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authorIan Campbell <ian.campbell@citrix.com>2016-01-15 13:23:40 +0000
committerStefano Stabellini <stefano.stabellini@eu.citrix.com>2016-01-26 17:19:32 +0000
commit9ed257d1d1c65dbe5a08f207e5106e98384e1860 (patch)
treea1f012fc7776a42b234c9bae8754373ad771dacb /xen-mapcache.c
parentc1345a88785b50ba2bf5e87b83c7e22f6b4ec83d (diff)
xen: Switch uses of xc_map_foreign_range into xc_map_foreign_pages
In Xen 4.7 we are refactoring parts libxenctrl into a number of separate libraries which will provide backward and forward API and ABI compatiblity. One such library will be libxenforeignmemory which provides access to privileged foreign mappings and which will provide an interface equivalent to xc_map_foreign_{pages,bulk}. In preparation for this switch all uses of xc_map_foreign_range to xc_map_foreign_pages. This is trivial because size was always XC_PAGE_SIZE so the necessary adjustments are trivial: * Pass &mfn (an array of length 1) instead of mfn. The function takes a pointer to const, so there is no possibily of mfn changing due to this change. * Pass nr_pages=1 instead of size=XC_PAGE_SIZE There is one wrinkle in xen_console.c:con_initialise() where con->ring_ref is an int but can in some code paths (when !xendev->dev) be treated as an mfn. I think this is an existing latent truncation hazard on platforms where xen_pfn_t is 64-bit and int is 32-bit (e.g. amd64, both arm* variants). I'm unsure under what circumstances xendev->dev can be NULL or if anything elsewhere ensures the value fits into an int. For now I just use a temporary xen_pfn_t to in effect upcast the pointer from int* to xen_pfn_t*. In xenfb.c:common_bind we now explicitly launder the mfn into a xen_pfn_t, so it has the correct type to be passed to xc_map_foreign_pages and doesn't provoke warnings on 32-bit x86. Signed-off-by: Ian Campbell <ian.campbell@citrix.com> Reviewed-by: Stefano Stabellini <stefano.stabellini@eu.citrix.com> Signed-off-by: Stefano Stabellini <stefano.stabellini@eu.citrix.com>
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