From 2032a93d66fa282ba0f2ea9152eeff9511fa9a96 Mon Sep 17 00:00:00 2001 From: Lai Jiangshan Date: Wed, 26 May 2010 16:49:59 +0800 Subject: 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 Signed-off-by: Avi Kivity --- arch/x86/kvm/paging_tmpl.h | 3 +++ 1 file changed, 3 insertions(+) (limited to 'arch/x86/kvm/paging_tmpl.h') 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; -- cgit v1.2.3