@@ -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.
@@ -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
new file mode 100644
@@ -0,0 +1,132 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * Copyright (c) 2022-2023 Qualcomm Innovation Center, Inc. All rights reserved.
+ */
+
+#include <linux/eventfd.h>
+#include <linux/device/driver.h>
+#include <linux/file.h>
+#include <linux/fs.h>
+#include <linux/gunyah.h>
+#include <linux/gunyah_vm_mgr.h>
+#include <linux/module.h>
+#include <linux/printk.h>
+
+#include <uapi/linux/gunyah.h>
+
+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;
+
+ eventfd_ctx_put(iofd->ctx);
+ gunyah_vm_remove_io_handler(iofd->f->ghvm, &iofd->io_handler);
+ 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;
+
+ return instance->addr == other->addr;
+}
+
+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");
@@ -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.