/blkback/xenbus.c   2008-09-15 15:10:36.000000000 +0200
  19 +++ head-2008-09-15/drivers/xen/blkback/xenbus.c        2008-09-15 15:10:39.000000000 +0200
  20 @@ -21,6 +21,7 @@
  21  #include <linux/module.h>
  22  #include <linux/kthread.h>
  23  #include "common.h"
  24 +#include "../core/domctl.h"
  25
  26  #undef DPRINTK
  27  #define DPRINTK(fmt, args...)                          \
  28 @@ -488,8 +489,10 @@ static int connect_ring(struct backend_i
  29         be->blkif->blk_protocol = BLKIF_PROTOCOL_NATIVE;
  30         err = xenbus_gather(XBT_NIL, dev->otherend, "protocol",
  31                             "%63s", protocol, NULL);
  32 -       if (err)
  33 -               strcpy(protocol, "unspecified, assuming native");
  34 +       if (err) {
  35 +               strcpy(protocol, "unspecified");
  36 +               be->blkif->blk_protocol = xen_guest_blkif_protocol(be->blkif->domid);
  37 +       }
  38         else if (0 == strcmp(protocol, XEN_IO_PROTO_ABI_NATIVE))
  39                 be->blkif->blk_protocol = BLKIF_PROTOCOL_NATIVE;
  40         else if (0 == strcmp(protocol, XEN_IO_PROTO_ABI_X86_32))
  41 Index: head-2008-09-15/drivers/xen/blktap/xenbus.c
  42 ===================================================================
  43 --- head-2008-09-15.orig/drivers/xen/blktap/xenbus.c    2008-09-15 15:10:36.000000000 +0200
  44 +++ head-2008-09-15/drivers/xen/blktap/xenbus.c 2008-09-15 15:10:39.000000000 +0200
  45 @@ -39,6 +39,7 @@
  46  #include <linux/kthread.h>
  47  #include <xen/xenbus.h>
  48  #include "common.h"
  49 +#include "../core/domctl.h"
  50
  51
  52  struct backend_info
  53 @@ -426,8 +427,10 @@ static int connect_ring(struct backend_i
  54         be->blkif->blk_protocol = BLKIF_PROTOCOL_NATIVE;
  55         err = xenbus_gather(XBT_NIL, dev->otherend, "protocol",
  56                             "%63s", protocol, NULL);
  57 -       if (err)
  58 -               strcpy(protocol, "unspecified, assuming native");
  59 +       if (err) {
  60 +               strcpy(protocol, "unspecified");
  61 +               be->blkif->blk_protocol = xen_guest_blkif_protocol(be->blkif->domid);
  62 +       }
  63         else if (0 == strcmp(protocol, XEN_IO_PROTO_ABI_NATIVE))
  64                 be->blkif->blk_protocol = BLKIF_PROTOCOL_NATIVE;
  65         else if (0 == strcmp(protocol, XEN_IO_PROTO_ABI_X86_32))
  66 Index: head-2008-09-15/drivers/xen/core/Makefile
  67 ===================================================================
  68 --- head-2008-09-15.orig/drivers/xen/core/Makefile      2008-09-15 14:45:31.000000000 +0200
  69 +++ head-2008-09-15/drivers/xen/core/Makefile   2008-09-15 15:10:39.000000000 +0200
  70 @@ -2,7 +2,7 @@
  71  # Makefile for the linux kernel.
  72  #
  73
  74 -obj-y := evtchn.o gnttab.o features.o reboot.o machine_reboot.o firmware.o
  75 +obj-y := evtchn.o gnttab.o features.o reboot.o machine_reboot.o firmware.o domctl.o
  76
  77  obj-$(CONFIG_PCI)              += pci.o
  78  obj-$(CONFIG_PROC_FS)          += xen_proc.o
  79 Index: head-2008-09-15/drivers/xen/core/domctl.c
  80 ===================================================================
  81 --- /dev/null   1970-01-01 00:00:00.000000000 +0000
  82 +++ head-2008-09-15/drivers/xen/core/domctl.c   2008-09-15 15:10:39.000000000 +0200
  83 @@ -0,0 +1,113 @@
  84 +/*
  85 + * !!!  dirty hack alert  !!!
  86 + *
  87 + * Problem: old guests kernels don't have a "protocol" node
  88 + *          in the frontend xenstore directory, so mixing
  89 + *          32 and 64bit domains doesn't work.
  90 + *
  91 + * Upstream plans to solve this in the tools, by letting them
  92 + * create a protocol node.  Which certainly makes sense.
  93 + * But it isn't trivial and isn't done yet.  Too bad.
  94 + *
  95 + * So for the time being we use the get_address_size domctl
  96 + * hypercall for a pretty good guess.  Not nice as the domctl
  97 + * hypercall isn't supposed to be used by the kernel.  Because
  98 + * we don't want to have dependencies between dom0 kernel and
  99 + * xen kernel versions.  Now we have one.  Ouch.
 100 + */
 101 +
 102 +#include <linux/kernel.h>
 103 +#include <linux/module.h>
 104 +#include <asm/hypervisor.h>
 105 +#include <xen/blkif.h>
 106 +
 107 +#include "domctl.h"
 108 +
 109 +/* stuff copied from xen/interface/domctl.h, which we can't
 110 + * include directly for the reasons outlined above .... */
 111 +
 112 +#define XEN_DOMCTL_get_address_size 36
 113 +typedef struct xen_domctl_address_size {
 114 +       uint32_t size;
 115 +} xen_domctl_address_size_t;
 116 +
 117 +typedef __attribute__((aligned(8))) uint64_t uint64_aligned_t;
 118 +
 119 +union xen_domctl {
 120 +       /* v4: sles10 sp1: xen 3.0.4 + 32-on-64 patches */
 121 +       struct {
 122 +               uint32_t cmd;
 123 +               uint32_t interface_version;
 124 +               domid_t  domain;
 125 +               union {
 126 +                       /* left out lots of other struct xen_domctl_foobar */
 127 +                       struct xen_domctl_address_size       address_size;
 128 +                       uint64_t                             dummy_align;
 129 +                       uint8_t                              dummy_pad[128];
 130 +               } u;
 131 +       } v4;
 132 +
 133 +       /* v5: upstream: xen 3.1 */
 134 +       struct {
 135 +               uint32_t cmd;
 136 +               uint32_t interface_version;
 137 +               domid_t  domain;
 138 +               union {
 139 +                       struct xen_domctl_address_size       address_size;
 140 +                       uint64_aligned_t                     dummy_align;
 141 +                       uint8_t                              dummy_pad[128];
 142 +               } u;
 143 +       } v5;
 144 +};
 145 +
 146 +/* The actual code comes here */
 147 +
 148 +static inline int hypervisor_domctl(void *domctl)
 149 +{
 150 +       return _hypercall1(int, domctl, domctl);
 151 +}
 152 +
 153 +int xen_guest_address_size(int domid)
 154 +{
 155 +       union xen_domctl domctl;
 156 +       int low, ret;
 157 +
 158 +#define guest_address_size(ver) do {                                   \
 159 +       memset(&domctl, 0, sizeof(domctl));                             \
 160 +       domctl.v##ver.cmd = XEN_DOMCTL_get_address_size;                \
 161 +       domctl.v##ver.interface_version = low = ver;                    \
 162 +       domctl.v##ver.domain = domid;                                   \
 163 +       ret = hypervisor_domctl(&domctl) ?: domctl.v##ver.u.address_size.size; \
 164 +       if (ret == 32 || ret == 64) {                                   \
 165 +               printk("v" #ver " domctl worked ok: dom%d is %d-bit\n", \
 166 +                      domid, ret);                                     \
 167 +               return ret;                                             \
 168 +       }                                                               \
 169 +} while (0)
 170 +
 171 +       guest_address_size(5);
 172 +#if CONFIG_XEN_COMPAT < 0x030100
 173 +       guest_address_size(4);
 174 +#endif
 175 +
 176 +       ret = BITS_PER_LONG;
 177 +       printk("v%d...5 domctls failed, assuming dom%d is native: %d\n",
 178 +              low, domid, ret);
 179 +
 180 +       return ret;
 181 +}
 182 +EXPORT_SYMBOL_GPL(xen_guest_address_size);
 183 +
 184 +int xen_guest_blkif_protocol(int domid)
 185 +{
 186 +       int address_size = xen_guest_address_size(domid);
 187 +
 188 +       if (address_size == BITS_PER_LONG)
 189 +               return BLKIF_PROTOCOL_NATIVE;
 190 +       if (address_size == 32)
 191 +               return BLKIF_PROTOCOL_X86_32;
 192 +       if (address_size == 64)
 193 +               return BLKIF_PROTOCOL_X86_64;
 194 +       return BLKIF_PROTOCOL_NATIVE;
 195 +}
 196 +EXPORT_SYMBOL_GPL(xen_guest_blkif_protocol);
 197 Index: head-2008-09-15/drivers/xen/core/domctl.h
 198 ===================================================================
 199 --- /dev/null   1970-01-01 00:00:00.000000000 +0000
 200 +++ head-2008-09-15/drivers/xen/core/domctl.h   2008-09-15 15:10:39.000000000 +0200
 201 @@ -0,0 +1,2 @@
 202 +int xen_guest_address_size(int domid);
 203 +int xen_guest_blkif_protocol(int domid);