On Wed, Sep 14, 2022 at 12:41:34AM +0100, Jason A. Donenfeld wrote: > If setup_data is being read into a specific memory location, then > generally the setup_data address parameter is read first, so that the > caller knows where to read it into. In that case, we should return > setup_data containing the absolute addresses that are hard coded and > determined a priori. This is the case when kernels are loaded by BIOS, > for example. In contrast, when setup_data is read as a file, then we > shouldn't modify setup_data, since the absolute address will be wrong by > definition. This is the case when OVMF loads the image. > > This allows setup_data to be used like normal, without crashing when EFI > tries to use it. > > (As a small development note, strangely, fw_cfg_add_file_callback() was > exported but fw_cfg_add_bytes_callback() wasn't, so this makes that > consistent.) > > Cc: Gerd Hoffmann <kra...@redhat.com> > Cc: Laurent Vivier <laur...@vivier.eu> > Cc: Michael S. Tsirkin <m...@redhat.com> > Cc: Paolo Bonzini <pbonz...@redhat.com> > Cc: Peter Maydell <peter.mayd...@linaro.org> > Cc: Philippe Mathieu-Daudé <f4...@amsat.org> > Cc: Richard Henderson <richard.hender...@linaro.org> > Suggested-by: Ard Biesheuvel <a...@kernel.org> > Signed-off-by: Jason A. Donenfeld <ja...@zx2c4.com> > --- > hw/i386/x86.c | 37 +++++++++++++++++++++++++++---------- > hw/nvram/fw_cfg.c | 12 ++++++------ > include/hw/nvram/fw_cfg.h | 22 ++++++++++++++++++++++ > 3 files changed, 55 insertions(+), 16 deletions(-) > > diff --git a/hw/i386/x86.c b/hw/i386/x86.c > index 050eedc0c8..933bbdd836 100644 > --- a/hw/i386/x86.c > +++ b/hw/i386/x86.c > @@ -764,6 +764,18 @@ static bool load_elfboot(const char *kernel_filename, > return true; > } > > +struct setup_data_fixup { > + void *pos; > + hwaddr val; > + uint32_t addr; > +}; > +
btw typedef struct SetupDataFixup { void *pos; hwaddr val; uint32_t addr; } SetupDataFixup; and use typedef everywhere. Yes I know setup_data is like this but that probably should be fixed too. > +static void fixup_setup_data(void *opaque) > +{ > + struct setup_data_fixup *fixup = opaque; > + stq_p(fixup->pos, fixup->val); > +} > + > void x86_load_linux(X86MachineState *x86ms, > FWCfgState *fw_cfg, > int acpi_data_size, > @@ -1088,8 +1100,11 @@ void x86_load_linux(X86MachineState *x86ms, > qemu_guest_getrandom_nofail(setup_data->data, RNG_SEED_LENGTH); > } > > - /* Offset 0x250 is a pointer to the first setup_data link. */ > - stq_p(header + 0x250, first_setup_data); > + fw_cfg_add_i32(fw_cfg, FW_CFG_KERNEL_ADDR, prot_addr); > + fw_cfg_add_i32(fw_cfg, FW_CFG_KERNEL_SIZE, kernel_size); > + fw_cfg_add_bytes(fw_cfg, FW_CFG_KERNEL_DATA, kernel, kernel_size); > + sev_load_ctx.kernel_data = (char *)kernel; > + sev_load_ctx.kernel_size = kernel_size; > > /* > * If we're starting an encrypted VM, it will be OVMF based, which uses > the > @@ -1099,16 +1114,18 @@ void x86_load_linux(X86MachineState *x86ms, > * file the user passed in. > */ > if (!sev_enabled()) { > + struct setup_data_fixup *fixup = g_malloc(sizeof(*fixup)); > + > memcpy(setup, header, MIN(sizeof(header), setup_size)); > + /* Offset 0x250 is a pointer to the first setup_data link. */ > + fixup->pos = setup + 0x250; > + fixup->val = first_setup_data; > + fixup->addr = real_addr; > + fw_cfg_add_bytes_callback(fw_cfg, FW_CFG_SETUP_ADDR, > fixup_setup_data, NULL, > + fixup, &fixup->addr, sizeof(fixup->addr), > true); > + } else { > + fw_cfg_add_i32(fw_cfg, FW_CFG_SETUP_ADDR, real_addr); > } > - > - fw_cfg_add_i32(fw_cfg, FW_CFG_KERNEL_ADDR, prot_addr); > - fw_cfg_add_i32(fw_cfg, FW_CFG_KERNEL_SIZE, kernel_size); > - fw_cfg_add_bytes(fw_cfg, FW_CFG_KERNEL_DATA, kernel, kernel_size); > - sev_load_ctx.kernel_data = (char *)kernel; > - sev_load_ctx.kernel_size = kernel_size; > - > - fw_cfg_add_i32(fw_cfg, FW_CFG_SETUP_ADDR, real_addr); > fw_cfg_add_i32(fw_cfg, FW_CFG_SETUP_SIZE, setup_size); > fw_cfg_add_bytes(fw_cfg, FW_CFG_SETUP_DATA, setup, setup_size); > sev_load_ctx.setup_data = (char *)setup; > diff --git a/hw/nvram/fw_cfg.c b/hw/nvram/fw_cfg.c > index d605f3f45a..564bda3395 100644 > --- a/hw/nvram/fw_cfg.c > +++ b/hw/nvram/fw_cfg.c > @@ -692,12 +692,12 @@ static const VMStateDescription vmstate_fw_cfg = { > } > }; > > -static void fw_cfg_add_bytes_callback(FWCfgState *s, uint16_t key, > - FWCfgCallback select_cb, > - FWCfgWriteCallback write_cb, > - void *callback_opaque, > - void *data, size_t len, > - bool read_only) > +void fw_cfg_add_bytes_callback(FWCfgState *s, uint16_t key, > + FWCfgCallback select_cb, > + FWCfgWriteCallback write_cb, > + void *callback_opaque, > + void *data, size_t len, > + bool read_only) > { > int arch = !!(key & FW_CFG_ARCH_LOCAL); > > diff --git a/include/hw/nvram/fw_cfg.h b/include/hw/nvram/fw_cfg.h > index 0e7a8bc7af..e4fef393be 100644 > --- a/include/hw/nvram/fw_cfg.h > +++ b/include/hw/nvram/fw_cfg.h > @@ -117,6 +117,28 @@ struct FWCfgMemState { > */ > void fw_cfg_add_bytes(FWCfgState *s, uint16_t key, void *data, size_t len); > > +/** > + * fw_cfg_add_bytes_callback: > + * @s: fw_cfg device being modified > + * @key: selector key value for new fw_cfg item > + * @select_cb: callback function when selecting > + * @write_cb: callback function after a write > + * @callback_opaque: argument to be passed into callback function > + * @data: pointer to start of item data > + * @len: size of item data > + * @read_only: is file read only > + * > + * Add a new fw_cfg item, available by selecting the given key, as a raw > + * "blob" of the given size. The data referenced by the starting pointer > + * is only linked, NOT copied, into the data structure of the fw_cfg device. > + */ > +void fw_cfg_add_bytes_callback(FWCfgState *s, uint16_t key, > + FWCfgCallback select_cb, > + FWCfgWriteCallback write_cb, > + void *callback_opaque, > + void *data, size_t len, > + bool read_only); > + > /** > * fw_cfg_add_string: > * @s: fw_cfg device being modified > -- > 2.37.3