Re: [RFC v1 10/25] hw/core/loader: Add a ROM loader notifier

[Mathieu Poirier <mathieu.poirier@linaro.org>]

On Mon, Jul 20, 2026 at 04:47:53PM +1000, Gavin Shan wrote:
> On 7/17/26 7:10 AM, Mathieu Poirier wrote:
> > On Tue, Jul 14, 2026 at 08:52:43PM +1000, Gavin Shan wrote:
> > > On 7/8/26 8:42 AM, Mathieu Poirier wrote:
> > > > From: Jean-Philippe Brucker <jean-philippe@linaro.org>
> > > > 
> > > > Add a function to register a notifier that is invoked when ROMs get
> > > > loaded into guest memory.
> > > > 
> > > > It will be used by Arm confidential guest support, in order to register
> > > > all blobs loaded into memory with KVM, so that their content is moved
> > > > into Realm state and measured into the initial VM state.
> > > > 
> > > > Signed-off-by: Jean-Philippe Brucker <jean-philippe@linaro.org>
> > > > Signed-off-by: Mathieu Poirier <mathieu.poirier@linaro.org>
> > > > ---
> > > >    hw/core/loader.c         | 15 +++++++++++++++
> > > >    include/hw/core/loader.h | 17 +++++++++++++++++
> > > >    2 files changed, 32 insertions(+)
> > > > 
> > > > diff --git a/hw/core/loader.c b/hw/core/loader.c
> > > > index 5cbfba0a86d2..b3d769bec5cb 100644
> > > > --- a/hw/core/loader.c
> > > > +++ b/hw/core/loader.c
> > > > @@ -74,6 +74,8 @@
> > > >    #endif
> > > 
> > > The (edk2) firmware for the realm guest can be specified by the legacy
> > > '-drive if=pflash' or '-bios'. The memory region corresponding to the
> > > firmware image specified by '-bios' is recorded by the newly added notifier
> > > and populated to TF-RMM properly.
> > > 
> > > I don't see how the memory region corresponding to (edk2) firmware image
> > > specified by '-drive if=pflash' is recorded and populated to TF-RMM
> > > accordingly in this series. So I guess '-drive if=pflash' isn't supported
> > > yet?
> > 
> > Please give '-drive if=pflash' a try and let me know how you fare.  Edk2 is not
> > part of the bootstack I'm currently testing with but I know of configurations
> > where it does work.
> > 
> > I'll add it to my list of things to do if it doesn't work, though I may not
> > address it in this patchset.  We'll see how busy things get.
> > 
> 
> Ok, I don't think '-driver if=pflash' or the 'pflash0' property of the virt machine
> aren't supported any more due to [RFC v1 21/25], where the 'pflash0' property has
> been removed.
> 
>   [RFC v1 21/25] hw/arm/virt: Use RAM instead of flash for confidential guest firmware
> 
> - Tried to boot the realm guest with '-driver if=pflash' and I was told it's not supported.
> 
>   qemu-system-aarch64: -drive if=pflash,format=raw,unit=0,file=/mnt/edk2/Build/ArmVirtQemu-AARCH64/RELEASE_GCC5/FV/QEMU_EFI.fd,readonly=on: machine type   does not support if=pflash,bus=0,unit=0
> 
> - Tried to use 'pflash0' property, and I was told it's not supported either.
> 
>   qemu-system-aarch64: Property 'virt-11.1-machine.pflash0' not found
> 
> So the only option to specify the firmware image is '-bios', which worked for me.

Thanks for the follow-up.

> 
> Thanks,
> Gavin
> 
> 
> > > 
> > > Note that I didn't give '-drive if=pflash' a try yet.
> > > 
> > > >    static int roms_loaded;
> > > > +static NotifierList rom_loader_notifier =
> > > > +    NOTIFIER_LIST_INITIALIZER(rom_loader_notifier);
> > > >    /* return the size or -1 if error */
> > > >    int64_t get_image_size(const char *filename, Error **errp)
> > > > @@ -1201,6 +1203,11 @@ MemoryRegion *rom_add_blob(const char *name, const void *blob, size_t len,
> > > >        return mr;
> > > >    }
> > > > +void rom_add_load_notifier(Notifier *notifier)
> > > > +{
> > > > +    notifier_list_add(&rom_loader_notifier, notifier);
> > > > +}
> > > > +
> > > >    /* This function is specific for elf program because we don't need to allocate
> > > >     * all the rom. We just allocate the first part and the rest is just zeros. This
> > > >     * is why romsize and datasize are different. Also, this function takes its own
> > > > @@ -1242,6 +1249,7 @@ ssize_t rom_add_option(const char *file, int32_t bootindex)
> > > >    static void rom_reset(void *unused)
> > > >    {
> > > >        Rom *rom;
> > > > +    RomLoaderNotifyData notify;
> > > >        QTAILQ_FOREACH(rom, &roms, next) {
> > > >            if (rom->fw_file) {
> > > > @@ -1290,6 +1298,13 @@ static void rom_reset(void *unused)
> > > >            address_space_flush_icache_range(rom->as, rom->addr, rom->datasize);
> > > >            trace_loader_write_rom(rom->name, rom->addr, rom->datasize, rom->isrom);
> > > > +
> > > > +        notify = (RomLoaderNotifyData) {
> > > > +            .addr = rom->addr,
> > > > +            .len = rom->datasize,
> > > > +            .as = rom->as,
> > > > +        };
> > > > +        notifier_list_notify(&rom_loader_notifier, &notify);
> > > >        }
> > > >    }
> > > > diff --git a/include/hw/core/loader.h b/include/hw/core/loader.h
> > > > index d9431e8a8d12..94cf6ad2e26b 100644
> > > > --- a/include/hw/core/loader.h
> > > > +++ b/include/hw/core/loader.h
> > > > @@ -342,6 +342,23 @@ void *rom_ptr_for_as(AddressSpace *as, hwaddr addr, size_t size);
> > > >    ssize_t rom_add_vga(const char *file);
> > > >    ssize_t rom_add_option(const char *file, int32_t bootindex);
> > > > +typedef struct RomLoaderNotifyData {
> > > > +    /* Address of the blob in guest memory */
> > > > +    hwaddr addr;
> > > > +    /* Length of the blob */
> > > > +    size_t len;
> > > > +    /* Address space of the blob */
> > > > +    AddressSpace *as;
> > > > +} RomLoaderNotifyData;
> > > > +
> > > > +/**
> > > > + * rom_add_load_notifier - Add a notifier for loaded images
> > > > + *
> > > > + * Add a notifier that will be invoked with a RomLoaderNotifyData structure for
> > > > + * each blob loaded into guest memory, after the blob is loaded.
> > > > + */
> > > > +void rom_add_load_notifier(Notifier *notifier);
> > > > +
> > > >    /* This is the usual maximum in uboot, so if a uImage overflows this, it would
> > > >     * overflow on real hardware too. */
> > > >    #define UBOOT_MAX_DECOMPRESSED_BYTES (64 << 20)
> > > 
> > > Thanks,
> > > Gavin
> > > 
> > 
>