Re: PATCH: Increase System Firmware Max Size

["Daniel P. Berrangé" <berrange@redhat.com>]

On Wed, Sep 16, 2020 at 11:52:41AM +0200, Laszlo Ersek wrote:
> Hi Erich,
> 
> (1) this patch is really not trivial; please do not continue CC'ing
> qemu-trivial
> 
> (2) Please do CC people that have given you feedback previously. I
> primarily mean Daniel and David.
> 
> (3) Generally speaking, please post new versions of a patch stand-alone
> (not in reply to another message) on the list.
> 
> (4) Please use git-send-email (or suitable wrapper utilities) for
> sending your patch.
> 
> https://wiki.qemu.org/Contribute/SubmitAPatch
> 
> 
> One non-meta comment below:
> 
> On 09/15/20 21:10, McMillan, Erich via wrote:
> > Apologies, ignore previous patch. The relevant patch is below:
> >
> > From 473daf6129debf8d158a9ae1aff788c5bdbbc799 Mon Sep 17 00:00:00 2001
> > From: Erich McMillan <erich.mcmillan@hp.com>
> > Date: Tue, 15 Sep 2020 13:23:25 -0500
> > Subject: [PATCH 2/2] Add max firmware size as optional parameter
> >
> > Signed-off-by: Erich McMillan <erich.mcmillan@hp.com>
> > ---
> >  hw/i386/pc_sysfw.c  | 13 ++-----------
> >  include/hw/loader.h |  9 +++++++++
> >  qemu-options.hx     |  8 ++++++++
> >  softmmu/vl.c        | 40 ++++++++++++++++++++++++++++++++++++++++
> >  4 files changed, 59 insertions(+), 11 deletions(-)
> >
> > diff --git a/hw/i386/pc_sysfw.c b/hw/i386/pc_sysfw.c
> > index b6c0822..ba6c99d 100644
> > --- a/hw/i386/pc_sysfw.c
> > +++ b/hw/i386/pc_sysfw.c
> > @@ -39,15 +39,6 @@
> >  #include "hw/block/flash.h"
> >  #include "sysemu/kvm.h"
> >
> > -/*
> > - * We don't have a theoretically justifiable exact lower bound on the base
> > - * address of any flash mapping. In practice, the IO-APIC MMIO range is
> > - * [0xFEE00000..0xFEE01000] -- see IO_APIC_DEFAULT_ADDRESS --, leaving free
> > - * only 18MB-4KB below 4G. For now, restrict the cumulative mapping to 8MB in
> > - * size.
> > - */
> > -#define FLASH_SIZE_LIMIT (8 * MiB)
> > -
> >  #define FLASH_SECTOR_SIZE 4096
> >
> >  static void pc_isa_bios_init(MemoryRegion *rom_memory,
> > @@ -182,10 +173,10 @@ static void pc_system_flash_map(PCMachineState *pcms,
> >          }
> >          if ((hwaddr)size != size
> >              || total_size > HWADDR_MAX - size
> > -            || total_size + size > FLASH_SIZE_LIMIT) {
> > +            || total_size + size > MaxCombinedFirmwareSize) {
> >              error_report("combined size of system firmware exceeds "
> >                           "%" PRIu64 " bytes",
> > -                         FLASH_SIZE_LIMIT);
> > +                         MaxCombinedFirmwareSize);
> >              exit(1);
> >          }
> >
> > diff --git a/include/hw/loader.h b/include/hw/loader.h
> > index a9eeea3..7898b63 100644
> > --- a/include/hw/loader.h
> > +++ b/include/hw/loader.h
> > @@ -318,4 +318,13 @@ int rom_add_option(const char *file, int32_t bootindex);
> >   * overflow on real hardware too. */
> >  #define UBOOT_MAX_GUNZIP_BYTES (64 << 20)
> >
> > +/*
> > + * We don't have a theoretically justifiable exact lower bound on the base
> > + * address of any flash mapping. In practice, the IO-APIC MMIO range is
> > + * [0xFEE00000..0xFEE01000] -- see IO_APIC_DEFAULT_ADDRESS --, leaving free
> > + * only 18MB-4KB below 4G. For now, restrict the cumulative mapping to 8MB in
> > + * size, but allow user to specify larger size via command line.
> > + */
> > +extern uint64_t MaxCombinedFirmwareSize;
> > +
> >  #endif
> > diff --git a/qemu-options.hx b/qemu-options.hx
> > index b0f0205..32eed3a 100644
> > --- a/qemu-options.hx
> > +++ b/qemu-options.hx
> > @@ -1377,6 +1377,14 @@ SRST
> >          |qemu_system_x86| -hda a -hdb b
> >  ERST
> >
> > +DEF("maxfirmwaresize", HAS_ARG, QEMU_OPTION_maxfirmwaresize,
> > +    "-maxfirmwaresize [size=]megs  specify maximum combined firmware size, default is 8MiB. Known issues if value exceeds 16MiB.\n",
> > +    QEMU_ARCH_ALL)
> > +SRST
> > +``-maxfirmwaresize [size=]megs``
> > +    Specify maximum combined firmware size, default is 8MiB. Known issues if value exceeds 16MiB.
> > +ERST
> > +
> >  DEF("mtdblock", HAS_ARG, QEMU_OPTION_mtdblock,
> >      "-mtdblock file  use 'file' as on-board Flash memory image\n",
> >      QEMU_ARCH_ALL)
> > diff --git a/softmmu/vl.c b/softmmu/vl.c
> > index 0cc86b0..fcf41d2 100644
> > --- a/softmmu/vl.c
> > +++ b/softmmu/vl.c
> > @@ -116,6 +116,8 @@
> >
> >  #define MAX_VIRTIO_CONSOLES 1
> >
> > +uint64_t MaxCombinedFirmwareSize = 8 * MiB;
> > +
> >  static const char *data_dir[16];
> >  static int data_dir_idx;
> >  const char *bios_name = NULL;
> > @@ -448,6 +450,20 @@ static QemuOptsList qemu_mem_opts = {
> >      },
> >  };
> >
> > +static QemuOptsList qemu_max_fw_size_opts = {
> > +    .name = "maxfirmwaresize",
> > +    .implied_opt_name = "size",
> > +    .head = QTAILQ_HEAD_INITIALIZER(qemu_max_fw_size_opts.head),
> > +    .merge_lists = true,
> > +    .desc = {
> > +        {
> > +            .name = "size",
> > +            .type = QEMU_OPT_SIZE,
> > +        },
> > +        { /* end of list */ }
> > +    },
> > +};
> > +
> >  static QemuOptsList qemu_icount_opts = {
> >      .name = "icount",
> >      .implied_opt_name = "shift",
> > @@ -2576,6 +2592,23 @@ static bool object_create_delayed(const char *type, QemuOpts *opts)
> >      return !object_create_initial(type, opts);
> >  }
> >
> > +static void set_max_firmware_size(uint64_t *maxfwsize)
> > +{
> > +    const char *max_fw_size_str;
> > +    QemuOpts *opts = qemu_find_opts_singleton("maxfirmwaresize");
> > +
> > +    max_fw_size_str = qemu_opt_get(opts, "size");
> > +
> > +    if (max_fw_size_str) {
> > +        if (!*max_fw_size_str) {
> > +            error_report("missing 'size' option value");
> > +            exit(EXIT_FAILURE);
> > +        }
> > +
> > +        *maxfwsize = qemu_opt_get_size(opts, "size", 8 * MiB);
> > +    }
> > +}
> > +
> >
> >  static bool set_memory_options(uint64_t *ram_slots, ram_addr_t *maxram_size,
> >                                 MachineClass *mc)
> > @@ -2904,6 +2937,7 @@ void qemu_init(int argc, char **argv, char **envp)
> >      qemu_add_opts(&qemu_machine_opts);
> >      qemu_add_opts(&qemu_accel_opts);
> >      qemu_add_opts(&qemu_mem_opts);
> > +    qemu_add_opts(&qemu_max_fw_size_opts);
> >      qemu_add_opts(&qemu_smp_opts);
> >      qemu_add_opts(&qemu_boot_opts);
> >      qemu_add_opts(&qemu_add_fd_opts);
> > @@ -3160,6 +3194,10 @@ void qemu_init(int argc, char **argv, char **envp)
> >                      exit(EXIT_FAILURE);
> >                  }
> >                  break;
> > +            case QEMU_OPTION_maxfirmwaresize:
> > +                opts = qemu_opts_parse_noisily(qemu_find_opts("maxfirmwaresize"),
> > +                                               optarg, true);
> > +                break;
> >  #ifdef CONFIG_TPM
> >              case QEMU_OPTION_tpmdev:
> >                  if (tpm_config_parse(qemu_find_opts("tpmdev"), optarg) < 0) {
> > @@ -3845,6 +3883,8 @@ void qemu_init(int argc, char **argv, char **envp)
> >      have_custom_ram_size = set_memory_options(&ram_slots, &maxram_size,
> >                                                machine_class);
> >
> > +    set_max_firmware_size(&MaxCombinedFirmwareSize);
> > +
> >      os_daemonize();
> >      rcu_disable_atfork();
> >
> 
> (5) In my opinion (which could be wrong of course), we shouldn't
> introduce a new command line option for this, but a new PC machine type
> property called "x-firmware-max-size".

Yeah, we definitely do not want a new top level CLI arg, just a
machine type property.  We don't need any "x-" prefix on it
though, just a plain "firmware-max-size" prop is fine.

Regards,
Daniel
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