qemu-kvm/kvm-acpi-fix-acpi_index-migration.patch

From 3deffc03c2e9b0053eec5aeb5b5d633dfe29f499 Mon Sep 17 00:00:00 2001
From: "Dr. David Alan Gilbert" <dgilbert@redhat.com>
Date: Wed, 6 Apr 2022 14:58:12 -0400
Subject: [PATCH 1/3] acpi: fix acpi_index migration
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RH-Author: Peter Xu <peterx@redhat.com>
RH-MergeRequest: 343: acpi: fix acpi_index migration
RH-Jira: RHEL-20189
RH-Acked-by: Leonardo Brás <leobras@redhat.com>
RH-Acked-by: Igor Mammedov <imammedo@redhat.com>
RH-Acked-by: Prasad Pandit <None>
RH-Commit: [1/2] c5b9cdf5791cd856207b7df7e2ef5df360ec8de4

vmstate_acpi_pcihp_use_acpi_index() was expecting AcpiPciHpState
as state but it actually received PIIX4PMState, because
VMSTATE_PCI_HOTPLUG is a macro and not another struct.
So it ended up accessing random pointer, which resulted
in 'false' return value and acpi_index field wasn't ever
sent.

However in 7.0 that pointer de-references to value > 0, and
destination QEMU starts to expect the field which isn't
sent in migratioon stream from older QEMU (6.2 and older).
As result migration fails with:
  qemu-system-x86_64: Missing section footer for 0000:00:01.3/piix4_pm
  qemu-system-x86_64: load of migration failed: Invalid argument

In addition with QEMU-6.2, destination due to not expected
state, also never expects the acpi_index field in migration
stream.

Q35 is not affected as it always sends/expects the field as
long as acpi based PCI hotplug is enabled.

Fix issue by introducing compat knob to never send/expect
acpi_index in migration stream for 6.2 and older PC machine
types and always send it for 7.0 and newer PC machine types.

Diagnosed-by: Dr. David Alan Gilbert <dgilbert@redhat.com>
Fixes: b32bd76 ("pci: introduce acpi-index property for PCI device")
Resolves: https://gitlab.com/qemu-project/qemu/-/issues/932
Signed-off-by: Igor Mammedov <imammedo@redhat.com>
Reviewed-by: Dr. David Alan Gilbert <dgilbert@redhat.com>
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
(cherry picked from commit a83c2844903c45aa7d32cdd17305f23ce2c56ab9)
Signed-off-by: Peter Xu <peterx@redhat.com>
---
 hw/acpi/acpi-pci-hotplug-stub.c |  4 ----
 hw/acpi/pcihp.c                 |  6 ------
 hw/acpi/piix4.c                 | 15 ++++++++++++++-
 hw/core/machine.c               |  5 +++++
 include/hw/acpi/pcihp.h         |  2 --
 5 files changed, 19 insertions(+), 13 deletions(-)

diff --git a/hw/acpi/acpi-pci-hotplug-stub.c b/hw/acpi/acpi-pci-hotplug-stub.c
index 734e4c5986..a43f6dafc9 100644
--- a/hw/acpi/acpi-pci-hotplug-stub.c
+++ b/hw/acpi/acpi-pci-hotplug-stub.c
@@ -41,7 +41,3 @@ void acpi_pcihp_reset(AcpiPciHpState *s, bool acpihp_root_off)
     return;
 }
 
-bool vmstate_acpi_pcihp_use_acpi_index(void *opaque, int version_id)
-{
-    return false;
-}
diff --git a/hw/acpi/pcihp.c b/hw/acpi/pcihp.c
index be0e846b34..ec861661c3 100644
--- a/hw/acpi/pcihp.c
+++ b/hw/acpi/pcihp.c
@@ -559,12 +559,6 @@ void acpi_pcihp_init(Object *owner, AcpiPciHpState *s, PCIBus *root_bus,
                                    OBJ_PROP_FLAG_READ);
 }
 
-bool vmstate_acpi_pcihp_use_acpi_index(void *opaque, int version_id)
-{
-     AcpiPciHpState *s = opaque;
-     return s->acpi_index;
-}
-
 const VMStateDescription vmstate_acpi_pcihp_pci_status = {
     .name = "acpi_pcihp_pci_status",
     .version_id = 1,
diff --git a/hw/acpi/piix4.c b/hw/acpi/piix4.c
index 8d6011c0a3..033e75ce5b 100644
--- a/hw/acpi/piix4.c
+++ b/hw/acpi/piix4.c
@@ -82,6 +82,7 @@ struct PIIX4PMState {
     AcpiPciHpState acpi_pci_hotplug;
     bool use_acpi_hotplug_bridge;
     bool use_acpi_root_pci_hotplug;
+    bool not_migrate_acpi_index;
 
     uint8_t disable_s3;
     uint8_t disable_s4;
@@ -269,6 +270,16 @@ static bool piix4_vmstate_need_smbus(void *opaque, int version_id)
     return pm_smbus_vmstate_needed();
 }
 
+/*
+ * This is a fudge to turn off the acpi_index field,
+ * whose test was always broken on piix4 with 6.2 and older machine types.
+ */
+static bool vmstate_test_migrate_acpi_index(void *opaque, int version_id)
+{
+    PIIX4PMState *s = PIIX4_PM(opaque);
+    return s->use_acpi_hotplug_bridge && !s->not_migrate_acpi_index;
+}
+
 /* qemu-kvm 1.2 uses version 3 but advertised as 2
  * To support incoming qemu-kvm 1.2 migration, change version_id
  * and minimum_version_id to 2 below (which breaks migration from
@@ -299,7 +310,7 @@ static const VMStateDescription vmstate_acpi = {
             struct AcpiPciHpPciStatus),
         VMSTATE_PCI_HOTPLUG(acpi_pci_hotplug, PIIX4PMState,
                             vmstate_test_use_acpi_hotplug_bridge,
-                            vmstate_acpi_pcihp_use_acpi_index),
+                            vmstate_test_migrate_acpi_index),
         VMSTATE_END_OF_LIST()
     },
     .subsections = (const VMStateDescription*[]) {
@@ -654,6 +665,8 @@ static Property piix4_pm_properties[] = {
     DEFINE_PROP_BOOL("memory-hotplug-support", PIIX4PMState,
                      acpi_memory_hotplug.is_enabled, true),
     DEFINE_PROP_BOOL("smm-compat", PIIX4PMState, smm_compat, false),
+    DEFINE_PROP_BOOL("x-not-migrate-acpi-index", PIIX4PMState,
+                      not_migrate_acpi_index, false),
     DEFINE_PROP_END_OF_LIST(),
 };
 
diff --git a/hw/core/machine.c b/hw/core/machine.c
index 76fcabec7a..2724f6848a 100644
--- a/hw/core/machine.c
+++ b/hw/core/machine.c
@@ -331,6 +331,11 @@ GlobalProperty hw_compat_rhel_7_1[] = {
 };
 const size_t hw_compat_rhel_7_1_len = G_N_ELEMENTS(hw_compat_rhel_7_1);
 
+GlobalProperty hw_compat_6_2[] = {
+    { "PIIX4_PM", "x-not-migrate-acpi-index", "on"},
+};
+const size_t hw_compat_6_2_len = G_N_ELEMENTS(hw_compat_6_2);
+
 GlobalProperty hw_compat_6_1[] = {
     { "vhost-user-vsock-device", "seqpacket", "off" },
     { "nvme-ns", "shared", "off" },
diff --git a/include/hw/acpi/pcihp.h b/include/hw/acpi/pcihp.h
index af1a169fc3..7e268c2c9c 100644
--- a/include/hw/acpi/pcihp.h
+++ b/include/hw/acpi/pcihp.h
@@ -73,8 +73,6 @@ void acpi_pcihp_reset(AcpiPciHpState *s, bool acpihp_root_off);
 
 extern const VMStateDescription vmstate_acpi_pcihp_pci_status;
 
-bool vmstate_acpi_pcihp_use_acpi_index(void *opaque, int version_id);
-
 #define VMSTATE_PCI_HOTPLUG(pcihp, state, test_pcihp, test_acpi_index) \
         VMSTATE_UINT32_TEST(pcihp.hotplug_select, state, \
                             test_pcihp), \
-- 
2.41.0