arm_gicv3_kvm: kvm_dist_get/put: skip the registers banked by GICR

While we skip the GIC_INTERNAL irqs, we don't change the register offset
accordingly. This will overlap the GICR registers value and leave the
last GIC_INTERNAL irq's registers out of update.

Fix this by skipping the registers banked by GICR.

Also for migration compatibility if the migration source (old version
qemu) doesn't send gicd_no_migration_shift_bug = 1 to destination, then
we shift the data of PPI to get the right data for SPI.

Fixes: 367b9f527becdd20ddf116e17a3c0c2bbc486920
Cc: qemu-stable@nongnu.org
Reviewed-by: Eric Auger <eric.auger@redhat.com>
Reviewed-by: Peter Maydell <peter.maydell@linaro.org>
Signed-off-by: Shannon Zhao <zhaoshenglong@huawei.com>
Message-id: 1527816987-16108-1-git-send-email-zhaoshenglong@huawei.com
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>

1 files changed, 79 insertions, 0 deletions

diff --git a/hw/intc/arm_gicv3_common.c b/hw/intc/arm_gicv3_common.c
index 7b54d52376..864b7c6515 100644
--- a/hw/intc/arm_gicv3_common.c
+++ b/hw/intc/arm_gicv3_common.c
@@ -27,6 +27,7 @@
 #include "hw/intc/arm_gicv3_common.h"
 #include "gicv3_internal.h"
 #include "hw/arm/linux-boot-if.h"
+#include "sysemu/kvm.h"
 
 static int gicv3_pre_save(void *opaque)
 {
@@ -141,6 +142,79 @@ static const VMStateDescription vmstate_gicv3_cpu = {
     }
 };
 
+static int gicv3_gicd_no_migration_shift_bug_pre_load(void *opaque)
+{
+    GICv3State *cs = opaque;
+
+   /*
+    * The gicd_no_migration_shift_bug flag is used for migration compatibility
+    * for old version QEMU which may have the GICD bmp shift bug under KVM mode.
+    * Strictly, what we want to know is whether the migration source is using
+    * KVM. Since we don't have any way to determine that, we look at whether the
+    * destination is using KVM; this is close enough because for the older QEMU
+    * versions with this bug KVM -> TCG migration didn't work anyway. If the
+    * source is a newer QEMU without this bug it will transmit the migration
+    * subsection which sets the flag to true; otherwise it will remain set to
+    * the value we select here.
+    */
+    if (kvm_enabled()) {
+        cs->gicd_no_migration_shift_bug = false;
+    }
+
+    return 0;
+}
+
+static int gicv3_gicd_no_migration_shift_bug_post_load(void *opaque,
+                                                       int version_id)
+{
+    GICv3State *cs = opaque;
+
+    if (cs->gicd_no_migration_shift_bug) {
+        return 0;
+    }
+
+    /* Older versions of QEMU had a bug in the handling of state save/restore
+     * to the KVM GICv3: they got the offset in the bitmap arrays wrong,
+     * so that instead of the data for external interrupts 32 and up
+     * starting at bit position 32 in the bitmap, it started at bit
+     * position 64. If we're receiving data from a QEMU with that bug,
+     * we must move the data down into the right place.
+     */
+    memmove(cs->group, (uint8_t *)cs->group + GIC_INTERNAL / 8,
+            sizeof(cs->group) - GIC_INTERNAL / 8);
+    memmove(cs->grpmod, (uint8_t *)cs->grpmod + GIC_INTERNAL / 8,
+            sizeof(cs->grpmod) - GIC_INTERNAL / 8);
+    memmove(cs->enabled, (uint8_t *)cs->enabled + GIC_INTERNAL / 8,
+            sizeof(cs->enabled) - GIC_INTERNAL / 8);
+    memmove(cs->pending, (uint8_t *)cs->pending + GIC_INTERNAL / 8,
+            sizeof(cs->pending) - GIC_INTERNAL / 8);
+    memmove(cs->active, (uint8_t *)cs->active + GIC_INTERNAL / 8,
+            sizeof(cs->active) - GIC_INTERNAL / 8);
+    memmove(cs->edge_trigger, (uint8_t *)cs->edge_trigger + GIC_INTERNAL / 8,
+            sizeof(cs->edge_trigger) - GIC_INTERNAL / 8);
+
+    /*
+     * While this new version QEMU doesn't have this kind of bug as we fix it,
+     * so it needs to set the flag to true to indicate that and it's necessary
+     * for next migration to work from this new version QEMU.
+     */
+    cs->gicd_no_migration_shift_bug = true;
+
+    return 0;
+}
+
+const VMStateDescription vmstate_gicv3_gicd_no_migration_shift_bug = {
+    .name = "arm_gicv3/gicd_no_migration_shift_bug",
+    .version_id = 1,
+    .minimum_version_id = 1,
+    .pre_load = gicv3_gicd_no_migration_shift_bug_pre_load,
+    .post_load = gicv3_gicd_no_migration_shift_bug_post_load,
+    .fields = (VMStateField[]) {
+        VMSTATE_BOOL(gicd_no_migration_shift_bug, GICv3State),
+        VMSTATE_END_OF_LIST()
+    }
+};
+
 static const VMStateDescription vmstate_gicv3 = {
     .name = "arm_gicv3",
     .version_id = 1,
@@ -165,6 +239,10 @@ static const VMStateDescription vmstate_gicv3 = {
         VMSTATE_STRUCT_VARRAY_POINTER_UINT32(cpu, GICv3State, num_cpu,
                                              vmstate_gicv3_cpu, GICv3CPUState),
         VMSTATE_END_OF_LIST()
+    },
+    .subsections = (const VMStateDescription * []) {
+        &vmstate_gicv3_gicd_no_migration_shift_bug,
+        NULL
     }
 };
 
@@ -364,6 +442,7 @@ static void arm_gicv3_common_reset(DeviceState *dev)
             gicv3_gicd_group_set(s, i);
         }
     }
+    s->gicd_no_migration_shift_bug = true;
 }
 
 static void arm_gic_common_linux_init(ARMLinuxBootIf *obj,