On Wed, 26 Mar 2025, Manuel Bouyer wrote:
On Wed, Mar 26, 2025 at 05:24:39PM +0000, Stephen Borrill wrote:On XenServer/XCP-ng VMs can have 'Viridian enlightenments' enabled. This is used by Windows VMs to get some features that would otherwise require Hyper-V, for instance, VM generation counter as used by Active Directory to spot it if is has been rolled back. These shouldn't affect any non-Windows VMs, but NetBSD mistakenly thinks it is running on Hyper-V rather than Xen, so the PVH code is not enabled. I tried the following naive patch: --- sys/arch/x86/x86/identcpu.c 2 Feb 2025 14:51:59 -0000 1.123.4.2 +++ sys/arch/x86/x86/identcpu.c 26 Mar 2025 17:20:44 -0000 @@ -1132,8 +1132,22 @@ vm_guest = VM_GUEST_VMWARE; else if (memcmp(hv_vendor, "Microsoft Hv", 12) == 0) { vm_guest = VM_GUEST_HV; + p = pmf_get_platform("system-vendor"); + if (p != NULL) { + if (strncmp(p, "Xen", 3) == 0) { + /* + * XenServer VMs may have + * Viridian enlightenments + * enabled which may make + * Hyper-V be falsely matched + */ + vm_guest = VM_GUEST_XENHVM; + } + } #if NHYPERV > 0 - hyperv_early_init(); + if (vm_guest == VM_GUEST_HV) { + hyperv_early_init(); + } #endif } else if (memcmp(hv_vendor, "KVMKVMKVM\0\0\0", 12) == 0) vm_guest = VM_GUEST_KVM; It correctly "Identified Guest XEN in HVM mode" instead of Hyper-C, but immediately panicked in xen_hvm_init(). Is there a less naive patch I could try? :-)Can you give more details about the panic ?
[ 1.0000000] NetBSD 10.1_STABLE (GENERIC) #6: Wed Mar 26 17:13:37 GMT 2025 [ 1.0000000] root@builder10:/usr/work/obj/10/amd64/sys/arch/amd64/compile/GENERIC [ 1.0000000] total memory = 1019 MB [ 1.0000000] avail memory = 957 MB [ 1.0000040] efi: systbl at pa 3f5ee018 [ 1.0000040] mainbus0 (root) [ 1.0000040] Identified Guest XEN in HVM mode. [ 1.0000040] fatal protection fault in supervisor mode [ 1.0000040] trap type 4 code 0 rip 0xffffffff802499cd cs 0x8 rflags 0x246 cr2 0 ilevel 0x8 rsp 0xffffffff81d40cf0 [ 1.0000040] curlwp 0xffffffff8188b000 pid 0.0 lowest kstack 0xffffffff81d3b2c0 kernel: protection fault trap, code=0 Stopped in pid 0.0 (system) at netbsd:xen_hvm_init+0xad: wrmsr xen_hvm_init() at netbsd:xen_hvm_init+0xad mainbus_attach() at netbsd:mainbus_attach+0x38 config_attach_internal() at netbsd:config_attach_internal+0x214 config_rootfound() at netbsd:config_rootfound+0x6e cpu_configure() at netbsd:cpu_configure+0x38 main() at netbsd:main+0x2f1 ds 8 es cb0 fs cf0 gs 8 rdi 8 rsi 3f8 rbp ffffffff81d40d40 rbx 60000 rdx 0 rcx 60000 rax 20f000 r8 0 r9 7 r10 ffffd91b555ced58 r11 fffffff8 r12 0 r13 fc r14 0 r15 ffffffff818a7f60 cfdata+0x6de0 rip ffffffff802499cd xen_hvm_init+0xad cs 8 rflags 246 rsp ffffff81d3fcf0 ss 10 netbsd@xen_hvm_init+0xad: wrmsrFor record, I got this by running the following in the dom0 to output the serial console to a file:
xenstore-write /local/logconsole/@ /tmp/console.%d.logBecause of the --db_more-- prompt and the console being output-only, I had to hand-copy from r12 onwards from a second boot with the VGA ocnsole. With the serial console, I tried to send input into its console tty, but it didn't help:
# xenstore-read /local/domain/60/console/tty /dev/pts/25 # echo " " >> /dev/pts/25 -- Stephen