Re: [Xen-devel] Re: [PATCH] Xen Guest Kexec

[Gerd Hoffmann <kraxel@xxxxxxx>]

> The default segment descriptors are *always* available. A guest can only
> install up to a 14-page GDT: the 15th and 16th pages are reserved by Xen
> and always present.

Ok, managed to fixup that, switching to the default descriptors and
killing the GDT works, so the gdt doesn't stop validating any more.

But I ran into the next bug now.  I think we have a funny
chicken-and-egg problem when validating a self-consistent but new page
table set (which also maps itself) from scratch, see messages attached
below.

cheers,
  Gerd

-- 
Gerd 'just married' Hoffmann <kraxel@xxxxxxx>
I'm the hacker formerly known as Gerd Knorr.
http://www.suse.de/~kraxel/just-married.jpeg

(XEN) DOM1: (file=mm.c, line=1501) Bad type (saw 33020001 != exp e0000000) for 
mfn 1c711 (pfn 0)
(XEN) DOM1: (file=mm.c, line=479) Error getting mfn 1c711 (pfn 0) from L1 entry 
1c711063 for dom1
(XEN) DOM1: (file=mm.c, line=685) Failure in alloc_l1_table: entry 0
(XEN) DOM1: (file=mm.c, line=1542) Error while validating mfn 18c92 (pfn 35a8) 
for type 20000000: caf=80000003 taf=20000001
(XEN) DOM1: (file=mm.c, line=402) Attempt to create linear p.t. with write perms
(XEN) DOM1: (file=mm.c, line=846) Failure in alloc_l2_table: entry 0
(XEN) DOM1: (file=mm.c, line=1542) Error while validating mfn 18c95 (pfn 35a5) 
for type 40000000: caf=80000003 taf=40000001
(XEN) DOM1: (file=mm.c, line=1579) trying slow path via idle pagetables ...
(XEN) DOM1: (file=mm.c, line=1501) Bad type (saw 40000001 != exp e0000000) for 
mfn 18c95 (pfn 35a5)
(XEN) DOM1: (file=mm.c, line=479) Error getting mfn 18c95 (pfn 35a5) from L1 
entry 18c95063 for dom1
(XEN) DOM1: (file=mm.c, line=685) Failure in alloc_l1_table: entry 421
(XEN) DOM1: (file=mm.c, line=1542) Error while validating mfn 18c85 (pfn 35b5) 
for type 200d0000: caf=80000002 taf=200d0001
(XEN) DOM1: (file=mm.c, line=402) Attempt to create linear p.t. with write perms
(XEN) DOM1: (file=mm.c, line=846) Failure in alloc_l2_table: entry 13
(XEN) DOM1: (file=mm.c, line=1542) Error while validating mfn 18c95 (pfn 35a5) 
for type 40000000: caf=80000002 taf=40000001
(XEN) DOM1: (file=mm.c, line=1593) Fatal error while installing new baseptr 
18c95
(XEN) domain_crash called from mm.c:1594
(XEN) Domain 1 (vcpu#0) crashed on cpu#1:
(XEN) ----[ Xen-3.0.0    Not tainted ]----
(XEN) CPU:    1
(XEN) EIP:    e019:[<c010ed3d>]
(XEN) EFLAGS: 00010206   CONTEXT: guest
(XEN) eax: c0012000   ebx: 00000000   ecx: fbf8d000   edx: 18c95000
(XEN) esi: 035a4000   edi: c0732400   ebp: c3e57e88   esp: c3e57e60
(XEN) cr0: 8005003b   cr3: 001b6000
(XEN) ds: e021   es: e021   fs: e021   gs: e021   ss: e021   cs: e019
(XEN) Guest stack trace from esp=c3e57e60:
(XEN)    Fault while accessing guest memory.

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