diff mbox series

[5/5] s390x: pv: Add dump support

Message ID 20220310112547.3823-6-frankja@linux.ibm.com (mailing list archive)
State New, archived
Headers show
Series s390x: dump: Add PV dump support | expand

Commit Message

Janosch Frank March 10, 2022, 11:25 a.m. UTC
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 a tool to convert the encrypted QEMU dump to an
unencrypted one.

Signed-off-by: Janosch Frank <frankja@linux.ibm.com>
---
 dump/dump.c              |  27 -----
 include/elf.h            |   1 +
 include/sysemu/dump.h    |  27 +++++
 target/s390x/arch_dump.c | 247 ++++++++++++++++++++++++++++++++++-----
 4 files changed, 244 insertions(+), 58 deletions(-)

Comments

Richard Henderson March 12, 2022, 2:52 p.m. UTC | #1
On 3/10/22 03:25, Janosch Frank wrote:
> 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 a tool to convert the encrypted QEMU dump to an
> unencrypted one.
> 
> Signed-off-by: Janosch Frank <frankja@linux.ibm.com>
> ---
>   dump/dump.c              |  27 -----
>   include/elf.h            |   1 +
>   include/sysemu/dump.h    |  27 +++++
>   target/s390x/arch_dump.c | 247 ++++++++++++++++++++++++++++++++++-----
>   4 files changed, 244 insertions(+), 58 deletions(-)
> 
> diff --git a/dump/dump.c b/dump/dump.c
> index a9d9ea514d..4b7d333866 100644
> --- a/dump/dump.c
> +++ b/dump/dump.c
> @@ -708,33 +708,6 @@ static void dump_begin(DumpState *s, Error **errp)
>       write_elf_notes(s, errp);
>   }
>   
> -static int get_next_block(DumpState *s, GuestPhysBlock *block)
> -{
> -    while (1) {
> -        block = QTAILQ_NEXT(block, next);
> -        if (!block) {
> -            /* no more block */
> -            return 1;
> -        }
> -
> -        s->start = 0;
> -        s->next_block = block;
> -        if (s->has_filter) {
> -            if (block->target_start >= s->begin + s->length ||
> -                block->target_end <= s->begin) {
> -                /* This block is out of the range */
> -                continue;
> -            }
> -
> -            if (s->begin > block->target_start) {
> -                s->start = s->begin - block->target_start;
> -            }
> -        }
> -
> -        return 0;
> -    }
> -}

No reason to make this inline, surely.  Just export it.
Anyway, this should be it's own patch.

> @@ -76,9 +77,12 @@ typedef struct noteStruct {
>           uint64_t todcmp;
>           uint32_t todpreg;
>           uint64_t ctrs[16];
> +        uint8_t dynamic;  /* Real size comes from PV info interface */

This needs a better comment.  Possibly

     uint8_t dynamic[1];  /* Would be a flexible array member, if that was legal inside a 
union. Real size comes from PV info interface. */

Alternately, rewrite everything to work with

typedef struct noteStruct {
     Elf64_Nhdr hdr;
     char name[8];
     uint8_t contents[];
} QEMU_PACKED Note;

which is a better description of what's going on in this file anyway.


r~
Janosch Frank March 14, 2022, 10:15 a.m. UTC | #2
On 3/12/22 15:52, Richard Henderson wrote:
> On 3/10/22 03:25, Janosch Frank wrote:
>> 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 a tool to convert the encrypted QEMU dump to an
>> unencrypted one.
>>
>> Signed-off-by: Janosch Frank <frankja@linux.ibm.com>
>> ---
>>    dump/dump.c              |  27 -----
>>    include/elf.h            |   1 +
>>    include/sysemu/dump.h    |  27 +++++
>>    target/s390x/arch_dump.c | 247 ++++++++++++++++++++++++++++++++++-----
>>    4 files changed, 244 insertions(+), 58 deletions(-)
>>
>> diff --git a/dump/dump.c b/dump/dump.c
>> index a9d9ea514d..4b7d333866 100644
>> --- a/dump/dump.c
>> +++ b/dump/dump.c
>> @@ -708,33 +708,6 @@ static void dump_begin(DumpState *s, Error **errp)
>>        write_elf_notes(s, errp);
>>    }
>>    
>> -static int get_next_block(DumpState *s, GuestPhysBlock *block)
>> -{
>> -    while (1) {
>> -        block = QTAILQ_NEXT(block, next);
>> -        if (!block) {
>> -            /* no more block */
>> -            return 1;
>> -        }
>> -
>> -        s->start = 0;
>> -        s->next_block = block;
>> -        if (s->has_filter) {
>> -            if (block->target_start >= s->begin + s->length ||
>> -                block->target_end <= s->begin) {
>> -                /* This block is out of the range */
>> -                continue;
>> -            }
>> -
>> -            if (s->begin > block->target_start) {
>> -                s->start = s->begin - block->target_start;
>> -            }
>> -        }
>> -
>> -        return 0;
>> -    }
>> -}
> 
> No reason to make this inline, surely.  Just export it.
> Anyway, this should be it's own patch.

Yeah, will do.

> 
>> @@ -76,9 +77,12 @@ typedef struct noteStruct {
>>            uint64_t todcmp;
>>            uint32_t todpreg;
>>            uint64_t ctrs[16];
>> +        uint8_t dynamic;  /* Real size comes from PV info interface */
> 
> This needs a better comment.  Possibly
> 
>       uint8_t dynamic[1];  /* Would be a flexible array member, if that was legal inside a
> union. Real size comes from PV info interface. */
> 
> Alternately, rewrite everything to work with
> 
> typedef struct noteStruct {
>       Elf64_Nhdr hdr;
>       char name[8];
>       uint8_t contents[];
> } QEMU_PACKED Note;
> 
> which is a better description of what's going on in this file anyway.

I'll have a look at that

> 
> r~
>
diff mbox series

Patch

diff --git a/dump/dump.c b/dump/dump.c
index a9d9ea514d..4b7d333866 100644
--- a/dump/dump.c
+++ b/dump/dump.c
@@ -708,33 +708,6 @@  static void dump_begin(DumpState *s, Error **errp)
     write_elf_notes(s, errp);
 }
 
-static int get_next_block(DumpState *s, GuestPhysBlock *block)
-{
-    while (1) {
-        block = QTAILQ_NEXT(block, next);
-        if (!block) {
-            /* no more block */
-            return 1;
-        }
-
-        s->start = 0;
-        s->next_block = block;
-        if (s->has_filter) {
-            if (block->target_start >= s->begin + s->length ||
-                block->target_end <= s->begin) {
-                /* This block is out of the range */
-                continue;
-            }
-
-            if (s->begin > block->target_start) {
-                s->start = s->begin - block->target_start;
-            }
-        }
-
-        return 0;
-    }
-}
-
 /* write all memory to vmcore */
 static void dump_iterate(DumpState *s, Error **errp)
 {
diff --git a/include/elf.h b/include/elf.h
index 3a4bcb646a..58f76fd5b4 100644
--- a/include/elf.h
+++ b/include/elf.h
@@ -1649,6 +1649,7 @@  typedef struct elf64_shdr {
 #define NT_TASKSTRUCT	4
 #define NT_AUXV		6
 #define NT_PRXFPREG     0x46e62b7f      /* copied from gdb5.1/include/elf/common.h */
+#define NT_S390_PV_DATA 0x30e           /* s390 protvirt cpu dump data */
 #define NT_S390_GS_CB   0x30b           /* s390 guarded storage registers */
 #define NT_S390_VXRS_HIGH 0x30a         /* s390 vector registers 16-31 */
 #define NT_S390_VXRS_LOW  0x309         /* s390 vector registers 0-15 (lower half) */
diff --git a/include/sysemu/dump.h b/include/sysemu/dump.h
index 9a000e7483..6106e0de78 100644
--- a/include/sysemu/dump.h
+++ b/include/sysemu/dump.h
@@ -213,4 +213,31 @@  typedef struct DumpState {
 uint16_t cpu_to_dump16(DumpState *s, uint16_t val);
 uint32_t cpu_to_dump32(DumpState *s, uint32_t val);
 uint64_t cpu_to_dump64(DumpState *s, uint64_t val);
+
+static inline int get_next_block(DumpState *s, GuestPhysBlock *block)
+{
+    while (1) {
+        block = QTAILQ_NEXT(block, next);
+        if (!block) {
+            /* no more block */
+            return 1;
+        }
+
+        s->start = 0;
+        s->next_block = block;
+        if (s->has_filter) {
+            if (block->target_start >= s->begin + s->length ||
+                block->target_end <= s->begin) {
+                /* This block is out of the range */
+                continue;
+            }
+
+            if (s->begin > block->target_start) {
+                s->start = s->begin - block->target_start;
+            }
+        }
+
+        return 0;
+    }
+}
 #endif
diff --git a/target/s390x/arch_dump.c b/target/s390x/arch_dump.c
index 08daf93ae1..e8e8cfbc9f 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 +77,12 @@  typedef struct noteStruct {
         uint64_t todcmp;
         uint32_t todpreg;
         uint64_t ctrs[16];
+        uint8_t dynamic;  /* 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 +181,82 @@  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_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;
@@ -233,7 +267,6 @@  static int s390x_write_elf64_notes(const char *note_name,
     return 0;
 }
 
-
 int s390_cpu_write_elf64_note(WriteCoreDumpFunction f, CPUState *cs,
                               int cpuid, void *opaque)
 {
@@ -247,12 +280,161 @@  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_mem_size_from_len(uint64_t len)
+{
+    return (len / (1 << 20)) * kvm_s390_pv_dmp_get_size_mem();
+}
+
+static uint64_t get_size_mem(DumpState *s)
+{
+    return get_dump_mem_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_finish(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)
+{
+    GuestPhysBlock *block;
+    uint64_t off;
+    int64_t size;
+
+    do {
+        block = s->next_block;
+
+        size = block->target_end - block->target_start;
+        if (s->has_filter) {
+            size -= s->start;
+            if (s->begin + s->length < block->target_end) {
+                size -= block->target_end - (s->begin + s->length);
+            }
+        }
+        off = get_dump_mem_size_from_len(block->target_start);
+        dump_mem(s, block->target_start, buff + off,
+                 get_dump_mem_size_from_len(size));
+    } while (!get_next_block(s, block));
+
+    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_mem, 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 +443,7 @@  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 +452,15 @@  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;