[Qemu-devel] [PATCH v3] ivshmem: Fix 64 bit memory bar configuration

[Zhuangyanying]

From: Zhuang Yanying <address@hidden>

    Device ivshmem property use64=0 is designed to make the device
    expose a 32 bit shared memory BAR instead of 64 bit one.  The
    default is a 64 bit BAR, except pc-1.2 and older retain a 32 bit
    BAR.  A 32 bit BAR can support only up to 1 GiB of shared memory.

    This worked as designed until commit 5400c02 accidentally flipped
    its sense: since then, we misinterpret use64=0 as use64=1 and vice
    versa.  Worse, the default got flipped as well.  Devices
    ivshmem-plain and ivshmem-doorbell are not affected.

    Fix by restoring the test of IVShmemState member not_legacy_32bit
    that got messed up in commit 5400c02.  Also update its
    initialization for devices ivhsmem-plain and ivshmem-doorbell.
    Without that, they'd regress to 32 bit BARs.

    Cc: address@hidden
    Signed-off-by: Zhuang Yanying <address@hidden>
    Reviewed-by: Gonglei <address@hidden>
    Reviewed-by: Marc-Andr?? Lureau <address@hidden>

---
 hw/misc/ivshmem.c | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/hw/misc/ivshmem.c b/hw/misc/ivshmem.c
index 230e51b..abeaf3d 100644
--- a/hw/misc/ivshmem.c
+++ b/hw/misc/ivshmem.c
@@ -858,7 +858,7 @@ static void ivshmem_common_realize(PCIDevice *dev, Error 
**errp)
     pci_register_bar(dev, 0, PCI_BASE_ADDRESS_SPACE_MEMORY,
                      &s->ivshmem_mmio);
 
-    if (!s->not_legacy_32bit) {
+    if (s->not_legacy_32bit) {
         attr |= PCI_BASE_ADDRESS_MEM_TYPE_64;
     }
 
@@ -1045,6 +1045,7 @@ static void ivshmem_plain_init(Object *obj)
                              ivshmem_check_memdev_is_busy,
                              OBJ_PROP_LINK_UNREF_ON_RELEASE,
                              &error_abort);
+    s->not_legacy_32bit = 1;
 }
 
 static void ivshmem_plain_realize(PCIDevice *dev, Error **errp)
@@ -1116,6 +1117,7 @@ static void ivshmem_doorbell_init(Object *obj)
 
     s->features |= (1 << IVSHMEM_MSI);
     s->legacy_size = SIZE_MAX;  /* whatever the server sends */
+    s->not_legacy_32bit = 1;
 }
 
 static void ivshmem_doorbell_realize(PCIDevice *dev, Error **errp)
-- 
1.8.3.1