Hi everyone:

In order to support QXL display during the UEFI phase of the arm64 virtual machine, the modified code is as follows (based on master branch, commit id:17143c4837393d42c484b42d1789b85b2cff1aaf):

diff --git a/ArmVirtPkg/ArmVirtQemu.dsc b/ArmVirtPkg/ArmVirtQemu.dsc
index 7ef5e7297b..d73cf6aba0 100644
--- a/ArmVirtPkg/ArmVirtQemu.dsc
+++ b/ArmVirtPkg/ArmVirtQemu.dsc
@@ -501,6 +501,7 @@
   OvmfPkg/QemuRamfbDxe/QemuRamfbDxe.inf
   OvmfPkg/VirtioGpuDxe/VirtioGpu.inf
   OvmfPkg/PlatformDxe/Platform.inf
+  OvmfPkg/QemuVideoDxe/QemuVideoDxe.inf
 
   #
   # USB Support
diff --git a/ArmVirtPkg/ArmVirtQemu.fdf b/ArmVirtPkg/ArmVirtQemu.fdf
index b5e2253295..289d0c580b 100644
--- a/ArmVirtPkg/ArmVirtQemu.fdf
+++ b/ArmVirtPkg/ArmVirtQemu.fdf
@@ -126,3 +126,8 @@ READ_LOCK_STATUS   = TRUE
   }
 
 !include ArmVirtRules.fdf.inc
+
+#
+# VGA Module
+#
+# INF OvmfPkg/QemuVideoDxe/QemuVideoDxe.inf

Compiled it and generate QEMU_EFI.fd, Create virtual machines by qemu, as follows:

./qemu-6.0.0/build/qemu-system-aarch64 \
-machine virt,accel=kvm,usb=off,dump-guest-core=off,gic-version=3 \
-cpu host \
-m 8192 \
-smp 16 \
-bios QEMU_EFI.fd \
-vnc 127.0.0.1:19 \
-device pcie-root-port,port=0x8,chassis=1,id=pci.1,bus=pcie.0,multifunction=on,addr=0x1 \
-device pcie-root-port,port=0x9,chassis=2,id=pci.2,bus=pcie.0,addr=0x1.0x1 \
-device pcie-root-port,port=0xa,chassis=3,id=pci.3,bus=pcie.0,addr=0x1.0x2 \
-device pcie-root-port,port=0xb,chassis=4,id=pci.4,bus=pcie.0,addr=0x1.0x3 \
-device pcie-root-port,port=0xc,chassis=5,id=pci.5,bus=pcie.0,addr=0x1.0x4 \
-device pcie-root-port,port=0xd,chassis=6,id=pci.6,bus=pcie.0,addr=0x1.0x5 \
-device pcie-root-port,port=0xe,chassis=7,id=pci.7,bus=pcie.0,addr=0x1.0x6 \
-device pcie-root-port,port=0xf,chassis=8,id=pci.8,bus=pcie.0,addr=0x1.0x7 \
-device pcie-pci-bridge,id=pci.9,bus=pci.6,addr=0x0 \
-netdev user,id=hostnet0 \
-device virtio-net-pci,id=hostnet0,mac=52:54:00:14:72:20,bus=pci.1,addr=0x0 \
-drive file=/var/lib/libvirt/images/tlj-kylin.qcow2,format=qcow2,if=none,id=drive-virtio-disk0 \
-device virtio-blk-pci,scsi=off,bus=pcie.0,addr=0x6,drive=drive-virtio-disk0,id=virtio-disk0,bootindex=1 \
-device qxl-vga,id=video0,bus=pci.7,addr=0x0

The test results are as follows:
1. When the QXL device hangs on the bus=pci.9, addr=0x1 or bus=pci.7, addr=0x0, there is no display during the UEFI phase, and the following error is found by debug UEFI firmware log:
  QemuVideo: BochsID mismatch (got 0x0). From the OgmfPkg/QemuVideoDxe/Driver .c
2. When the qxl device hangs in the bus=pci.8, addr=0x0, it can be displayed normally during the UEFI phase. BochsID=0xb0c5

The way to read BochsID is PIO, and ARM does not support PIO commands, should it be changed to MMIO? Or others?
Hope to receive your suggestions or comments. Thank you!

Best regards