From d38e48563c1f70460503de7ffff9a7f46b54b67d Mon Sep 17 00:00:00 2001 From: Alexander Gordeev Date: Mon, 3 Jun 2024 21:03:42 +0200 Subject: s390/crash: Do not use VM info if os_info does not have it The virtual memory information stored in os_info area is required for creation of the kernel image PT_LOAD program header for kernels since commit a2ec5bec56dd ("s390/mm: uncouple physical vs virtual address spaces"). By contrast, if such information in os_info is absent the PT_LOAD program header should not be created. Currently the proper PT_LOAD program header is created for kernels that contain the virtual memory information, but for kernels without one an invalid header of zero size is created. That in turn leads to stand-alone dump failures. Use OS_INFO_KASLR_OFFSET variable to check whether os_info is present or not (same as crash and makedumpfile tools do) and based on that create or do not create the kernel image PT_LOAD program header. Fixes: f4cac27dc0d6 ("s390/crash: Use old os_info to create PT_LOAD headers") Tested-by: Mikhail Zaslonko Acked-by: Mikhail Zaslonko Acked-by: Heiko Carstens Signed-off-by: Alexander Gordeev --- arch/s390/kernel/crash_dump.c | 54 ++++++++++++++++++++++++------------------- 1 file changed, 30 insertions(+), 24 deletions(-) diff --git a/arch/s390/kernel/crash_dump.c b/arch/s390/kernel/crash_dump.c index 9863ebe75019..edae13416196 100644 --- a/arch/s390/kernel/crash_dump.c +++ b/arch/s390/kernel/crash_dump.c @@ -451,7 +451,7 @@ static void *nt_final(void *ptr) /* * Initialize ELF header (new kernel) */ -static void *ehdr_init(Elf64_Ehdr *ehdr, int mem_chunk_cnt) +static void *ehdr_init(Elf64_Ehdr *ehdr, int phdr_count) { memset(ehdr, 0, sizeof(*ehdr)); memcpy(ehdr->e_ident, ELFMAG, SELFMAG); @@ -465,11 +465,8 @@ static void *ehdr_init(Elf64_Ehdr *ehdr, int mem_chunk_cnt) ehdr->e_phoff = sizeof(Elf64_Ehdr); ehdr->e_ehsize = sizeof(Elf64_Ehdr); ehdr->e_phentsize = sizeof(Elf64_Phdr); - /* - * Number of memory chunk PT_LOAD program headers plus one kernel - * image PT_LOAD program header plus one PT_NOTE program header. - */ - ehdr->e_phnum = mem_chunk_cnt + 1 + 1; + /* Number of PT_LOAD program headers plus PT_NOTE program header */ + ehdr->e_phnum = phdr_count + 1; return ehdr + 1; } @@ -503,12 +500,14 @@ static int get_mem_chunk_cnt(void) /* * Initialize ELF loads (new kernel) */ -static void loads_init(Elf64_Phdr *phdr) +static void loads_init(Elf64_Phdr *phdr, bool os_info_has_vm) { - unsigned long old_identity_base = os_info_old_value(OS_INFO_IDENTITY_BASE); + unsigned long old_identity_base = 0; phys_addr_t start, end; u64 idx; + if (os_info_has_vm) + old_identity_base = os_info_old_value(OS_INFO_IDENTITY_BASE); for_each_physmem_range(idx, &oldmem_type, &start, &end) { phdr->p_type = PT_LOAD; phdr->p_vaddr = old_identity_base + start; @@ -522,6 +521,11 @@ static void loads_init(Elf64_Phdr *phdr) } } +static bool os_info_has_vm(void) +{ + return os_info_old_value(OS_INFO_KASLR_OFFSET); +} + /* * Prepare PT_LOAD type program header for kernel image region */ @@ -566,7 +570,7 @@ static void *notes_init(Elf64_Phdr *phdr, void *ptr, u64 notes_offset) return ptr; } -static size_t get_elfcorehdr_size(int mem_chunk_cnt) +static size_t get_elfcorehdr_size(int phdr_count) { size_t size; @@ -581,10 +585,8 @@ static size_t get_elfcorehdr_size(int mem_chunk_cnt) size += nt_vmcoreinfo_size(); /* nt_final */ size += sizeof(Elf64_Nhdr); - /* PT_LOAD type program header for kernel text region */ - size += sizeof(Elf64_Phdr); /* PT_LOADS */ - size += mem_chunk_cnt * sizeof(Elf64_Phdr); + size += phdr_count * sizeof(Elf64_Phdr); return size; } @@ -595,8 +597,8 @@ static size_t get_elfcorehdr_size(int mem_chunk_cnt) int elfcorehdr_alloc(unsigned long long *addr, unsigned long long *size) { Elf64_Phdr *phdr_notes, *phdr_loads, *phdr_text; + int mem_chunk_cnt, phdr_text_cnt; size_t alloc_size; - int mem_chunk_cnt; void *ptr, *hdr; u64 hdr_off; @@ -615,12 +617,14 @@ int elfcorehdr_alloc(unsigned long long *addr, unsigned long long *size) } mem_chunk_cnt = get_mem_chunk_cnt(); + phdr_text_cnt = os_info_has_vm() ? 1 : 0; - alloc_size = get_elfcorehdr_size(mem_chunk_cnt); + alloc_size = get_elfcorehdr_size(mem_chunk_cnt + phdr_text_cnt); hdr = kzalloc(alloc_size, GFP_KERNEL); - /* Without elfcorehdr /proc/vmcore cannot be created. Thus creating + /* + * Without elfcorehdr /proc/vmcore cannot be created. Thus creating * a dump with this crash kernel will fail. Panic now to allow other * dump mechanisms to take over. */ @@ -628,21 +632,23 @@ int elfcorehdr_alloc(unsigned long long *addr, unsigned long long *size) panic("s390 kdump allocating elfcorehdr failed"); /* Init elf header */ - ptr = ehdr_init(hdr, mem_chunk_cnt); + phdr_notes = ehdr_init(hdr, mem_chunk_cnt + phdr_text_cnt); /* Init program headers */ - phdr_notes = ptr; - ptr = PTR_ADD(ptr, sizeof(Elf64_Phdr)); - phdr_text = ptr; - ptr = PTR_ADD(ptr, sizeof(Elf64_Phdr)); - phdr_loads = ptr; - ptr = PTR_ADD(ptr, sizeof(Elf64_Phdr) * mem_chunk_cnt); + if (phdr_text_cnt) { + phdr_text = phdr_notes + 1; + phdr_loads = phdr_text + 1; + } else { + phdr_loads = phdr_notes + 1; + } + ptr = PTR_ADD(phdr_loads, sizeof(Elf64_Phdr) * mem_chunk_cnt); /* Init notes */ hdr_off = PTR_DIFF(ptr, hdr); ptr = notes_init(phdr_notes, ptr, ((unsigned long) hdr) + hdr_off); /* Init kernel text program header */ - text_init(phdr_text); + if (phdr_text_cnt) + text_init(phdr_text); /* Init loads */ - loads_init(phdr_loads); + loads_init(phdr_loads, phdr_text_cnt); /* Finalize program headers */ hdr_off = PTR_DIFF(ptr, hdr); *addr = (unsigned long long) hdr; -- cgit v1.2.3 From 01c51a32dc18f128d2e55a7b2128b77fc01a2285 Mon Sep 17 00:00:00 2001 From: David Hildenbrand Date: Fri, 12 Apr 2024 10:43:29 +0200 Subject: KVM: s390x: selftests: Add shared zeropage test 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. [ agordeev: Fixed checkpatch complaint, added ucall_common.h include ] Cc: Christian Borntraeger Cc: Janosch Frank Cc: Claudio Imbrenda Cc: Thomas Huth Cc: Alexander Gordeev Cc: Paolo Bonzini Cc: Shuah Khan Signed-off-by: David Hildenbrand Acked-by: Christian Borntraeger Acked-by: Muhammad Usama Anjum Tested-by: Alexander Gordeev Link: https://lore.kernel.org/r/20240412084329.30315-1-david@redhat.com Signed-off-by: Alexander Gordeev --- tools/testing/selftests/kvm/Makefile | 1 + .../selftests/kvm/s390x/shared_zeropage_test.c | 111 +++++++++++++++++++++ 2 files changed, 112 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 ce8ff8e8ce3a..ac280dcba996 100644 --- a/tools/testing/selftests/kvm/Makefile +++ b/tools/testing/selftests/kvm/Makefile @@ -183,6 +183,7 @@ 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..bba0d9a6dcc8 --- /dev/null +++ b/tools/testing/selftests/kvm/s390x/shared_zeropage_test.c @@ -0,0 +1,111 @@ +// SPDX-License-Identifier: GPL-2.0-or-later +/* + * Test shared zeropage handling (with/without storage keys) + * + * Copyright (C) 2024, Red Hat, Inc. + */ +#include + +#include + +#include "test_util.h" +#include "kvm_util.h" +#include "kselftest.h" +#include "ucall_common.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); +} + +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(); +} -- cgit v1.2.3