On Tue, Aug 23, 2022 at 11:47:21PM +0000, Ricardo Koller wrote:
> The vm_create() helpers are hardcoded to place most page types (code,
> page-tables, stacks, etc) in the same memslot #0, and always backed with
> anonymous 4K. There are a couple of issues with that. First, tests willing
> to
> differ a bit, like placing page-tables in a different backing source type must
> replicate much of what's already done by the vm_create() functions. Second,
> the hardcoded assumption of memslot #0 holding most things is spreaded
> everywhere; this makes it very hard to change.
>
> Fix the above issues by having selftests specify how they want memory to be
> laid out: define the memory regions to use for code, pt (page-tables), and
> data. Introduce a new structure, struct kvm_vm_mem_params, that defines: guest
> mode, a list of memory region descriptions, and some fields specifying what
> regions to use for code, pt, and data.
>
> There is no functional change intended. The current commit adds a default
> struct kvm_vm_mem_params that lays out memory exactly as before. The next
> commit will change the allocators to get the region they should be using,
> e.g.,: like the page table allocators using the pt memslot.
>
> Cc: Sean Christopherson <sea...@google.com>
> Cc: Andrew Jones <andrew.jo...@linux.dev>
> Signed-off-by: Ricardo Koller <ricar...@google.com>
> ---
> .../selftests/kvm/include/kvm_util_base.h | 61 ++++++++++++++++-
> .../selftests/kvm/lib/aarch64/processor.c | 3 +-
> tools/testing/selftests/kvm/lib/kvm_util.c | 65 +++++++++++++++++--
> 3 files changed, 119 insertions(+), 10 deletions(-)
>
> diff --git a/tools/testing/selftests/kvm/include/kvm_util_base.h
> b/tools/testing/selftests/kvm/include/kvm_util_base.h
> index b2dbe253d4d0..abe6c4e390ff 100644
> --- a/tools/testing/selftests/kvm/include/kvm_util_base.h
> +++ b/tools/testing/selftests/kvm/include/kvm_util_base.h
> @@ -93,6 +93,16 @@ struct kvm_vm {
> int stats_fd;
> struct kvm_stats_header stats_header;
> struct kvm_stats_desc *stats_desc;
> +
> + /*
> + * KVM region slots. These are the default memslots used by page
> + * allocators, e.g., lib/elf uses the code memslot.
> + */
> + struct {
> + uint32_t code;
> + uint32_t pt;
> + uint32_t data;
> + } memslot;
> };
>
>
> @@ -105,6 +115,21 @@ struct kvm_vm {
> struct userspace_mem_region *
> memslot2region(struct kvm_vm *vm, uint32_t memslot);
>
> +inline struct userspace_mem_region *vm_get_code_region(struct kvm_vm *vm)
> +{
> + return memslot2region(vm, vm->memslot.code);
> +}
> +
> +inline struct userspace_mem_region *vm_get_pt_region(struct kvm_vm *vm)
> +{
> + return memslot2region(vm, vm->memslot.pt);
> +}
> +
> +inline struct userspace_mem_region *vm_get_data_region(struct kvm_vm *vm)
> +{
> + return memslot2region(vm, vm->memslot.data);
> +}
I feel we'll be revisiting this frequently when more and more region types
are desired. For example, Sean wants a read-only memory region for ucall
exits. How about putting a mem slot array in struct kvm_vm, defining an
enum to index it (which will expand), and then single helper function,
something like
inline struct userspace_mem_region *
vm_get_mem_region(struct kvm_vm *vm, enum memslot_type mst)
{
return memslot2region(vm, vm->memslots[mst]);
}
> +
> /* Minimum allocated guest virtual and physical addresses */
> #define KVM_UTIL_MIN_VADDR 0x2000
> #define KVM_GUEST_PAGE_TABLE_MIN_PADDR 0x180000
> @@ -637,19 +662,51 @@ vm_paddr_t vm_phy_pages_alloc(struct kvm_vm *vm, size_t
> num,
> vm_paddr_t paddr_min, uint32_t memslot);
> vm_paddr_t vm_alloc_page_table(struct kvm_vm *vm);
>
> +#define MEM_PARAMS_MAX_MEMSLOTS 3
And this becomes MEMSLOT_MAX of the enum proposed above
enum memslot_type {
MEMSLOT_CODE,
MEMSLOT_PT,
MEMSLOT_DATA,
MEMSLOT_MAX,
};
> +
> +struct kvm_vm_mem_params {
> + enum vm_guest_mode mode;
> +
> + struct {
> + enum vm_mem_backing_src_type src_type;
> + uint64_t guest_paddr;
> + /*
> + * KVM region slot (same meaning as in struct
> + * kvm_userspace_memory_region).
> + */
> + uint32_t slot;
> + uint64_t npages;
> + uint32_t flags;
> + bool enabled;
> + } region[MEM_PARAMS_MAX_MEMSLOTS];
> +
> + /* Indexes into the above array. */
> + struct {
> + uint16_t code;
> + uint16_t pt;
> + uint16_t data;
> + } region_idx;
And this changes to another array of memslots also indexed with
enum memslot_type.
> +};
> +
> +extern struct kvm_vm_mem_params kvm_vm_mem_default;
> +
> /*
> * ____vm_create() does KVM_CREATE_VM and little else. __vm_create() also
> * loads the test binary into guest memory and creates an IRQ chip (x86
> only).
> * __vm_create() does NOT create vCPUs, @nr_runnable_vcpus is used purely to
> * calculate the amount of memory needed for per-vCPU data, e.g. stacks.
> */
> -struct kvm_vm *____vm_create(enum vm_guest_mode mode, uint64_t nr_pages);
> +struct kvm_vm *____vm_create(struct kvm_vm_mem_params *mem_params);
> struct kvm_vm *__vm_create(enum vm_guest_mode mode, uint32_t
> nr_runnable_vcpus,
> uint64_t nr_extra_pages);
>
> static inline struct kvm_vm *vm_create_barebones(void)
> {
> - return ____vm_create(VM_MODE_DEFAULT, 0);
> + struct kvm_vm_mem_params params_wo_memslots = {
> + .mode = kvm_vm_mem_default.mode,
> + };
> +
> + return ____vm_create(¶ms_wo_memslots);
> }
>
> static inline struct kvm_vm *vm_create(uint32_t nr_runnable_vcpus)
> diff --git a/tools/testing/selftests/kvm/lib/aarch64/processor.c
> b/tools/testing/selftests/kvm/lib/aarch64/processor.c
> index 26f0eccff6fe..5a31dc85d054 100644
> --- a/tools/testing/selftests/kvm/lib/aarch64/processor.c
> +++ b/tools/testing/selftests/kvm/lib/aarch64/processor.c
> @@ -508,7 +508,8 @@ void aarch64_get_supported_page_sizes(uint32_t ipa,
> */
> void __attribute__((constructor)) init_guest_modes(void)
> {
> - guest_modes_append_default();
> + guest_modes_append_default();
> + kvm_vm_mem_default.mode = VM_MODE_DEFAULT;
> }
>
> void smccc_hvc(uint32_t function_id, uint64_t arg0, uint64_t arg1,
> diff --git a/tools/testing/selftests/kvm/lib/kvm_util.c
> b/tools/testing/selftests/kvm/lib/kvm_util.c
> index 5a9f080ff888..91b42d6b726b 100644
> --- a/tools/testing/selftests/kvm/lib/kvm_util.c
> +++ b/tools/testing/selftests/kvm/lib/kvm_util.c
> @@ -143,12 +143,41 @@ const struct vm_guest_mode_params
> vm_guest_mode_params[] = {
> _Static_assert(sizeof(vm_guest_mode_params)/sizeof(struct
> vm_guest_mode_params) == NUM_VM_MODES,
> "Missing new mode params?");
>
> -struct kvm_vm *____vm_create(enum vm_guest_mode mode, uint64_t nr_pages)
> +/* A single memslot #0 for code, data, and page tables. */
> +struct kvm_vm_mem_params kvm_vm_mem_default = {
> +#if defined(__aarch64__)
> + /* arm64 is the only arch without a true default mode. */
> + .mode = NUM_VM_MODES,
How about
#ifndef __arch64__
/* arm64 kvm_vm_mem_default.mode set in init_guest_modes() */
.mode = VM_MODE_DEFAULT,
#endif
> +#else
> + .mode = VM_MODE_DEFAULT,
> +#endif
> + .region[0] = {
> + .src_type = VM_MEM_SRC_ANONYMOUS,
> + .guest_paddr = 0,
> + .slot = 0,
> + /*
> + * 4mb when page size is 4kb. Note that vm_nr_pages_required(),
> + * the function used by most tests to calculate guest memory
> + * requirements uses around ~520 pages for more tests.
...requirements, currently returns ~520 pages for the majority of tests.
> + */
> + .npages = 1024,
And here we double it, but it's still fragile. I see we override this
in __vm_create() below though, so now I wonder why we set it at all.
> + .flags = 0,
> + .enabled = true,
> + },
> + .region_idx = {
> + .code = 0,
> + .pt = 0,
> + .data = 0,
> + },
> +};
> +
> +struct kvm_vm *____vm_create(struct kvm_vm_mem_params *mem_params)
> {
> + enum vm_guest_mode mode = mem_params->mode;
> struct kvm_vm *vm;
> + int idx;
>
> - pr_debug("%s: mode='%s' pages='%ld'\n", __func__,
> - vm_guest_mode_string(mode), nr_pages);
> + pr_debug("%s: mode='%s'\n", __func__, vm_guest_mode_string(mode));
>
> vm = calloc(1, sizeof(*vm));
> TEST_ASSERT(vm != NULL, "Insufficient Memory");
> @@ -245,9 +274,28 @@ struct kvm_vm *____vm_create(enum vm_guest_mode mode,
> uint64_t nr_pages)
>
> /* Allocate and setup memory for guest. */
> vm->vpages_mapped = sparsebit_alloc();
> - if (nr_pages != 0)
> - vm_userspace_mem_region_add(vm, VM_MEM_SRC_ANONYMOUS,
> - 0, 0, nr_pages, 0);
> +
> + /* Setup the code, pt, and data memslots according to the spec */
> + for (idx = 0; idx < MEM_PARAMS_MAX_MEMSLOTS; idx++) {
> + if (!mem_params->region[idx].enabled)
> + continue;
> +
> + vm_userspace_mem_region_add(vm,
> + mem_params->region[idx].src_type,
> + mem_params->region[idx].guest_paddr,
> + mem_params->region[idx].slot,
> + mem_params->region[idx].npages,
> + mem_params->region[idx].flags);
> + }
> +
> + TEST_ASSERT(mem_params->region_idx.code < MEM_PARAMS_MAX_MEMSLOTS &&
> + mem_params->region_idx.pt < MEM_PARAMS_MAX_MEMSLOTS &&
> + mem_params->region_idx.data < MEM_PARAMS_MAX_MEMSLOTS,
> + "region_idx should be valid indexes\n");
> +
> + vm->memslot.code = mem_params->region[mem_params->region_idx.code].slot;
> + vm->memslot.pt = mem_params->region[mem_params->region_idx.pt].slot;
> + vm->memslot.data = mem_params->region[mem_params->region_idx.data].slot;
>
> return vm;
> }
> @@ -292,9 +340,12 @@ struct kvm_vm *__vm_create(enum vm_guest_mode mode,
> uint32_t nr_runnable_vcpus,
> {
> uint64_t nr_pages = vm_nr_pages_required(mode, nr_runnable_vcpus,
> nr_extra_pages);
> + struct kvm_vm_mem_params mem_params = kvm_vm_mem_default;
> struct kvm_vm *vm;
>
> - vm = ____vm_create(mode, nr_pages);
> + mem_params.region[0].npages = nr_pages;
> + mem_params.mode = mode;
> + vm = ____vm_create(&mem_params);
>
> kvm_vm_elf_load(vm, program_invocation_name);
>
> --
> 2.37.1.595.g718a3a8f04-goog
>
Thanks,
drew
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