[Xen-devel] [HYBRID] : mapping IO mems in the EPT

[Mukesh Rathor <mukesh.rathor@xxxxxxxxxx>]

Hi guys,

During my refresh to latest linux, I noticed, direct mapping of all
non-RAM pages in xen_set_identity_and_release(). I currently don't map
all at front, but as needed looking at the PAGE_IO bit in the pte. One
result of that is minor change to common code macro:

        __set_fixmap(idx, phys, PAGE_KERNEL_NOCACHE) to
to        __set_fixmap(idx, phys, PAGE_KERNEL_IO_NOCACHE)


To avoid this change, and keep all my changes limited to xen files only,
I thought I could just map the entire non-ram pages up front too. But
I am concerned the EPT may grow too large? Specially, when we get to 
*really* large NUMA boxes. What do you guys think? Should I worry about
it?

thanks
Mukesh

E820 on my small box:
Xen: [mem 0x0000000000000000-0x000000000009cfff] usable
Xen: [mem 0x000000000009d800-0x00000000000fffff] reserved
Xen: [mem 0x0000000000100000-0x00000000bf30cfff] usable
Xen: [mem 0x00000000bf30d000-0x00000000bf38cfff] ACPI NVS
Xen: [mem 0x00000000bf38d000-0x00000000bf3a2fff] reserved
Xen: [mem 0x00000000bf3a3000-0x00000000bf3a3fff] ACPI NVS
Xen: [mem 0x00000000bf3a4000-0x00000000bf3b4fff] reserved
Xen: [mem 0x00000000bf3b5000-0x00000000bf3b7fff] ACPI NVS
Xen: [mem 0x00000000bf3b8000-0x00000000bf3defff] reserved
Xen: [mem 0x00000000bf3df000-0x00000000bf3dffff] usable
Xen: [mem 0x00000000bf3e0000-0x00000000bf3e0fff] ACPI NVS
Xen: [mem 0x00000000bf3e1000-0x00000000bf415fff] reserved
Xen: [mem 0x00000000bf416000-0x00000000bf41ffff] ACPI data
Xen: [mem 0x00000000bf420000-0x00000000bf420fff] ACPI NVS
Xen: [mem 0x00000000bf421000-0x00000000bf422fff] ACPI data
Xen: [mem 0x00000000bf423000-0x00000000bf42afff] ACPI NVS
Xen: [mem 0x00000000bf42b000-0x00000000bf453fff] reserved
Xen: [mem 0x00000000bf454000-0x00000000bf656fff] ACPI NVS
Xen: [mem 0x00000000bf657000-0x00000000bf7fffff] usable
Xen: [mem 0x00000000c0000000-0x00000000cfffffff] reserved
Xen: [mem 0x00000000fec00000-0x00000000fec02fff] reserved
Xen: [mem 0x00000000fec90000-0x00000000fec90fff] reserved
Xen: [mem 0x00000000fed1c000-0x00000000fed1ffff] reserved
Xen: [mem 0x00000000fee00000-0x00000000fee00fff] reserved
Xen: [mem 0x00000000ff000000-0x00000000ffffffff] reserved
Xen: [mem 0x0000000100000000-0x00000002bfffffff] usable



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