Re: xenpaging crashes xen in is_iomem_page()

[Patrick Colp <pjcolp@cs.ubc.ca>]

I've not seen this error before. Does your computer have EPT support?
What's the patch at the end? Is that a fix or a recent change that you
think might be causing the problem?


Patrick


On 26 July 2010 07:58, Olaf Hering <olaf@aepfle.de> wrote:
>
> Is xenpaging supposed to work?
> For me its crashing on a 4x3.6GHz Xeon, 4G system running SLES11 SP1.
>
> There is one guest running.
> A simple minded test of xenpaging crashes the host with xen 4.0 and
> xen-unstable the same way:
>
>  # xenpaging 1 1
> xc: error: Error flushing ioemu cache: Internal error
> (XEN) mm.c:768:d0 mfn 431f page ffff82f6000863e0 ci 0180000000000000/0000000000000000 32
> (XEN) mm.c:769:d0 ffff82f6000863e0: 0000000000000000 0180000000000000 0000000000000000 0000000000000000
> (XEN) Assertion '(page->count_info & ((1UL<<(64 - (9)))-1)) != 0' failed at mm.c:772
> (XEN) Debugging connection not set up.
> (XEN) ----[ Xen-4.1.21836-20100726.111138  x86_64  debug=y  Not tainted ]----
> (XEN) CPU:    3
> (XEN) RIP:    e008:[<ffff82c480161d92>] is_iomem_page+0x11e/0x16c
> (XEN) RFLAGS: 0000000000010246   CONTEXT: hypervisor
> (XEN) rax: 007fffffffffffff   rbx: ffffffffffffffff   rcx: 00000000c8c7d8ae
> (XEN) rdx: 00000000000000d5   rsi: 000000000036cb58   rdi: 00000000000003e8
> (XEN) rbp: ffff83012fecfbd8   rsp: ffff83012fecfb98   r8:  0000000000000003
> (XEN) r9:  0000000000000004   r10: 0000000000000004   r11: 0000000000000001
> (XEN) r12: 0000000000000000   r13: 0180000000000000   r14: 0000000000000000
> (XEN) r15: ffff82f6000863e0   cr0: 0000000080050033   cr4: 00000000000006f0
> (XEN) cr3: 0000000127c2e000   cr2: 00007f2aeea5d270
> (XEN) ds: 0000   es: 0000   fs: 0000   gs: 0000   ss: e010   cs: e008
> (XEN) Xen stack trace from rsp=ffff83012fecfb98:
> (XEN)    0180000000000000 0000000000000000 0000000000000000 ffff8301192c0000
> (XEN)    000000000000431f ffff8301192c0000 000000000000431f 000000000060c000
> (XEN)    ffff83012fecfc18 ffff82c4801ca912 0000000000000000 0000000100000000
> (XEN)    ffff8301192c0000 000000000060c000 ffff8800cd749e58 0000000000000000
> (XEN)    ffff83012fecfc28 ffff82c4801cee3d ffff83012fecfc78 ffff82c4801ceddd
> (XEN)    000000000010e540 7400000000000002 ffff82f6021ca810 fffffffffffffff3
> (XEN)    000000000060c000 ffff8800cd749e58 0000000000000000 000000000060c000
> (XEN)    ffff83012fecfda8 ffff82c48014fc53 ffff83012fecff18 4c00000000000002
> (XEN)    ffff82f6024f85d0 000000002ffe4c60 4000000000000000 ffff82f602510fa0
> (XEN)    000000000012887d 0000000000000067 ffff83012fea0000 ffff83012fea0000
> (XEN)    000000000010e540 ffff83012fecfe38 ffff83012fecfcf8 ffff82c480167c59
> (XEN)    ffff83012fecfd88 ffff82c480167e96 ffff83012fecfd48 000000000012887d
> (XEN)    0000000000000000 0000000000000000 ffff83012fecfd58 0000000000249b00
> (XEN)    00000000001288a0 00000000124d8125 ffff8301288a02e8 0000000000000000
> (XEN)    0000000000000000 0000000000000001 00000000124d8125 ffff83012fea0000
> (XEN)    0000000000000202 fffffffffffffff3 000000000060c000 ffff8800cd749e58
> (XEN)    0000000000000000 00007fffe5f712b0 ffff83012fecfef8 ffff82c480103568
> (XEN)    ffff83012fea0000 0000000000000000 ffff83012fecfe08 ffff82c480163b65
> (XEN)    0000000100000082 ffff82f602511400 ffff83012fea0000 ffff83012fea0000
> (XEN)    0000000000000000 ffff82f602511400 ffff83012fecfee8 ffff82c48016e8d5
> (XEN) Xen call trace:
> (XEN)    [<ffff82c480161d92>] is_iomem_page+0x11e/0x16c
> (XEN)    [<ffff82c4801ca912>] p2m_mem_paging_nominate+0xc3/0x252
> (XEN)    [<ffff82c4801cee3d>] mem_paging_domctl+0x2d/0x70
> (XEN)    [<ffff82c4801ceddd>] mem_event_domctl+0x36f/0x3a2
> (XEN)    [<ffff82c48014fc53>] arch_do_domctl+0x2573/0x2740
> (XEN)    [<ffff82c480103568>] do_domctl+0x1222/0x12aa
> (XEN)    [<ffff82c4801fd392>] syscall_enter+0xf2/0x14c
> (XEN)
> (XEN)
> (XEN) ****************************************
> (XEN) Panic on CPU 3:
> (XEN) Assertion '(page->count_info & ((1UL<<(64 - (9)))-1)) != 0' failed at mm.c:772
> (XEN) ****************************************
> (XEN)
> (XEN) Reboot in five seconds...
> (XEN) Debugging connection not set up.
>
>
> ---
>  xen/arch/x86/mm.c |    7 +++++++
>  1 file changed, 7 insertions(+)
>
> --- xen-unstable.hg-4.1.21836.orig/xen/arch/x86/mm.c
> +++ xen-unstable.hg-4.1.21836/xen/arch/x86/mm.c
> @@ -99,6 +99,7 @@
>  #include <xen/event.h>
>  #include <xen/iocap.h>
>  #include <xen/guest_access.h>
> +#include <xen/delay.h>
>  #include <asm/paging.h>
>  #include <asm/shadow.h>
>  #include <asm/page.h>
> @@ -762,6 +763,12 @@ int is_iomem_page(unsigned long mfn)
>
>     /* Caller must know that it is an iomem page, or a reference is held. */
>     page = mfn_to_page(mfn);
> +    if ((page->count_info & PGC_count_mask) == 0) {
> +    unsigned long **p = (unsigned long **)page;
> +    MEM_LOG("mfn %lx page %p ci %p/%p %d", mfn, page, (void *)page->count_info, (void *)(page->count_info & PGC_count_mask), (int)sizeof(*page));
> +    MEM_LOG("%p: %p %p %p %p",page,p[0],p[1],p[2],p[3]);
> +    mdelay(1234);
> +    }
>     ASSERT((page->count_info & PGC_count_mask) != 0);
>
>     return (page_get_owner(page) == dom_io);
>
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