Commit e12f3a13 authored by Laszlo Ersek's avatar Laszlo Ersek Committed by Michael S. Tsirkin
Browse files

fw-cfg: turn FW_CFG_FILE_SLOTS into a device property 



We'd like to raise the value of FW_CFG_FILE_SLOTS. Doing it naively could
lead to problems with backward migration: a more recent QEMU (running an
older machine type) would allow the guest, in fw_cfg_select(), to select a
high key value that is unavailable in the same machine type implemented by
the older (target) QEMU. On the target host, fw_cfg_data_read() for
example could dereference nonexistent entries.

As first step, size the FWCfgState.entries[*] and FWCfgState.entry_order
arrays dynamically. All three array sizes will be influenced by the new
field FWCfgState.file_slots (and matching device property).

Make the following changes:

- Replace the FW_CFG_FILE_SLOTS macro with FW_CFG_FILE_SLOTS_MIN (minimum
  count of fw_cfg file slots) in the header file. The value remains 0x10.

- Replace all uses of FW_CFG_FILE_SLOTS with a helper function called
  fw_cfg_file_slots(), returning the new property.

- Eliminate the macro FW_CFG_MAX_ENTRY, and replace all its uses with a
  helper function called fw_cfg_max_entry().

- In the MMIO- and IO-mapped realize functions both, allocate all three
  arrays dynamically, based on the new property.

- The new property defaults to FW_CFG_FILE_SLOTS_MIN. This is going to be
  customized in the following patches.

Cc: "Gabriel L. Somlo" <somlo@cmu.edu>
Cc: "Michael S. Tsirkin" <mst@redhat.com>
Cc: Gerd Hoffmann <kraxel@redhat.com>
Cc: Igor Mammedov <imammedo@redhat.com>
Cc: Paolo Bonzini <pbonzini@redhat.com>
Signed-off-by: default avatarLaszlo Ersek <lersek@redhat.com>
Acked-by: default avatarGabriel Somlo <somlo@cmu.edu>
Tested-by: default avatarGabriel Somlo <somlo@cmu.edu>
Reviewed-by: default avatarMichael S. Tsirkin <mst@redhat.com>
Signed-off-by: default avatarMichael S. Tsirkin <mst@redhat.com>
Reviewed-by: default avatarEduardo Habkost <ehabkost@redhat.com>
parent baf2d5bf

docs/specs/fw_cfg.txt

+1 −1
Original line number Diff line number Diff line
@@ -156,7 +156,7 @@ Selector Reg. Range Usage 
0xc000 - 0xffff  Arch. Specific (0x0000 - 0x3fff, RW, ignored in v2.4+)



In practice, the number of allowed firmware configuration items is given

by the value of FW_CFG_MAX_ENTRY (see fw_cfg.h).

by the value (FW_CFG_FILE_FIRST + FW_CFG_FILE_SLOTS_MIN) (see fw_cfg.h).



= Guest-side DMA Interface =

hw/nvram/fw_cfg.c

+63 −8
Original line number Diff line number Diff line
@@ -33,6 +33,7 @@ 
#include "qemu/error-report.h"

#include "qemu/config-file.h"

#include "qemu/cutils.h"

#include "qapi/error.h"



#define FW_CFG_NAME "fw_cfg"

#define FW_CFG_PATH "/machine/" FW_CFG_NAME
@@ -71,8 +72,9 @@ struct FWCfgState { 
    SysBusDevice parent_obj;

    /*< public >*/



    FWCfgEntry entries[2][FW_CFG_MAX_ENTRY];

    int entry_order[FW_CFG_MAX_ENTRY];

    uint16_t file_slots;

    FWCfgEntry *entries[2];

    int *entry_order;

    FWCfgFiles *files;

    uint16_t cur_entry;

    uint32_t cur_offset;
@@ -257,13 +259,24 @@ static void fw_cfg_write(FWCfgState *s, uint8_t value) 
    /* nothing, write support removed in QEMU v2.4+ */

}



static inline uint16_t fw_cfg_file_slots(const FWCfgState *s)

{

    return s->file_slots;

}



/* Note: this function returns an exclusive limit. */

static inline uint32_t fw_cfg_max_entry(const FWCfgState *s)

{

    return FW_CFG_FILE_FIRST + fw_cfg_file_slots(s);

}



static int fw_cfg_select(FWCfgState *s, uint16_t key)

{

    int arch, ret;

    FWCfgEntry *e;



    s->cur_offset = 0;

    if ((key & FW_CFG_ENTRY_MASK) >= FW_CFG_MAX_ENTRY) {

    if ((key & FW_CFG_ENTRY_MASK) >= fw_cfg_max_entry(s)) {

        s->cur_entry = FW_CFG_INVALID;

        ret = 0;

    } else {
@@ -610,7 +623,7 @@ static void fw_cfg_add_bytes_read_callback(FWCfgState *s, uint16_t key, 


    key &= FW_CFG_ENTRY_MASK;



    assert(key < FW_CFG_MAX_ENTRY && len < UINT32_MAX);

    assert(key < fw_cfg_max_entry(s) && len < UINT32_MAX);

    assert(s->entries[arch][key].data == NULL); /* avoid key conflict */



    s->entries[arch][key].data = data;
@@ -628,7 +641,7 @@ static void *fw_cfg_modify_bytes_read(FWCfgState *s, uint16_t key, 


    key &= FW_CFG_ENTRY_MASK;



    assert(key < FW_CFG_MAX_ENTRY && len < UINT32_MAX);

    assert(key < fw_cfg_max_entry(s) && len < UINT32_MAX);



    /* return the old data to the function caller, avoid memory leak */

    ptr = s->entries[arch][key].data;
@@ -777,13 +790,13 @@ void fw_cfg_add_file_callback(FWCfgState *s, const char *filename, 
    int order = 0;



    if (!s->files) {

        dsize = sizeof(uint32_t) + sizeof(FWCfgFile) * FW_CFG_FILE_SLOTS;

        dsize = sizeof(uint32_t) + sizeof(FWCfgFile) * fw_cfg_file_slots(s);

        s->files = g_malloc0(dsize);

        fw_cfg_add_bytes(s, FW_CFG_FILE_DIR, s->files, dsize);

    }



    count = be32_to_cpu(s->files->count);

    assert(count < FW_CFG_FILE_SLOTS);

    assert(count < fw_cfg_file_slots(s));



    /* Find the insertion point. */

    if (mc->legacy_fw_cfg_order) {
@@ -857,7 +870,7 @@ void *fw_cfg_modify_file(FWCfgState *s, const char *filename, 
    assert(s->files);



    index = be32_to_cpu(s->files->count);

    assert(index < FW_CFG_FILE_SLOTS);

    assert(index < fw_cfg_file_slots(s));



    for (i = 0; i < index; i++) {

        if (strcmp(filename, s->files->f[i].name) == 0) {
@@ -1014,12 +1027,38 @@ static const TypeInfo fw_cfg_info = { 
    .class_init    = fw_cfg_class_init,

};



static void fw_cfg_file_slots_allocate(FWCfgState *s, Error **errp)

{

    uint16_t file_slots_max;



    if (fw_cfg_file_slots(s) < FW_CFG_FILE_SLOTS_MIN) {

        error_setg(errp, "\"file_slots\" must be at least 0x%x",

                   FW_CFG_FILE_SLOTS_MIN);

        return;

    }



    /* (UINT16_MAX & FW_CFG_ENTRY_MASK) is the highest inclusive selector value

     * that we permit. The actual (exclusive) value coming from the

     * configuration is (FW_CFG_FILE_FIRST + fw_cfg_file_slots(s)). */

    file_slots_max = (UINT16_MAX & FW_CFG_ENTRY_MASK) - FW_CFG_FILE_FIRST + 1;

    if (fw_cfg_file_slots(s) > file_slots_max) {

        error_setg(errp, "\"file_slots\" must not exceed 0x%" PRIx16,

                   file_slots_max);

        return;

    }



    s->entries[0] = g_new0(FWCfgEntry, fw_cfg_max_entry(s));

    s->entries[1] = g_new0(FWCfgEntry, fw_cfg_max_entry(s));

    s->entry_order = g_new0(int, fw_cfg_max_entry(s));

}



static Property fw_cfg_io_properties[] = {

    DEFINE_PROP_UINT32("iobase", FWCfgIoState, iobase, -1),

    DEFINE_PROP_UINT32("dma_iobase", FWCfgIoState, dma_iobase, -1),

    DEFINE_PROP_BOOL("dma_enabled", FWCfgIoState, parent_obj.dma_enabled,

                     true),

    DEFINE_PROP_UINT16("x-file-slots", FWCfgIoState, parent_obj.file_slots,

                       FW_CFG_FILE_SLOTS_MIN),

    DEFINE_PROP_END_OF_LIST(),

};
@@ -1027,6 +1066,13 @@ static void fw_cfg_io_realize(DeviceState *dev, Error **errp) 
{

    FWCfgIoState *s = FW_CFG_IO(dev);

    SysBusDevice *sbd = SYS_BUS_DEVICE(dev);

    Error *local_err = NULL;



    fw_cfg_file_slots_allocate(FW_CFG(s), &local_err);

    if (local_err) {

        error_propagate(errp, local_err);

        return;

    }



    /* when using port i/o, the 8-bit data register ALWAYS overlaps

     * with half of the 16-bit control register. Hence, the total size
@@ -1063,6 +1109,8 @@ static Property fw_cfg_mem_properties[] = { 
    DEFINE_PROP_UINT32("data_width", FWCfgMemState, data_width, -1),

    DEFINE_PROP_BOOL("dma_enabled", FWCfgMemState, parent_obj.dma_enabled,

                     true),

    DEFINE_PROP_UINT16("x-file-slots", FWCfgMemState, parent_obj.file_slots,

                       FW_CFG_FILE_SLOTS_MIN),

    DEFINE_PROP_END_OF_LIST(),

};
@@ -1071,6 +1119,13 @@ static void fw_cfg_mem_realize(DeviceState *dev, Error **errp) 
    FWCfgMemState *s = FW_CFG_MEM(dev);

    SysBusDevice *sbd = SYS_BUS_DEVICE(dev);

    const MemoryRegionOps *data_ops = &fw_cfg_data_mem_ops;

    Error *local_err = NULL;



    fw_cfg_file_slots_allocate(FW_CFG(s), &local_err);

    if (local_err) {

        error_propagate(errp, local_err);

        return;

    }



    memory_region_init_io(&s->ctl_iomem, OBJECT(s), &fw_cfg_ctl_mem_ops,

                          FW_CFG(s), "fwcfg.ctl", FW_CFG_CTL_SIZE);

include/hw/nvram/fw_cfg_keys.h

+1 −2
Original line number Diff line number Diff line
@@ -29,8 +29,7 @@ 
#define FW_CFG_FILE_DIR         0x19



#define FW_CFG_FILE_FIRST       0x20

#define FW_CFG_FILE_SLOTS       0x10

#define FW_CFG_MAX_ENTRY        (FW_CFG_FILE_FIRST + FW_CFG_FILE_SLOTS)

#define FW_CFG_FILE_SLOTS_MIN   0x10



#define FW_CFG_WRITE_CHANNEL    0x4000

#define FW_CFG_ARCH_LOCAL       0x8000