[PATCH v14 11/25] gunyah: vm_mgr: Add/remove user memory regions
Alex Elder
elder at linaro.org
Fri Jun 16 09:33:28 PDT 2023
On 6/13/23 12:20 PM, Elliot Berman wrote:
> 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 at quicinc.com>
> Signed-off-by: Prakruthi Deepak Heragu <quic_pheragu at quicinc.com>
> Signed-off-by: Elliot Berman <quic_eberman at quicinc.com>
I have one trivial comment below. This patch adds some complexity
but this time around I'm going to assume I checked those things
in some detail previously. This time I'm doing more of a scan
through the patch and I find it looks good. (If you want me to
spend more time on this, say so.)
Reviewed-by: Alex Elder <elder at linaro.org>
> ---
> 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;
Don't you use "ret" for return values most of the time?
(Not a big deal, maybe there's another reason you used
"r" here.)
> +
> + 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(®ion, 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, ®ion);
> + 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
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