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| author | Lai Jiangshan <laijs@cn.fujitsu.com> | 2010-05-26 16:49:59 +0800 |
|---|---|---|
| committer | Avi Kivity <avi@redhat.com> | 2010-08-01 10:35:52 +0300 |
| commit | 2032a93d66fa282ba0f2ea9152eeff9511fa9a96 (patch) | |
| tree | f0bbd50c3f237fa93c87207dc29602cbdcf9ad63 /arch/x86/kvm/paging_tmpl.h | |
| parent | c8174f7b35b3018c4c7b3237ed1c792e454fd5c3 (diff) | |
| download | lwn-2032a93d66fa282ba0f2ea9152eeff9511fa9a96.tar.gz lwn-2032a93d66fa282ba0f2ea9152eeff9511fa9a96.zip | |
KVM: MMU: Don't allocate gfns page for direct mmu pages
When sp->role.direct is set, sp->gfns does not contain any essential
information, leaf sptes reachable from this sp are for a continuous
guest physical memory range (a linear range).
So sp->gfns[i] (if it was set) equals to sp->gfn + i. (PT_PAGE_TABLE_LEVEL)
Obviously, it is not essential information, we can calculate it when need.
It means we don't need sp->gfns when sp->role.direct=1,
Thus we can save one page usage for every kvm_mmu_page.
Note:
Access to sp->gfns must be wrapped by kvm_mmu_page_get_gfn()
or kvm_mmu_page_set_gfn().
It is only exposed in FNAME(sync_page).
Signed-off-by: Lai Jiangshan <laijs@cn.fujitsu.com>
Signed-off-by: Avi Kivity <avi@redhat.com>
Diffstat (limited to 'arch/x86/kvm/paging_tmpl.h')
| -rw-r--r-- | arch/x86/kvm/paging_tmpl.h | 3 |
1 files changed, 3 insertions, 0 deletions
diff --git a/arch/x86/kvm/paging_tmpl.h b/arch/x86/kvm/paging_tmpl.h index 167f53357eef..2ee7060a80a5 100644 --- a/arch/x86/kvm/paging_tmpl.h +++ b/arch/x86/kvm/paging_tmpl.h @@ -582,6 +582,9 @@ static int FNAME(sync_page)(struct kvm_vcpu *vcpu, struct kvm_mmu_page *sp) offset = nr_present = 0; + /* direct kvm_mmu_page can not be unsync. */ + BUG_ON(sp->role.direct); + if (PTTYPE == 32) offset = sp->role.quadrant << PT64_LEVEL_BITS; |