Hi all, This series is trying to fix the reported guest magic region alloc issue for 11 Dom0less domUs, an error message can seen from the init-dom0less application on 1:1 direct-mapped Dom0less DomUs: ``` Allocating magic pages memory.c:238:d0v0 mfn 0x39000 doesn't belong to d1 Error on alloc magic pages ```
This is because populate_physmap() automatically assumes gfn == mfn for direct mapped domains. This cannot be true for the magic pages that are allocated later for 1:1 Dom0less DomUs from the init-dom0less helper application executed in Dom0. For domain using statically allocated memory but not 1:1 direct-mapped, similar error "failed to retrieve a reserved page" can be seen as the reserved memory list is empty at that time. In [1] I've tried to fix this issue by the domctl approach, and discussions in [2] and [3] indicates that a domctl is not really necessary, as we can simplify the issue to "allocate the Dom0less guest magic regions at the Dom0less DomU build time and pass the region base PFN to init-dom0less application". The later on discussion [4] reached an agreement that we only need to allocate one single page for XenStore, and set the HVM_PARAM_STORE_PFN from hypervisor with some Linux XenStore late init protocol improvements. Therefore, this series tries to fix the issue based on all discussions. The first patch puts a restriction that static shared memory on direct-mapped DomUs should also be direct mapped, as otherwise it will clash [5]. Patch 2 allocates the XenStore page from Xen and set the initial connection status to RECONNECTED. Patch 3 is the update of the init-dom0less application with all of the changes. Patch 4 is the doc change to reflect the changes introduced by this series. **NOTE**: This series should work with the Linux change [6]. [1] https://lore.kernel.org/xen-devel/20240409045357.236802-1-xin.wa...@amd.com/ [2] https://lore.kernel.org/xen-devel/c7857223-eab8-409a-b618-6ec70f616...@apertussolutions.com/ [3] https://lore.kernel.org/xen-devel/alpine.DEB.2.22.394.2404251508470.3940@ubuntu-linux-20-04-desktop/ [4] https://lore.kernel.org/xen-devel/d33ea00d-890d-45cc-9583-64c953abd...@xen.org/ [5] https://lore.kernel.org/xen-devel/686ba256-f8bf-47e7-872f-d277bf7df...@xen.org/ [6] https://lore.kernel.org/xen-devel/20240517011516.1451087-1-xin.wa...@amd.com/ Henry Wang (4): xen/arm/static-shmem: Static-shmem should be direct-mapped for direct-mapped domains xen/arm: Alloc XenStore page for Dom0less DomUs from hypervisor tools/init-dom0less: Avoid hardcoding GUEST_MAGIC_BASE docs/features/dom0less: Update the late XenStore init protocol docs/features/dom0less.pandoc | 12 +++--- docs/misc/arm/device-tree/booting.txt | 3 ++ tools/helpers/init-dom0less.c | 58 +++++++-------------------- xen/arch/arm/dom0less-build.c | 44 +++++++++++++++++++- xen/arch/arm/static-shmem.c | 6 +++ 5 files changed, 73 insertions(+), 50 deletions(-) -- 2.34.1
