Re: [Xen-devel] [PATCH v2 0/2] x86/HVM: Properly handle SMAP check in certain cases

["Wu, Feng" <feng.wu@xxxxxxxxx>]

Sorry, forget to add the change history. Adding it here:

V2: Remove ' VCPUOP_enable_smap_check_vcpu_time_memory_area' hypercall,
hence always do the SMAP checking for the secondary system time.

> -----Original Message-----
> From: Wu, Feng
> Sent: Monday, January 08, 2001 8:11 AM
> To: xen-devel@xxxxxxxxxxxxx
> Cc: keir@xxxxxxx; jbeulich@xxxxxxxx; tim@xxxxxxx; linux@xxxxxxxxxxxxxx;
> Wu, Feng
> Subject: [PATCH v2 0/2] x86/HVM: Properly handle SMAP check in certain cases
> 
> This patch set fixs a issue found by Sander Eikelenboom. Here is the log
> when this issue occurs:
> 
> (d2)  Booting from Hard Disk...
> (d2)  Booting from 0000:7c00
> (XEN) irq.c:380: Dom1 callback via changed to Direct Vector 0xf3
> (XEN) irq.c:380: Dom2 callback via changed to Direct Vector 0xf3
> (XEN) Segment register inaccessible for d1v0
> (XEN) (If you see this outside of debugging activity, please report to
> xen-devel@xxxxxxxxxxxxxxxxxxxx)
> 
> And here is the Xen call trace:
> (XEN) [<ffff82d0801dc9c5>] vmx_get_segment_register+0x4d/0x422
> (XEN) [<ffff82d0801f4415>] guest_walk_tables_3_levels+0x189/0x520
> (XEN) [<ffff82d0802204a8>] hap_p2m_ga_to_gfn_3_levels+0x158/0x2c2
> (XEN) [<ffff82d08022062e>] hap_gva_to_gfn_3_levels+0x1c/0x1e
> (XEN) [<ffff82d0801ec215>] paging_gva_to_gfn+0xb8/0xce
> (XEN) [<ffff82d0801ba88d>] __hvm_copy+0x87/0x354
> (XEN) [<ffff82d0801bac7c>] hvm_copy_to_guest_virt_nofault+0x1e/0x20
> (XEN) [<ffff82d0801bace5>] copy_to_user_hvm+0x67/0x87
> (XEN) [<ffff82d08016237c>] update_runstate_area+0x98/0xfb
> (XEN) [<ffff82d0801623f0>] _update_runstate_area+0x11/0x39
> (XEN) [<ffff82d0801634db>] context_switch+0x10c3/0x10fa
> (XEN) [<ffff82d080126a19>] schedule+0x5a8/0x5da
> (XEN) [<ffff82d0801297f9>] __do_softirq+0x81/0x8c
> (XEN) [<ffff82d080129852>] do_softirq+0x13/0x15
> (XEN) [<ffff82d08015f70a>] idle_loop+0x67/0x77
> 
> We need get guest's SS register via hvm_get_segment_register()
> to do the SMAP checking, however, in these two cases, we cannot
> do it that way since it is between setting 'current' and reloading
> the VMCS context for it. As an alternative, here we treat these
> accesses as implicit supervisor mode access, hence SMAP checking is
> always need.
> 
> Feng Wu (2):
>   x86/hvm: Always do SMAP check when updating runstate_guest(v)
>   x86/hvm: Always do SMAP check when updating secondary system time for
>     guest
> 
>  xen/arch/x86/domain.c        | 15 ++++++++++++---
>  xen/arch/x86/mm/guest_walk.c | 41
> ++++++++++++++++++++++++++++-------------
>  xen/arch/x86/time.c          |  9 ++++++++-
>  xen/include/asm-x86/domain.h | 17 +++++++++++++++--
>  4 files changed, 63 insertions(+), 19 deletions(-)
> 
> --
> 1.8.3.1


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