lk/linux-kernel-test
1
0
Fork 0
Code Issues Pull Requests Releases Wiki Activity

KVM: MMU: large page support

Browse Source 
Create large pages mappings if the guest PTE's are marked as such and
the underlying memory is hugetlbfs backed.  If the largepage contains
write-protected pages, a large pte is not used.

Gives a consistent 2% improvement for data copies on ram mounted
filesystem, without NPT/EPT.

Anthony measures a 4% improvement on 4-way kernbench, with NPT.

Signed-off-by: Marcelo Tosatti <mtosatti@redhat.com>
Signed-off-by: Avi Kivity <avi@qumranet.com>
This commit is contained in:
Marcelo Tosatti
2008-02-23 11:44:30 -03:00
committed by Avi Kivity
parent 2e53d63acb
commit 05da45583d
6 changed files with 262 additions and 32 deletions
Download Patch File Download Diff File Expand all files Collapse all files

32
arch/x86/kvm/paging_tmpl.h
View File

@ -248,6 +248,7 @@ static void FNAME(update_pte)(struct kvm_vcpu *vcpu, struct kvm_mmu_page *page,
pt_element_t gpte;
unsigned pte_access;
struct page *npage;
int largepage = vcpu->arch.update_pte.largepage;
gpte = *(const pt_element_t *)pte;
if (~gpte & (PT_PRESENT_MASK | PT_ACCESSED_MASK)) {
@ -264,7 +265,8 @@ static void FNAME(update_pte)(struct kvm_vcpu *vcpu, struct kvm_mmu_page *page,
return;
get_page(npage);
mmu_set_spte(vcpu, spte, page->role.access, pte_access, 0, 0,
gpte & PT_DIRTY_MASK, NULL, gpte_to_gfn(gpte), npage);
gpte & PT_DIRTY_MASK, NULL, largepage, gpte_to_gfn(gpte),
npage);
}
/*
@ -272,8 +274,8 @@ static void FNAME(update_pte)(struct kvm_vcpu *vcpu, struct kvm_mmu_page *page,
*/
static u64 *FNAME(fetch)(struct kvm_vcpu *vcpu, gva_t addr,
struct guest_walker *walker,
int user_fault, int write_fault, int *ptwrite,
struct page *page)
int user_fault, int write_fault, int largepage,
int *ptwrite, struct page *page)
{
hpa_t shadow_addr;
int level;
@ -301,11 +303,19 @@ static u64 *FNAME(fetch)(struct kvm_vcpu *vcpu, gva_t addr,
shadow_ent = ((u64 *)__va(shadow_addr)) + index;
if (level == PT_PAGE_TABLE_LEVEL)
break;
if (is_shadow_present_pte(*shadow_ent)) {
if (largepage && level == PT_DIRECTORY_LEVEL)
break;
if (is_shadow_present_pte(*shadow_ent)
&& !is_large_pte(*shadow_ent)) {
shadow_addr = *shadow_ent & PT64_BASE_ADDR_MASK;
continue;
}
if (is_large_pte(*shadow_ent))
rmap_remove(vcpu->kvm, shadow_ent);
if (level - 1 == PT_PAGE_TABLE_LEVEL
&& walker->level == PT_DIRECTORY_LEVEL) {
metaphysical = 1;
@ -339,7 +349,7 @@ static u64 *FNAME(fetch)(struct kvm_vcpu *vcpu, gva_t addr,
mmu_set_spte(vcpu, shadow_ent, access, walker->pte_access & access,
user_fault, write_fault,
walker->ptes[walker->level-1] & PT_DIRTY_MASK,
ptwrite, walker->gfn, page);
ptwrite, largepage, walker->gfn, page);
return shadow_ent;
}
@ -369,6 +379,7 @@ static int FNAME(page_fault)(struct kvm_vcpu *vcpu, gva_t addr,
int write_pt = 0;
int r;
struct page *page;
int largepage = 0;
pgprintk("%s: addr %lx err %x\n", __FUNCTION__, addr, error_code);
kvm_mmu_audit(vcpu, "pre page fault");
@ -396,6 +407,14 @@ static int FNAME(page_fault)(struct kvm_vcpu *vcpu, gva_t addr,
}
down_read(&current->mm->mmap_sem);
if (walker.level == PT_DIRECTORY_LEVEL) {
gfn_t large_gfn;
large_gfn = walker.gfn & ~(KVM_PAGES_PER_HPAGE-1);
if (is_largepage_backed(vcpu, large_gfn)) {
walker.gfn = large_gfn;
largepage = 1;
}
}
page = gfn_to_page(vcpu->kvm, walker.gfn);
up_read(&current->mm->mmap_sem);
@ -410,7 +429,8 @@ static int FNAME(page_fault)(struct kvm_vcpu *vcpu, gva_t addr,
spin_lock(&vcpu->kvm->mmu_lock);
kvm_mmu_free_some_pages(vcpu);
shadow_pte = FNAME(fetch)(vcpu, addr, &walker, user_fault, write_fault,
&write_pt, page);
largepage, &write_pt, page);
pgprintk("%s: shadow pte %p %llx ptwrite %d\n", __FUNCTION__,
shadow_pte, *shadow_pte, write_pt);