On Thu, Jun 28, 2018 at 12:15:33PM +0200, Greg Kurz wrote:
> It is unsafe to rely on *_enabled() helpers before the accelerator has
> been initialized, ie, accel_init_machine() has succeeded, because they
> always return false. But it is still possible to end up calling them
> indirectly by inadvertance, and cause QEMU to misbehave.
>
> This patch causes QEMU to abort if we try to check for an accelerator
> before it has been set up. This will help to catch bugs earlier.
>
> Signed-off-by: Greg Kurz <gr...@kaod.org>
> ---
> accel/accel.c | 7 +++++++
> include/qemu-common.h | 3 ++-
> include/sysemu/accel.h | 1 +
> include/sysemu/kvm.h | 3 ++-
> qom/cpu.c | 1 +
> stubs/Makefile.objs | 1 +
> stubs/accel.c | 14 ++++++++++++++
> target/i386/hax-all.c | 2 +-
> target/i386/whpx-all.c | 2 +-
> 9 files changed, 30 insertions(+), 4 deletions(-)
> create mode 100644 stubs/accel.c
>
> diff --git a/accel/accel.c b/accel/accel.c
> index 966b2d8f536c..27900aac9cc5 100644
> --- a/accel/accel.c
> +++ b/accel/accel.c
> @@ -51,6 +51,13 @@ static AccelClass *accel_find(const char *opt_name)
> return ac;
> }
>
> +bool assert_accelerator_initialized(bool allowed)
> +{
> + assert(current_machine != NULL);
> + assert(current_machine->accelerator != NULL);
> + return allowed;
> +}
> +
> static int accel_init_machine(AccelClass *acc, MachineState *ms)
> {
> ObjectClass *oc = OBJECT_CLASS(acc);
> diff --git a/include/qemu-common.h b/include/qemu-common.h
> index 85f4749aefb7..01d5e4d97dbf 100644
> --- a/include/qemu-common.h
> +++ b/include/qemu-common.h
> @@ -82,7 +82,8 @@ int qemu_openpty_raw(int *aslave, char *pty_name);
> extern bool tcg_allowed;
> void tcg_exec_init(unsigned long tb_size);
> #ifdef CONFIG_TCG
> -#define tcg_enabled() (tcg_allowed)
> +#include "sysemu/accel.h"
> +#define tcg_enabled() (assert_accelerator_initialized(tcg_allowed))
> #else
> #define tcg_enabled() 0
It would be nice to catch mistakes even if
the CONFIG_{TCG,KVM,HAX,XEN} is disabled. That would require making
assert_accelerator_initialized() a macro or inline function,
though.
> #endif
> diff --git a/include/sysemu/accel.h b/include/sysemu/accel.h
> index 637358f43014..76965cb69cc9 100644
> --- a/include/sysemu/accel.h
> +++ b/include/sysemu/accel.h
> @@ -71,5 +71,6 @@ void configure_accelerator(MachineState *ms);
> void accel_register_compat_props(AccelState *accel);
> /* Called just before os_setup_post (ie just before drop OS privs) */
> void accel_setup_post(MachineState *ms);
> +bool assert_accelerator_initialized(bool allowed);
>
> #endif
> diff --git a/include/sysemu/kvm.h b/include/sysemu/kvm.h
> index 0b64b8e06786..ac4dbb2d6d6d 100644
> --- a/include/sysemu/kvm.h
> +++ b/include/sysemu/kvm.h
> @@ -18,6 +18,7 @@
> #include "qom/cpu.h"
> #include "exec/memattrs.h"
> #include "hw/irq.h"
> +#include "sysemu/accel.h"
>
> #ifdef NEED_CPU_H
> # ifdef CONFIG_KVM
> @@ -46,7 +47,7 @@ extern bool kvm_direct_msi_allowed;
> extern bool kvm_ioeventfd_any_length_allowed;
> extern bool kvm_msi_use_devid;
>
> -#define kvm_enabled() (kvm_allowed)
> +#define kvm_enabled() (assert_accelerator_initialized(kvm_allowed))
> /**
> * kvm_irqchip_in_kernel:
> *
> diff --git a/qom/cpu.c b/qom/cpu.c
> index 92599f35413b..65a8f03a66a4 100644
> --- a/qom/cpu.c
> +++ b/qom/cpu.c
> @@ -23,6 +23,7 @@
> #include "qemu-common.h"
> #include "qom/cpu.h"
> #include "sysemu/hw_accel.h"
> +#include "sysemu/accel.h"
> #include "qemu/notify.h"
> #include "qemu/log.h"
> #include "exec/log.h"
> diff --git a/stubs/Makefile.objs b/stubs/Makefile.objs
> index 53d3f32cb258..2d5142287525 100644
> --- a/stubs/Makefile.objs
> +++ b/stubs/Makefile.objs
> @@ -43,3 +43,4 @@ stub-obj-y += xen-common.o
> stub-obj-y += xen-hvm.o
> stub-obj-y += pci-host-piix.o
> stub-obj-y += ram-block.o
> +stub-obj-y += accel.o
> diff --git a/stubs/accel.c b/stubs/accel.c
> new file mode 100644
> index 000000000000..4f480f2d3f29
> --- /dev/null
> +++ b/stubs/accel.c
> @@ -0,0 +1,14 @@
> +/*
> + * accel stubs
> + *
> + * This work is licensed under the terms of the GNU GPL, version 2 or later.
> + * See the COPYING file in the top-level directory.
> + */
> +
> +#include "qemu/osdep.h"
> +#include "sysemu/accel.h"
> +
> +bool assert_accelerator_initialized(bool allowed)
> +{
> + return allowed;
> +}
> diff --git a/target/i386/hax-all.c b/target/i386/hax-all.c
> index d2e512856bb8..7c78bd7d094d 100644
> --- a/target/i386/hax-all.c
> +++ b/target/i386/hax-all.c
> @@ -57,7 +57,7 @@ static int hax_arch_get_registers(CPUArchState *env);
>
> int hax_enabled(void)
> {
> - return hax_allowed;
> + return assert_accelerator_initialized(hax_allowed);
> }
>
> int valid_hax_tunnel_size(uint16_t size)
> diff --git a/target/i386/whpx-all.c b/target/i386/whpx-all.c
> index 6b42096698ee..e7f6bc5958e7 100644
> --- a/target/i386/whpx-all.c
> +++ b/target/i386/whpx-all.c
> @@ -1422,7 +1422,7 @@ static int whpx_accel_init(MachineState *ms)
>
> int whpx_enabled(void)
> {
> - return whpx_allowed;
> + return assert_accelerator_initialized(whpx_allowed);
> }
>
> static void whpx_accel_class_init(ObjectClass *oc, void *data)
>
--
Eduardo
