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From 9f136b4ed4ecd83a2de6ffa52775286b106bb5f5 Mon Sep 17 00:00:00 2001
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From: Laszlo Ersek <lersek@redhat.com>
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Date: Thu, 17 Apr 2014 11:13:59 +0200
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Subject: [PATCH 10/12] qemu_loadvm_state(): shadow SeaBIOS for VM incoming from RHEL-6 host
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RH-Author: Laszlo Ersek <lersek@redhat.com>
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Message-id: <1397733239-8835-1-git-send-email-lersek@redhat.com>
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Patchwork-id: 58498
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O-Subject: [RHEL-7.0 0day qemu-kvm PATCH v2] qemu_loadvm_state(): shadow SeaBIOS for VM incoming from RHEL-6 host
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Bugzilla: 1027565
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RH-Acked-by: Dr. David Alan Gilbert (git) <dgilbert@redhat.com>
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RH-Acked-by: Marcel Apfelbaum <marcel.a@redhat.com>
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RH-Acked-by: Eduardo Habkost <ehabkost@redhat.com>
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Bugzilla: https://bugzilla.redhat.com/show_bug.cgi?id=1027565
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Brew:     https://brewweb.devel.redhat.com/taskinfo?taskID=7352678
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RHEL-only patch.
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SeaBIOS's shadowing logic has no effect on "pc.ram" (only on "pc.bios" and
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"pc.rom") when it runs on the RHEL-6 emulator. When such a guest is
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migrated to the RHEL-7 emulator, where the PAM registers actually work,
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these two UMBs under 1MB simply disappear from the guest's view, breaking
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reboot and S3 resume.
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Tested extensively by QE.
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Signed-off-by: Laszlo Ersek <lersek@redhat.com>
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---
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Notes:
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    Changes in v2:
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    - print message to stderr when we shadow the UMBs manually [Dave]
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    - also copy C and D segments from pc.rom to pc.ram
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    - move to qemu_loadvm_state() from ram_load() -- we must shadow only
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      when all RAMBlocks have been loaded [Dave]
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 include/sysemu/sysemu.h |  1 +
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 hw/i386/pc_piix.c       |  1 +
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 savevm.c                | 66 +++++++++++++++++++++++++++++++++++++++++++++++++
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 3 files changed, 68 insertions(+)
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Signed-off-by: Miroslav Rezanina <mrezanin@redhat.com>
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---
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 hw/i386/pc_piix.c       |    1 +
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 include/sysemu/sysemu.h |    1 +
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 savevm.c                |   66 +++++++++++++++++++++++++++++++++++++++++++++++
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 3 files changed, 68 insertions(+), 0 deletions(-)
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diff --git a/hw/i386/pc_piix.c b/hw/i386/pc_piix.c
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index 940816f..fea98b6 100644
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--- a/hw/i386/pc_piix.c
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+++ b/hw/i386/pc_piix.c
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@@ -954,6 +954,7 @@ static void pc_compat_rhel650(QEMUMachineInitArgs *args)
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     rom_file_has_mr = false; 
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     has_acpi_build = false;
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     gigabyte_align = false;
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+    shadow_bios_after_incoming = true;
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 }
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 static void pc_init_rhel650(QEMUMachineInitArgs *args)
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diff --git a/include/sysemu/sysemu.h b/include/sysemu/sysemu.h
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index 8dc0a4c..07181ac 100644
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--- a/include/sysemu/sysemu.h
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+++ b/include/sysemu/sysemu.h
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@@ -84,6 +84,7 @@ void qemu_savevm_state_complete(QEMUFile *f);
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 void qemu_savevm_state_cancel(void);
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 uint64_t qemu_savevm_state_pending(QEMUFile *f, uint64_t max_size);
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 int qemu_loadvm_state(QEMUFile *f);
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+extern bool shadow_bios_after_incoming;
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 /* SLIRP */
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 void do_info_slirp(Monitor *mon);
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diff --git a/savevm.c b/savevm.c
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index 4d92a7b..6efbb75 100644
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--- a/savevm.c
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+++ b/savevm.c
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@@ -52,6 +52,8 @@
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 #define ARP_PTYPE_IP 0x0800
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 #define ARP_OP_REQUEST_REV 0x3
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+bool shadow_bios_after_incoming;
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+
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 static int announce_self_create(uint8_t *buf,
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 				uint8_t *mac_addr)
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 {
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@@ -2195,6 +2197,63 @@ typedef struct LoadStateEntry {
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     int version_id;
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 } LoadStateEntry;
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+static void shadow_bios(void)
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+{
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+    RAMBlock *block, *ram, *oprom, *bios;
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+    size_t one_meg, oprom_size, bios_size;
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+    uint8_t *cd_seg_host, *ef_seg_host;
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+
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+    ram = NULL;
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+    oprom = NULL;
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+    bios = NULL;
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+    QTAILQ_FOREACH(block, &ram_list.blocks, next) {
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+        if (strcmp("pc.ram", block->idstr) == 0) {
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+            assert(ram == NULL);
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+            ram = block;
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+        } else if (strcmp("pc.rom", block->idstr) == 0) {
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+            assert(oprom == NULL);
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+            oprom = block;
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+        } else if (strcmp("pc.bios", block->idstr) == 0) {
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+            assert(bios == NULL);
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+            bios = block;
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+        }
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+    }
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+    assert(ram != NULL);
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+    assert(oprom != NULL);
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+    assert(bios != NULL);
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+    assert(memory_region_is_ram(ram->mr));
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+    assert(memory_region_is_ram(oprom->mr));
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+    assert(memory_region_is_ram(bios->mr));
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+    assert(int128_eq(ram->mr->size, int128_make64(ram->length)));
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+    assert(int128_eq(oprom->mr->size, int128_make64(oprom->length)));
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+    assert(int128_eq(bios->mr->size, int128_make64(bios->length)));
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+
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+    one_meg = 1024 * 1024;
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+    oprom_size = 128 * 1024;
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+    bios_size = 128 * 1024;
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+    assert(ram->length >= one_meg);
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+    assert(oprom->length == oprom_size);
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+    assert(bios->length == bios_size);
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+
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+    ef_seg_host = memory_region_get_ram_ptr(ram->mr) + (one_meg - bios_size);
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+    cd_seg_host = ef_seg_host - oprom_size;
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+
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+    /* This is a crude hack, but we must distinguish a rhel6.x.0 machtype guest
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+     * coming in from a RHEL-6 emulator (where shadowing has had no effect on
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+     * "pc.ram") from a similar guest coming in from a RHEL-7 emulator (where
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+     * shadowing has worked). In the latter case we must not trample the live
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+     * SeaBIOS variables in "pc.ram".
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+     */
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+    if (buffer_is_zero(ef_seg_host, bios_size)) {
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+        fprintf(stderr, "copying E and F segments from pc.bios to pc.ram\n");
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+        memcpy(ef_seg_host, memory_region_get_ram_ptr(bios->mr), bios_size);
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+    }
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+    if (buffer_is_zero(cd_seg_host, oprom_size)) {
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+        fprintf(stderr, "copying C and D segments from pc.rom to pc.ram\n");
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+        memcpy(cd_seg_host, memory_region_get_ram_ptr(oprom->mr), oprom_size);
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+    }
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+}
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+
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 int qemu_loadvm_state(QEMUFile *f)
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 {
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     QLIST_HEAD(, LoadStateEntry) loadvm_handlers =
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@@ -2297,6 +2356,13 @@ int qemu_loadvm_state(QEMUFile *f)
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         }
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     }
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+    /* Supplement SeaBIOS's shadowing now, because it was useless when the
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+     * incoming VM started on the RHEL-6 emulator.
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+     */
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+    if (shadow_bios_after_incoming) {
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+        shadow_bios();
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+    }
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+
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     cpu_synchronize_all_post_init();
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     ret = 0;
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-- 
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1.7.1
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