Enable support for creating irqfds which can raise an interrupt on a
Gunyah virtual machine. irqfds are exposed to userspace as a Gunyah VM
function with the name "irqfd". If the VM devicetree is not configured
to create a doorbell with the corresponding label, userspace will still
be able to assert the eventfd but no interrupt will be raised on the
guest.
Acked-by: Alex Elder <elder@xxxxxxxxxx>
Co-developed-by: Prakruthi Deepak Heragu <quic_pheragu@xxxxxxxxxxx>
Signed-off-by: Prakruthi Deepak Heragu <quic_pheragu@xxxxxxxxxxx>
Signed-off-by: Elliot Berman <quic_eberman@xxxxxxxxxxx>
---
drivers/virt/gunyah/Kconfig | 9 ++
drivers/virt/gunyah/Makefile | 1 +
drivers/virt/gunyah/gunyah_irqfd.c | 187 +++++++++++++++++++++++++++++++++++++
include/uapi/linux/gunyah.h | 35 +++++++
4 files changed, 232 insertions(+)
diff --git a/drivers/virt/gunyah/Kconfig b/drivers/virt/gunyah/Kconfig
index fe2823dc48bac..1685b75fb77a0 100644
--- a/drivers/virt/gunyah/Kconfig
+++ b/drivers/virt/gunyah/Kconfig
@@ -27,3 +27,12 @@ config GUNYAH_QCOM_PLATFORM
extra platform-specific support.
Say Y/M here to use Gunyah on Qualcomm platforms.
+
+config GUNYAH_IRQFD
+ tristate "Gunyah irqfd interface"
+ depends on GUNYAH
+ help
+ Enable kernel support for creating irqfds which can raise an interrupt
+ on Gunyah virtual machine.
+
+ 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 c4505fce177dd..b41b02792921c 100644
--- a/drivers/virt/gunyah/Makefile
+++ b/drivers/virt/gunyah/Makefile
@@ -5,3 +5,4 @@ gunyah_rsc_mgr-y += rsc_mgr.o rsc_mgr_rpc.o vm_mgr.o vm_mgr_mem.o guest_memfd.o
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
diff --git a/drivers/virt/gunyah/gunyah_irqfd.c b/drivers/virt/gunyah/gunyah_irqfd.c
new file mode 100644
index 0000000000000..951da6e8d321e
--- /dev/null
+++ b/drivers/virt/gunyah/gunyah_irqfd.c
@@ -0,0 +1,187 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * Copyright (c) 2022-2024 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/module.h>
+#include <linux/poll.h>
+#include <linux/printk.h>
+
+#include <uapi/linux/gunyah.h>
+
+struct gunyah_irqfd {
+ struct gunyah_resource *ghrsc;
+ struct gunyah_vm_resource_ticket ticket;
+ struct gunyah_vm_function_instance *f;
+
+ bool level;
+
+ struct eventfd_ctx *ctx;
+ wait_queue_entry_t wait;
+ poll_table pt;
+};
+
+static int irqfd_wakeup(wait_queue_entry_t *wait, unsigned int mode, int sync,
+ void *key)
+{
+ struct gunyah_irqfd *irqfd =
+ container_of(wait, struct gunyah_irqfd, wait);
+ __poll_t flags = key_to_poll(key);
+ int ret = 0;
+
+ if (flags & EPOLLIN) {
+ if (irqfd->ghrsc) {
+ ret = gunyah_hypercall_bell_send(irqfd->ghrsc->capid, 1,
+ NULL);
+ if (ret)
+ pr_err_ratelimited(
+ "Failed to inject interrupt %d: %d\n",
+ irqfd->ticket.label, ret);
+ } else
+ pr_err_ratelimited(
+ "Premature injection of interrupt\n");
+ }
+
+ return 0;
+}
+
+static void irqfd_ptable_queue_proc(struct file *file, wait_queue_head_t *wqh,
+ poll_table *pt)
+{
+ struct gunyah_irqfd *irq_ctx =
+ container_of(pt, struct gunyah_irqfd, pt);
+
+ add_wait_queue(wqh, &irq_ctx->wait);
+}
+
+static bool gunyah_irqfd_populate(struct gunyah_vm_resource_ticket *ticket,
+ struct gunyah_resource *ghrsc)
+{
+ struct gunyah_irqfd *irqfd =
+ container_of(ticket, struct gunyah_irqfd, ticket);
+ int ret;
+
+ if (irqfd->ghrsc) {
+ pr_warn("irqfd%d already got a Gunyah resource. Check if multiple resources with same label were configured.\n",
+ irqfd->ticket.label);
+ return false;
+ }
+
+ irqfd->ghrsc = ghrsc;
+ if (irqfd->level) {
+ /* Configure the bell to trigger when bit 0 is asserted (see
+ * irq_wakeup) and for bell to automatically clear bit 0 once
+ * received by the VM (ack_mask). need to make sure bit 0 is cleared right away,
+ * otherwise the line will never be deasserted. Emulating edge
+ * trigger interrupt does not need to set either mask
+ * because irq is listed only once per gunyah_hypercall_bell_send
+ */
+ ret = gunyah_hypercall_bell_set_mask(irqfd->ghrsc->capid, 1, 1);
+ if (ret)
+ pr_warn("irq %d couldn't be set as level triggered. Might cause IRQ storm if asserted\n",
+ irqfd->ticket.label);
+ }
+
+ return true;
+}
+
+static void gunyah_irqfd_unpopulate(struct gunyah_vm_resource_ticket *ticket,
+ struct gunyah_resource *ghrsc)
+{
+}
+
+static long gunyah_irqfd_bind(struct gunyah_vm_function_instance *f)
+{
+ struct gunyah_fn_irqfd_arg *args = f->argp;
+ struct gunyah_irqfd *irqfd;
+ __poll_t events;
+ struct fd fd;
+ long r;
+
+ if (f->arg_size != sizeof(*args))
+ return -EINVAL;
+
+ /* All other flag bits are reserved for future use */
+ if (args->flags & ~GUNYAH_IRQFD_FLAGS_LEVEL)
+ return -EINVAL;
+
+ irqfd = kzalloc(sizeof(*irqfd), GFP_KERNEL);
+ if (!irqfd)
+ return -ENOMEM;
+
+ irqfd->f = f;
+ f->data = irqfd;
+
+ fd = fdget(args->fd);
+ if (!fd.file) {
+ kfree(irqfd);
+ return -EBADF;
+ }
+
+ irqfd->ctx = eventfd_ctx_fileget(fd.file);
+ if (IS_ERR(irqfd->ctx)) {
+ r = PTR_ERR(irqfd->ctx);
+ goto err_fdput;
+ }
+
+ if (args->flags & GUNYAH_IRQFD_FLAGS_LEVEL)
+ irqfd->level = true;
+
+ init_waitqueue_func_entry(&irqfd->wait, irqfd_wakeup);
+ init_poll_funcptr(&irqfd->pt, irqfd_ptable_queue_proc);
+
+ irqfd->ticket.resource_type = GUNYAH_RESOURCE_TYPE_BELL_TX;
+ irqfd->ticket.label = args->label;
+ irqfd->ticket.owner = THIS_MODULE;
+ irqfd->ticket.populate = gunyah_irqfd_populate;
+ irqfd->ticket.unpopulate = gunyah_irqfd_unpopulate;
+
+ r = gunyah_vm_add_resource_ticket(f->ghvm, &irqfd->ticket);
+ if (r)
+ goto err_ctx;
+
+ events = vfs_poll(fd.file, &irqfd->pt);
+ if (events & EPOLLIN)
+ pr_warn("Premature injection of interrupt\n");
+ fdput(fd);
+
+ return 0;
+err_ctx:
+ eventfd_ctx_put(irqfd->ctx);
+err_fdput:
+ fdput(fd);
+ kfree(irqfd);
+ return r;
+}
+
+static void gunyah_irqfd_unbind(struct gunyah_vm_function_instance *f)
+{
+ struct gunyah_irqfd *irqfd = f->data;
+ u64 cnt;
+
+ eventfd_ctx_remove_wait_queue(irqfd->ctx, &irqfd->wait, &cnt);
+ gunyah_vm_remove_resource_ticket(irqfd->f->ghvm, &irqfd->ticket);
+ eventfd_ctx_put(irqfd->ctx);
+ kfree(irqfd);
+}
+
+static bool gunyah_irqfd_compare(const struct gunyah_vm_function_instance *f,
+ const void *arg, size_t size)
+{
+ const struct gunyah_fn_irqfd_arg *instance = f->argp, *other = arg;
+
+ if (sizeof(*other) != size)
+ return false;
+
+ return instance->label == other->label;
+}
+
+DECLARE_GUNYAH_VM_FUNCTION_INIT(irqfd, GUNYAH_FN_IRQFD, 2, gunyah_irqfd_bind,
+ gunyah_irqfd_unbind, gunyah_irqfd_compare);
+MODULE_DESCRIPTION("Gunyah irqfd VM Function");
+MODULE_LICENSE("GPL");
diff --git a/include/uapi/linux/gunyah.h b/include/uapi/linux/gunyah.h
index 574116f544722..cb7b0bb9bef38 100644
--- a/include/uapi/linux/gunyah.h
+++ b/include/uapi/linux/gunyah.h
@@ -63,9 +63,12 @@ struct gunyah_vm_dtb_config {
* @GUNYAH_FN_VCPU: create a vCPU instance to control a vCPU
* &struct gunyah_fn_desc.arg is a pointer to &struct gunyah_fn_vcpu_arg
* 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
*/
enum gunyah_fn_type {
GUNYAH_FN_VCPU = 1,
+ GUNYAH_FN_IRQFD,
};
#define GUNYAH_FN_MAX_ARG_SIZE 256
@@ -85,6 +88,38 @@ struct gunyah_fn_vcpu_arg {
__u32 id;
};
+/**
+ * enum gunyah_irqfd_flags - flags for use in gunyah_fn_irqfd_arg
+ * @GUNYAH_IRQFD_FLAGS_LEVEL: make the interrupt operate like a level triggered
+ * interrupt on guest side. Triggering IRQFD before
+ * guest handles the interrupt causes interrupt to
+ * stay asserted.
+ */
+enum gunyah_irqfd_flags {
+ GUNYAH_IRQFD_FLAGS_LEVEL = 1UL << 0,
+};
+
+/**
+ * struct gunyah_fn_irqfd_arg - Arguments to create an irqfd function.
+ *
+ * Create this function with &GUNYAH_VM_ADD_FUNCTION using type &GUNYAH_FN_IRQFD.
+ *
+ * Allows setting an eventfd to directly trigger a guest interrupt.
+ * irqfd.fd specifies the file descriptor to use as the eventfd.
+ * irqfd.label corresponds to the doorbell label used in the guest VM's devicetree.
+ *
+ * @fd: an eventfd which when written to will raise a doorbell
+ * @label: Label of the doorbell created on the guest VM
+ * @flags: see &enum gunyah_irqfd_flags
+ * @padding: padding bytes
+ */
+struct gunyah_fn_irqfd_arg {
+ __u32 fd;
+ __u32 label;
+ __u32 flags;
+ __u32 padding;
+};
+
/**
* struct gunyah_fn_desc - Arguments to create a VM function
* @type: Type of the function. See &enum gunyah_fn_type.
--
2.34.1
