Gunyah allows vCPUs that are configured as proxy-scheduled to be scheduled by
another virtual machine (host) that holds capabilities to those vCPUs with
suitable rights.
Gunyah also supports configuring regions of a proxy-scheduled VM's address
space to be virtualized by the host VM. This permits a host VMM to emulate MMIO
devices in the proxy-scheduled VM.
vCPUs are presented to the host as a Gunyah resource and represented to
userspace as a Gunyah VM function.
Creating the vcpu function on the VM will create a file descriptor that:
- can handle an ioctl to run the vCPU. When called, Gunyah will directly
context-switch to the selected vCPU and run it until one of the following
events occurs:
* the host vcpu's time slice ends
* the host vcpu receives an interrupt or would have been pre-empted
by the hypervisor
* a fault occurs in the proxy-scheduled vcpu
* a power management event, such as idle or cpu-off call in the vcpu
- can be mmap'd to share the gunyah_vcpu_run structure with userspace. This
allows the vcpu_run result codes to be accessed, and for arguments to
vcpu_run to be passed, e.g. for resuming the vcpu when handling certain fault
and exit cases.
Co-developed-by: Prakruthi Deepak Heragu <[email protected]>
Signed-off-by: Prakruthi Deepak Heragu <[email protected]>
Signed-off-by: Elliot Berman <[email protected]>
---
drivers/virt/gunyah/Makefile | 2 +-
drivers/virt/gunyah/gunyah_vcpu.c | 561 ++++++++++++++++++++++++++++++++++++++
drivers/virt/gunyah/vm_mgr.c | 5 +
drivers/virt/gunyah/vm_mgr.h | 2 +
include/uapi/linux/gunyah.h | 163 +++++++++++
5 files changed, 732 insertions(+), 1 deletion(-)
diff --git a/drivers/virt/gunyah/Makefile b/drivers/virt/gunyah/Makefile
index 47f1fae5419bf..3f82af8c5ce79 100644
--- a/drivers/virt/gunyah/Makefile
+++ b/drivers/virt/gunyah/Makefile
@@ -2,4 +2,4 @@
gunyah_rsc_mgr-y += rsc_mgr.o rsc_mgr_rpc.o vm_mgr.o
-obj-$(CONFIG_GUNYAH) += gunyah.o gunyah_rsc_mgr.o
+obj-$(CONFIG_GUNYAH) += gunyah.o gunyah_rsc_mgr.o gunyah_vcpu.o
diff --git a/drivers/virt/gunyah/gunyah_vcpu.c b/drivers/virt/gunyah/gunyah_vcpu.c
new file mode 100644
index 0000000000000..8192350f180b0
--- /dev/null
+++ b/drivers/virt/gunyah/gunyah_vcpu.c
@@ -0,0 +1,561 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * Copyright (c) 2022-2024 Qualcomm Innovation Center, Inc. All rights reserved.
+ */
+
+#include <linux/anon_inodes.h>
+#include <linux/file.h>
+#include <linux/gunyah.h>
+#include <linux/interrupt.h>
+#include <linux/kref.h>
+#include <linux/mm.h>
+#include <linux/module.h>
+#include <linux/types.h>
+#include <linux/wait.h>
+
+#include "vm_mgr.h"
+
+#include <uapi/linux/gunyah.h>
+
+#define MAX_VCPU_NAME 20 /* gh-vcpu:strlen(U32::MAX)+NUL */
+
+/**
+ * struct gunyah_vcpu - Track an instance of gunyah vCPU
+ * @f: Function instance (how we get associated with the main VM)
+ * @rsc: Pointer to the Gunyah vCPU resource, will be NULL until VM starts
+ * @run_lock: One userspace thread at a time should run the vCPU
+ * @ghvm: Pointer to the main VM struct; quicker look up than going through
+ * @f->ghvm
+ * @vcpu_run: Pointer to page shared with userspace to communicate vCPU state
+ * @state: Our copy of the state of the vCPU, since userspace could trick
+ * kernel to behave incorrectly if we relied on @vcpu_run
+ * @mmio_read_len: Our copy of @vcpu_run->mmio.len; see also @state
+ * @mmio_addr: Our copy of @vcpu_run->mmio.phys_addr; see also @state
+ * @ready: if vCPU goes to sleep, hypervisor reports to us that it's sleeping
+ * and will signal interrupt (from @rsc) when it's time to wake up.
+ * This completion signals that we can run vCPU again.
+ * @nb: When VM exits, the status of VM is reported via @vcpu_run->status.
+ * We need to track overall VM status, and the nb gives us the updates from
+ * Resource Manager.
+ * @ticket: resource ticket to claim vCPU# for the VM
+ * @kref: Reference counter
+ */
+struct gunyah_vcpu {
+ struct gunyah_vm_function_instance *f;
+ struct gunyah_resource *rsc;
+ struct mutex run_lock;
+ struct gunyah_vm *ghvm;
+
+ struct gunyah_vcpu_run *vcpu_run;
+
+ /**
+ * Track why the vcpu_run hypercall returned. This mirrors the vcpu_run
+ * structure shared with userspace, except is used internally to avoid
+ * trusting userspace to not modify the vcpu_run structure.
+ */
+ enum {
+ GUNYAH_VCPU_RUN_STATE_UNKNOWN = 0,
+ GUNYAH_VCPU_RUN_STATE_READY,
+ GUNYAH_VCPU_RUN_STATE_MMIO_READ,
+ GUNYAH_VCPU_RUN_STATE_MMIO_WRITE,
+ GUNYAH_VCPU_RUN_STATE_SYSTEM_DOWN,
+ } state;
+ u8 mmio_read_len;
+ u64 mmio_addr;
+
+ struct completion ready;
+
+ struct notifier_block nb;
+ struct gunyah_vm_resource_ticket ticket;
+ struct kref kref;
+};
+
+static void vcpu_release(struct kref *kref)
+{
+ struct gunyah_vcpu *vcpu = container_of(kref, struct gunyah_vcpu, kref);
+
+ free_page((unsigned long)vcpu->vcpu_run);
+ kfree(vcpu);
+}
+
+/*
+ * When hypervisor allows us to schedule vCPU again, it gives us an interrupt
+ */
+static irqreturn_t gunyah_vcpu_irq_handler(int irq, void *data)
+{
+ struct gunyah_vcpu *vcpu = data;
+
+ complete(&vcpu->ready);
+ return IRQ_HANDLED;
+}
+
+static void gunyah_handle_page_fault(
+ struct gunyah_vcpu *vcpu,
+ const struct gunyah_hypercall_vcpu_run_resp *vcpu_run_resp)
+{
+ u64 addr = vcpu_run_resp->state_data[0];
+
+ vcpu->vcpu_run->page_fault.resume_action = GUNYAH_VCPU_RESUME_FAULT;
+ vcpu->vcpu_run->page_fault.attempt = 0;
+ vcpu->vcpu_run->page_fault.phys_addr = addr;
+ vcpu->vcpu_run->exit_reason = GUNYAH_VCPU_EXIT_PAGE_FAULT;
+}
+
+static void
+gunyah_handle_mmio(struct gunyah_vcpu *vcpu,
+ const struct gunyah_hypercall_vcpu_run_resp *vcpu_run_resp)
+{
+ u64 addr = vcpu_run_resp->state_data[0],
+ len = vcpu_run_resp->state_data[1],
+ data = vcpu_run_resp->state_data[2];
+
+ if (WARN_ON(len > sizeof(u64)))
+ len = sizeof(u64);
+
+ if (vcpu_run_resp->state == GUNYAH_VCPU_ADDRSPACE_VMMIO_READ) {
+ vcpu->vcpu_run->mmio.is_write = 0;
+ /* Record that we need to give vCPU user's supplied value next gunyah_vcpu_run() */
+ vcpu->state = GUNYAH_VCPU_RUN_STATE_MMIO_READ;
+ vcpu->mmio_read_len = len;
+ } else { /* GUNYAH_VCPU_ADDRSPACE_VMMIO_WRITE */
+ vcpu->vcpu_run->mmio.is_write = 1;
+ memcpy(vcpu->vcpu_run->mmio.data, &data, len);
+ vcpu->state = GUNYAH_VCPU_RUN_STATE_MMIO_WRITE;
+ }
+
+ /* Assume userspace is okay and handles the access due to existing userspace */
+ vcpu->vcpu_run->mmio.resume_action = GUNYAH_VCPU_RESUME_HANDLED;
+ vcpu->mmio_addr = vcpu->vcpu_run->mmio.phys_addr = addr;
+ vcpu->vcpu_run->mmio.len = len;
+ vcpu->vcpu_run->exit_reason = GUNYAH_VCPU_EXIT_MMIO;
+}
+
+static int gunyah_handle_mmio_resume(struct gunyah_vcpu *vcpu,
+ unsigned long resume_data[3])
+{
+ switch (vcpu->vcpu_run->mmio.resume_action) {
+ case GUNYAH_VCPU_RESUME_HANDLED:
+ if (vcpu->state == GUNYAH_VCPU_RUN_STATE_MMIO_READ) {
+ if (unlikely(vcpu->mmio_read_len >
+ sizeof(resume_data[0])))
+ vcpu->mmio_read_len = sizeof(resume_data[0]);
+ memcpy(&resume_data[0], vcpu->vcpu_run->mmio.data,
+ vcpu->mmio_read_len);
+ }
+ resume_data[1] = GUNYAH_ADDRSPACE_VMMIO_ACTION_EMULATE;
+ break;
+ case GUNYAH_VCPU_RESUME_FAULT:
+ resume_data[1] = GUNYAH_ADDRSPACE_VMMIO_ACTION_FAULT;
+ break;
+ case GUNYAH_VCPU_RESUME_RETRY:
+ resume_data[1] = GUNYAH_ADDRSPACE_VMMIO_ACTION_RETRY;
+ break;
+ default:
+ return -EINVAL;
+ }
+
+ return 0;
+}
+
+static int gunyah_vcpu_rm_notification(struct notifier_block *nb,
+ unsigned long action, void *data)
+{
+ struct gunyah_vcpu *vcpu = container_of(nb, struct gunyah_vcpu, nb);
+ struct gunyah_rm_vm_exited_payload *exit_payload = data;
+
+ /* Wake up userspace waiting for the vCPU to be runnable again */
+ if (action == GUNYAH_RM_NOTIFICATION_VM_EXITED &&
+ le16_to_cpu(exit_payload->vmid) == vcpu->ghvm->vmid)
+ complete(&vcpu->ready);
+
+ return NOTIFY_OK;
+}
+
+static inline enum gunyah_vm_status
+remap_vm_status(enum gunyah_rm_vm_status rm_status)
+{
+ switch (rm_status) {
+ case GUNYAH_RM_VM_STATUS_INIT_FAILED:
+ return GUNYAH_VM_STATUS_LOAD_FAILED;
+ case GUNYAH_RM_VM_STATUS_EXITED:
+ return GUNYAH_VM_STATUS_EXITED;
+ default:
+ return GUNYAH_VM_STATUS_CRASHED;
+ }
+}
+
+/**
+ * gunyah_vcpu_check_system() - Check whether VM as a whole is running
+ * @vcpu: Pointer to gunyah_vcpu
+ *
+ * Returns true if the VM is alive.
+ * Returns false if the vCPU is the VM is not alive (can only be that VM is shutting down).
+ */
+static bool gunyah_vcpu_check_system(struct gunyah_vcpu *vcpu)
+ __must_hold(&vcpu->run_lock)
+{
+ bool ret = true;
+
+ down_read(&vcpu->ghvm->status_lock);
+ if (likely(vcpu->ghvm->vm_status == GUNYAH_RM_VM_STATUS_RUNNING))
+ goto out;
+
+ vcpu->vcpu_run->status.status = remap_vm_status(vcpu->ghvm->vm_status);
+ vcpu->vcpu_run->status.exit_info = vcpu->ghvm->exit_info;
+ vcpu->vcpu_run->exit_reason = GUNYAH_VCPU_EXIT_STATUS;
+ vcpu->state = GUNYAH_VCPU_RUN_STATE_SYSTEM_DOWN;
+ ret = false;
+out:
+ up_read(&vcpu->ghvm->status_lock);
+ return ret;
+}
+
+/**
+ * gunyah_vcpu_run() - Request Gunyah to begin scheduling this vCPU.
+ * @vcpu: The client descriptor that was obtained via gunyah_vcpu_alloc()
+ */
+static int gunyah_vcpu_run(struct gunyah_vcpu *vcpu)
+{
+ struct gunyah_hypercall_vcpu_run_resp vcpu_run_resp;
+ unsigned long resume_data[3] = { 0 };
+ enum gunyah_error gunyah_error;
+ int ret = 0;
+
+ if (!vcpu->f)
+ return -ENODEV;
+
+ if (mutex_lock_interruptible(&vcpu->run_lock))
+ return -ERESTARTSYS;
+
+ if (!vcpu->rsc) {
+ ret = -ENODEV;
+ goto out;
+ }
+
+ switch (vcpu->state) {
+ case GUNYAH_VCPU_RUN_STATE_UNKNOWN:
+ if (vcpu->ghvm->vm_status != GUNYAH_RM_VM_STATUS_RUNNING) {
+ /**
+ * Check if VM is up. If VM is starting, will block
+ * until VM is fully up since that thread does
+ * down_write.
+ */
+ if (!gunyah_vcpu_check_system(vcpu))
+ goto out;
+ }
+ vcpu->state = GUNYAH_VCPU_RUN_STATE_READY;
+ break;
+ case GUNYAH_VCPU_RUN_STATE_MMIO_READ:
+ case GUNYAH_VCPU_RUN_STATE_MMIO_WRITE:
+ ret = gunyah_handle_mmio_resume(vcpu, resume_data);
+ if (ret)
+ goto out;
+ vcpu->state = GUNYAH_VCPU_RUN_STATE_READY;
+ break;
+ case GUNYAH_VCPU_RUN_STATE_SYSTEM_DOWN:
+ goto out;
+ default:
+ break;
+ }
+
+ while (!ret && !signal_pending(current)) {
+ if (vcpu->vcpu_run->immediate_exit) {
+ ret = -EINTR;
+ goto out;
+ }
+
+ gunyah_error = gunyah_hypercall_vcpu_run(
+ vcpu->rsc->capid, resume_data, &vcpu_run_resp);
+ if (gunyah_error == GUNYAH_ERROR_OK) {
+ memset(resume_data, 0, sizeof(resume_data));
+ switch (vcpu_run_resp.state) {
+ case GUNYAH_VCPU_STATE_READY:
+ if (need_resched())
+ schedule();
+ break;
+ case GUNYAH_VCPU_STATE_POWERED_OFF:
+ /**
+ * vcpu might be off because the VM is shut down
+ * If so, it won't ever run again
+ */
+ if (!gunyah_vcpu_check_system(vcpu))
+ goto out;
+ /**
+ * Otherwise, another vcpu will turn it on (e.g.
+ * by PSCI) and hyp sends an interrupt to wake
+ * Linux up.
+ */
+ fallthrough;
+ case GUNYAH_VCPU_STATE_EXPECTS_WAKEUP:
+ ret = wait_for_completion_interruptible(
+ &vcpu->ready);
+ /**
+ * reinitialize completion before next
+ * hypercall. If we reinitialize after the
+ * hypercall, interrupt may have already come
+ * before re-initializing the completion and
+ * then end up waiting for event that already
+ * happened.
+ */
+ reinit_completion(&vcpu->ready);
+ /**
+ * Check VM status again. Completion
+ * might've come from VM exiting
+ */
+ if (!ret && !gunyah_vcpu_check_system(vcpu))
+ goto out;
+ break;
+ case GUNYAH_VCPU_STATE_BLOCKED:
+ schedule();
+ break;
+ case GUNYAH_VCPU_ADDRSPACE_VMMIO_READ:
+ case GUNYAH_VCPU_ADDRSPACE_VMMIO_WRITE:
+ gunyah_handle_mmio(vcpu, &vcpu_run_resp);
+ goto out;
+ case GUNYAH_VCPU_ADDRSPACE_PAGE_FAULT:
+ gunyah_handle_page_fault(vcpu, &vcpu_run_resp);
+ goto out;
+ default:
+ pr_warn_ratelimited(
+ "Unknown vCPU state: %llx\n",
+ vcpu_run_resp.sized_state);
+ schedule();
+ break;
+ }
+ } else if (gunyah_error == GUNYAH_ERROR_RETRY) {
+ schedule();
+ } else {
+ ret = gunyah_error_remap(gunyah_error);
+ }
+ }
+
+out:
+ mutex_unlock(&vcpu->run_lock);
+
+ if (signal_pending(current))
+ return -ERESTARTSYS;
+
+ return ret;
+}
+
+static long gunyah_vcpu_ioctl(struct file *filp, unsigned int cmd,
+ unsigned long arg)
+{
+ struct gunyah_vcpu *vcpu = filp->private_data;
+ long ret = -ENOTTY;
+
+ switch (cmd) {
+ case GUNYAH_VCPU_RUN:
+ ret = gunyah_vcpu_run(vcpu);
+ break;
+ case GUNYAH_VCPU_MMAP_SIZE:
+ ret = PAGE_SIZE;
+ break;
+ default:
+ break;
+ }
+ return ret;
+}
+
+static int gunyah_vcpu_release(struct inode *inode, struct file *filp)
+{
+ struct gunyah_vcpu *vcpu = filp->private_data;
+
+ gunyah_vm_put(vcpu->ghvm);
+ kref_put(&vcpu->kref, vcpu_release);
+ return 0;
+}
+
+static vm_fault_t gunyah_vcpu_fault(struct vm_fault *vmf)
+{
+ struct gunyah_vcpu *vcpu = vmf->vma->vm_file->private_data;
+ struct page *page;
+
+ if (vmf->pgoff)
+ return VM_FAULT_SIGBUS;
+
+ page = virt_to_page(vcpu->vcpu_run);
+ get_page(page);
+ vmf->page = page;
+ return 0;
+}
+
+static const struct vm_operations_struct gunyah_vcpu_ops = {
+ .fault = gunyah_vcpu_fault,
+};
+
+static int gunyah_vcpu_mmap(struct file *file, struct vm_area_struct *vma)
+{
+ vma->vm_ops = &gunyah_vcpu_ops;
+ return 0;
+}
+
+static const struct file_operations gunyah_vcpu_fops = {
+ .owner = THIS_MODULE,
+ .unlocked_ioctl = gunyah_vcpu_ioctl,
+ .release = gunyah_vcpu_release,
+ .llseek = noop_llseek,
+ .mmap = gunyah_vcpu_mmap,
+};
+
+static bool gunyah_vcpu_populate(struct gunyah_vm_resource_ticket *ticket,
+ struct gunyah_resource *ghrsc)
+{
+ struct gunyah_vcpu *vcpu =
+ container_of(ticket, struct gunyah_vcpu, ticket);
+ int ret;
+
+ mutex_lock(&vcpu->run_lock);
+ if (vcpu->rsc) {
+ pr_warn("vcpu%d already got a Gunyah resource. Check if multiple resources with same label were configured.\n",
+ vcpu->ticket.label);
+ ret = -EEXIST;
+ goto out;
+ }
+
+ vcpu->rsc = ghrsc;
+
+ ret = request_irq(vcpu->rsc->irq, gunyah_vcpu_irq_handler,
+ IRQF_TRIGGER_RISING, "gunyah_vcpu", vcpu);
+ if (ret) {
+ pr_warn("Failed to request vcpu irq %d: %d", vcpu->rsc->irq,
+ ret);
+ goto out;
+ }
+
+ enable_irq_wake(vcpu->rsc->irq);
+
+out:
+ mutex_unlock(&vcpu->run_lock);
+ return !ret;
+}
+
+static void gunyah_vcpu_unpopulate(struct gunyah_vm_resource_ticket *ticket,
+ struct gunyah_resource *ghrsc)
+{
+ struct gunyah_vcpu *vcpu =
+ container_of(ticket, struct gunyah_vcpu, ticket);
+
+ vcpu->vcpu_run->immediate_exit = true;
+ complete_all(&vcpu->ready);
+ mutex_lock(&vcpu->run_lock);
+ free_irq(vcpu->rsc->irq, vcpu);
+ vcpu->rsc = NULL;
+ mutex_unlock(&vcpu->run_lock);
+}
+
+static long gunyah_vcpu_bind(struct gunyah_vm_function_instance *f)
+{
+ struct gunyah_fn_vcpu_arg *arg = f->argp;
+ struct gunyah_vcpu *vcpu;
+ char name[MAX_VCPU_NAME];
+ struct file *file;
+ struct page *page;
+ int fd;
+ long r;
+
+ if (f->arg_size != sizeof(*arg))
+ return -EINVAL;
+
+ vcpu = kzalloc(sizeof(*vcpu), GFP_KERNEL);
+ if (!vcpu)
+ return -ENOMEM;
+
+ vcpu->f = f;
+ f->data = vcpu;
+ mutex_init(&vcpu->run_lock);
+ kref_init(&vcpu->kref);
+ init_completion(&vcpu->ready);
+
+ page = alloc_page(GFP_KERNEL | __GFP_ZERO);
+ if (!page) {
+ r = -ENOMEM;
+ goto err_destroy_vcpu;
+ }
+ vcpu->vcpu_run = page_address(page);
+
+ vcpu->ticket.resource_type = GUNYAH_RESOURCE_TYPE_VCPU;
+ vcpu->ticket.label = arg->id;
+ vcpu->ticket.owner = THIS_MODULE;
+ vcpu->ticket.populate = gunyah_vcpu_populate;
+ vcpu->ticket.unpopulate = gunyah_vcpu_unpopulate;
+
+ r = gunyah_vm_add_resource_ticket(f->ghvm, &vcpu->ticket);
+ if (r)
+ goto err_destroy_page;
+
+ if (!gunyah_vm_get(f->ghvm)) {
+ r = -ENODEV;
+ goto err_remove_resource_ticket;
+ }
+ vcpu->ghvm = f->ghvm;
+
+ vcpu->nb.notifier_call = gunyah_vcpu_rm_notification;
+ /**
+ * Ensure we run after the vm_mgr handles the notification and does
+ * any necessary state changes.
+ */
+ vcpu->nb.priority = -1;
+ r = gunyah_rm_notifier_register(f->rm, &vcpu->nb);
+ if (r)
+ goto err_put_gunyah_vm;
+
+ kref_get(&vcpu->kref);
+
+ fd = get_unused_fd_flags(O_CLOEXEC);
+ if (fd < 0) {
+ r = fd;
+ goto err_notifier;
+ }
+
+ snprintf(name, sizeof(name), "gh-vcpu:%u", vcpu->ticket.label);
+ file = anon_inode_getfile(name, &gunyah_vcpu_fops, vcpu, O_RDWR);
+ if (IS_ERR(file)) {
+ r = PTR_ERR(file);
+ goto err_put_fd;
+ }
+
+ fd_install(fd, file);
+
+ return fd;
+err_put_fd:
+ put_unused_fd(fd);
+err_notifier:
+ gunyah_rm_notifier_unregister(f->rm, &vcpu->nb);
+err_put_gunyah_vm:
+ gunyah_vm_put(vcpu->ghvm);
+err_remove_resource_ticket:
+ gunyah_vm_remove_resource_ticket(f->ghvm, &vcpu->ticket);
+err_destroy_page:
+ free_page((unsigned long)vcpu->vcpu_run);
+err_destroy_vcpu:
+ kfree(vcpu);
+ return r;
+}
+
+static void gunyah_vcpu_unbind(struct gunyah_vm_function_instance *f)
+{
+ struct gunyah_vcpu *vcpu = f->data;
+
+ gunyah_rm_notifier_unregister(f->rm, &vcpu->nb);
+ gunyah_vm_remove_resource_ticket(vcpu->ghvm, &vcpu->ticket);
+ vcpu->f = NULL;
+
+ kref_put(&vcpu->kref, vcpu_release);
+}
+
+static bool gunyah_vcpu_compare(const struct gunyah_vm_function_instance *f,
+ const void *arg, size_t size)
+{
+ const struct gunyah_fn_vcpu_arg *instance = f->argp, *other = arg;
+
+ if (sizeof(*other) != size)
+ return false;
+
+ return instance->id == other->id;
+}
+
+DECLARE_GUNYAH_VM_FUNCTION_INIT(vcpu, GUNYAH_FN_VCPU, 1, gunyah_vcpu_bind,
+ gunyah_vcpu_unbind, gunyah_vcpu_compare);
+MODULE_DESCRIPTION("Gunyah vCPU Function");
+MODULE_LICENSE("GPL");
diff --git a/drivers/virt/gunyah/vm_mgr.c b/drivers/virt/gunyah/vm_mgr.c
index a619dd10972a5..a6e25901dcea3 100644
--- a/drivers/virt/gunyah/vm_mgr.c
+++ b/drivers/virt/gunyah/vm_mgr.c
@@ -309,6 +309,11 @@ static int gunyah_vm_rm_notification_exited(struct gunyah_vm *ghvm, void *data)
down_write(&ghvm->status_lock);
ghvm->vm_status = GUNYAH_RM_VM_STATUS_EXITED;
+ ghvm->exit_info.type = le16_to_cpu(payload->exit_type);
+ ghvm->exit_info.reason_size = le32_to_cpu(payload->exit_reason_size);
+ memcpy(&ghvm->exit_info.reason, payload->exit_reason,
+ min(GUNYAH_VM_MAX_EXIT_REASON_SIZE,
+ ghvm->exit_info.reason_size));
up_write(&ghvm->status_lock);
wake_up(&ghvm->vm_status_wait);
diff --git a/drivers/virt/gunyah/vm_mgr.h b/drivers/virt/gunyah/vm_mgr.h
index 190a95ee8da64..8c5b94101b2cf 100644
--- a/drivers/virt/gunyah/vm_mgr.h
+++ b/drivers/virt/gunyah/vm_mgr.h
@@ -28,6 +28,7 @@ long gunyah_dev_vm_mgr_ioctl(struct gunyah_rm *rm, unsigned int cmd,
* @vm_status: Current state of the VM, as last reported by RM
* @vm_status_wait: Wait queue for status @vm_status changes
* @status_lock: Serializing state transitions
+ * @exit_info: Breadcrumbs why VM is not running anymore
* @kref: Reference counter for VM functions
* @fn_lock: Serialization addition of functions
* @functions: List of &struct gunyah_vm_function_instance that have been
@@ -48,6 +49,7 @@ struct gunyah_vm {
enum gunyah_rm_vm_status vm_status;
wait_queue_head_t vm_status_wait;
struct rw_semaphore status_lock;
+ struct gunyah_vm_exit_info exit_info;
struct kref kref;
struct mutex fn_lock;
diff --git a/include/uapi/linux/gunyah.h b/include/uapi/linux/gunyah.h
index 1b7cb5fde70a2..46f7d3aa61d05 100644
--- a/include/uapi/linux/gunyah.h
+++ b/include/uapi/linux/gunyah.h
@@ -25,8 +25,33 @@
*/
#define GUNYAH_VM_START _IO(GUNYAH_IOCTL_TYPE, 0x3)
+/**
+ * enum gunyah_fn_type - Valid types of Gunyah VM functions
+ * @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.
+ */
+enum gunyah_fn_type {
+ GUNYAH_FN_VCPU = 1,
+};
+
#define GUNYAH_FN_MAX_ARG_SIZE 256
+/**
+ * struct gunyah_fn_vcpu_arg - Arguments to create a vCPU.
+ * @id: vcpu id
+ *
+ * Create this function with &GUNYAH_VM_ADD_FUNCTION using type &GUNYAH_FN_VCPU.
+ *
+ * The vcpu type will register with the VM Manager to expect to control
+ * vCPU number `vcpu_id`. It returns a file descriptor allowing interaction with
+ * the vCPU. See the Gunyah vCPU API description sections for interacting with
+ * the Gunyah vCPU file descriptors.
+ */
+struct gunyah_fn_vcpu_arg {
+ __u32 id;
+};
+
/**
* struct gunyah_fn_desc - Arguments to create a VM function
* @type: Type of the function. See &enum gunyah_fn_type.
@@ -43,4 +68,142 @@ struct gunyah_fn_desc {
#define GUNYAH_VM_ADD_FUNCTION _IOW(GUNYAH_IOCTL_TYPE, 0x4, struct gunyah_fn_desc)
#define GUNYAH_VM_REMOVE_FUNCTION _IOW(GUNYAH_IOCTL_TYPE, 0x7, struct gunyah_fn_desc)
+/*
+ * ioctls for vCPU fds
+ */
+
+/**
+ * enum gunyah_vm_status - Stores status reason why VM is not runnable (exited).
+ * @GUNYAH_VM_STATUS_LOAD_FAILED: VM didn't start because it couldn't be loaded.
+ * @GUNYAH_VM_STATUS_EXITED: VM requested shutdown/reboot.
+ * Use &struct gunyah_vm_exit_info.reason for further details.
+ * @GUNYAH_VM_STATUS_CRASHED: VM state is unknown and has crashed.
+ */
+enum gunyah_vm_status {
+ GUNYAH_VM_STATUS_LOAD_FAILED = 1,
+ GUNYAH_VM_STATUS_EXITED = 2,
+ GUNYAH_VM_STATUS_CRASHED = 3,
+};
+
+/*
+ * Gunyah presently sends max 4 bytes of exit_reason.
+ * If that changes, this macro can be safely increased without breaking
+ * userspace so long as struct gunyah_vcpu_run < PAGE_SIZE.
+ */
+#define GUNYAH_VM_MAX_EXIT_REASON_SIZE 8u
+
+/**
+ * struct gunyah_vm_exit_info - Reason for VM exit as reported by Gunyah
+ * See Gunyah documentation for values.
+ * @type: Describes how VM exited
+ * @padding: padding bytes
+ * @reason_size: Number of bytes valid for `reason`
+ * @reason: See Gunyah documentation for interpretation. Note: these values are
+ * not interpreted by Linux and need to be converted from little-endian
+ * as applicable.
+ */
+struct gunyah_vm_exit_info {
+ __u16 type;
+ __u16 padding;
+ __u32 reason_size;
+ __u8 reason[GUNYAH_VM_MAX_EXIT_REASON_SIZE];
+};
+
+/**
+ * enum gunyah_vcpu_exit - Stores reason why &GUNYAH_VCPU_RUN ioctl recently exited with status 0
+ * @GUNYAH_VCPU_EXIT_UNKNOWN: Not used, status != 0
+ * @GUNYAH_VCPU_EXIT_MMIO: vCPU performed a read or write that could not be handled
+ * by hypervisor or Linux. Use @struct gunyah_vcpu_run.mmio for
+ * details of the read/write.
+ * @GUNYAH_VCPU_EXIT_STATUS: vCPU not able to run because the VM has exited.
+ * Use @struct gunyah_vcpu_run.status for why VM has exited.
+ * @GUNYAH_VCPU_EXIT_PAGE_FAULT: vCPU tried to execute an instruction at an address
+ * for which memory hasn't been provided. Use
+ * @struct gunyah_vcpu_run.page_fault for details.
+ */
+enum gunyah_vcpu_exit {
+ GUNYAH_VCPU_EXIT_UNKNOWN,
+ GUNYAH_VCPU_EXIT_MMIO,
+ GUNYAH_VCPU_EXIT_STATUS,
+ GUNYAH_VCPU_EXIT_PAGE_FAULT,
+};
+
+/**
+ * enum gunyah_vcpu_resume_action - Provide resume action after an MMIO or page fault
+ * @GUNYAH_VCPU_RESUME_HANDLED: The mmio or page fault has been handled, continue
+ * normal operation of vCPU
+ * @GUNYAH_VCPU_RESUME_FAULT: The mmio or page fault could not be satisfied and
+ * inject the original fault back to the guest.
+ * @GUNYAH_VCPU_RESUME_RETRY: Retry the faulting instruction. Perhaps you added
+ * memory binding to satisfy the request.
+ */
+enum gunyah_vcpu_resume_action {
+ GUNYAH_VCPU_RESUME_HANDLED = 0,
+ GUNYAH_VCPU_RESUME_FAULT,
+ GUNYAH_VCPU_RESUME_RETRY,
+};
+
+/**
+ * struct gunyah_vcpu_run - Application code obtains a pointer to the gunyah_vcpu_run
+ * structure by mmap()ing a vcpu fd.
+ * @immediate_exit: polled when scheduling the vcpu. If set, immediately returns -EINTR.
+ * @padding: padding bytes
+ * @exit_reason: Set when GUNYAH_VCPU_RUN returns successfully and gives reason why
+ * GUNYAH_VCPU_RUN has stopped running the vCPU. See &enum gunyah_vcpu_exit.
+ * @mmio: Used when exit_reason == GUNYAH_VCPU_EXIT_MMIO
+ * The guest has faulted on an memory-mapped I/O that
+ * couldn't be satisfied by gunyah.
+ * @mmio.phys_addr: Address guest tried to access
+ * @mmio.data: the value that was written if `is_write == 1`. Filled by
+ * user for reads (`is_write == 0`).
+ * @mmio.len: Length of write. Only the first `len` bytes of `data`
+ * are considered by Gunyah.
+ * @mmio.is_write: 1 if VM tried to perform a write, 0 for a read
+ * @mmio.resume_action: See &enum gunyah_vcpu_resume_action
+ * @status: Used when exit_reason == GUNYAH_VCPU_EXIT_STATUS.
+ * The guest VM is no longer runnable. This struct informs why.
+ * @status.status: See &enum gunyah_vm_status for possible values
+ * @status.exit_info: Used when status == GUNYAH_VM_STATUS_EXITED
+ * @page_fault: Used when EXIT_REASON == GUNYAH_VCPU_EXIT_PAGE_FAULT
+ * The guest has faulted on a region that can only be provided
+ * by mapping memory at phys_addr.
+ * @page_fault.phys_addr: Address guest tried to access.
+ * @page_fault.attempt: Error code why Linux wasn't able to handle fault itself
+ * Typically, if no memory was mapped: -ENOENT,
+ * If permission bits weren't what the VM wanted: -EPERM
+ * @page_fault.resume_action: See &enum gunyah_vcpu_resume_action
+ */
+struct gunyah_vcpu_run {
+ /* in */
+ __u8 immediate_exit;
+ __u8 padding[7];
+
+ /* out */
+ __u32 exit_reason;
+
+ union {
+ struct {
+ __u64 phys_addr;
+ __u8 data[8];
+ __u32 len;
+ __u8 is_write;
+ __u8 resume_action;
+ } mmio;
+
+ struct {
+ enum gunyah_vm_status status;
+ struct gunyah_vm_exit_info exit_info;
+ } status;
+
+ struct {
+ __u64 phys_addr;
+ __s32 attempt;
+ __u8 resume_action;
+ } page_fault;
+ };
+};
+
+#define GUNYAH_VCPU_RUN _IO(GUNYAH_IOCTL_TYPE, 0x5)
+#define GUNYAH_VCPU_MMAP_SIZE _IO(GUNYAH_IOCTL_TYPE, 0x6)
+
#endif
--
2.34.1
* Elliot Berman <[email protected]> [2024-02-22 15:16:38]:
> Gunyah allows vCPUs that are configured as proxy-scheduled to be scheduled by
> another virtual machine (host) that holds capabilities to those vCPUs with
> suitable rights.
>
> Gunyah also supports configuring regions of a proxy-scheduled VM's address
> space to be virtualized by the host VM. This permits a host VMM to emulate MMIO
> devices in the proxy-scheduled VM.
>
> vCPUs are presented to the host as a Gunyah resource and represented to
> userspace as a Gunyah VM function.
>
> Creating the vcpu function on the VM will create a file descriptor that:
> - can handle an ioctl to run the vCPU. When called, Gunyah will directly
> context-switch to the selected vCPU and run it until one of the following
> events occurs:
> * the host vcpu's time slice ends
> * the host vcpu receives an interrupt or would have been pre-empted
> by the hypervisor
> * a fault occurs in the proxy-scheduled vcpu
> * a power management event, such as idle or cpu-off call in the vcpu
> - can be mmap'd to share the gunyah_vcpu_run structure with userspace. This
> allows the vcpu_run result codes to be accessed, and for arguments to
> vcpu_run to be passed, e.g. for resuming the vcpu when handling certain fault
> and exit cases.
>
> Co-developed-by: Prakruthi Deepak Heragu <[email protected]>
> Signed-off-by: Prakruthi Deepak Heragu <[email protected]>
> Signed-off-by: Elliot Berman <[email protected]>
LGTM
Reviewed-by: Srivatsa Vaddagiri <[email protected]>
- vatsa
* Elliot Berman <[email protected]> [2024-02-22 15:16:38]:
> +/**
> + * struct gunyah_vm_exit_info - Reason for VM exit as reported by Gunyah
> + * See Gunyah documentation for values.
> + * @type: Describes how VM exited
> + * @padding: padding bytes
> + * @reason_size: Number of bytes valid for `reason`
> + * @reason: See Gunyah documentation for interpretation. Note: these values are
> + * not interpreted by Linux and need to be converted from little-endian
> + * as applicable.
> + */
> +struct gunyah_vm_exit_info {
> + __u16 type;
Pls add an enum to describe the various exit types.
> + __u16 padding;
> + __u32 reason_size;
> + __u8 reason[GUNYAH_VM_MAX_EXIT_REASON_SIZE];
> +};
- vatsa
On Wed, Apr 24, 2024 at 03:09:57PM +0530, Srivatsa Vaddagiri wrote:
> * Elliot Berman <[email protected]> [2024-02-22 15:16:38]:
>
> > +/**
> > + * struct gunyah_vm_exit_info - Reason for VM exit as reported by Gunyah
> > + * See Gunyah documentation for values.
> > + * @type: Describes how VM exited
> > + * @padding: padding bytes
> > + * @reason_size: Number of bytes valid for `reason`
> > + * @reason: See Gunyah documentation for interpretation. Note: these values are
> > + * not interpreted by Linux and need to be converted from little-endian
> > + * as applicable.
> > + */
> > +struct gunyah_vm_exit_info {
> > + __u16 type;
>
> Pls add an enum to describe the various exit types.
>
When I was first added the exit_info, I thought a bunch on whether to
add the enum. I was thinking that if we add it to the UAPI, kernel need
to parse and validate the values from RM. In the current scheme, I can
leave it to userspace to interpret the value from RM. I could be
convinced to go the other way though. Currently this is less code :) Let
me know your thoughts!
> > + __u16 padding;
> > + __u32 reason_size;
> > + __u8 reason[GUNYAH_VM_MAX_EXIT_REASON_SIZE];
If we start interpreting the @type, then maybe we should also start
interpreting the @reason, and that will also add debt to the kernel
driver.
Thanks,
Elliot