diff options
| author | Emanuele Giuseppe Esposito <eesposit@redhat.com> | 2022-11-11 10:47:56 -0500 |
|---|---|---|
| committer | Paolo Bonzini <pbonzini@redhat.com> | 2023-01-11 09:59:39 +0100 |
| commit | bd688fc93120fb3e28aa70e3dfdf567ccc1e0bc1 (patch) | |
| tree | d763c7b30c195a31dedf67d708b7d770fd16b5ef /include | |
| parent | b585edca34a817fdb751dfe94fbd3cde32ffe60d (diff) | |
accel: introduce accelerator blocker API
This API allows the accelerators to prevent vcpus from issuing
new ioctls while execting a critical section marked with the
accel_ioctl_inhibit_begin/end functions.
Note that all functions submitting ioctls must mark where the
ioctl is being called with accel_{cpu_}ioctl_begin/end().
This API requires the caller to always hold the BQL.
API documentation is in sysemu/accel-blocker.h
Internally, it uses a QemuLockCnt together with a per-CPU QemuLockCnt
(to minimize cache line bouncing) to keep avoid that new ioctls
run when the critical section starts, and a QemuEvent to wait
that all running ioctls finish.
Signed-off-by: Emanuele Giuseppe Esposito <eesposit@redhat.com>
Reviewed-by: Philippe Mathieu-Daudé <philmd@linaro.org>
Message-Id: <20221111154758.1372674-2-eesposit@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Diffstat (limited to 'include')
| -rw-r--r-- | include/hw/core/cpu.h | 3 | ||||
| -rw-r--r-- | include/sysemu/accel-blocker.h | 56 |
2 files changed, 59 insertions, 0 deletions
diff --git a/include/hw/core/cpu.h b/include/hw/core/cpu.h index 8830546121..2417597236 100644 --- a/include/hw/core/cpu.h +++ b/include/hw/core/cpu.h @@ -398,6 +398,9 @@ struct CPUState { uint32_t kvm_fetch_index; uint64_t dirty_pages; + /* Use by accel-block: CPU is executing an ioctl() */ + QemuLockCnt in_ioctl_lock; + /* Used for events with 'vcpu' and *without* the 'disabled' properties */ DECLARE_BITMAP(trace_dstate_delayed, CPU_TRACE_DSTATE_MAX_EVENTS); DECLARE_BITMAP(trace_dstate, CPU_TRACE_DSTATE_MAX_EVENTS); diff --git a/include/sysemu/accel-blocker.h b/include/sysemu/accel-blocker.h new file mode 100644 index 0000000000..72020529ef --- /dev/null +++ b/include/sysemu/accel-blocker.h @@ -0,0 +1,56 @@ +/* + * Accelerator blocking API, to prevent new ioctls from starting and wait the + * running ones finish. + * This mechanism differs from pause/resume_all_vcpus() in that it does not + * release the BQL. + * + * Copyright (c) 2022 Red Hat Inc. + * + * Author: Emanuele Giuseppe Esposito <eesposit@redhat.com> + * + * This work is licensed under the terms of the GNU GPL, version 2 or later. + * See the COPYING file in the top-level directory. + */ +#ifndef ACCEL_BLOCKER_H +#define ACCEL_BLOCKER_H + +#include "qemu/osdep.h" +#include "sysemu/cpus.h" + +extern void accel_blocker_init(void); + +/* + * accel_{cpu_}ioctl_begin/end: + * Mark when ioctl is about to run or just finished. + * + * accel_{cpu_}ioctl_begin will block after accel_ioctl_inhibit_begin() is + * called, preventing new ioctls to run. They will continue only after + * accel_ioctl_inibith_end(). + */ +extern void accel_ioctl_begin(void); +extern void accel_ioctl_end(void); +extern void accel_cpu_ioctl_begin(CPUState *cpu); +extern void accel_cpu_ioctl_end(CPUState *cpu); + +/* + * accel_ioctl_inhibit_begin: start critical section + * + * This function makes sure that: + * 1) incoming accel_{cpu_}ioctl_begin() calls block + * 2) wait that all ioctls that were already running reach + * accel_{cpu_}ioctl_end(), kicking vcpus if necessary. + * + * This allows the caller to access shared data or perform operations without + * worrying of concurrent vcpus accesses. + */ +extern void accel_ioctl_inhibit_begin(void); + +/* + * accel_ioctl_inhibit_end: end critical section started by + * accel_ioctl_inhibit_begin() + * + * This function allows blocked accel_{cpu_}ioctl_begin() to continue. + */ +extern void accel_ioctl_inhibit_end(void); + +#endif /* ACCEL_BLOCKER_H */ |