On 4/12/24 1:43 PM, David Hildenbrand wrote: > Let's test that we can have shared zeropages in our process as long as > storage keys are not getting used, that shared zeropages are properly > unshared (replaced by anonymous pages) once storage keys are enabled, > and that no new shared zeropages are populated after storage keys > were enabled. > > We require the new pagemap interface to detect the shared zeropage. > > On an old kernel (zeropages always disabled): > # ./s390x/shared_zeropage_test > TAP version 13 > 1..3 > not ok 1 Shared zeropages should be enabled > ok 2 Shared zeropage should be gone > ok 3 Shared zeropages should be disabled > # Totals: pass:2 fail:1 xfail:0 xpass:0 skip:0 error:0 > > On a fixed kernel: > # ./s390x/shared_zeropage_test > TAP version 13 > 1..3 > ok 1 Shared zeropages should be enabled > ok 2 Shared zeropage should be gone > ok 3 Shared zeropages should be disabled > # Totals: pass:3 fail:0 xfail:0 xpass:0 skip:0 error:0 > > Testing of UFFDIO_ZEROPAGE can be added later. > > Cc: Christian Borntraeger <borntrae...@linux.ibm.com> > Cc: Janosch Frank <fran...@linux.ibm.com> > Cc: Claudio Imbrenda <imbre...@linux.ibm.com> > Cc: Thomas Huth <th...@redhat.com> > Cc: Alexander Gordeev <agord...@linux.ibm.com> > Cc: Paolo Bonzini <pbonz...@redhat.com> > Cc: Shuah Khan <sh...@kernel.org> > Signed-off-by: David Hildenbrand <da...@redhat.com> Acked-by: Muhammad Usama Anjum <usama.an...@collabora.com>
> --- > > To get it right this time, test the relevant cases. > > v3 of fixes are at: > https://lore.kernel.org/all/20240411161441.910170-1-da...@redhat.com/T/#u > > --- > tools/testing/selftests/kvm/Makefile | 1 + > .../kvm/s390x/shared_zeropage_test.c | 110 ++++++++++++++++++ > 2 files changed, 111 insertions(+) > create mode 100644 tools/testing/selftests/kvm/s390x/shared_zeropage_test.c > > diff --git a/tools/testing/selftests/kvm/Makefile > b/tools/testing/selftests/kvm/Makefile > index 741c7dc16afc..ed4ad591f193 100644 > --- a/tools/testing/selftests/kvm/Makefile > +++ b/tools/testing/selftests/kvm/Makefile > @@ -180,6 +180,7 @@ TEST_GEN_PROGS_s390x += s390x/sync_regs_test > TEST_GEN_PROGS_s390x += s390x/tprot > TEST_GEN_PROGS_s390x += s390x/cmma_test > TEST_GEN_PROGS_s390x += s390x/debug_test > +TEST_GEN_PROGS_s390x += s390x/shared_zeropage_test > TEST_GEN_PROGS_s390x += demand_paging_test > TEST_GEN_PROGS_s390x += dirty_log_test > TEST_GEN_PROGS_s390x += guest_print_test > diff --git a/tools/testing/selftests/kvm/s390x/shared_zeropage_test.c > b/tools/testing/selftests/kvm/s390x/shared_zeropage_test.c > new file mode 100644 > index 000000000000..74e829748fb1 > --- /dev/null > +++ b/tools/testing/selftests/kvm/s390x/shared_zeropage_test.c > @@ -0,0 +1,110 @@ > +// SPDX-License-Identifier: GPL-2.0-or-later > +/* > + * Test shared zeropage handling (with/without storage keys) > + * > + * Copyright (C) 2024, Red Hat, Inc. > + */ > +#include <sys/mman.h> > + > +#include <linux/fs.h> > + > +#include "test_util.h" > +#include "kvm_util.h" > +#include "kselftest.h" > + > +static void set_storage_key(void *addr, uint8_t skey) > +{ > + asm volatile("sske %0,%1" : : "d" (skey), "a" (addr)); > +} > + > +static void guest_code(void) > +{ > + /* Issue some storage key instruction. */ > + set_storage_key((void *)0, 0x98); > + GUEST_DONE(); > +} > + > +/* > + * Returns 1 if the shared zeropage is mapped, 0 if something else is mapped. > + * Returns < 0 on error or if nothing is mapped. > + */ > +static int maps_shared_zeropage(int pagemap_fd, void *addr) > +{ > + struct page_region region; > + struct pm_scan_arg arg = { > + .start = (uintptr_t)addr, > + .end = (uintptr_t)addr + 4096, > + .vec = (uintptr_t)®ion, > + .vec_len = 1, > + .size = sizeof(struct pm_scan_arg), > + .category_mask = PAGE_IS_PFNZERO, > + .category_anyof_mask = PAGE_IS_PRESENT, > + .return_mask = PAGE_IS_PFNZERO, > + }; > + return ioctl(pagemap_fd, PAGEMAP_SCAN, &arg);Its good to see more users > for it. > +} > + > +int main(int argc, char *argv[]) > +{ > + char *mem, *page0, *page1, *page2, tmp; > + const size_t pagesize = getpagesize(); > + struct kvm_vcpu *vcpu; > + struct kvm_vm *vm; > + struct ucall uc; > + int pagemap_fd; > + > + ksft_print_header(); > + ksft_set_plan(3); > + > + /* > + * We'll use memory that is not mapped into the VM for simplicity. > + * Shared zeropages are enabled/disabled per-process. > + */ > + mem = mmap(0, 3 * pagesize, PROT_READ, MAP_PRIVATE|MAP_ANON, -1, 0); > + TEST_ASSERT(mem != MAP_FAILED, "mmap() failed"); > + > + /* Disable THP. Ignore errors on older kernels. */ > + madvise(mem, 3 * pagesize, MADV_NOHUGEPAGE); > + > + page0 = mem; > + page1 = page0 + pagesize; > + page2 = page1 + pagesize; > + > + /* Can we even detect shared zeropages? */ > + pagemap_fd = open("/proc/self/pagemap", O_RDONLY); > + TEST_REQUIRE(pagemap_fd >= 0); > + > + tmp = *page0; > + asm volatile("" : "+r" (tmp)); > + TEST_REQUIRE(maps_shared_zeropage(pagemap_fd, page0) == 1); > + > + vm = vm_create_with_one_vcpu(&vcpu, guest_code); > + > + /* Verify that we get the shared zeropage after VM creation. */ > + tmp = *page1; > + asm volatile("" : "+r" (tmp)); > + ksft_test_result(maps_shared_zeropage(pagemap_fd, page1) == 1, > + "Shared zeropages should be enabled\n"); > + > + /* > + * Let our VM execute a storage key instruction that should > + * unshare all shared zeropages. > + */ > + vcpu_run(vcpu); > + get_ucall(vcpu, &uc); > + TEST_ASSERT_EQ(uc.cmd, UCALL_DONE); > + > + /* Verify that we don't have a shared zeropage anymore. */ > + ksft_test_result(!maps_shared_zeropage(pagemap_fd, page1), > + "Shared zeropage should be gone\n"); > + > + /* Verify that we don't get any new shared zeropages. */ > + tmp = *page2; > + asm volatile("" : "+r" (tmp)); > + ksft_test_result(!maps_shared_zeropage(pagemap_fd, page2), > + "Shared zeropages should be disabled\n"); > + > + kvm_vm_free(vm); > + > + ksft_finished(); > +} -- BR, Muhammad Usama Anjum
