[PATCH v4 17/17] s390x: pv: Add dump support

[Janosch Frank <frankja@linux.ibm.com>]

Sometimes dumping a guest from the outside is the only way to get the
data that is needed. This can be the case if a dumping mechanism like
KDUMP hasn't been configured or data needs to be fetched at a specific
point. Dumping a protected guest from the outside without help from
fw/hw doesn't yield sufficient data to be useful. Hence we now
introduce PV dump support.

The PV dump support works by integrating the firmware into the dump
process. New Ultravisor calls are used to initiate the dump process,
dump cpu data, dump memory state and lastly complete the dump process.
The UV calls are exposed by KVM via the new KVM_PV_DUMP command and
its subcommands. The guest's data is fully encrypted and can only be
decrypted by the entity that owns the customer communication key for
the dumped guest. Also dumping needs to be allowed via a flag in the
SE header.

On the QEMU side of things we store the PV dump data in the newly
introduced architecture ELF sections (storage state and completion
data) and the cpu notes (for cpu dump data).

Users can use the zgetdump tool to convert the encrypted QEMU dump to an
unencrypted one.

Signed-off-by: Janosch Frank <frankja@linux.ibm.com>
---
 target/s390x/arch_dump.c | 248 ++++++++++++++++++++++++++++++++++-----
 1 file changed, 218 insertions(+), 30 deletions(-)

diff --git a/target/s390x/arch_dump.c b/target/s390x/arch_dump.c
index 08daf93ae1..8afef4127c 100644
--- a/target/s390x/arch_dump.c
+++ b/target/s390x/arch_dump.c
@@ -16,7 +16,8 @@
 #include "s390x-internal.h"
 #include "elf.h"
 #include "sysemu/dump.h"
-
+#include "hw/s390x/pv.h"
+#include "kvm/kvm_s390x.h"
 
 struct S390xUserRegsStruct {
     uint64_t psw[2];
@@ -76,9 +77,16 @@ typedef struct noteStruct {
         uint64_t todcmp;
         uint32_t todpreg;
         uint64_t ctrs[16];
+        uint8_t dynamic[1];  /*
+                              * Would be a flexible array member, if
+                              * that was legal inside a union. Real
+                              * size comes from PV info interface.
+                              */
     } contents;
 } QEMU_PACKED Note;
 
+static bool pv_dump_initialized;
+
 static void s390x_write_elf64_prstatus(Note *note, S390CPU *cpu, int id)
 {
     int i;
@@ -177,52 +185,82 @@ static void s390x_write_elf64_prefix(Note *note, S390CPU *cpu, int id)
     note->contents.prefix = cpu_to_be32((uint32_t)(cpu->env.psa));
 }
 
+static void s390x_write_elf64_pv(Note *note, S390CPU *cpu, int id)
+{
+    note->hdr.n_type = cpu_to_be32(NT_S390_PV_CPU_DATA);
+    if (!pv_dump_initialized) {
+        return;
+    }
+    kvm_s390_dump_cpu(cpu, &note->contents.dynamic);
+}
 
 typedef struct NoteFuncDescStruct {
     int contents_size;
+    uint64_t (*note_size_func)(void); /* NULL for non-dynamic sized contents */
     void (*note_contents_func)(Note *note, S390CPU *cpu, int id);
+    bool pvonly;
 } NoteFuncDesc;
 
 static const NoteFuncDesc note_core[] = {
-    {sizeof_field(Note, contents.prstatus), s390x_write_elf64_prstatus},
-    {sizeof_field(Note, contents.fpregset), s390x_write_elf64_fpregset},
-    { 0, NULL}
+    {sizeof_field(Note, contents.prstatus), NULL, s390x_write_elf64_prstatus, false},
+    {sizeof_field(Note, contents.fpregset), NULL, s390x_write_elf64_fpregset, false},
+    { 0, NULL, NULL}
 };
 
 static const NoteFuncDesc note_linux[] = {
-    {sizeof_field(Note, contents.prefix),   s390x_write_elf64_prefix},
-    {sizeof_field(Note, contents.ctrs),     s390x_write_elf64_ctrs},
-    {sizeof_field(Note, contents.timer),    s390x_write_elf64_timer},
-    {sizeof_field(Note, contents.todcmp),   s390x_write_elf64_todcmp},
-    {sizeof_field(Note, contents.todpreg),  s390x_write_elf64_todpreg},
-    {sizeof_field(Note, contents.vregslo),  s390x_write_elf64_vregslo},
-    {sizeof_field(Note, contents.vregshi),  s390x_write_elf64_vregshi},
-    {sizeof_field(Note, contents.gscb),     s390x_write_elf64_gscb},
-    { 0, NULL}
+    {sizeof_field(Note, contents.prefix),   NULL, s390x_write_elf64_prefix,  false},
+    {sizeof_field(Note, contents.ctrs),     NULL, s390x_write_elf64_ctrs,    false},
+    {sizeof_field(Note, contents.timer),    NULL, s390x_write_elf64_timer,   false},
+    {sizeof_field(Note, contents.todcmp),   NULL, s390x_write_elf64_todcmp,  false},
+    {sizeof_field(Note, contents.todpreg),  NULL, s390x_write_elf64_todpreg, false},
+    {sizeof_field(Note, contents.vregslo),  NULL, s390x_write_elf64_vregslo, false},
+    {sizeof_field(Note, contents.vregshi),  NULL, s390x_write_elf64_vregshi, false},
+    {sizeof_field(Note, contents.gscb),     NULL, s390x_write_elf64_gscb,    false},
+    {0, kvm_s390_pv_dmp_get_size_cpu,       s390x_write_elf64_pv, true},
+    { 0, NULL, NULL}
 };
 
 static int s390x_write_elf64_notes(const char *note_name,
-                                       WriteCoreDumpFunction f,
-                                       S390CPU *cpu, int id,
-                                       void *opaque,
-                                       const NoteFuncDesc *funcs)
+                                   WriteCoreDumpFunction f,
+                                   S390CPU *cpu, int id,
+                                   void *opaque,
+                                   const NoteFuncDesc *funcs)
 {
-    Note note;
+    Note note, *notep;
     const NoteFuncDesc *nf;
-    int note_size;
+    int note_size, content_size;
     int ret = -1;
 
     assert(strlen(note_name) < sizeof(note.name));
 
     for (nf = funcs; nf->note_contents_func; nf++) {
-        memset(&note, 0, sizeof(note));
-        note.hdr.n_namesz = cpu_to_be32(strlen(note_name) + 1);
-        note.hdr.n_descsz = cpu_to_be32(nf->contents_size);
-        g_strlcpy(note.name, note_name, sizeof(note.name));
-        (*nf->note_contents_func)(&note, cpu, id);
+        notep = &note;
+        if (nf->pvonly && !s390_is_pv()) {
+            continue;
+        }
 
-        note_size = sizeof(note) - sizeof(note.contents) + nf->contents_size;
-        ret = f(&note, note_size, opaque);
+        content_size = nf->contents_size ? nf->contents_size : nf->note_size_func();
+        note_size = sizeof(note) - sizeof(notep->contents) + content_size;
+
+        /* Notes with dynamic sizes need to allocate a note */
+        if (nf->note_size_func) {
+            notep = g_malloc0(note_size);
+        }
+
+        memset(notep, 0, sizeof(note));
+
+        /* Setup note header data */
+        notep->hdr.n_descsz = cpu_to_be32(content_size);
+        notep->hdr.n_namesz = cpu_to_be32(strlen(note_name) + 1);
+        g_strlcpy(notep->name, note_name, sizeof(notep->name));
+
+        /* Get contents and write them out */
+        (*nf->note_contents_func)(notep, cpu, id);
+        ret = f(notep, note_size, opaque);
+
+        if (nf->note_size_func) {
+            g_free(notep);
+        }
 
         if (ret < 0) {
             return -1;
@@ -247,12 +285,159 @@ int s390_cpu_write_elf64_note(WriteCoreDumpFunction f, CPUState *cs,
     return s390x_write_elf64_notes("LINUX", f, cpu, cpuid, opaque, note_linux);
 }
 
+/* PV dump section size functions */
+static uint64_t get_dump_stor_state_size_from_len(uint64_t len)
+{
+    return (len / (1 << 20)) * kvm_s390_pv_dmp_get_size_stor_state();
+}
+
+static uint64_t get_size_stor_state(DumpState *s)
+{
+    return get_dump_stor_state_size_from_len(s->total_size);
+}
+
+static uint64_t get_size_complete(DumpState *s)
+{
+    return kvm_s390_pv_dmp_get_size_complete();
+}
+
+/* PV dump section data functions*/
+static int get_data_complete(DumpState *s, uint8_t *buff)
+{
+    int rc;
+
+    if (!pv_dump_initialized) {
+        return 0;
+    }
+    rc = kvm_s390_dump_complete(buff);
+    if (!rc) {
+            pv_dump_initialized = false;
+    }
+    return rc;
+}
+
+static int dump_mem(DumpState *s, uint64_t gaddr, uint8_t *buff, uint64_t buff_len)
+{
+    /* We need the gaddr + len and something to write to */
+    if (!pv_dump_initialized) {
+        return 0;
+    }
+    return kvm_s390_dump_mem(gaddr, buff_len, buff);
+}
+
+static int get_data_mem(DumpState *s, uint8_t *buff)
+{
+    int64_t memblock_size, memblock_start;
+    GuestPhysBlock *block;
+    uint64_t off;
+
+    QTAILQ_FOREACH(block, &s->guest_phys_blocks.head, next) {
+        memblock_start = dump_get_memblock_start(block, s->begin, s->length);
+        if (memblock_start == -1) {
+            continue;
+        }
+
+        memblock_size = dump_get_memblock_size(block, s->begin, s->length);
+
+        off = get_dump_stor_state_size_from_len(block->target_start);
+        dump_mem(s, block->target_start, buff + off,
+                 get_dump_stor_state_size_from_len(memblock_size));
+    }
+
+    return 0;
+}
+
+struct sections {
+    uint64_t (*sections_size_func)(DumpState *s);
+    int (*sections_contents_func)(DumpState *s, uint8_t *buff);
+    char sctn_str[12];
+} sections[] = {
+    { get_size_stor_state, get_data_mem, "pv_mem_meta"},
+    { get_size_complete, get_data_complete, "pv_compl"},
+    {NULL , NULL, ""}
+};
+
+static uint64_t arch_sections_write_hdr(void *opaque, uint8_t *buff)
+{
+    DumpState *s = opaque;
+    Elf64_Shdr *shdr = (void *)buff;
+    struct sections *sctn = sections;
+    uint64_t off = s->section_offset;
+
+    if (!s390_is_pv()) {
+        return 0;
+    }
+
+    for (; sctn->sections_size_func; off += shdr->sh_size, sctn++, shdr++) {
+        memset(shdr, 0, sizeof(*shdr));
+        shdr->sh_type = SHT_PROGBITS;
+        shdr->sh_offset = off;
+        shdr->sh_size = sctn->sections_size_func(s);
+        shdr->sh_name = s->string_table_buf->len;
+        g_array_append_vals(s->string_table_buf, sctn->sctn_str, sizeof(sctn->sctn_str));
+    }
+
+    return (uintptr_t)shdr - (uintptr_t)buff;
+}
+
+
+/* Add arch specific number of sections and their respective sizes */
+static void arch_sections_add(void *opaque)
+{
+    DumpState *s = opaque;
+    struct sections *sctn = sections;
+
+    /*
+     * We only do a PV dump if we are running a PV guest, KVM supports
+     * the dump API and we got valid dump length information.
+     */
+    if (!s390_is_pv() || !kvm_s390_get_protected_dump() ||
+        !kvm_s390_pv_info_basic_valid()) {
+        return;
+    }
+
+    /*
+     * Start the UV dump process by doing the initialize dump call via
+     * KVM as the proxy.
+     */
+    if (!kvm_s390_dump_init()) {
+            pv_dump_initialized = true;
+    }
+
+    for (; sctn->sections_size_func; sctn++) {
+        s->shdr_num += 1;
+        s->elf_section_data_size += sctn->sections_size_func(s);
+    }
+}
+
+/*
+ * After the PV dump has been initialized, the CPU data has been
+ * fetched and memory has been dumped, we need to grab the tweak data
+ * and the completion data.
+ */
+static void arch_sections_write(void *opaque, uint8_t *buff)
+{
+    DumpState *s = opaque;
+    struct sections *sctn = sections;
+
+    /* shdr_num should only have been set > 1 if we are protected */
+    assert(s390_is_pv());
+
+    for (; sctn->sections_size_func; sctn++) {
+        sctn->sections_contents_func(s, buff);
+        buff += sctn->sections_size_func(s);
+    }
+}
+
 int cpu_get_dump_info(ArchDumpInfo *info,
                       const struct GuestPhysBlockList *guest_phys_blocks)
 {
     info->d_machine = EM_S390;
     info->d_endian = ELFDATA2MSB;
     info->d_class = ELFCLASS64;
+    info->arch_sections_add_fn = *arch_sections_add;
+    info->arch_sections_write_hdr_fn = *arch_sections_write_hdr;
+    info->arch_sections_write_fn = *arch_sections_write;
 
     return 0;
 }
@@ -261,7 +446,7 @@ ssize_t cpu_get_note_size(int class, int machine, int nr_cpus)
 {
     int name_size = 8; /* "LINUX" or "CORE" + pad */
     size_t elf_note_size = 0;
-    int note_head_size;
+    int note_head_size, content_size;
     const NoteFuncDesc *nf;
 
     assert(class == ELFCLASS64);
@@ -270,12 +455,15 @@ ssize_t cpu_get_note_size(int class, int machine, int nr_cpus)
     note_head_size = sizeof(Elf64_Nhdr);
 
     for (nf = note_core; nf->note_contents_func; nf++) {
-        elf_note_size = elf_note_size + note_head_size + name_size +
-                        nf->contents_size;
+        elf_note_size = elf_note_size + note_head_size + name_size + nf->contents_size;
     }
     for (nf = note_linux; nf->note_contents_func; nf++) {
+        if (nf->pvonly && !s390_is_pv()) {
+            continue;
+        }
+        content_size = nf->contents_size ? nf->contents_size : nf->note_size_func();
         elf_note_size = elf_note_size + note_head_size + name_size +
-                        nf->contents_size;
+                        content_size;
     }
 
     return (elf_note_size) * nr_cpus;
-- 
2.34.1