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authorDavid Vrabel <david.vrabel@citrix.com>2016-05-17 15:54:50 +0100
committerDavid Vrabel <david.vrabel@citrix.com>2016-06-23 14:50:30 +0100
commitd6b186c1e2d852a92c43f090d0d8fad4704d51ef (patch)
tree987a93a917bb2d377d52482e1a4da8010d1a37f1 /drivers/xen
parent02ef871ecac290919ea0c783d05da7eedeffc10e (diff)
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x86/xen: avoid m2p lookup when setting early page table entries
When page tables entries are set using xen_set_pte_init() during early boot there is no page fault handler that could handle a fault when performing an M2P lookup. In 64 bit guests (usually dom0) early_ioremap() would fault in xen_set_pte_init() because an M2P lookup faults because the MFN is in MMIO space and not mapped in the M2P. This lookup is done to see if the PFN in in the range used for the initial page table pages, so that the PTE may be set as read-only. The M2P lookup can be avoided by moving the check (and clear of RW) earlier when the PFN is still available. Reported-by: Kevin Moraga <kmoragas@riseup.net> Signed-off-by: David Vrabel <david.vrabel@citrix.com> Reviewed-by: Boris Ostrovsky <boris.ostrovsky@oracle.com> Reviewed-by: Juergen Gross <jgross@suse.com>
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