> > You can always just add a new page to the domain to be used for #VE.
It's there a method to directly assign physical pages to guest from dom0? Using xc_map_foreign_address just like libvmi? 2016-04-28 23:07 GMT+08:00 Tamas K Lengyel <tamas.k.leng...@gmail.com>: > > > On Thu, Apr 28, 2016 at 8:36 AM, Big Strong <fangtu...@gmail.com> wrote: > >> I want to set up an EPT page so as to trigger the #VE for testing >> purpose. However, some problems are met. >> >> As the Intel Manual said, there are many conditions to trigger a #VE: >> >> a) If an access to a guest-physical address causes an EPT >> violation, bit 63 (0) of exactly one of the EPT paging-structure entries >> used to translate that address is used to determine *whether the EPT >> violation is convertible*: either an entry that is not present (if the >> guest-physical address does not translate to a physical address) or an >> entry that maps a page (if it does). >> >> b) A convertible EPT violation instead causes a virtualization >> exception if the following all hold: >> >> • CR0.PE = 1; >> >> • the logical processor is not in the process of delivering an event >> through the IDT; and >> >> • the 32 bits at offset 4 in the virtualization-exception information >> area are all 0. >> In xc_altp2m.c, there is a function xc_altp2m_set_vcpu_enable_notify >> which is used to set up the #VE information area. However, as the arguments >> gfn is a physical address (of the guest?), how can I safely assign an >> unused physical memory space to store #VE info? >> > > You can always just add a new page to the domain to be used for #VE. > > >> >> Besides, there is no xenctrl interface for setting the suprress_ve bit >> (63) of the EPT PTE, which is needed to trigger #VE. Even though I can set >> that with ept_set_entry function, this is an internal function of Xen and >> unavailble to dom0. >> > > It's undocumented enough (and it took me a bit to find as well) but if you > use xc_altp2m_set_mem_access and have used xc_altp2m_set_vcpu_enable_notify > before, then those EPT PTE entries will be converted to #VE automatically. > > Tamas > >
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