hw/arm/boot.c | 9 +++++++++ hw/arm/sbsa-ref.c | 7 ------- 2 files changed, 9 insertions(+), 7 deletions(-)
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 <peter.maydell@linaro.org>
---
I didn't reuse exactly the same wording sbsa-ref used to have,
because the bit about loading an OS from hard disk might not
apply to all machine types.
---
hw/arm/boot.c | 9 +++++++++
hw/arm/sbsa-ref.c | 7 -------
2 files changed, 9 insertions(+), 7 deletions(-)
diff --git a/hw/arm/boot.c b/hw/arm/boot.c
index d7b059225e6..57efb61ee41 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);
diff --git a/hw/arm/sbsa-ref.c b/hw/arm/sbsa-ref.c
index 43c19b49234..c1629df6031 100644
--- a/hw/arm/sbsa-ref.c
+++ b/hw/arm/sbsa-ref.c
@@ -691,13 +691,6 @@ static void sbsa_ref_init(MachineState *machine)
firmware_loaded = sbsa_firmware_init(sms, sysmem, secure_sysmem);
- if (machine->kernel_filename && firmware_loaded) {
- error_report("sbsa-ref: No fw_cfg device on this machine, "
- "so -kernel option is not supported when firmware loaded, "
- "please load OS from hard disk instead");
- exit(1);
- }
-
/*
* This machine has EL3 enabled, external firmware should supply PSCI
* implementation, so the QEMU's internal PSCI is disabled.
--
2.20.1
On 7/26/21 6:33 AM, Peter Maydell wrote: > 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<peter.maydell@linaro.org> > --- Reviewed-by: Richard Henderson <richard.henderson@linaro.org> r~
On 7/26/21 6:33 PM, Peter Maydell wrote: > 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 <peter.maydell@linaro.org> > --- > I didn't reuse exactly the same wording sbsa-ref used to have, > because the bit about loading an OS from hard disk might not > apply to all machine types. > --- > hw/arm/boot.c | 9 +++++++++ > hw/arm/sbsa-ref.c | 7 ------- > 2 files changed, 9 insertions(+), 7 deletions(-) Thanks for fixing this. Reviewed-by: Philippe Mathieu-Daudé <f4bug@amsat.org>
On Mon, Jul 26, 2021 at 17:33:51 +0100, Peter Maydell wrote: > 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 <peter.maydell@linaro.org> Reviewed-by: Leif Lindholm <leif@nuviainc.com> However, the subject line threw me slightly. How about:? "Report error if trying to load kernel with no fw_cfg" > --- > I didn't reuse exactly the same wording sbsa-ref used to have, > because the bit about loading an OS from hard disk might not > apply to all machine types. > --- > hw/arm/boot.c | 9 +++++++++ > hw/arm/sbsa-ref.c | 7 ------- > 2 files changed, 9 insertions(+), 7 deletions(-) > > diff --git a/hw/arm/boot.c b/hw/arm/boot.c > index d7b059225e6..57efb61ee41 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); > > diff --git a/hw/arm/sbsa-ref.c b/hw/arm/sbsa-ref.c > index 43c19b49234..c1629df6031 100644 > --- a/hw/arm/sbsa-ref.c > +++ b/hw/arm/sbsa-ref.c > @@ -691,13 +691,6 @@ static void sbsa_ref_init(MachineState *machine) > > firmware_loaded = sbsa_firmware_init(sms, sysmem, secure_sysmem); > > - if (machine->kernel_filename && firmware_loaded) { > - error_report("sbsa-ref: No fw_cfg device on this machine, " > - "so -kernel option is not supported when firmware loaded, " > - "please load OS from hard disk instead"); > - exit(1); > - } > - > /* > * This machine has EL3 enabled, external firmware should supply PSCI > * implementation, so the QEMU's internal PSCI is disabled. > -- > 2.20.1 >
On Tue, 3 Aug 2021 at 15:29, Leif Lindholm <leif@nuviainc.com> wrote: > > On Mon, Jul 26, 2021 at 17:33:51 +0100, Peter Maydell wrote: > > 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 <peter.maydell@linaro.org> > > Reviewed-by: Leif Lindholm <leif@nuviainc.com> > > However, the subject line threw me slightly. How about:? > "Report error if trying to load kernel with no fw_cfg" Yeah, in retrospect that would have been a better subject. However, the commit is in master already (dae257394ae5) so it is what it is :-/ thanks -- PMM
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