When launching a virtual machine, Gunyah userspace allocates memory for
the guest and informs Gunyah about these memory regions through
SET_USER_MEMORY_REGION ioctl.

Co-developed-by: Prakruthi Deepak Heragu <redacted>
Signed-off-by: Prakruthi Deepak Heragu <redacted>
Signed-off-by: Elliot Berman <redacted>
---
  drivers/virt/gunyah/Makefile    |   2 +-
  drivers/virt/gunyah/vm_mgr.c    |  44 ++++++
  drivers/virt/gunyah/vm_mgr.h    |  25 ++++
  drivers/virt/gunyah/vm_mgr_mm.c | 235 ++++++++++++++++++++++++++++++++
  include/uapi/linux/gunyah.h     |  33 +++++
  5 files changed, 338 insertions(+), 1 deletion(-)
  create mode 100644 drivers/virt/gunyah/vm_mgr_mm.c

diff --git a/drivers/virt/gunyah/Makefile b/drivers/virt/gunyah/Makefile
index 03951cf82023..ff8bc4925392 100644
--- a/drivers/virt/gunyah/Makefile
+++ b/drivers/virt/gunyah/Makefile

@@ -2,5 +2,5 @@
  
  obj-$(CONFIG_GUNYAH) += gunyah.o
  
-gunyah_rsc_mgr-y += rsc_mgr.o rsc_mgr_rpc.o vm_mgr.o
+gunyah_rsc_mgr-y += rsc_mgr.o rsc_mgr_rpc.o vm_mgr.o vm_mgr_mm.o
  obj-$(CONFIG_GUNYAH) += gunyah_rsc_mgr.o

diff --git a/drivers/virt/gunyah/vm_mgr.c b/drivers/virt/gunyah/vm_mgr.c
index fd890a57172e..84102bac03cc 100644
--- a/drivers/virt/gunyah/vm_mgr.c
+++ b/drivers/virt/gunyah/vm_mgr.c

@@ -18,8 +18,16 @@
  static void gh_vm_free(struct work_struct *work)
  {
  	struct gh_vm *ghvm = container_of(work, struct gh_vm, free_work);
+	struct gh_vm_mem *mapping, *tmp;
  	int ret;
  
+	mutex_lock(&ghvm->mm_lock);
+	list_for_each_entry_safe(mapping, tmp, &ghvm->memory_mappings, list) {
+		gh_vm_mem_reclaim(ghvm, mapping);
+		kfree(mapping);
+	}
+	mutex_unlock(&ghvm->mm_lock);
+
  	ret = gh_rm_dealloc_vmid(ghvm->rm, ghvm->vmid);
  	if (ret)
  		pr_warn("Failed to deallocate vmid: %d\n", ret);

@@ -48,11 +56,46 @@ static __must_check struct gh_vm *gh_vm_alloc(struct gh_rm *rm)
  	ghvm->vmid = vmid;
  	ghvm->rm = rm;
  
+	mutex_init(&ghvm->mm_lock);
+	INIT_LIST_HEAD(&ghvm->memory_mappings);
  	INIT_WORK(&ghvm->free_work, gh_vm_free);
  
  	return ghvm;
  }
  
+static long gh_vm_ioctl(struct file *filp, unsigned int cmd, unsigned long arg)
+{
+	struct gh_vm *ghvm = filp->private_data;
+	void __user *argp = (void __user *)arg;
+	long r;
+
+	switch (cmd) {
+	case GH_VM_SET_USER_MEM_REGION: {
+		struct gh_userspace_memory_region region;
+
+		if (copy_from_user(&region, argp, sizeof(region)))
+			return -EFAULT;
+
+		/* All other flag bits are reserved for future use */
+		if (region.flags & ~(GH_MEM_ALLOW_READ | GH_MEM_ALLOW_WRITE | GH_MEM_ALLOW_EXEC |
+			GH_MEM_LENT))
+			return -EINVAL;
+
+
+		if (region.memory_size)
+			r = gh_vm_mem_alloc(ghvm, &region);
+		else
+			r = gh_vm_mem_free(ghvm, region.label);

+		break;
+	}
+	default:
+		r = -ENOTTY;
+		break;
+	}
+
+	return r;
+}
+
  static int gh_vm_release(struct inode *inode, struct file *filp)
  {
  	struct gh_vm *ghvm = filp->private_data;

@@ -65,6 +108,7 @@ static int gh_vm_release(struct inode *inode, struct file *filp)
  }
  
  static const struct file_operations gh_vm_fops = {
+	.unlocked_ioctl = gh_vm_ioctl,
  	.release = gh_vm_release,
  	.compat_ioctl	= compat_ptr_ioctl,
  	.llseek = noop_llseek,

diff --git a/drivers/virt/gunyah/vm_mgr.h b/drivers/virt/gunyah/vm_mgr.h
index 76954da706e9..97bc00c34878 100644
--- a/drivers/virt/gunyah/vm_mgr.h
+++ b/drivers/virt/gunyah/vm_mgr.h

@@ -7,16 +7,41 @@
  #define _GH_PRIV_VM_MGR_H
  
  #include <linux/gunyah_rsc_mgr.h>
+#include <linux/list.h>
+#include <linux/miscdevice.h>
+#include <linux/mutex.h>
  
  #include <uapi/linux/gunyah.h>
  
  long gh_dev_vm_mgr_ioctl(struct gh_rm *rm, unsigned int cmd, unsigned long arg);
  
+enum gh_vm_mem_share_type {
+	VM_MEM_SHARE,
+	VM_MEM_LEND,
+};
+
+struct gh_vm_mem {
+	struct list_head list;
+	enum gh_vm_mem_share_type share_type;
+	struct gh_rm_mem_parcel parcel;
+
+	__u64 guest_phys_addr;
+	struct page **pages;
+	unsigned long npages;
+};
+
  struct gh_vm {
  	u16 vmid;
  	struct gh_rm *rm;
  
  	struct work_struct free_work;
+	struct mutex mm_lock;
+	struct list_head memory_mappings;
  };
  
+int gh_vm_mem_alloc(struct gh_vm *ghvm, struct gh_userspace_memory_region *region);
+void gh_vm_mem_reclaim(struct gh_vm *ghvm, struct gh_vm_mem *mapping);
+int gh_vm_mem_free(struct gh_vm *ghvm, u32 label);
+struct gh_vm_mem *gh_vm_mem_find(struct gh_vm *ghvm, u32 label);
+
  #endif

diff --git a/drivers/virt/gunyah/vm_mgr_mm.c b/drivers/virt/gunyah/vm_mgr_mm.c
new file mode 100644
index 000000000000..03e71a36ea3b
--- /dev/null
+++ b/drivers/virt/gunyah/vm_mgr_mm.c

@@ -0,0 +1,235 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * Copyright (c) 2022-2023 Qualcomm Innovation Center, Inc. All rights reserved.
+ */
+
+#define pr_fmt(fmt) "gh_vm_mgr: " fmt
+
+#include <linux/gunyah_rsc_mgr.h>
+#include <linux/mm.h>
+
+#include <uapi/linux/gunyah.h>
+
+#include "vm_mgr.h"
+
+static inline bool page_contiguous(phys_addr_t p, phys_addr_t t)
+{
+	return t - p == PAGE_SIZE;
+}
+
+static struct gh_vm_mem *__gh_vm_mem_find(struct gh_vm *ghvm, u32 label)
+	__must_hold(&ghvm->mm_lock)
+{
+	struct gh_vm_mem *mapping;
+
+	list_for_each_entry(mapping, &ghvm->memory_mappings, list)
+		if (mapping->parcel.label == label)
+			return mapping;
+
+	return NULL;
+}
+
+void gh_vm_mem_reclaim(struct gh_vm *ghvm, struct gh_vm_mem *mapping)
+	__must_hold(&ghvm->mm_lock)
+{
+	int i, ret = 0;
+
+	if (mapping->parcel.mem_handle != GH_MEM_HANDLE_INVAL) {
+		ret = gh_rm_mem_reclaim(ghvm->rm, &mapping->parcel);
+		if (ret)
+			pr_warn("Failed to reclaim memory parcel for label %d: %d\n",
+				mapping->parcel.label, ret);

+	for (i = 1, j = 0; i < mapping->npages; i++) {
+		curr_page = page_to_phys(mapping->pages[i]);
+		if (page_contiguous(prev_page, curr_page)) {
+			entry_size += PAGE_SIZE;
+		} else {
+			mem_entries[j].size = cpu_to_le64(entry_size);
+			j++;
+			mem_entries[j].ipa_base = cpu_to_le64(curr_page);
+			entry_size = PAGE_SIZE;
+		}
+
+		prev_page = curr_page;
+	}
+	mem_entries[j].size = cpu_to_le64(entry_size);
+
+	parcel->n_mem_entries = j + 1;
+	parcel->mem_entries = kmemdup(mem_entries, sizeof(*mem_entries) * parcel->n_mem_entries,
+					GFP_KERNEL);
+	kfree(mem_entries);
+	if (!parcel->mem_entries) {
+		ret = -ENOMEM;
+		goto reclaim;
+	}
+
+	mutex_unlock(&ghvm->mm_lock);
+	return 0;
+reclaim:
+	gh_vm_mem_reclaim(ghvm, mapping);
+free_mapping:
+	kfree(mapping);
+	mutex_unlock(&ghvm->mm_lock);
+	return ret;
+}
+
+int gh_vm_mem_free(struct gh_vm *ghvm, u32 label)
+{
+	struct gh_vm_mem *mapping;
+	int ret;
+
+	ret = mutex_lock_interruptible(&ghvm->mm_lock);
+	if (ret)
+		return ret;
+
+	mapping = __gh_vm_mem_find(ghvm, label);
+	if (!mapping)
+		goto out;
+
+	gh_vm_mem_reclaim(ghvm, mapping);
+	kfree(mapping);
+out:
+	mutex_unlock(&ghvm->mm_lock);
+	return ret;
+}

diff --git a/include/uapi/linux/gunyah.h b/include/uapi/linux/gunyah.h
index 10ba32d2b0a6..d85d12119a48 100644
--- a/include/uapi/linux/gunyah.h
+++ b/include/uapi/linux/gunyah.h

@@ -20,4 +20,37 @@
   */
  #define GH_CREATE_VM			_IO(GH_IOCTL_TYPE, 0x0) /* Returns a Gunyah VM fd */
  
+/*
+ * ioctls for VM fds
+ */
+
+/**
+ * struct gh_userspace_memory_region - Userspace memory descripion for GH_VM_SET_USER_MEM_REGION
+ * @label: Unique identifer to the region.
+ * @flags: Flags for memory parcel behavior
+ * @guest_phys_addr: Location of the memory region in guest's memory space (page-aligned)#