Attachment 885838 Details for Bug 1027565 – proposed patch (downstream only)

[patch] proposed patch (downstream only)

0001-ram_load-shadow-SeaBIOS-to-pc.ram-for-VM-incoming-fr.patch (text/plain), 4.01 KB, created by Laszlo Ersek on 2014-04-13 07:48:18 UTC

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Creator: Laszlo Ersek

Created: 2014-04-13 07:48:18 UTC

Size: 4.01 KB

patch

obsolete

>From 1fc9875f87bc748acda55f6f3824f32341c6de3e Mon Sep 17 00:00:00 2001
>From: Laszlo Ersek <lersek@redhat.com>
>Date: Sun, 13 Apr 2014 09:04:49 +0200
>Subject: [RHEL-7.0 qemu-kvm PATCH] ram_load(): shadow SeaBIOS to pc.ram for VM
> incoming from RHEL-6 host
>
>SeaBIOS's shadowing logic has no effect on "pc.ram" (only on "pc.bios)
>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, the BIOS copy
>under 1MB simply disappears from the guest's view, breaking reboot and S3
>resume.
>
>Reading bug 1027565 wholly is strongly recommended.
>
>Signed-off-by: Laszlo Ersek <lersek@redhat.com>
>---
> include/sysemu/arch_init.h |  1 +
> arch_init.c                | 50 ++++++++++++++++++++++++++++++++++++++++++++++
> hw/i386/pc_piix.c          |  1 +
> 3 files changed, 52 insertions(+)
>
>diff --git a/include/sysemu/arch_init.h b/include/sysemu/arch_init.h
>index be71bca..ddfcf73 100644
>--- a/include/sysemu/arch_init.h
>+++ b/include/sysemu/arch_init.h
>@@ -25,6 +25,7 @@ enum {
> };
> 
> extern const uint32_t arch_type;
>+extern bool shadow_bios_after_incoming;
> 
> void select_soundhw(const char *optarg);
> void do_acpitable_option(const QemuOpts *opts);
>diff --git a/arch_init.c b/arch_init.c
>index f5d521a..dbe9fef 100644
>--- a/arch_init.c
>+++ b/arch_init.c
>@@ -106,6 +106,7 @@ int graphic_depth = 15;
> #endif
> 
> const uint32_t arch_type = QEMU_ARCH;
>+bool shadow_bios_after_incoming;
> static bool mig_throttle_on;
> static int dirty_rate_high_cnt;
> static void check_guest_throttling(void);
>@@ -950,6 +951,48 @@ void ram_handle_compressed(void *host, uint8_t ch, uint64_t size)
>     }
> }
> 
>+static void shadow_bios(void)
>+{
>+    RAMBlock *block, *ram, *bios;
>+    size_t one_meg, bios_size;
>+    void *ef_seg_host;
>+
>+    ram = 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.bios", block->idstr) == 0) {
>+            assert(bios == NULL);
>+            bios = block;
>+        }
>+    }
>+    assert(ram != NULL);
>+    assert(bios != NULL);
>+    assert(memory_region_is_ram(ram->mr));
>+    assert(memory_region_is_ram(bios->mr));
>+    assert(int128_eq(ram->mr->size, int128_make64(ram->length)));
>+    assert(int128_eq(bios->mr->size, int128_make64(bios->length)));
>+
>+    one_meg = 1024 * 1024;
>+    bios_size = 128 * 1024;
>+    assert(ram->length >= one_meg);
>+    assert(bios->length == bios_size);
>+
>+    ef_seg_host = memory_region_get_ram_ptr(ram->mr) + (one_meg - bios_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)) {
>+        memcpy(ef_seg_host, memory_region_get_ram_ptr(bios->mr), bios_size);
>+    }
>+}
>+
> static int ram_load(QEMUFile *f, void *opaque, int version_id)
> {
>     ram_addr_t addr;
>@@ -1048,6 +1091,13 @@ static int ram_load(QEMUFile *f, void *opaque, int version_id)
>     } while (!(flags & RAM_SAVE_FLAG_EOS));
> 
> done:
>+    /* Supplement SeaBIOS's shadowing now, because it was useless when the
>+     * incoming VM started on the RHEL-6 emulator.
>+     */
>+    if (ret == 0 && shadow_bios_after_incoming) {
>+        shadow_bios();
>+    }
>+
>     DPRINTF("Completed load of VM with exit code %d seq iteration "
>             "%" PRIu64 "\n", ret, seq_iter);
>     return ret;
>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)
>-- 
>1.8.3.1
>

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Attachments on bug 1027565: 885244 | 885245 | 885252 | 885649 | 885650 | 885795 | 885838 | 886494 | 886593 | 886840 | 886841 | 886964 | 888022 | 888273