From: George Dunlap <george.dunlap@eu.citrix.com>
To: Andrew Cooper <andrew.cooper3@citrix.com>,
Xen-devel <xen-devel@lists.xen.org>
Cc: Kevin Tian <kevin.tian@intel.com>,
Eddie Dong <eddie.dong@intel.com>,
Jun Nakajima <jun.nakajima@intel.com>,
Jan Beulich <JBeulich@suse.com>
Subject: Re: [PATCH] x86/p2m-ept: Don't unmap the EPT pagetable while it is still in use
Date: Thu, 2 Jul 2015 11:07:30 +0100 [thread overview]
Message-ID: <55950D62.8030300@eu.citrix.com> (raw)
In-Reply-To: <1435684155-11807-1-git-send-email-andrew.cooper3@citrix.com>
On 06/30/2015 06:09 PM, Andrew Cooper wrote:
> The call to iommu_pte_flush() between the two hunks uses &ept_entry->epte
> which is a pointer into the mapped page.
>
> It is eventually passed to `clflush` instruction which will suffer a pagefault
> if the virtual mapping has fallen out of the TLB.
>
> (XEN) ----[ Xen-4.5.0-xs102594-d x86_64 debug=y Not tainted ]----
> (XEN) CPU: 7
> (XEN) RIP: e008:[<ffff82d0801572f0>] cacheline_flush+0x4/0x9
> <snip>
> (XEN) Xen call trace:
> (XEN) [<ffff82d0801572f0>] cacheline_flush+0x4/0x9
> (XEN) [<ffff82d08014ffff>] __iommu_flush_cache+0x4a/0x6a
> (XEN) [<ffff82d0801532e2>] iommu_pte_flush+0x2b/0xd5
> (XEN) [<ffff82d0801f909a>] ept_set_entry+0x4bc/0x61f
> (XEN) [<ffff82d0801f0c25>] p2m_set_entry+0xd1/0x112
> (XEN) [<ffff82d0801f25b1>] clear_mmio_p2m_entry+0x1a0/0x200
> (XEN) [<ffff82d0801f4aac>] unmap_mmio_regions+0x49/0x73
> (XEN) [<ffff82d080106292>] do_domctl+0x15bd/0x1edb
> (XEN) [<ffff82d080234fcb>] syscall_enter+0xeb/0x145
> (XEN)
> (XEN) Pagetable walk from ffff820040004ae0:
> (XEN) L4[0x104] = 00000008668a5063 ffffffffffffffff
> (XEN) L3[0x001] = 00000008668a3063 ffffffffffffffff
> (XEN) L2[0x000] = 000000086689c063 ffffffffffffffff
> (XEN) L1[0x004] = 000000056f078063 000000000007f678
> (XEN)
> (XEN) ****************************************
> (XEN) Panic on CPU 7:
> (XEN) FATAL PAGE FAULT
> (XEN) [error_code=0000]
> (XEN) Faulting linear address: ffff820040004ae0
> (XEN) ****************************************
>
> Signed-off-by: Andrew Cooper <andrew.cooper3@citrix.com>
> CC: Jan Beulich <JBeulich@suse.com>
> CC: George Dunlap <george.dunlap@eu.citrix.com>
> CC: Jun Nakajima <jun.nakajima@intel.com>
> CC: Eddie Dong <eddie.dong@intel.com>
> CC: Kevin Tian <kevin.tian@intel.com>
Reviewed-by: George Dunlap <george.dunlap@eu.citrix.com>
-George
prev parent reply other threads:[~2015-07-02 10:07 UTC|newest]
Thread overview: 2+ messages / expand[flat|nested] mbox.gz Atom feed top
2015-06-30 17:09 [PATCH] x86/p2m-ept: Don't unmap the EPT pagetable while it is still in use Andrew Cooper
2015-07-02 10:07 ` George Dunlap [this message]
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