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From 4fb30d2478b2d030262bcd1699a683973e481cfd Mon Sep 17 00:00:00 2001
Message-Id: <4fb30d2478b2d030262bcd1699a683973e481cfd.1387298827.git.minovotn@redhat.com>
In-Reply-To: <3ed0fb61a3dc912ef036d7ef450bed192090709e.1387298827.git.minovotn@redhat.com>
References: <3ed0fb61a3dc912ef036d7ef450bed192090709e.1387298827.git.minovotn@redhat.com>
From: "Michael S. Tsirkin" <mst@redhat.com>
Date: Tue, 17 Dec 2013 15:17:19 +0100
Subject: [PATCH 12/56] loader: store FW CFG ROM files in RAM

RH-Author: Michael S. Tsirkin <mst@redhat.com>
Message-id: <1387293161-4085-13-git-send-email-mst@redhat.com>
Patchwork-id: 56317
O-Subject: [PATCH qemu-kvm RHEL7.0 v2 12/57] loader: store FW CFG ROM files in RAM
Bugzilla: 1034876
RH-Acked-by: Igor Mammedov <imammedo@redhat.com>
RH-Acked-by: Marcel Apfelbaum <marcel.a@redhat.com>
RH-Acked-by: Laszlo Ersek <lersek@redhat.com>

ROM files that are put in FW CFG are copied to guest ram, by BIOS, but
they are not backed by RAM so they don't get migrated.

Each time we change two bytes in such a ROM this breaks cross-version
migration: since we can migrate after BIOS has read the first byte but
before it has read the second one, getting an inconsistent state.

Future-proof this by creating, for each such ROM,
an MR serving as the backing store.
This MR is never mapped into guest memory, but it's registered
as RAM so it's migrated with the guest.

Naturally, this only helps for -M 1.7 and up, older machine types
will still have the cross-version migration bug.
Luckily the race window for the problem to trigger is very small,
which is also likely why we didn't notice the cross-version
migration bug in testing yet.

Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
Reviewed-by: Laszlo Ersek <lersek@redhat.com>
(cherry picked from commit 04920fc0faa4760f9c4fc0e73b992b768099be70)

Conflicts:
	hw/i386/pc_piix.c
	hw/i386/pc_q35.c
---
 include/hw/loader.h |  1 +
 hw/core/loader.c    | 49 ++++++++++++++++++++++++++++++++++++++++++++++---
 hw/i386/pc_piix.c   |  2 ++
 hw/i386/pc_q35.c    |  1 +
 4 files changed, 50 insertions(+), 3 deletions(-)

Signed-off-by: Michal Novotny <minovotn@redhat.com>
---
 hw/core/loader.c    | 49 ++++++++++++++++++++++++++++++++++++++++++++++---
 hw/i386/pc_piix.c   |  2 ++
 hw/i386/pc_q35.c    |  1 +
 include/hw/loader.h |  1 +
 4 files changed, 50 insertions(+), 3 deletions(-)

diff --git a/hw/core/loader.c b/hw/core/loader.c
index 7d61537..6bdbd15 100644
--- a/hw/core/loader.c
+++ b/hw/core/loader.c
@@ -54,6 +54,8 @@
 
 #include <zlib.h>
 
+bool rom_file_in_ram = true;
+
 static int roms_loaded;
 
 /* return the size or -1 if error */
@@ -542,6 +544,7 @@ struct Rom {
     size_t datasize;
 
     uint8_t *data;
+    MemoryRegion *mr;
     int isrom;
     char *fw_dir;
     char *fw_file;
@@ -571,6 +574,21 @@ static void rom_insert(Rom *rom)
     QTAILQ_INSERT_TAIL(&roms, rom, next);
 }
 
+static void *rom_set_mr(Rom *rom, const char *name)
+{
+    void *data;
+
+    rom->mr = g_malloc(sizeof(*rom->mr));
+    memory_region_init_ram(rom->mr, name, rom->datasize);
+    memory_region_set_readonly(rom->mr, true);
+    vmstate_register_ram_global(rom->mr);
+
+    data = memory_region_get_ram_ptr(rom->mr);
+    memcpy(data, rom->data, rom->datasize);
+
+    return data;
+}
+
 int rom_add_file(const char *file, const char *fw_dir,
                  hwaddr addr, int32_t bootindex)
 {
@@ -612,6 +630,7 @@ int rom_add_file(const char *file, const char *fw_dir,
     if (rom->fw_file && fw_cfg) {
         const char *basename;
         char fw_file_name[56];
+        void *data;
 
         basename = strrchr(rom->fw_file, '/');
         if (basename) {
@@ -621,8 +640,15 @@ int rom_add_file(const char *file, const char *fw_dir,
         }
         snprintf(fw_file_name, sizeof(fw_file_name), "%s/%s", rom->fw_dir,
                  basename);
-        fw_cfg_add_file(fw_cfg, fw_file_name, rom->data, rom->romsize);
         snprintf(devpath, sizeof(devpath), "/rom@%s", fw_file_name);
+
+        if (rom_file_in_ram) {
+            data = rom_set_mr(rom, devpath);
+        } else {
+            data = rom->data;
+        }
+
+        fw_cfg_add_file(fw_cfg, fw_file_name, data, rom->romsize);
     } else {
         snprintf(devpath, sizeof(devpath), "/rom@" TARGET_FMT_plx, addr);
     }
@@ -697,7 +723,12 @@ static void rom_reset(void *unused)
         if (rom->data == NULL) {
             continue;
         }
-        cpu_physical_memory_write_rom(rom->addr, rom->data, rom->datasize);
+        if (rom->mr) {
+            void *host = memory_region_get_ram_ptr(rom->mr);
+            memcpy(host, rom->data, rom->datasize);
+        } else {
+            cpu_physical_memory_write_rom(rom->addr, rom->data, rom->datasize);
+        }
         if (rom->isrom) {
             /* rom needs to be written only once */
             g_free(rom->data);
@@ -746,6 +777,9 @@ static Rom *find_rom(hwaddr addr)
         if (rom->fw_file) {
             continue;
         }
+        if (rom->mr) {
+            continue;
+        }
         if (rom->addr > addr) {
             continue;
         }
@@ -773,6 +807,9 @@ int rom_copy(uint8_t *dest, hwaddr addr, size_t size)
         if (rom->fw_file) {
             continue;
         }
+        if (rom->mr) {
+            continue;
+        }
         if (rom->addr + rom->romsize < addr) {
             continue;
         }
@@ -831,7 +868,13 @@ void do_info_roms(Monitor *mon, const QDict *qdict)
     Rom *rom;
 
     QTAILQ_FOREACH(rom, &roms, next) {
-        if (!rom->fw_file) {
+        if (rom->mr) {
+            monitor_printf(mon, "%s"
+                           " size=0x%06zx name=\"%s\"\n",
+                           rom->mr->name,
+                           rom->romsize,
+                           rom->name);
+        } else if (!rom->fw_file) {
             monitor_printf(mon, "addr=" TARGET_FMT_plx
                            " size=0x%06zx mem=%s name=\"%s\"\n",
                            rom->addr, rom->romsize,
diff --git a/hw/i386/pc_piix.c b/hw/i386/pc_piix.c
index b6f9288..07848c1 100644
--- a/hw/i386/pc_piix.c
+++ b/hw/i386/pc_piix.c
@@ -25,6 +25,7 @@
 #include <glib.h>
 
 #include "hw/hw.h"
+#include "hw/loader.h"
 #include "hw/i386/pc.h"
 #include "hw/i386/apic.h"
 #include "hw/i386/smbios.h"
@@ -883,6 +884,7 @@ static void pc_init_rhel650(QEMUMachineInitArgs *args)
     x86_cpu_compat_set_features("Opteron_G3", FEAT_8000_0001_EDX,
                                 0, CPUID_EXT2_RDTSCP);
 
+    rom_file_in_ram = false; 
     pc_init_rhel700(args);
 }
 
diff --git a/hw/i386/pc_q35.c b/hw/i386/pc_q35.c
index f308098..8fa6793 100644
--- a/hw/i386/pc_q35.c
+++ b/hw/i386/pc_q35.c
@@ -28,6 +28,7 @@
  * THE SOFTWARE.
  */
 #include "hw/hw.h"
+#include "hw/loader.h"
 #include "sysemu/arch_init.h"
 #include "hw/i2c/smbus.h"
 #include "hw/boards.h"
diff --git a/include/hw/loader.h b/include/hw/loader.h
index 15d4cc9..19e11ea 100644
--- a/include/hw/loader.h
+++ b/include/hw/loader.h
@@ -23,6 +23,7 @@ void pstrcpy_targphys(const char *name,
                       hwaddr dest, int buf_size,
                       const char *source);
 
+extern bool rom_file_in_ram;
 
 int rom_add_file(const char *file, const char *fw_dir,
                  hwaddr addr, int32_t bootindex);
-- 
1.7.11.7