| Message ID | 20220413175944.71705-7-bgardon@google.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | KVM: x86: Add a cap to disable NX hugepages on a VM | expand |
On Wed, Apr 13, 2022, Ben Gardon wrote: > There's currently no test coverage of NX hugepages in KVM selftests, so > add a basic test to ensure that the feature works as intended. ... > diff --git a/tools/testing/selftests/kvm/x86_64/nx_huge_pages_test.c b/tools/testing/selftests/kvm/x86_64/nx_huge_pages_test.c > new file mode 100644 > index 000000000000..7f80e48781fd > --- /dev/null > +++ b/tools/testing/selftests/kvm/x86_64/nx_huge_pages_test.c > @@ -0,0 +1,166 @@ > +// SPDX-License-Identifier: GPL-2.0-only > +/* > + * tools/testing/selftests/kvm/nx_huge_page_test.c > + * > + * Usage: to be run via nx_huge_page_test.sh, which does the necessary > + * environment setup and teardown It would be really nice if this test could either (a) do something useful without having to manually set /sys/kernel/mm/hugepages/hugepages-2048kB/nr_hugepages, or (b) refuse to run unless it's (likely) been invoked by the script. E.g. maybe add a magic token that must be passed in? That way just running the bare test will provide a helpful skip message, but someone that wants to fiddle with it can still run it manually. > +int main(int argc, char **argv) > +{ > + struct kvm_vm *vm; > + struct timespec ts; > + void *hva; This needs to check if the workaround is actually enabled via module param. Not as big a deal if there's a magic number, but it's also not too hard to query a module param. Or at least, it shouldn't be, I'm fairly certain that's one of the things I want to address in the selftests overhaul. Aha! Actually, IIUC, the patch that validates the per-VM override adds full support for the module param being turned off. So, how about pull in the tweaks to the expected number to this patch, and then the per-VM override test just makes disable_nx a logical OR of the module param beyond off or the test using the per-VM override. > diff --git a/tools/testing/selftests/kvm/x86_64/nx_huge_pages_test.sh b/tools/testing/selftests/kvm/x86_64/nx_huge_pages_test.sh > new file mode 100755 > index 000000000000..19fc95723fcb > --- /dev/null > +++ b/tools/testing/selftests/kvm/x86_64/nx_huge_pages_test.sh > @@ -0,0 +1,25 @@ > +#!/bin/bash > +# SPDX-License-Identifier: GPL-2.0-only */ > + > +# tools/testing/selftests/kvm/nx_huge_page_test.sh > +# Copyright (C) 2022, Google LLC. This should either check for root or use sudo. > +NX_HUGE_PAGES=$(cat /sys/module/kvm/parameters/nx_huge_pages) > +NX_HUGE_PAGES_RECOVERY_RATIO=$(cat /sys/module/kvm/parameters/nx_huge_pages_recovery_ratio) > +NX_HUGE_PAGES_RECOVERY_PERIOD=$(cat /sys/module/kvm/parameters/nx_huge_pages_recovery_period_ms) > +HUGE_PAGES=$(cat /sys/kernel/mm/hugepages/hugepages-2048kB/nr_hugepages) > + > +echo 1 > /sys/module/kvm/parameters/nx_huge_pages > +echo 1 > /sys/module/kvm/parameters/nx_huge_pages_recovery_ratio > +echo 100 > /sys/module/kvm/parameters/nx_huge_pages_recovery_period_ms > +echo 200 > /sys/kernel/mm/hugepages/hugepages-2048kB/nr_hugepages > + > +./nx_huge_pages_test I would much prefer this find its path and use that to reference the test, e.g. this fails if invoking the script from anything but the x86_64 subdirectory. I'd provide a snippet of how to do that, but my scripting skills are garbage :-) > +RET=$? > + > +echo $NX_HUGE_PAGES > /sys/module/kvm/parameters/nx_huge_pages > +echo $NX_HUGE_PAGES_RECOVERY_RATIO > /sys/module/kvm/parameters/nx_huge_pages_recovery_ratio > +echo $NX_HUGE_PAGES_RECOVERY_PERIOD > /sys/module/kvm/parameters/nx_huge_pages_recovery_period_ms > +echo $HUGE_PAGES > /sys/kernel/mm/hugepages/hugepages-2048kB/nr_hugepages > + > +exit $RET > -- > 2.35.1.1178.g4f1659d476-goog >
On Wed, Apr 13, 2022 at 3:35 PM Sean Christopherson <seanjc@google.com> wrote: > > On Wed, Apr 13, 2022, Ben Gardon wrote: > > There's currently no test coverage of NX hugepages in KVM selftests, so > > add a basic test to ensure that the feature works as intended. > > ... > > > diff --git a/tools/testing/selftests/kvm/x86_64/nx_huge_pages_test.c b/tools/testing/selftests/kvm/x86_64/nx_huge_pages_test.c > > new file mode 100644 > > index 000000000000..7f80e48781fd > > --- /dev/null > > +++ b/tools/testing/selftests/kvm/x86_64/nx_huge_pages_test.c > > @@ -0,0 +1,166 @@ > > +// SPDX-License-Identifier: GPL-2.0-only > > +/* > > + * tools/testing/selftests/kvm/nx_huge_page_test.c > > + * > > + * Usage: to be run via nx_huge_page_test.sh, which does the necessary > > + * environment setup and teardown > > It would be really nice if this test could either (a) do something useful without > having to manually set /sys/kernel/mm/hugepages/hugepages-2048kB/nr_hugepages, > or (b) refuse to run unless it's (likely) been invoked by the script. E.g. maybe > add a magic token that must be passed in? That way just running the bare test > will provide a helpful skip message, but someone that wants to fiddle with it can > still run it manually. > > > +int main(int argc, char **argv) > > +{ > > + struct kvm_vm *vm; > > + struct timespec ts; > > + void *hva; > > This needs to check if the workaround is actually enabled via module param. Not > as big a deal if there's a magic number, but it's also not too hard to query a > module param. Or at least, it shouldn't be, I'm fairly certain that's one of the > things I want to address in the selftests overhaul. > > Aha! Actually, IIUC, the patch that validates the per-VM override adds full support > for the module param being turned off. > > So, how about pull in the tweaks to the expected number to this patch, and then > the per-VM override test just makes disable_nx a logical OR of the module param > beyond off or the test using the per-VM override. > > > diff --git a/tools/testing/selftests/kvm/x86_64/nx_huge_pages_test.sh b/tools/testing/selftests/kvm/x86_64/nx_huge_pages_test.sh > > new file mode 100755 > > index 000000000000..19fc95723fcb > > --- /dev/null > > +++ b/tools/testing/selftests/kvm/x86_64/nx_huge_pages_test.sh > > @@ -0,0 +1,25 @@ > > +#!/bin/bash > > +# SPDX-License-Identifier: GPL-2.0-only */ > > + > > +# tools/testing/selftests/kvm/nx_huge_page_test.sh > > +# Copyright (C) 2022, Google LLC. > > This should either check for root or use sudo. Is there not any scenario where the below setup commands could work without root? > > > +NX_HUGE_PAGES=$(cat /sys/module/kvm/parameters/nx_huge_pages) > > +NX_HUGE_PAGES_RECOVERY_RATIO=$(cat /sys/module/kvm/parameters/nx_huge_pages_recovery_ratio) > > +NX_HUGE_PAGES_RECOVERY_PERIOD=$(cat /sys/module/kvm/parameters/nx_huge_pages_recovery_period_ms) > > +HUGE_PAGES=$(cat /sys/kernel/mm/hugepages/hugepages-2048kB/nr_hugepages) > > + > > +echo 1 > /sys/module/kvm/parameters/nx_huge_pages > > +echo 1 > /sys/module/kvm/parameters/nx_huge_pages_recovery_ratio > > +echo 100 > /sys/module/kvm/parameters/nx_huge_pages_recovery_period_ms > > +echo 200 > /sys/kernel/mm/hugepages/hugepages-2048kB/nr_hugepages > > + > > +./nx_huge_pages_test > > I would much prefer this find its path and use that to reference the test, e.g. this > fails if invoking the script from anything but the x86_64 subdirectory. I'd provide > a snippet of how to do that, but my scripting skills are garbage :-) > > > +RET=$? > > + > > +echo $NX_HUGE_PAGES > /sys/module/kvm/parameters/nx_huge_pages > > +echo $NX_HUGE_PAGES_RECOVERY_RATIO > /sys/module/kvm/parameters/nx_huge_pages_recovery_ratio > > +echo $NX_HUGE_PAGES_RECOVERY_PERIOD > /sys/module/kvm/parameters/nx_huge_pages_recovery_period_ms > > +echo $HUGE_PAGES > /sys/kernel/mm/hugepages/hugepages-2048kB/nr_hugepages > > + > > +exit $RET > > -- > > 2.35.1.1178.g4f1659d476-goog > >
On Thu, Apr 14, 2022, Ben Gardon wrote: > On Wed, Apr 13, 2022 at 3:35 PM Sean Christopherson <seanjc@google.com> wrote: > > > diff --git a/tools/testing/selftests/kvm/x86_64/nx_huge_pages_test.sh b/tools/testing/selftests/kvm/x86_64/nx_huge_pages_test.sh > > > new file mode 100755 > > > index 000000000000..19fc95723fcb > > > --- /dev/null > > > +++ b/tools/testing/selftests/kvm/x86_64/nx_huge_pages_test.sh > > > @@ -0,0 +1,25 @@ > > > +#!/bin/bash > > > +# SPDX-License-Identifier: GPL-2.0-only */ > > > + > > > +# tools/testing/selftests/kvm/nx_huge_page_test.sh > > > +# Copyright (C) 2022, Google LLC. > > > > This should either check for root or use sudo. > > Is there not any scenario where the below setup commands could work > without root? Technically, yes, someone could be running the test as a non-root user with the necessary permissions. Practically speaking, I would be surprised if anyone configures module params in that way. That said, there's certainly no harm in using sudo as a fall back.
diff --git a/tools/testing/selftests/kvm/Makefile b/tools/testing/selftests/kvm/Makefile index af582d168621..9bb9bce4df37 100644 --- a/tools/testing/selftests/kvm/Makefile +++ b/tools/testing/selftests/kvm/Makefile @@ -43,6 +43,10 @@ LIBKVM_aarch64 = lib/aarch64/processor.c lib/aarch64/ucall.c lib/aarch64/handler LIBKVM_s390x = lib/s390x/processor.c lib/s390x/ucall.c lib/s390x/diag318_test_handler.c LIBKVM_riscv = lib/riscv/processor.c lib/riscv/ucall.c +# Non-compiled test targets +TEST_PROGS_x86_64 += x86_64/nx_huge_pages_test.sh + +# Compiled test targets TEST_GEN_PROGS_x86_64 = x86_64/cpuid_test TEST_GEN_PROGS_x86_64 += x86_64/cr4_cpuid_sync_test TEST_GEN_PROGS_x86_64 += x86_64/get_msr_index_features @@ -104,6 +108,9 @@ TEST_GEN_PROGS_x86_64 += steal_time TEST_GEN_PROGS_x86_64 += kvm_binary_stats_test TEST_GEN_PROGS_x86_64 += system_counter_offset_test +# Compiled outputs used by test targets +TEST_GEN_PROGS_EXTENDED_x86_64 += x86_64/nx_huge_pages_test + TEST_GEN_PROGS_aarch64 += aarch64/arch_timer TEST_GEN_PROGS_aarch64 += aarch64/debug-exceptions TEST_GEN_PROGS_aarch64 += aarch64/get-reg-list @@ -142,7 +149,9 @@ TEST_GEN_PROGS_riscv += kvm_page_table_test TEST_GEN_PROGS_riscv += set_memory_region_test TEST_GEN_PROGS_riscv += kvm_binary_stats_test +TEST_PROGS += $(TEST_PROGS_$(UNAME_M)) TEST_GEN_PROGS += $(TEST_GEN_PROGS_$(UNAME_M)) +TEST_GEN_PROGS_EXTENDED += $(TEST_GEN_PROGS_EXTENDED_$(UNAME_M)) LIBKVM += $(LIBKVM_$(UNAME_M)) INSTALL_HDR_PATH = $(top_srcdir)/usr @@ -193,6 +202,7 @@ $(OUTPUT)/libkvm.a: $(LIBKVM_OBJS) x := $(shell mkdir -p $(sort $(dir $(TEST_GEN_PROGS)))) all: $(STATIC_LIBS) $(TEST_GEN_PROGS): $(STATIC_LIBS) +$(TEST_GEN_PROGS_EXTENDED): $(STATIC_LIBS) cscope: include_paths = $(LINUX_TOOL_INCLUDE) $(LINUX_HDR_PATH) include lib .. cscope: diff --git a/tools/testing/selftests/kvm/include/kvm_util_base.h b/tools/testing/selftests/kvm/include/kvm_util_base.h index 2a3a4d9ed8e3..001b55ae25f8 100644 --- a/tools/testing/selftests/kvm/include/kvm_util_base.h +++ b/tools/testing/selftests/kvm/include/kvm_util_base.h @@ -406,6 +406,7 @@ struct kvm_stats_desc *read_stats_desc(int stats_fd, int read_stat_data(int stats_fd, struct kvm_stats_header *header, struct kvm_stats_desc *desc, uint64_t *data, ssize_t max_elements); +uint64_t vm_get_stat(struct kvm_vm *vm, const char *stat_name); uint32_t guest_get_vcpuid(void); diff --git a/tools/testing/selftests/kvm/lib/kvm_util.c b/tools/testing/selftests/kvm/lib/kvm_util.c index fc2321055a69..d332f02370d1 100644 --- a/tools/testing/selftests/kvm/lib/kvm_util.c +++ b/tools/testing/selftests/kvm/lib/kvm_util.c @@ -2651,3 +2651,65 @@ int read_stat_data(int stats_fd, struct kvm_stats_header *header, return ret; } + +static int __vm_get_stat(struct kvm_vm *vm, const char *stat_name, + uint64_t *data, ssize_t max_elements) +{ + struct kvm_stats_desc *stats_desc; + struct kvm_stats_header header; + struct kvm_stats_desc *desc; + size_t size_desc; + int stats_fd; + int ret = -EINVAL; + int i; + + stats_fd = vm_get_stats_fd(vm); + + read_stats_header(stats_fd, &header); + + stats_desc = read_stats_desc(stats_fd, &header); + + size_desc = sizeof(struct kvm_stats_desc) + header.name_size; + + /* Read kvm stats data one by one */ + for (i = 0; i < header.num_desc; ++i) { + desc = (void *)stats_desc + (i * size_desc); + + if (strcmp(desc->name, stat_name)) + continue; + + ret = read_stat_data(stats_fd, &header, desc, data, + max_elements); + } + + free(stats_desc); + close(stats_fd); + return ret; +} + +/* + * Read the value of the named stat + * + * Input Args: + * vm - the VM for which the stat should be read + * stat_name - the name of the stat to read + * + * Output Args: None + * + * Return: + * The value of the stat + * + * Reads the value of the named stat through the binary stat interface. If + * the named stat has multiple data elements, only the first will be returned. + */ +uint64_t vm_get_stat(struct kvm_vm *vm, const char *stat_name) +{ + uint64_t data; + int ret; + + ret = __vm_get_stat(vm, stat_name, &data, 1); + TEST_ASSERT(ret == 1, + "Stat %s expected to have 1 element, but %d returned", + stat_name, ret); + return data; +} diff --git a/tools/testing/selftests/kvm/x86_64/nx_huge_pages_test.c b/tools/testing/selftests/kvm/x86_64/nx_huge_pages_test.c new file mode 100644 index 000000000000..7f80e48781fd --- /dev/null +++ b/tools/testing/selftests/kvm/x86_64/nx_huge_pages_test.c @@ -0,0 +1,166 @@ +// SPDX-License-Identifier: GPL-2.0-only +/* + * tools/testing/selftests/kvm/nx_huge_page_test.c + * + * Usage: to be run via nx_huge_page_test.sh, which does the necessary + * environment setup and teardown + * + * Copyright (C) 2022, Google LLC. + */ + +#define _GNU_SOURCE + +#include <fcntl.h> +#include <stdint.h> +#include <time.h> + +#include <test_util.h> +#include "kvm_util.h" + +#define HPAGE_SLOT 10 +#define HPAGE_GVA (23*1024*1024) +#define HPAGE_GPA (10*1024*1024) +#define HPAGE_SLOT_NPAGES (512 * 3) +#define PAGE_SIZE 4096 + +/* + * x86 opcode for the return instruction. Used to call into, and then + * immediately return from, memory backed with hugepages. + */ +#define RETURN_OPCODE 0xC3 + +/* + * Exit the VM after each memory access so that the userspace component of the + * test can make assertions about the pages backing the VM. + */ +void guest_code(void) +{ + uint64_t hpage_1 = HPAGE_GVA; + uint64_t hpage_2 = hpage_1 + (PAGE_SIZE * 512); + uint64_t hpage_3 = hpage_2 + (PAGE_SIZE * 512); + + READ_ONCE(*(uint64_t *)hpage_1); + GUEST_SYNC(1); + + READ_ONCE(*(uint64_t *)hpage_2); + GUEST_SYNC(2); + + ((void (*)(void)) hpage_1)(); + GUEST_SYNC(3); + + ((void (*)(void)) hpage_3)(); + GUEST_SYNC(4); + + READ_ONCE(*(uint64_t *)hpage_1); + GUEST_SYNC(5); + + READ_ONCE(*(uint64_t *)hpage_3); + GUEST_SYNC(6); +} + +static void check_2m_page_count(struct kvm_vm *vm, int expected_pages_2m) +{ + int actual_pages_2m; + + actual_pages_2m = vm_get_stat(vm, "pages_2m"); + + TEST_ASSERT(actual_pages_2m == expected_pages_2m, + "Unexpected 2m page count. Expected %d, got %d", + expected_pages_2m, actual_pages_2m); +} + +static void check_split_count(struct kvm_vm *vm, int expected_splits) +{ + int actual_splits; + + actual_splits = vm_get_stat(vm, "nx_lpage_splits"); + + TEST_ASSERT(actual_splits == expected_splits, + "Unexpected nx lpage split count. Expected %d, got %d", + expected_splits, actual_splits); +} + +int main(int argc, char **argv) +{ + struct kvm_vm *vm; + struct timespec ts; + void *hva; + + vm = vm_create_default(0, 0, guest_code); + + vm_userspace_mem_region_add(vm, VM_MEM_SRC_ANONYMOUS_HUGETLB, + HPAGE_GPA, HPAGE_SLOT, + HPAGE_SLOT_NPAGES, 0); + + virt_map(vm, HPAGE_GVA, HPAGE_GPA, HPAGE_SLOT_NPAGES); + + hva = addr_gpa2hva(vm, HPAGE_GPA); + memset(hva, RETURN_OPCODE, HPAGE_SLOT_NPAGES * PAGE_SIZE); + + check_2m_page_count(vm, 0); + check_split_count(vm, 0); + + /* + * The guest code will first read from the first hugepage, resulting + * in a huge page mapping being created. + */ + vcpu_run(vm, 0); + check_2m_page_count(vm, 1); + check_split_count(vm, 0); + + /* + * Then the guest code will read from the second hugepage, resulting + * in another huge page mapping being created. + */ + vcpu_run(vm, 0); + check_2m_page_count(vm, 2); + check_split_count(vm, 0); + + /* + * Next, the guest will execute from the first huge page, causing it + * to be remapped at 4k. + */ + vcpu_run(vm, 0); + check_2m_page_count(vm, 1); + check_split_count(vm, 1); + + /* + * Executing from the third huge page (previously unaccessed) will + * cause part to be mapped at 4k. + */ + vcpu_run(vm, 0); + check_2m_page_count(vm, 1); + check_split_count(vm, 2); + + /* Reading from the first huge page again should have no effect. */ + vcpu_run(vm, 0); + check_2m_page_count(vm, 1); + check_split_count(vm, 2); + + /* + * Give recovery thread time to run. The wrapper script sets + * recovery_period_ms to 100, so wait 5x that. + */ + ts.tv_sec = 0; + ts.tv_nsec = 500000000; + nanosleep(&ts, NULL); + + /* + * Now that the reclaimer has run, all the split pages should be gone. + */ + check_2m_page_count(vm, 1); + check_split_count(vm, 0); + + /* + * The 4k mapping on hpage 3 should have been removed, so check that + * reading from it causes a huge page mapping to be installed. + */ + vcpu_run(vm, 0); + check_2m_page_count(vm, 2); + check_split_count(vm, 0); + + kvm_vm_free(vm); + + return 0; +} + diff --git a/tools/testing/selftests/kvm/x86_64/nx_huge_pages_test.sh b/tools/testing/selftests/kvm/x86_64/nx_huge_pages_test.sh new file mode 100755 index 000000000000..19fc95723fcb --- /dev/null +++ b/tools/testing/selftests/kvm/x86_64/nx_huge_pages_test.sh @@ -0,0 +1,25 @@ +#!/bin/bash +# SPDX-License-Identifier: GPL-2.0-only */ + +# tools/testing/selftests/kvm/nx_huge_page_test.sh +# Copyright (C) 2022, Google LLC. + +NX_HUGE_PAGES=$(cat /sys/module/kvm/parameters/nx_huge_pages) +NX_HUGE_PAGES_RECOVERY_RATIO=$(cat /sys/module/kvm/parameters/nx_huge_pages_recovery_ratio) +NX_HUGE_PAGES_RECOVERY_PERIOD=$(cat /sys/module/kvm/parameters/nx_huge_pages_recovery_period_ms) +HUGE_PAGES=$(cat /sys/kernel/mm/hugepages/hugepages-2048kB/nr_hugepages) + +echo 1 > /sys/module/kvm/parameters/nx_huge_pages +echo 1 > /sys/module/kvm/parameters/nx_huge_pages_recovery_ratio +echo 100 > /sys/module/kvm/parameters/nx_huge_pages_recovery_period_ms +echo 200 > /sys/kernel/mm/hugepages/hugepages-2048kB/nr_hugepages + +./nx_huge_pages_test +RET=$? + +echo $NX_HUGE_PAGES > /sys/module/kvm/parameters/nx_huge_pages +echo $NX_HUGE_PAGES_RECOVERY_RATIO > /sys/module/kvm/parameters/nx_huge_pages_recovery_ratio +echo $NX_HUGE_PAGES_RECOVERY_PERIOD > /sys/module/kvm/parameters/nx_huge_pages_recovery_period_ms +echo $HUGE_PAGES > /sys/kernel/mm/hugepages/hugepages-2048kB/nr_hugepages + +exit $RET
There's currently no test coverage of NX hugepages in KVM selftests, so add a basic test to ensure that the feature works as intended. Signed-off-by: Ben Gardon <bgardon@google.com> --- tools/testing/selftests/kvm/Makefile | 10 ++ .../selftests/kvm/include/kvm_util_base.h | 1 + tools/testing/selftests/kvm/lib/kvm_util.c | 62 +++++++ .../selftests/kvm/x86_64/nx_huge_pages_test.c | 166 ++++++++++++++++++ .../kvm/x86_64/nx_huge_pages_test.sh | 25 +++ 5 files changed, 264 insertions(+) create mode 100644 tools/testing/selftests/kvm/x86_64/nx_huge_pages_test.c create mode 100755 tools/testing/selftests/kvm/x86_64/nx_huge_pages_test.sh