Hi Mathieu,
On 7/8/26 8:42 AM, Mathieu Poirier wrote:
This patchset provides minimal functionality to start a Realm VM
from an Arm RME cabable host using the following command line:
qemu-system-aarch64 -M confidential-guest-support=rme0 -object
rme-guest,id=rme0 \
-cpu host -M virt -enable-kvm -M gic-version=3,its=on -nodefaults ..
This set is a refactoring of Jean-Philippe Brucker's initial work dating from
a while back. It is compatible with Steven Price's v14 revision [1] of his work
adding CCA support to KVM.
The RME capable host it was tested on is the QEMU SBSA machine. For
convenicence
a repository is hosted here [2], along with the TF-A [3], RMM [4] and Linux
kernel [5] for the SBSA machine (all compatible with Steven's v14 patchset).
Device Assignment is not included.
From hereon I will keep this set up to date with new releases from Steven.
Thanks,
Mathieu
[1].
https://lore.kernel.org/kvm/[email protected]/T/#m06dd14216aaf76acab65b0a76fb84653141ea64f
[2]. https://gitlab.com/Linaro/cca-public/qemu/-/tree/upstream-v1?ref_type=heads
[3].
https://gitlab.com/Linaro/cca-public/tf-a/trusted-firmware-a/-/tree/cca/v13?ref_type=heads
[4]. https://gitlab.com/Linaro/cca-public/rmm/-/tree/cca/v14?ref_type=heads
[5]. https://gitlab.com/Linaro/cca-public/linux/-/tree/cca/v14?ref_type=heads
[...]
Gave this series + (v14) series a try and found the following issues so far.
Note
some of the HMP commands like those relevant to migration have been skipped
since
we know the migration isn't supported. I list the issues for record and we
eventually
need to figure them out one by one.
(1) qemu is terminiated on exeute qmp command 'dump-guest-memory'
(qemu) dump-guest-memory -p "/tmp/mem" 0x40000000 0x10000000
**
ERROR:../system/memory_mapping.c:215:guest_phys_block_add_section: assertion failed:
(predecessor->target_end <= target_start)
Bail out! ERROR:../system/memory_mapping.c:215:guest_phys_block_add_section:
assertion failed: (predecessor->target_end <= target_start)
Aborted
(2) qemu emulation can't be stopped and resumed
(qemu) stop
(qemu) cont
Failed to set KVM_REG_ARM_TIMER_CNT
(3) qemu is terminiated on qmp command 'system_reset'
(qemu) system_reset
cpus are not resettable, terminating
(4) Incompatible to virtio-iommu-pci. The realm guest doesn't boot up with
a virtio-iommu-pci device
host$ qemu-system-aarch64 -enable-kvm -object rme-guest,id=rme0 \
-machine virt,gic-version=3,confidential-guest-support=rme0 \
-m 2G -cpu host -smp maxcpus=4,cpus=4,sockets=1,clusters=1,cores=2,threads=2 \
-object memory-backend-ram,id=mem0,size=2G,share=yes \
-numa node,nodeid=0,cpus=0-3,memdev=mem0 \
-serial mon:stdio -monitor none -nographic -nodefaults \
-bios /mnt/edk2/Build/ArmVirtQemu-AARCH64/RELEASE_GCC5/FV/QEMU_EFI.fd \
-kernel /mnt/linux/arch/arm64/boot/Image \
-initrd /mnt/buildroot/output/images/rootfs.cpio.xz \
-append earlycon=pl011,mmio,0x10009000000 \
-device pcie-root-port,bus=pcie.0,chassis=1,id=pcie.1 \
-device pcie-root-port,bus=pcie.0,chassis=2,id=pcie.2 \
-device virtio-iommu-pci,bus=pcie.0 \
-netdev tap,id=tap1,vhost=on,script=/etc/qemu-ifup,downscript=/etc/qemu-ifdown \
-device virtio-net-pci,bus=pcie.2,netdev=tap1,mac=b8:3f:d2:1d:3e:c0
:
UEFI firmware (version built at 00:09:11 on Jun 30 2026)
:
[ 0.000000] Booting Linux on physical CPU 0x0000000000 [0x000f0510]
[ 0.000000] Linux version 7.2.0-rc4-gavin-g1590cf032971
([email protected]) (gcc (GCC) 14.3.1
20251022 (Red Hat 14.3.1-4), GNU ld version 2.41-65.el10) #46 SMP PREEMPT Mon
Jul 20 06:56:20 EDT 2026
[ 0.000000] KASLR enabled
[ 0.000000] earlycon: pl11 at MMIO 0x0000010009000000 (options '')
[ 0.000000] printk: legacy bootconsole [pl11] enabled
[ 0.000000] efi: EFI v2.7 by EDK II
[ 0.000000] efi: SMBIOS 3.0=0xbff60000 ACPI 2.0=0xbdee2018 INITRD=0xbdd94f18
RNG=0xbdee2a18 MEMRESERVE=0xbdd94f98
:
[ 18.374507] virtio-pci 0000:00:03.0: enabling device (0000 -> 0002)
[ 18.594890] Serial: 8250/16550 driver, 4 ports, IRQ sharing enabled
[ 18.651840] Serial: AMBA driver
[ 19.669576] software IO TLB: Memory encryption is active and system is using
DMA bounce buffers
[ 35.021315] Freeing initrd memory: 5772K
[ 40.984997] rcu: INFO: rcu_preempt detected stalls on CPUs/tasks:
[ 41.076752] rcu: 3-...0: (77 ticks this GP)
idle=aed4/1/0x4000000000000000 softirq=83/97 fqs=2365
[ 41.210687] rcu: (detected by 2, t=5307 jiffies, g=-1079, q=352 ncpus=4)
[ 41.311646] Sending NMI from CPU 2 to CPUs 3:
[ 51.631564] After 10 seconds, these CPUS still haven't responded to the NMI:
3
[ 51.739789] rcu: rcu_preempt kthread timer wakeup didn't happen for 2685
jiffies! g-1079 f0x0 RCU_GP_WAIT_FQS(5) ->state=0x402
[ 51.910690] rcu: Possible timer handling issue on cpu=2
timer-softirq=2168
[ 52.014654] rcu: rcu_preempt kthread starved for 2756 jiffies! g-1079 f0x0
RCU_GP_WAIT_FQS(5) ->state=0x402 ->cpu=2
[ 52.169468] rcu: Unless rcu_preempt kthread gets sufficient CPU time,
OOM is now expected behavior.
[ 52.304725] rcu: RCU grace-period kthread stack dump:
[ 52.379337] task:rcu_preempt state:I stack:0 pid:15 tgid:15
ppid:2 task_flags:0x208040 flags:0x00000010
[ 52.542813] Call trace:
[ 52.578516] __switch_to+0xfc/0x248 (T)
[ 52.636293] __schedule+0x3a4/0xe68
[ 52.686511] schedule+0x3c/0xe8
[ 52.731765] schedule_timeout+0x80/0x120
[ 52.788489] rcu_gp_fqs_loop+0x110/0x440
[ 52.846921] rcu_gp_kthread+0x10c/0x120
[ 52.906472] kthread+0x138/0x150
[ 52.955082] ret_from_fork+0x10/0x20
(5) As reported previously, 'reboot' on the realm guest causes the termination
of qemu process.
root@guest:~# reboot
:
The system is going down NOW!
Sent SIGTERM to all processes
Sent SIGKILL to all processes
Requesting system reboot
[ 61.874435] reboot: Restarting system
qemu-system-aarch64: cpus are not resettable, terminating
qemu-system-aarch64: cpus are not resettable, terminating
qemu-system-aarch64: cpus are not resettable, terminating
qemu-system-aarch64: cpus are not resettable, terminating
Thanks,
Gavin
