diff --git a/drivers/virt/gunyah/Kconfig b/drivers/virt/gunyah/Kconfig index 1685b75fb77a..855d41a88b16 100644 --- a/drivers/virt/gunyah/Kconfig +++ b/drivers/virt/gunyah/Kconfig @@ -36,3 +36,12 @@ config GUNYAH_IRQFD on Gunyah virtual machine. Say Y/M here if unsure and you want to support Gunyah VMMs. + +config GUNYAH_IOEVENTFD + tristate "Gunyah ioeventfd interface" + depends on GUNYAH + help + Enable kernel support for creating ioeventfds which can alert userspace + when a Gunyah virtual machine accesses a memory address. + + Say Y/M here if unsure and you want to support Gunyah VMMs. diff --git a/drivers/virt/gunyah/Makefile b/drivers/virt/gunyah/Makefile index b41b02792921..2aec5989402b 100644 --- a/drivers/virt/gunyah/Makefile +++ b/drivers/virt/gunyah/Makefile @@ -6,3 +6,4 @@ obj-$(CONFIG_GUNYAH) += gunyah.o gunyah_rsc_mgr.o gunyah_vcpu.o obj-$(CONFIG_GUNYAH_PLATFORM_HOOKS) += gunyah_platform_hooks.o obj-$(CONFIG_GUNYAH_QCOM_PLATFORM) += gunyah_qcom.o obj-$(CONFIG_GUNYAH_IRQFD) += gunyah_irqfd.o +obj-$(CONFIG_GUNYAH_IOEVENTFD) += gunyah_ioeventfd.o diff --git a/drivers/virt/gunyah/gunyah_ioeventfd.c b/drivers/virt/gunyah/gunyah_ioeventfd.c new file mode 100644 index 000000000000..894d303968c4 --- /dev/null +++ b/drivers/virt/gunyah/gunyah_ioeventfd.c @@ -0,0 +1,139 @@ +// SPDX-License-Identifier: GPL-2.0-only +/* + * Copyright (c) 2022-2024 Qualcomm Innovation Center, Inc. All rights reserved. + */ + +#include +#include +#include +#include +#include +#include +#include + +#include + +struct gunyah_ioeventfd { + struct gunyah_vm_function_instance *f; + struct gunyah_vm_io_handler io_handler; + + struct eventfd_ctx *ctx; +}; + +static int gunyah_write_ioeventfd(struct gunyah_vm_io_handler *io_dev, u64 addr, + u32 len, u64 data) +{ + struct gunyah_ioeventfd *iofd = + container_of(io_dev, struct gunyah_ioeventfd, io_handler); + + eventfd_signal(iofd->ctx); + return 0; +} + +static struct gunyah_vm_io_handler_ops io_ops = { + .write = gunyah_write_ioeventfd, +}; + +static long gunyah_ioeventfd_bind(struct gunyah_vm_function_instance *f) +{ + const struct gunyah_fn_ioeventfd_arg *args = f->argp; + struct gunyah_ioeventfd *iofd; + struct eventfd_ctx *ctx; + int ret; + + if (f->arg_size != sizeof(*args)) + return -EINVAL; + + /* All other flag bits are reserved for future use */ + if (args->flags & ~GUNYAH_IOEVENTFD_FLAGS_DATAMATCH) + return -EINVAL; + + /* must be natural-word sized, or 0 to ignore length */ + switch (args->len) { + case 0: + case 1: + case 2: + case 4: + case 8: + break; + default: + return -EINVAL; + } + + /* check for range overflow */ + if (overflows_type(args->addr + args->len, u64)) + return -EINVAL; + + /* ioeventfd with no length can't be combined with DATAMATCH */ + if (!args->len && (args->flags & GUNYAH_IOEVENTFD_FLAGS_DATAMATCH)) + return -EINVAL; + + ctx = eventfd_ctx_fdget(args->fd); + if (IS_ERR(ctx)) + return PTR_ERR(ctx); + + iofd = kzalloc(sizeof(*iofd), GFP_KERNEL); + if (!iofd) { + ret = -ENOMEM; + goto err_eventfd; + } + + f->data = iofd; + iofd->f = f; + + iofd->ctx = ctx; + + if (args->flags & GUNYAH_IOEVENTFD_FLAGS_DATAMATCH) { + iofd->io_handler.datamatch = true; + iofd->io_handler.len = args->len; + iofd->io_handler.data = args->datamatch; + } + iofd->io_handler.addr = args->addr; + iofd->io_handler.ops = &io_ops; + + ret = gunyah_vm_add_io_handler(f->ghvm, &iofd->io_handler); + if (ret) + goto err_io_dev_add; + + return 0; + +err_io_dev_add: + kfree(iofd); +err_eventfd: + eventfd_ctx_put(ctx); + return ret; +} + +static void gunyah_ioevent_unbind(struct gunyah_vm_function_instance *f) +{ + struct gunyah_ioeventfd *iofd = f->data; + + gunyah_vm_remove_io_handler(iofd->f->ghvm, &iofd->io_handler); + eventfd_ctx_put(iofd->ctx); + kfree(iofd); +} + +static bool gunyah_ioevent_compare(const struct gunyah_vm_function_instance *f, + const void *arg, size_t size) +{ + const struct gunyah_fn_ioeventfd_arg *instance = f->argp, *other = arg; + + if (sizeof(*other) != size) + return false; + + if (instance->addr != other->addr || instance->len != other->len || + instance->flags != other->flags) + return false; + + if ((instance->flags & GUNYAH_IOEVENTFD_FLAGS_DATAMATCH) && + instance->datamatch != other->datamatch) + return false; + + return true; +} + +DECLARE_GUNYAH_VM_FUNCTION_INIT(ioeventfd, GUNYAH_FN_IOEVENTFD, 3, + gunyah_ioeventfd_bind, gunyah_ioevent_unbind, + gunyah_ioevent_compare); +MODULE_DESCRIPTION("Gunyah ioeventfd VM Function"); +MODULE_LICENSE("GPL"); diff --git a/include/uapi/linux/gunyah.h b/include/uapi/linux/gunyah.h index cb7b0bb9bef3..fd461e2fe8b5 100644 --- a/include/uapi/linux/gunyah.h +++ b/include/uapi/linux/gunyah.h @@ -65,10 +65,13 @@ struct gunyah_vm_dtb_config { * Return: file descriptor to manipulate the vcpu. * @GUNYAH_FN_IRQFD: register eventfd to assert a Gunyah doorbell * &struct gunyah_fn_desc.arg is a pointer to &struct gunyah_fn_irqfd_arg + * @GUNYAH_FN_IOEVENTFD: register ioeventfd to trigger when VM faults on parameter + * &struct gunyah_fn_desc.arg is a pointer to &struct gunyah_fn_ioeventfd_arg */ enum gunyah_fn_type { GUNYAH_FN_VCPU = 1, GUNYAH_FN_IRQFD, + GUNYAH_FN_IOEVENTFD, }; #define GUNYAH_FN_MAX_ARG_SIZE 256 @@ -120,6 +123,40 @@ struct gunyah_fn_irqfd_arg { __u32 padding; }; +/** + * enum gunyah_ioeventfd_flags - flags for use in gunyah_fn_ioeventfd_arg + * @GUNYAH_IOEVENTFD_FLAGS_DATAMATCH: the event will be signaled only if the + * written value to the registered address is + * equal to &struct gunyah_fn_ioeventfd_arg.datamatch + */ +enum gunyah_ioeventfd_flags { + GUNYAH_IOEVENTFD_FLAGS_DATAMATCH = 1UL << 0, +}; + +/** + * struct gunyah_fn_ioeventfd_arg - Arguments to create an ioeventfd function + * @datamatch: data used when GUNYAH_IOEVENTFD_DATAMATCH is set + * @addr: Address in guest memory + * @len: Length of access + * @fd: When ioeventfd is matched, this eventfd is written + * @flags: See &enum gunyah_ioeventfd_flags + * @padding: padding bytes + * + * Create this function with &GUNYAH_VM_ADD_FUNCTION using type &GUNYAH_FN_IOEVENTFD. + * + * Attaches an ioeventfd to a legal mmio address within the guest. A guest write + * in the registered address will signal the provided event instead of triggering + * an exit on the GUNYAH_VCPU_RUN ioctl. + */ +struct gunyah_fn_ioeventfd_arg { + __u64 datamatch; + __u64 addr; /* legal mmio address */ + __u32 len; /* 1, 2, 4, or 8 bytes; or 0 to ignore length */ + __s32 fd; + __u32 flags; + __u32 padding; +}; + /** * struct gunyah_fn_desc - Arguments to create a VM function * @type: Type of the function. See &enum gunyah_fn_type.