From df9e9e9c56c7fbf0ea54a342591c5427b508a7bf Mon Sep 17 00:00:00 2001

From: Laszlo Ersek <lersek@redhat.com>

Date: Thu, 17 Apr 2014 11:13:59 +0200

Subject: [PATCH 10/12] qemu_loadvm_state(): shadow SeaBIOS for VM incoming from RHEL-6 host

RH-Author: Laszlo Ersek <lersek@redhat.com>

Message-id: <1397733239-8835-1-git-send-email-lersek@redhat.com>

Patchwork-id: 58498

O-Subject: [RHEL-7.0 0day qemu-kvm PATCH v2] qemu_loadvm_state(): shadow SeaBIOS for VM incoming from RHEL-6 host

Bugzilla: 1090978

RH-Acked-by: Dr. David Alan Gilbert (git) <dgilbert@redhat.com>

RH-Acked-by: Marcel Apfelbaum <marcel.a@redhat.com>

RH-Acked-by: Eduardo Habkost <ehabkost@redhat.com>

Bugzilla: https://bugzilla.redhat.com/show_bug.cgi?id=1027565

Brew:     https://brewweb.devel.redhat.com/taskinfo?taskID=7352678

RHEL-only patch.

SeaBIOS's shadowing logic has no effect on "pc.ram" (only on "pc.bios" and

"pc.rom") when it runs on the RHEL-6 emulator. When such a guest is

migrated to the RHEL-7 emulator, where the PAM registers actually work,

these two UMBs under 1MB simply disappear from the guest's view, breaking

reboot and S3 resume.

Tested extensively by QE.

Signed-off-by: Laszlo Ersek <lersek@redhat.com>

---

Notes:

    Changes in v2:

    - print message to stderr when we shadow the UMBs manually [Dave]

    - also copy C and D segments from pc.rom to pc.ram

    - move to qemu_loadvm_state() from ram_load() -- we must shadow only

      when all RAMBlocks have been loaded [Dave]

 include/sysemu/sysemu.h |  1 +

 hw/i386/pc_piix.c       |  1 +

 savevm.c                | 66 +++++++++++++++++++++++++++++++++++++++++++++++++

 3 files changed, 68 insertions(+)

Signed-off-by: Miroslav Rezanina <mrezanin@redhat.com>

---

 hw/i386/pc_piix.c       |    1 +

 include/sysemu/sysemu.h |    1 +

 savevm.c                |   66 +++++++++++++++++++++++++++++++++++++++++++++++

 3 files changed, 68 insertions(+), 0 deletions(-)

diff --git a/hw/i386/pc_piix.c b/hw/i386/pc_piix.c

index 940816f..fea98b6 100644

--- a/hw/i386/pc_piix.c

+++ b/hw/i386/pc_piix.c

@@ -954,6 +954,7 @@ static void pc_compat_rhel650(QEMUMachineInitArgs *args)

     rom_file_has_mr = false; 

     has_acpi_build = false;

     gigabyte_align = false;

+    shadow_bios_after_incoming = true;

 }

 static void pc_init_rhel650(QEMUMachineInitArgs *args)

diff --git a/include/sysemu/sysemu.h b/include/sysemu/sysemu.h

index 8dc0a4c..07181ac 100644

--- a/include/sysemu/sysemu.h

+++ b/include/sysemu/sysemu.h

@@ -84,6 +84,7 @@ void qemu_savevm_state_complete(QEMUFile *f);

 void qemu_savevm_state_cancel(void);

 uint64_t qemu_savevm_state_pending(QEMUFile *f, uint64_t max_size);

 int qemu_loadvm_state(QEMUFile *f);

+extern bool shadow_bios_after_incoming;

 /* SLIRP */

 void do_info_slirp(Monitor *mon);

diff --git a/savevm.c b/savevm.c

index 4d92a7b..6efbb75 100644

--- a/savevm.c

+++ b/savevm.c

@@ -52,6 +52,8 @@

 #define ARP_PTYPE_IP 0x0800

 #define ARP_OP_REQUEST_REV 0x3

+bool shadow_bios_after_incoming;

+

 static int announce_self_create(uint8_t *buf,

 				uint8_t *mac_addr)

 {

@@ -2195,6 +2197,63 @@ typedef struct LoadStateEntry {

     int version_id;

 } LoadStateEntry;

+static void shadow_bios(void)

+{

+    RAMBlock *block, *ram, *oprom, *bios;

+    size_t one_meg, oprom_size, bios_size;

+    uint8_t *cd_seg_host, *ef_seg_host;

+

+    ram = NULL;

+    oprom = NULL;

+    bios = NULL;

+    QTAILQ_FOREACH(block, &ram_list.blocks, next) {

+        if (strcmp("pc.ram", block->idstr) == 0) {

+            assert(ram == NULL);

+            ram = block;

+        } else if (strcmp("pc.rom", block->idstr) == 0) {

+            assert(oprom == NULL);

+            oprom = block;

+        } else if (strcmp("pc.bios", block->idstr) == 0) {

+            assert(bios == NULL);

+            bios = block;

+        }

+    }

+    assert(ram != NULL);

+    assert(oprom != NULL);

+    assert(bios != NULL);

+    assert(memory_region_is_ram(ram->mr));

+    assert(memory_region_is_ram(oprom->mr));

+    assert(memory_region_is_ram(bios->mr));

+    assert(int128_eq(ram->mr->size, int128_make64(ram->length)));

+    assert(int128_eq(oprom->mr->size, int128_make64(oprom->length)));

+    assert(int128_eq(bios->mr->size, int128_make64(bios->length)));

+

+    one_meg = 1024 * 1024;

+    oprom_size = 128 * 1024;

+    bios_size = 128 * 1024;

+    assert(ram->length >= one_meg);

+    assert(oprom->length == oprom_size);

+    assert(bios->length == bios_size);

+

+    ef_seg_host = memory_region_get_ram_ptr(ram->mr) + (one_meg - bios_size);

+    cd_seg_host = ef_seg_host - oprom_size;

+

+    /* This is a crude hack, but we must distinguish a rhel6.x.0 machtype guest

+     * coming in from a RHEL-6 emulator (where shadowing has had no effect on

+     * "pc.ram") from a similar guest coming in from a RHEL-7 emulator (where

+     * shadowing has worked). In the latter case we must not trample the live

+     * SeaBIOS variables in "pc.ram".

+     */

+    if (buffer_is_zero(ef_seg_host, bios_size)) {

+        fprintf(stderr, "copying E and F segments from pc.bios to pc.ram\n");

+        memcpy(ef_seg_host, memory_region_get_ram_ptr(bios->mr), bios_size);

+    }

+    if (buffer_is_zero(cd_seg_host, oprom_size)) {

+        fprintf(stderr, "copying C and D segments from pc.rom to pc.ram\n");

+        memcpy(cd_seg_host, memory_region_get_ram_ptr(oprom->mr), oprom_size);

+    }

+}

+

 int qemu_loadvm_state(QEMUFile *f)

 {

     QLIST_HEAD(, LoadStateEntry) loadvm_handlers =

@@ -2297,6 +2356,13 @@ int qemu_loadvm_state(QEMUFile *f)

         }

     }

+    /* Supplement SeaBIOS's shadowing now, because it was useless when the

+     * incoming VM started on the RHEL-6 emulator.

+     */

+    if (shadow_bios_after_incoming) {

+        shadow_bios();

+    }

+

     cpu_synchronize_all_post_init();

     ret = 0;

-- 

1.7.1