From dae257394ae523aff0a9c4049c2e9934e3972ddc Mon Sep 17 00:00:00 2001 From: Peter Maydell Date: Mon, 26 Jul 2021 17:33:51 +0100 Subject: hw/arm/boot: Report error if there is no fw_cfg device in the machine If the user provides both a BIOS/firmware image and also a guest kernel filename, arm_setup_firmware_boot() will pass the kernel image to the firmware via the fw_cfg device. However we weren't checking whether there really was a fw_cfg device present, and if there wasn't we would crash. This crash can be provoked with a command line such as qemu-system-aarch64 -M raspi3 -kernel /dev/null -bios /dev/null -display none It is currently only possible on the raspi3 machine, because unless the machine sets info->firmware_loaded we won't call arm_setup_firmware_boot(), and the only machines which set that are: * virt (has a fw-cfg device) * sbsa-ref (checks itself for kernel_filename && firmware_loaded) * raspi3 (crashes) But this is an unfortunate beartrap to leave for future machine model implementors, so we should handle this situation in boot.c. Check in arm_setup_firmware_boot() whether the fw-cfg device exists before trying to load files into it, and if it doesn't exist then exit with a hopefully helpful error message. Because we now handle this check in a machine-agnostic way, we can remove the check from sbsa-ref. Resolves: https://gitlab.com/qemu-project/qemu/-/issues/503 Signed-off-by: Peter Maydell Reviewed-by: Richard Henderson Reviewed-by: Philippe Mathieu-Daudé Message-id: 20210726163351.32086-1-peter.maydell@linaro.org --- hw/arm/boot.c | 9 +++++++++ 1 file changed, 9 insertions(+) (limited to 'hw/arm/boot.c') diff --git a/hw/arm/boot.c b/hw/arm/boot.c index d7b059225e..57efb61ee4 100644 --- a/hw/arm/boot.c +++ b/hw/arm/boot.c @@ -1243,6 +1243,15 @@ static void arm_setup_firmware_boot(ARMCPU *cpu, struct arm_boot_info *info) bool try_decompressing_kernel; fw_cfg = fw_cfg_find(); + + if (!fw_cfg) { + error_report("This machine type does not support loading both " + "a guest firmware/BIOS image and a guest kernel at " + "the same time. You should change your QEMU command " + "line to specify one or the other, but not both."); + exit(1); + } + try_decompressing_kernel = arm_feature(&cpu->env, ARM_FEATURE_AARCH64); -- cgit v1.2.3-55-g7522