[PATCH v14 11/25] gunyah: vm_mgr: Add/remove user memory regions

[Elliot Berman]

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 <quic_pheragu@xxxxxxxxxxx>
Signed-off-by: Prakruthi Deepak Heragu <quic_pheragu@xxxxxxxxxxx>
Signed-off-by: Elliot Berman <quic_eberman@xxxxxxxxxxx>
---
 drivers/virt/gunyah/Makefile    |   2 +-
 drivers/virt/gunyah/vm_mgr.c    |  59 +++++++-
 drivers/virt/gunyah/vm_mgr.h    |  26 ++++
 drivers/virt/gunyah/vm_mgr_mm.c | 232 ++++++++++++++++++++++++++++++++
 include/uapi/linux/gunyah.h     |  37 +++++
 5 files changed, 352 insertions(+), 4 deletions(-)
 create mode 100644 drivers/virt/gunyah/vm_mgr_mm.c

diff --git a/drivers/virt/gunyah/Makefile b/drivers/virt/gunyah/Makefile
index e47e25895299c..bacf78b8fa337 100644
--- a/drivers/virt/gunyah/Makefile
+++ b/drivers/virt/gunyah/Makefile
@@ -1,4 +1,4 @@
 # SPDX-License-Identifier: GPL-2.0
 
-gunyah-y += rsc_mgr.o rsc_mgr_rpc.o vm_mgr.o
+gunyah-y += rsc_mgr.o rsc_mgr_rpc.o vm_mgr.o vm_mgr_mm.o
 obj-$(CONFIG_GUNYAH) += gunyah.o
diff --git a/drivers/virt/gunyah/vm_mgr.c b/drivers/virt/gunyah/vm_mgr.c
index a43401cb34f7d..297427952b8c7 100644
--- a/drivers/virt/gunyah/vm_mgr.c
+++ b/drivers/virt/gunyah/vm_mgr.c
@@ -15,6 +15,8 @@
 
 #include "vm_mgr.h"
 
+static void gh_vm_free(struct work_struct *work);
+
 static __must_check struct gh_vm *gh_vm_alloc(struct gh_rm *rm)
 {
 	struct gh_vm *ghvm;
@@ -26,20 +28,72 @@ static __must_check struct gh_vm *gh_vm_alloc(struct gh_rm *rm)
 	ghvm->parent = gh_rm_get(rm);
 	ghvm->rm = rm;
 
+	mmgrab(current->mm);
+	ghvm->mm = current->mm;
+	mutex_init(&ghvm->mm_lock);
+	INIT_LIST_HEAD(&ghvm->memory_mappings);
+	INIT_WORK(&ghvm->free_work, gh_vm_free);
+
 	return ghvm;
 }
 
-static int gh_vm_release(struct inode *inode, struct file *filp)
+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;
+
+		/* only allow owner task to add memory */
+		if (ghvm->mm != current->mm)
+			return -EPERM;
+
+		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))
+			return -EINVAL;
+
+		r = gh_vm_mem_alloc(ghvm, &region);
+		break;
+	}
+	default:
+		r = -ENOTTY;
+		break;
+	}
 
+	return r;
+}
+
+static void gh_vm_free(struct work_struct *work)
+{
+	struct gh_vm *ghvm = container_of(work, struct gh_vm, free_work);
+
+	gh_vm_mem_reclaim(ghvm);
 	gh_rm_put(ghvm->rm);
+	mmdrop(ghvm->mm);
 	kfree(ghvm);
+}
+
+static int gh_vm_release(struct inode *inode, struct file *filp)
+{
+	struct gh_vm *ghvm = filp->private_data;
+
+	/* VM will be reset and make RM calls which can interruptible sleep.
+	 * Defer to a work so this thread can receive signal.
+	 */
+	schedule_work(&ghvm->free_work);
 	return 0;
 }
 
 static const struct file_operations gh_vm_fops = {
 	.owner = THIS_MODULE,
+	.unlocked_ioctl = gh_vm_ioctl,
+	.compat_ioctl	= compat_ptr_ioctl,
 	.release = gh_vm_release,
 	.llseek = noop_llseek,
 };
@@ -77,8 +131,7 @@ static long gh_dev_ioctl_create_vm(struct gh_rm *rm, unsigned long arg)
 err_put_fd:
 	put_unused_fd(fd);
 err_destroy_vm:
-	gh_rm_put(ghvm->rm);
-	kfree(ghvm);
+	gh_vm_free(&ghvm->free_work);
 	return err;
 }
 
diff --git a/drivers/virt/gunyah/vm_mgr.h b/drivers/virt/gunyah/vm_mgr.h
index 1e94b58d7d34d..434ef9f662a7a 100644
--- a/drivers/virt/gunyah/vm_mgr.h
+++ b/drivers/virt/gunyah/vm_mgr.h
@@ -7,14 +7,40 @@
 #define _GH_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 {
 	struct gh_rm *rm;
 	struct device *parent;
+
+	struct work_struct free_work;
+	struct mm_struct *mm; /* userspace tied to this vm */
+	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);
+
 #endif
diff --git a/drivers/virt/gunyah/vm_mgr_mm.c b/drivers/virt/gunyah/vm_mgr_mm.c
new file mode 100644
index 0000000000000..6974607f02edd
--- /dev/null
+++ b/drivers/virt/gunyah/vm_mgr_mm.c
@@ -0,0 +1,232 @@
+// 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 bool pages_are_mergeable(struct page *a, struct page *b)
+{
+	return page_to_pfn(a) + 1 == page_to_pfn(b);
+}
+
+static bool gh_vm_mem_overlap(struct gh_vm_mem *a, u64 addr, u64 size)
+{
+	u64 a_end = a->guest_phys_addr + (a->npages << PAGE_SHIFT);
+	u64 end = addr + size;
+
+	return a->guest_phys_addr < end && addr < a_end;
+}
+
+static struct gh_vm_mem *__gh_vm_mem_find_by_label(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;
+}
+
+static void gh_vm_mem_reclaim_mapping(struct gh_vm *ghvm, struct gh_vm_mem *mapping)
+	__must_hold(&ghvm->mm_lock)
+{
+	int 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);
+	}
+
+	if (!ret) {
+		unpin_user_pages(mapping->pages, mapping->npages);
+		account_locked_vm(ghvm->mm, mapping->npages, false);
+	}
+
+	kfree(mapping->pages);
+	kfree(mapping->parcel.acl_entries);
+	kfree(mapping->parcel.mem_entries);
+
+	list_del(&mapping->list);
+}
+
+void gh_vm_mem_reclaim(struct gh_vm *ghvm)
+{
+	struct gh_vm_mem *mapping, *tmp;
+
+	mutex_lock(&ghvm->mm_lock);
+
+	list_for_each_entry_safe(mapping, tmp, &ghvm->memory_mappings, list) {
+		gh_vm_mem_reclaim_mapping(ghvm, mapping);
+		kfree(mapping);
+	}
+
+	mutex_unlock(&ghvm->mm_lock);
+}
+
+int gh_vm_mem_alloc(struct gh_vm *ghvm, struct gh_userspace_memory_region *region)
+{
+	struct gh_vm_mem *mapping, *tmp_mapping;
+	struct page *curr_page, *prev_page;
+	struct gh_rm_mem_parcel *parcel;
+	int i, j, pinned, ret = 0;
+	unsigned int gup_flags;
+	size_t entry_size;
+	u16 vmid;
+
+	if (!region->memory_size || !PAGE_ALIGNED(region->memory_size) ||
+		!PAGE_ALIGNED(region->userspace_addr) ||
+		!PAGE_ALIGNED(region->guest_phys_addr))
+		return -EINVAL;
+
+	if (overflows_type(region->guest_phys_addr + region->memory_size, u64))
+		return -EOVERFLOW;
+
+	ret = mutex_lock_interruptible(&ghvm->mm_lock);
+	if (ret)
+		return ret;
+
+	mapping = __gh_vm_mem_find_by_label(ghvm, region->label);
+	if (mapping) {
+		ret = -EEXIST;
+		goto unlock;
+	}
+
+	list_for_each_entry(tmp_mapping, &ghvm->memory_mappings, list) {
+		if (gh_vm_mem_overlap(tmp_mapping, region->guest_phys_addr,
+					region->memory_size)) {
+			ret = -EEXIST;
+			goto unlock;
+		}
+	}
+
+	mapping = kzalloc(sizeof(*mapping), GFP_KERNEL_ACCOUNT);
+	if (!mapping) {
+		ret = -ENOMEM;
+		goto unlock;
+	}
+
+	mapping->guest_phys_addr = region->guest_phys_addr;
+	mapping->npages = region->memory_size >> PAGE_SHIFT;
+	parcel = &mapping->parcel;
+	parcel->label = region->label;
+	parcel->mem_handle = GH_MEM_HANDLE_INVAL; /* to be filled later by mem_share/mem_lend */
+	parcel->mem_type = GH_RM_MEM_TYPE_NORMAL;
+
+	ret = account_locked_vm(ghvm->mm, mapping->npages, true);
+	if (ret)
+		goto free_mapping;
+
+	mapping->pages = kcalloc(mapping->npages, sizeof(*mapping->pages), GFP_KERNEL_ACCOUNT);
+	if (!mapping->pages) {
+		ret = -ENOMEM;
+		mapping->npages = 0; /* update npages for reclaim */
+		goto unlock_pages;
+	}
+
+	gup_flags = FOLL_LONGTERM;
+	if (region->flags & GH_MEM_ALLOW_WRITE)
+		gup_flags |= FOLL_WRITE;
+
+	pinned = pin_user_pages_fast(region->userspace_addr, mapping->npages,
+					gup_flags, mapping->pages);
+	if (pinned < 0) {
+		ret = pinned;
+		goto free_pages;
+	} else if (pinned != mapping->npages) {
+		ret = -EFAULT;
+		mapping->npages = pinned; /* update npages for reclaim */
+		goto unpin_pages;
+	}
+
+	parcel->n_acl_entries = 2;
+	mapping->share_type = VM_MEM_SHARE;
+	parcel->acl_entries = kcalloc(parcel->n_acl_entries, sizeof(*parcel->acl_entries),
+					GFP_KERNEL);
+	if (!parcel->acl_entries) {
+		ret = -ENOMEM;
+		goto unpin_pages;
+	}
+
+	/* acl_entries[0].vmid will be this VM's vmid. We'll fill it when the
+	 * VM is starting and we know the VM's vmid.
+	 */
+	if (region->flags & GH_MEM_ALLOW_READ)
+		parcel->acl_entries[0].perms |= GH_RM_ACL_R;
+	if (region->flags & GH_MEM_ALLOW_WRITE)
+		parcel->acl_entries[0].perms |= GH_RM_ACL_W;
+	if (region->flags & GH_MEM_ALLOW_EXEC)
+		parcel->acl_entries[0].perms |= GH_RM_ACL_X;
+
+	ret = gh_rm_get_vmid(ghvm->rm, &vmid);
+	if (ret)
+		goto free_acl;
+
+	parcel->acl_entries[1].vmid = cpu_to_le16(vmid);
+	/* Host assumed to have all these permissions. Gunyah will not
+	 * grant new permissions if host actually had less than RWX
+	 */
+	parcel->acl_entries[1].perms = GH_RM_ACL_R | GH_RM_ACL_W | GH_RM_ACL_X;
+
+	parcel->n_mem_entries = 1;
+	for (i = 1; i < mapping->npages; i++) {
+		if (!pages_are_mergeable(mapping->pages[i - 1], mapping->pages[i]))
+			parcel->n_mem_entries++;
+	}
+
+	parcel->mem_entries = kcalloc(parcel->n_mem_entries,
+					sizeof(parcel->mem_entries[0]),
+					GFP_KERNEL_ACCOUNT);
+	if (!parcel->mem_entries) {
+		ret = -ENOMEM;
+		goto free_acl;
+	}
+
+	/* reduce number of entries by combining contiguous pages into single memory entry */
+	prev_page = mapping->pages[0];
+	parcel->mem_entries[0].phys_addr = cpu_to_le64(page_to_phys(prev_page));
+	entry_size = PAGE_SIZE;
+	for (i = 1, j = 0; i < mapping->npages; i++) {
+		curr_page = mapping->pages[i];
+		if (pages_are_mergeable(prev_page, curr_page)) {
+			entry_size += PAGE_SIZE;
+		} else {
+			parcel->mem_entries[j].size = cpu_to_le64(entry_size);
+			j++;
+			parcel->mem_entries[j].phys_addr =
+				cpu_to_le64(page_to_phys(curr_page));
+			entry_size = PAGE_SIZE;
+		}
+
+		prev_page = curr_page;
+	}
+	parcel->mem_entries[j].size = cpu_to_le64(entry_size);
+
+	list_add(&mapping->list, &ghvm->memory_mappings);
+	mutex_unlock(&ghvm->mm_lock);
+	return 0;
+free_acl:
+	kfree(parcel->acl_entries);
+unpin_pages:
+	unpin_user_pages(mapping->pages, pinned);
+free_pages:
+	kfree(mapping->pages);
+unlock_pages:
+	account_locked_vm(ghvm->mm, mapping->npages, false);
+free_mapping:
+	kfree(mapping);
+unlock:
+	mutex_unlock(&ghvm->mm_lock);
+	return ret;
+}
diff --git a/include/uapi/linux/gunyah.h b/include/uapi/linux/gunyah.h
index 86b9cb60118dd..91d6dd26fcc89 100644
--- a/include/uapi/linux/gunyah.h
+++ b/include/uapi/linux/gunyah.h
@@ -20,4 +20,41 @@
  */
 #define GH_CREATE_VM			_IO(GH_IOCTL_TYPE, 0x0) /* Returns a Gunyah VM fd */
 
+/*
+ * ioctls for VM fds
+ */
+
+/**
+ * enum gh_mem_flags - Possible flags on &struct gh_userspace_memory_region
+ * @GH_MEM_ALLOW_READ: Allow guest to read the memory
+ * @GH_MEM_ALLOW_WRITE: Allow guest to write to the memory
+ * @GH_MEM_ALLOW_EXEC: Allow guest to execute instructions in the memory
+ */
+enum gh_mem_flags {
+	GH_MEM_ALLOW_READ	= 1UL << 0,
+	GH_MEM_ALLOW_WRITE	= 1UL << 1,
+	GH_MEM_ALLOW_EXEC	= 1UL << 2,
+};
+
+/**
+ * struct gh_userspace_memory_region - Userspace memory descripion for GH_VM_SET_USER_MEM_REGION
+ * @label: Identifer to the region which is unique to the VM.
+ * @flags: Flags for memory parcel behavior. See &enum gh_mem_flags.
+ * @guest_phys_addr: Location of the memory region in guest's memory space (page-aligned)
+ * @memory_size: Size of the region (page-aligned)
+ * @userspace_addr: Location of the memory region in caller (userspace)'s memory
+ *
+ * See Documentation/virt/gunyah/vm-manager.rst for further details.
+ */
+struct gh_userspace_memory_region {
+	__u32 label;
+	__u32 flags;
+	__u64 guest_phys_addr;
+	__u64 memory_size;
+	__u64 userspace_addr;
+};
+
+#define GH_VM_SET_USER_MEM_REGION	_IOW(GH_IOCTL_TYPE, 0x1, \
+						struct gh_userspace_memory_region)
+
 #endif
-- 
2.40.0