debian/patches/extra/0003-virtio-balloon-use-smaller-config-on-older-guests.patch

   1 From 0000000000000000000000000000000000000000 Mon Sep 17 00:00:00 2001
   2 From: Wolfgang Bumiller <w.bumiller@proxmox.com>
   3 Date: Tue, 2 Jul 2019 09:23:43 +0200
   4 Subject: [PATCH] virtio-balloon: use smaller config on older guests
   5
   6 The increased config size changes its alignment requirements
   7 preventing guests from migrating from old qemu versions if
   8 their balloon mapping isn't stricter aligned.
   9 So base the default config size on the machine version.
  10
  11 Signed-off-by: Wolfgang Bumiller <w.bumiller@proxmox.com>
  12 ---
  13  hw/i386/pc.c                       |  2 ++
  14  hw/virtio/virtio-balloon.c         | 52 +++++++++++++++++++++++++++---
  15  include/hw/virtio/virtio-balloon.h |  1 +
  16  3 files changed, 51 insertions(+), 4 deletions(-)
  17
  18 diff --git a/hw/i386/pc.c b/hw/i386/pc.c
  19 index f2c15bf1f2..a6c01203f5 100644
  20 --- a/hw/i386/pc.c
  21 +++ b/hw/i386/pc.c
  22 @@ -77,6 +77,7 @@
  23  #include "hw/i386/intel_iommu.h"
  24  #include "hw/net/ne2000-isa.h"
  25  #include "standard-headers/asm-x86/bootparam.h"
  26 +#include "hw/virtio/virtio-balloon.h"
  27
  28  /* debug PC/ISA interrupts */
  29  //#define DEBUG_IRQ
  30 @@ -137,6 +138,7 @@ GlobalProperty pc_compat_3_1[] = {
  31      { "Icelake-Server" "-" TYPE_X86_CPU,      "mpx", "on" },
  32      { "Cascadelake-Server" "-" TYPE_X86_CPU, "stepping", "5" },
  33      { TYPE_X86_CPU, "x-intel-pt-auto-level", "off" },
  34 +    { TYPE_VIRTIO_BALLOON, "x-use-large-balloon-config", "off" },
  35  };
  36  const size_t pc_compat_3_1_len = G_N_ELEMENTS(pc_compat_3_1);
  37
  38 diff --git a/hw/virtio/virtio-balloon.c b/hw/virtio/virtio-balloon.c
  39 index 2112874055..d10298786d 100644
  40 --- a/hw/virtio/virtio-balloon.c
  41 +++ b/hw/virtio/virtio-balloon.c
  42 @@ -328,6 +328,28 @@ static void balloon_stats_set_poll_interval(Object *obj, Visitor *v,
  43      balloon_stats_change_timer(s, 0);
  44  }
  45
  46 +static void balloon_get_large_config(Object *obj, Visitor *v,
  47 +                                     const char *name, void *opaque,
  48 +                                     Error **errp)
  49 +{
  50 +    VirtIOBalloon *s = opaque;
  51 +    visit_type_bool(v, name, &s->use_large_config, errp);
  52 +}
  53 +
  54 +static void balloon_set_large_config(Object *obj, Visitor *v,
  55 +                                     const char *name, void *opaque,
  56 +                                     Error **errp)
  57 +{
  58 +    VirtIOBalloon *s = opaque;
  59 +    DeviceState *dev = DEVICE(s);
  60 +
  61 +    if (dev->realized) {
  62 +        error_setg(errp, "balloon config size cannot be changed at runtime");
  63 +    } else {
  64 +        visit_type_bool(v, name, &s->use_large_config, errp);
  65 +    }
  66 +}
  67 +
  68  static void virtio_balloon_handle_output(VirtIODevice *vdev, VirtQueue *vq)
  69  {
  70      VirtIOBalloon *s = VIRTIO_BALLOON(vdev);
  71 @@ -526,6 +548,17 @@ static bool virtio_balloon_free_page_support(void *opaque)
  72      return virtio_vdev_has_feature(vdev, VIRTIO_BALLOON_F_FREE_PAGE_HINT);
  73  }
  74
  75 +static size_t virtio_balloon_config_size(void *opaque)
  76 +{
  77 +    VirtIOBalloon *s = opaque;
  78 +
  79 +    if (s->use_large_config) {
  80 +        return sizeof(struct virtio_balloon_config);
  81 +    } else {
  82 +        return offsetof(struct virtio_balloon_config, free_page_report_cmd_id);
  83 +    }
  84 +}
  85 +
  86  static void virtio_balloon_free_page_start(VirtIOBalloon *s)
  87  {
  88      VirtIODevice *vdev = VIRTIO_DEVICE(s);
  89 @@ -635,7 +668,7 @@ static void virtio_balloon_get_config(VirtIODevice *vdev, uint8_t *config_data)
  90      }
  91
  92      trace_virtio_balloon_get_config(config.num_pages, config.actual);
  93 -    memcpy(config_data, &config, sizeof(struct virtio_balloon_config));
  94 +    memcpy(config_data, &config, virtio_balloon_config_size(dev));
  95  }
  96
  97  static int build_dimm_list(Object *obj, void *opaque)
  98 @@ -679,7 +712,7 @@ static void virtio_balloon_set_config(VirtIODevice *vdev,
  99      uint32_t oldactual = dev->actual;
 100      ram_addr_t vm_ram_size = get_current_ram_size();
 101
 102 -    memcpy(&config, config_data, sizeof(struct virtio_balloon_config));
 103 +    memcpy(&config, config_data, virtio_balloon_config_size(dev));
 104      dev->actual = le32_to_cpu(config.actual);
 105      if (dev->actual != oldactual) {
 106          qapi_event_send_balloon_change(vm_ram_size -
 107 @@ -766,7 +799,7 @@ static void virtio_balloon_device_realize(DeviceState *dev, Error **errp)
 108      int ret;
 109
 110      virtio_init(vdev, "virtio-balloon", VIRTIO_ID_BALLOON,
 111 -                sizeof(struct virtio_balloon_config));
 112 +                virtio_balloon_config_size(s));
 113
 114      ret = qemu_add_balloon_handler(virtio_balloon_to_target,
 115                                     virtio_balloon_stat, s);
 116 @@ -791,7 +824,7 @@ static void virtio_balloon_device_realize(DeviceState *dev, Error **errp)
 117          s->free_page_report_notify.notify =
 118                                         virtio_balloon_free_page_report_notify;
 119          precopy_add_notifier(&s->free_page_report_notify);
 120 -        if (s->iothread) {
 121 +        if (s->iothread && s->use_large_config) {
 122              object_ref(OBJECT(s->iothread));
 123              s->free_page_bh = aio_bh_new(iothread_get_aio_context(s->iothread),
 124                                         virtio_ballloon_get_free_page_hints, s);
 125 @@ -804,6 +837,11 @@ static void virtio_balloon_device_realize(DeviceState *dev, Error **errp)
 126              virtio_error(vdev, "iothread is missing");
 127          }
 128      }
 129 +
 130 +    if (!s->use_large_config) {
 131 +        s->host_features &= ~(1 << VIRTIO_BALLOON_F_PAGE_POISON);
 132 +    }
 133 +
 134      reset_stats(s);
 135  }
 136
 137 @@ -880,6 +918,12 @@ static void virtio_balloon_instance_init(Object *obj)
 138                          balloon_stats_get_poll_interval,
 139                          balloon_stats_set_poll_interval,
 140                          NULL, s, NULL);
 141 +
 142 +    s->use_large_config = true;
 143 +    object_property_add(obj, "x-use-large-balloon-config", "bool",
 144 +                        balloon_get_large_config,
 145 +                        balloon_set_large_config,
 146 +                        NULL, s, NULL);
 147  }
 148
 149  static const VMStateDescription vmstate_virtio_balloon = {
 150 diff --git a/include/hw/virtio/virtio-balloon.h b/include/hw/virtio/virtio-balloon.h
 151 index 1afafb12f6..f212c08bd7 100644
 152 --- a/include/hw/virtio/virtio-balloon.h
 153 +++ b/include/hw/virtio/virtio-balloon.h
 154 @@ -45,6 +45,7 @@ enum virtio_balloon_free_page_report_status {
 155  typedef struct VirtIOBalloon {
 156      VirtIODevice parent_obj;
 157      VirtQueue *ivq, *dvq, *svq, *free_page_vq;
 158 +    bool use_large_config;
 159      uint32_t free_page_report_status;
 160      uint32_t num_pages;
 161      uint32_t actual;