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On Sat, Jan 06, 2018 at 03:20:36PM -0000, 'awokd' via qubes-devel wrote:
> Trying to debug an HVM PCI pass-through crash coming from:
>
> https://xenbits.xen.org/gitweb/?p=xen.git;a=blob;f=xen/arch/x86/hvm/svm/svm.c;h=8edc846a2ed4aec6a5711d272adbb10aaa741c27;hb=5e4598106ed02ae4b43abcb29889969eb12867b7
> 1536 /* Everything else is an error. */
> 1537 mfn = __get_gfn_type_access(p2m, gfn, &p2mt, &p2ma, 0, NULL, 0);
> 1538 gdprintk(XENLOG_ERR,
> 1539 "SVM violation gpa %#"PRIpaddr", mfn %#lx, type %i\n",
> 1540 gpa, mfn_x(mfn), p2mt);
> 1541 domain_crash(v->domain);
>
> Which results in:
>
> (XEN) domain_crash called from svm.c:1541
> (XEN) Domain 10 (vcpu#0) crashed on cpu#2:
> (XEN) ------[ Xen-4.8.2 x86_64 debug=n Not tainted ]------
> (XEN) CPU: 2
> (XEN) RIP: 0010:[<ffffffff97405f4e>]
> (XEN) RFLAGS: 0000000000000296 CONTEXT: hvm guest (d10v0)
> (XEN) rax: 0000000000000000 rbx: ffff97c946eb95c0 rcx: 0000000000000005
> (XEN) rdx: 0000000000000040 rsi: ffffaf5580700040 rdi: 0000000000000000
> (XEN) rbp: ffffaf55806cb8f8 rsp: ffffaf55806cb8c8 r8: 0000000000000000
> (XEN) r9: 00000000ffffff90 r10: 000000000000003f r11: 0000000000000000
> (XEN) r12: 0000000000000000 r13: ffffffffc04fb7d0 r14: 0000000000000100
> (XEN) r15: ffff97c946eb4028 cr0: 0000000080050033 cr4: 00000000000406f0
> (XEN) cr3: 0000000012e30000 cr2: 0000000000000000
> (XEN) ds: 0000 es: 0000 fs: 0000 gs: 0000 ss: 0018 cs: 0010
>
> Here's where I get lost. Can't find the output from that gdprintk
> anywhere, with both loglvl=all and guest_loglvl=all. I think I want to
> either change it to a printk and/or enable Xen debugging, which means a
> recompile.
Yes, gdprintk is noop in non-debug build.
> What is the most newbish/straight-forward way to do that? Looks
> like Qubes-builder compiles Xen in
> chroot-fc25/home/user/rpmbuild/BUILD/xen-4.8.2. I can find and edit svm.c,
> but can't figure out where I should enable Xen debugging and what to do
> next.
You need to chroot into chroot-fc25 and switch to 'user' to compile it.
There you have all build dependencies installed. You can enable debug
using menuconfig. So, the easiest way to get Xen debug build is:
sudo chroot chroot-fc25 su -c 'make -C rpmbuild/BUILD/xen-4.8.2/xen
menuconfig' - user
sudo chroot chroot-fc25 su -c 'make -C rpmbuild/BUILD/xen-4.8.2/xen' - user
Then get compiled Xen binary from
chroot-fc25/home/user/rpmbuild/BUILD/xen-4.8.2/xen/xen.{gz,efi}
- --
Best Regards,
Marek Marczykowski-Górecki
Invisible Things Lab
A: Because it messes up the order in which people normally read text.
Q: Why is top-posting such a bad thing?
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