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; +}; + +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