[V2 PATCH 2/6] KVM: Selftests: Add support for private memory

From: Vishal Annapurve
Date: Mon Dec 05 2022 - 18:24:05 EST

Add support for registering private memory with kvm using
KVM_SET_USER_MEMORY_REGION ioctl.

Helper function to query extended userspace mem region is introduced to
allow memory conversion.

vm_mem_backing_src types is extended to contain additional guest memory
source types to cover the cases where guest memory can be backed by both
anonymous memory and restricted memfd.

Signed-off-by: Vishal Annapurve <vannapurve@xxxxxxxxxx>
---
.../selftests/kvm/include/kvm_util_base.h | 12 +++-
.../testing/selftests/kvm/include/test_util.h | 4 ++
tools/testing/selftests/kvm/lib/kvm_util.c | 58 +++++++++++++++++--
tools/testing/selftests/kvm/lib/test_util.c | 11 ++++
4 files changed, 78 insertions(+), 7 deletions(-)

diff --git a/tools/testing/selftests/kvm/include/kvm_util_base.h b/tools/testing/selftests/kvm/include/kvm_util_base.h
index c7685c7038ff..4ad99f295f2a 100644
--- a/tools/testing/selftests/kvm/include/kvm_util_base.h
+++ b/tools/testing/selftests/kvm/include/kvm_util_base.h
@@ -31,7 +31,10 @@ typedef uint64_t vm_paddr_t; /* Virtual Machine (Guest) physical address */
typedef uint64_t vm_vaddr_t; /* Virtual Machine (Guest) virtual address */

struct userspace_mem_region {
- struct kvm_userspace_memory_region region;
+ union {
+ struct kvm_userspace_memory_region region;
+ struct kvm_userspace_memory_region_ext region_ext;
+ };
struct sparsebit *unused_phy_pages;
int fd;
off_t offset;
@@ -196,7 +199,7 @@ static inline bool kvm_has_cap(long cap)

#define kvm_do_ioctl(fd, cmd, arg) \
({ \
- static_assert(!_IOC_SIZE(cmd) || sizeof(*arg) == _IOC_SIZE(cmd), ""); \
+ static_assert(!_IOC_SIZE(cmd) || sizeof(*arg) >= _IOC_SIZE(cmd), ""); \
ioctl(fd, cmd, arg); \
})

@@ -384,6 +387,7 @@ void vm_userspace_mem_region_add(struct kvm_vm *vm,
void vm_mem_region_set_flags(struct kvm_vm *vm, uint32_t slot, uint32_t flags);
void vm_mem_region_move(struct kvm_vm *vm, uint32_t slot, uint64_t new_gpa);
void vm_mem_region_delete(struct kvm_vm *vm, uint32_t slot);
+
struct kvm_vcpu *__vm_vcpu_add(struct kvm_vm *vm, uint32_t vcpu_id);
vm_vaddr_t vm_vaddr_unused_gap(struct kvm_vm *vm, size_t sz, vm_vaddr_t vaddr_min);
vm_vaddr_t vm_vaddr_alloc(struct kvm_vm *vm, size_t sz, vm_vaddr_t vaddr_min);
@@ -715,6 +719,10 @@ struct kvm_userspace_memory_region *
kvm_userspace_memory_region_find(struct kvm_vm *vm, uint64_t start,
uint64_t end);

+struct kvm_userspace_memory_region_ext *
+kvm_userspace_memory_region_ext_find(struct kvm_vm *vm, uint64_t start,
+ uint64_t end);
+
#define sync_global_to_guest(vm, g) ({ \
typeof(g) *_p = addr_gva2hva(vm, (vm_vaddr_t)&(g)); \
memcpy(_p, &(g), sizeof(g)); \
diff --git a/tools/testing/selftests/kvm/include/test_util.h b/tools/testing/selftests/kvm/include/test_util.h
index 80d6416f3012..aea80071f2b8 100644
--- a/tools/testing/selftests/kvm/include/test_util.h
+++ b/tools/testing/selftests/kvm/include/test_util.h
@@ -103,6 +103,8 @@ enum vm_mem_backing_src_type {
VM_MEM_SRC_ANONYMOUS_HUGETLB_16GB,
VM_MEM_SRC_SHMEM,
VM_MEM_SRC_SHARED_HUGETLB,
+ VM_MEM_SRC_ANONYMOUS_AND_RESTRICTED_MEMFD,
+ VM_MEM_SRC_ANON_HTLB2M_AND_RESTRICTED_MEMFD,
NUM_SRC_TYPES,
};

@@ -110,7 +112,9 @@ enum vm_mem_backing_src_type {

struct vm_mem_backing_src_alias {
const char *name;
+ /* Flags applicable for normal host accessible guest memory */
uint32_t flag;
+ uint32_t need_restricted_memfd;
};

#define MIN_RUN_DELAY_NS 200000UL
diff --git a/tools/testing/selftests/kvm/lib/kvm_util.c b/tools/testing/selftests/kvm/lib/kvm_util.c
index 1d26a2160178..dba693d6446a 100644
--- a/tools/testing/selftests/kvm/lib/kvm_util.c
+++ b/tools/testing/selftests/kvm/lib/kvm_util.c
@@ -32,6 +32,11 @@ int open_path_or_exit(const char *path, int flags)
return fd;
}

+static int memfd_restricted(unsigned int flags)
+{
+ return syscall(__NR_memfd_restricted, flags);
+}
+
/*
* Open KVM_DEV_PATH if available, otherwise exit the entire program.
*
@@ -582,6 +587,35 @@ __weak void vcpu_arch_free(struct kvm_vcpu *vcpu)

}

+/*
+ * KVM Userspace Memory Region Ext Find
+ *
+ * Input Args:
+ * vm - Virtual Machine
+ * start - Starting VM physical address
+ * end - Ending VM physical address, inclusive.
+ *
+ * Output Args: None
+ *
+ * Return:
+ * Pointer to overlapping ext region, NULL if no such region.
+ *
+ * Public interface to userspace_mem_region_find. Allows tests to look up
+ * the memslot datastructure for a given range of guest physical memory.
+ */
+struct kvm_userspace_memory_region_ext *
+kvm_userspace_memory_region_ext_find(struct kvm_vm *vm, uint64_t start,
+ uint64_t end)
+{
+ struct userspace_mem_region *region;
+
+ region = userspace_mem_region_find(vm, start, end);
+ if (!region)
+ return NULL;
+
+ return &region->region_ext;
+}
+
/*
* VM VCPU Remove
*
@@ -881,6 +915,7 @@ void vm_userspace_mem_region_add(struct kvm_vm *vm,
struct userspace_mem_region *region;
size_t backing_src_pagesz = get_backing_src_pagesz(src_type);
size_t alignment;
+ int restricted_memfd = -1;

TEST_ASSERT(vm_adjust_num_guest_pages(vm->mode, npages) == npages,
"Number of guest pages is not compatible with the host. "
@@ -978,14 +1013,24 @@ void vm_userspace_mem_region_add(struct kvm_vm *vm,

/* As needed perform madvise */
if ((src_type == VM_MEM_SRC_ANONYMOUS ||
- src_type == VM_MEM_SRC_ANONYMOUS_THP) && thp_configured()) {
+ src_type == VM_MEM_SRC_ANONYMOUS_THP ||
+ src_type == VM_MEM_SRC_ANONYMOUS_AND_RESTRICTED_MEMFD) &&
+ thp_configured()) {
ret = madvise(region->host_mem, npages * vm->page_size,
- src_type == VM_MEM_SRC_ANONYMOUS ? MADV_NOHUGEPAGE : MADV_HUGEPAGE);
+ (src_type == VM_MEM_SRC_ANONYMOUS_THP) ?
+ MADV_HUGEPAGE : MADV_NOHUGEPAGE);
TEST_ASSERT(ret == 0, "madvise failed, addr: %p length: 0x%lx src_type: %s",
region->host_mem, npages * vm->page_size,
vm_mem_backing_src_alias(src_type)->name);
}

+ if (vm_mem_backing_src_alias(src_type)->need_restricted_memfd) {
+ restricted_memfd = memfd_restricted(0);
+ TEST_ASSERT(restricted_memfd != -1,
+ "Failed to create restricted memfd");
+ flags |= KVM_MEM_PRIVATE;
+ }
+
region->unused_phy_pages = sparsebit_alloc();
sparsebit_set_num(region->unused_phy_pages,
guest_paddr >> vm->page_shift, npages);
@@ -994,13 +1039,16 @@ void vm_userspace_mem_region_add(struct kvm_vm *vm,
region->region.guest_phys_addr = guest_paddr;
region->region.memory_size = npages * vm->page_size;
region->region.userspace_addr = (uintptr_t) region->host_mem;
- ret = __vm_ioctl(vm, KVM_SET_USER_MEMORY_REGION, &region->region);
+ region->region_ext.restricted_fd = restricted_memfd;
+ region->region_ext.restricted_offset = 0;
+ ret = ioctl(vm->fd, KVM_SET_USER_MEMORY_REGION, &region->region_ext);
TEST_ASSERT(ret == 0, "KVM_SET_USER_MEMORY_REGION IOCTL failed,\n"
" rc: %i errno: %i\n"
" slot: %u flags: 0x%x\n"
- " guest_phys_addr: 0x%lx size: 0x%lx",
+ " guest_phys_addr: 0x%lx size: 0x%lx restricted fd: %d\n",
ret, errno, slot, flags,
- guest_paddr, (uint64_t) region->region.memory_size);
+ guest_paddr, (uint64_t) region->region.memory_size,
+ restricted_memfd);

/* Add to quick lookup data structures */
vm_userspace_mem_region_gpa_insert(&vm->regions.gpa_tree, region);
diff --git a/tools/testing/selftests/kvm/lib/test_util.c b/tools/testing/selftests/kvm/lib/test_util.c
index 5c22fa4c2825..d33b98bfe8a3 100644
--- a/tools/testing/selftests/kvm/lib/test_util.c
+++ b/tools/testing/selftests/kvm/lib/test_util.c
@@ -271,6 +271,16 @@ const struct vm_mem_backing_src_alias *vm_mem_backing_src_alias(uint32_t i)
*/
.flag = MAP_SHARED,
},
+ [VM_MEM_SRC_ANONYMOUS_AND_RESTRICTED_MEMFD] = {
+ .name = "anonymous_and_restricted_memfd",
+ .flag = ANON_FLAGS,
+ .need_restricted_memfd = 1,
+ },
+ [VM_MEM_SRC_ANON_HTLB2M_AND_RESTRICTED_MEMFD] = {
+ .name = "anonymous_hugetlb_2mb_and_restricted_memfd",
+ .flag = ANON_HUGE_FLAGS | MAP_HUGE_2MB,
+ .need_restricted_memfd = 1,
+ },
};
_Static_assert(ARRAY_SIZE(aliases) == NUM_SRC_TYPES,
"Missing new backing src types?");
@@ -289,6 +299,7 @@ size_t get_backing_src_pagesz(uint32_t i)
switch (i) {
case VM_MEM_SRC_ANONYMOUS:
case VM_MEM_SRC_SHMEM:
+ case VM_MEM_SRC_ANONYMOUS_AND_RESTRICTED_MEMFD:
return getpagesize();
case VM_MEM_SRC_ANONYMOUS_THP:
return get_trans_hugepagesz();
--
2.39.0.rc0.267.gcb52ba06e7-goog