diff options
| -rw-r--r-- | include/linux/entry-kvm.h | 80 | ||||
| -rw-r--r-- | include/linux/kvm_host.h | 8 | ||||
| -rw-r--r-- | kernel/entry/Makefile | 3 | ||||
| -rw-r--r-- | kernel/entry/kvm.c | 51 | ||||
| -rw-r--r-- | virt/kvm/Kconfig | 3 |
5 files changed, 144 insertions, 1 deletions
diff --git a/include/linux/entry-kvm.h b/include/linux/entry-kvm.h new file mode 100644 index 000000000000..0cef17afb41a --- /dev/null +++ b/include/linux/entry-kvm.h @@ -0,0 +1,80 @@ +/* SPDX-License-Identifier: GPL-2.0 */ +#ifndef __LINUX_ENTRYKVM_H +#define __LINUX_ENTRYKVM_H + +#include <linux/entry-common.h> + +/* Transfer to guest mode work */ +#ifdef CONFIG_KVM_XFER_TO_GUEST_WORK + +#ifndef ARCH_XFER_TO_GUEST_MODE_WORK +# define ARCH_XFER_TO_GUEST_MODE_WORK (0) +#endif + +#define XFER_TO_GUEST_MODE_WORK \ + (_TIF_NEED_RESCHED | _TIF_SIGPENDING | \ + _TIF_NOTIFY_RESUME | ARCH_XFER_TO_GUEST_MODE_WORK) + +struct kvm_vcpu; + +/** + * arch_xfer_to_guest_mode_handle_work - Architecture specific xfer to guest + * mode work handling function. + * @vcpu: Pointer to current's VCPU data + * @ti_work: Cached TIF flags gathered in xfer_to_guest_mode_handle_work() + * + * Invoked from xfer_to_guest_mode_handle_work(). Defaults to NOOP. Can be + * replaced by architecture specific code. + */ +static inline int arch_xfer_to_guest_mode_handle_work(struct kvm_vcpu *vcpu, + unsigned long ti_work); + +#ifndef arch_xfer_to_guest_mode_work +static inline int arch_xfer_to_guest_mode_handle_work(struct kvm_vcpu *vcpu, + unsigned long ti_work) +{ + return 0; +} +#endif + +/** + * xfer_to_guest_mode_handle_work - Check and handle pending work which needs + * to be handled before going to guest mode + * @vcpu: Pointer to current's VCPU data + * + * Returns: 0 or an error code + */ +int xfer_to_guest_mode_handle_work(struct kvm_vcpu *vcpu); + +/** + * __xfer_to_guest_mode_work_pending - Check if work is pending + * + * Returns: True if work pending, False otherwise. + * + * Bare variant of xfer_to_guest_mode_work_pending(). Can be called from + * interrupt enabled code for racy quick checks with care. + */ +static inline bool __xfer_to_guest_mode_work_pending(void) +{ + unsigned long ti_work = READ_ONCE(current_thread_info()->flags); + + return !!(ti_work & XFER_TO_GUEST_MODE_WORK); +} + +/** + * xfer_to_guest_mode_work_pending - Check if work is pending which needs to be + * handled before returning to guest mode + * + * Returns: True if work pending, False otherwise. + * + * Has to be invoked with interrupts disabled before the transition to + * guest mode. + */ +static inline bool xfer_to_guest_mode_work_pending(void) +{ + lockdep_assert_irqs_disabled(); + return __xfer_to_guest_mode_work_pending(); +} +#endif /* CONFIG_KVM_XFER_TO_GUEST_WORK */ + +#endif diff --git a/include/linux/kvm_host.h b/include/linux/kvm_host.h index d564855243d8..ac83e9c1d82c 100644 --- a/include/linux/kvm_host.h +++ b/include/linux/kvm_host.h @@ -1439,4 +1439,12 @@ int kvm_vm_create_worker_thread(struct kvm *kvm, kvm_vm_thread_fn_t thread_fn, uintptr_t data, const char *name, struct task_struct **thread_ptr); +#ifdef CONFIG_KVM_XFER_TO_GUEST_WORK +static inline void kvm_handle_signal_exit(struct kvm_vcpu *vcpu) +{ + vcpu->run->exit_reason = KVM_EXIT_INTR; + vcpu->stat.signal_exits++; +} +#endif /* CONFIG_KVM_XFER_TO_GUEST_WORK */ + #endif diff --git a/kernel/entry/Makefile b/kernel/entry/Makefile index c207d202bf3a..34c8a3f1c735 100644 --- a/kernel/entry/Makefile +++ b/kernel/entry/Makefile @@ -9,4 +9,5 @@ KCOV_INSTRUMENT := n CFLAGS_REMOVE_common.o = -fstack-protector -fstack-protector-strong CFLAGS_common.o += -fno-stack-protector -obj-$(CONFIG_GENERIC_ENTRY) += common.o +obj-$(CONFIG_GENERIC_ENTRY) += common.o +obj-$(CONFIG_KVM_XFER_TO_GUEST_WORK) += kvm.o diff --git a/kernel/entry/kvm.c b/kernel/entry/kvm.c new file mode 100644 index 000000000000..eb1a8a4c867c --- /dev/null +++ b/kernel/entry/kvm.c @@ -0,0 +1,51 @@ +// SPDX-License-Identifier: GPL-2.0 + +#include <linux/entry-kvm.h> +#include <linux/kvm_host.h> + +static int xfer_to_guest_mode_work(struct kvm_vcpu *vcpu, unsigned long ti_work) +{ + do { + int ret; + + if (ti_work & _TIF_SIGPENDING) { + kvm_handle_signal_exit(vcpu); + return -EINTR; + } + + if (ti_work & _TIF_NEED_RESCHED) + schedule(); + + if (ti_work & _TIF_NOTIFY_RESUME) { + clear_thread_flag(TIF_NOTIFY_RESUME); + tracehook_notify_resume(NULL); + } + + ret = arch_xfer_to_guest_mode_handle_work(vcpu, ti_work); + if (ret) + return ret; + + ti_work = READ_ONCE(current_thread_info()->flags); + } while (ti_work & XFER_TO_GUEST_MODE_WORK || need_resched()); + return 0; +} + +int xfer_to_guest_mode_handle_work(struct kvm_vcpu *vcpu) +{ + unsigned long ti_work; + + /* + * This is invoked from the outer guest loop with interrupts and + * preemption enabled. + * + * KVM invokes xfer_to_guest_mode_work_pending() with interrupts + * disabled in the inner loop before going into guest mode. No need + * to disable interrupts here. + */ + ti_work = READ_ONCE(current_thread_info()->flags); + if (!(ti_work & XFER_TO_GUEST_MODE_WORK)) + return 0; + + return xfer_to_guest_mode_work(vcpu, ti_work); +} +EXPORT_SYMBOL_GPL(xfer_to_guest_mode_handle_work); diff --git a/virt/kvm/Kconfig b/virt/kvm/Kconfig index aad9284c043a..1c37ccd5d402 100644 --- a/virt/kvm/Kconfig +++ b/virt/kvm/Kconfig @@ -60,3 +60,6 @@ config HAVE_KVM_VCPU_RUN_PID_CHANGE config HAVE_KVM_NO_POLL bool + +config KVM_XFER_TO_GUEST_WORK + bool |