On 16.12.2022 12:48, Julien Grall wrote: > From: Hongyan Xia <hongy...@amazon.com> > > When mfn is not in direct map, never use mfn_to_virt for any mappings. > > We replace mfn_x(mfn) <= PFN_DOWN(__pa(HYPERVISOR_VIRT_END - 1)) with > arch_mfns_in_direct_map(mfn, 1) because these two are equivalent. The > extra comparison in arch_mfns_in_direct_map() looks different but because > DIRECTMAP_VIRT_END is always higher, it does not make any difference. > > Lastly, domain_page_map_to_mfn() needs to gain to a special case for > the PMAP. > > Signed-off-by: Hongyan Xia <hongy...@amazon.com> > Signed-off-by: Julien Grall <jgr...@amazon.com>
This looks plausible, but cannot really be fully judged upon before the mapcache_current_vcpu() aspects pointed out earlier have been sorted. As to using pmap - assuming you've done an audit and the number of simultaneous mappings that can be in use can be proven to not exceed the number of slots available, can you please say so in the description? I have to admit though that I'm wary - this isn't a per-CPU number of slots aiui, but a global one. But then you also have a BUG_ON() there restricting the use to early boot. The reasoning for this is also missing (and might address my concern). Jan
