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| author | Takuya Yoshikawa <yoshikawa.takuya@oss.ntt.co.jp> | 2011-04-21 19:34:44 +0400 |
|---|---|---|
| committer | Avi Kivity <avi@redhat.com> | 2011-05-22 16:39:38 +0400 |
| commit | 6e2ca7d1802bf8ed9908435e34daa116662e7790 (patch) | |
| tree | 802f56f655246d21cf722e06353bd2d30011252a /arch/x86 | |
| parent | 40e19b519caeb93def89c45082d776fccfb96dbb (diff) | |
| download | linux-6e2ca7d1802bf8ed9908435e34daa116662e7790.tar.xz | |
KVM: MMU: Optimize guest page table walk
This patch optimizes the guest page table walk by using get_user()
instead of copy_from_user().
With this patch applied, paging64_walk_addr_generic() has become
about 0.5us to 1.0us faster on my Phenom II machine with NPT on.
Signed-off-by: Takuya Yoshikawa <yoshikawa.takuya@oss.ntt.co.jp>
Signed-off-by: Avi Kivity <avi@redhat.com>
Diffstat (limited to 'arch/x86')
| -rw-r--r-- | arch/x86/kvm/paging_tmpl.h | 23 |
1 files changed, 20 insertions, 3 deletions
diff --git a/arch/x86/kvm/paging_tmpl.h b/arch/x86/kvm/paging_tmpl.h index 1b6899088f97..a32a1c809149 100644 --- a/arch/x86/kvm/paging_tmpl.h +++ b/arch/x86/kvm/paging_tmpl.h @@ -123,6 +123,7 @@ static int FNAME(walk_addr_generic)(struct guest_walker *walker, gva_t addr, u32 access) { pt_element_t pte; + pt_element_t __user *ptep_user; gfn_t table_gfn; unsigned index, pt_access, uninitialized_var(pte_access); gpa_t pte_gpa; @@ -158,6 +159,9 @@ walk: pt_access = ACC_ALL; for (;;) { + gfn_t real_gfn; + unsigned long host_addr; + index = PT_INDEX(addr, walker->level); table_gfn = gpte_to_gfn(pte); @@ -166,9 +170,22 @@ walk: walker->table_gfn[walker->level - 1] = table_gfn; walker->pte_gpa[walker->level - 1] = pte_gpa; - if (kvm_read_guest_page_mmu(vcpu, mmu, table_gfn, &pte, - offset, sizeof(pte), - PFERR_USER_MASK|PFERR_WRITE_MASK)) { + real_gfn = mmu->translate_gpa(vcpu, gfn_to_gpa(table_gfn), + PFERR_USER_MASK|PFERR_WRITE_MASK); + if (real_gfn == UNMAPPED_GVA) { + present = false; + break; + } + real_gfn = gpa_to_gfn(real_gfn); + + host_addr = gfn_to_hva(vcpu->kvm, real_gfn); + if (kvm_is_error_hva(host_addr)) { + present = false; + break; + } + + ptep_user = (pt_element_t __user *)((void *)host_addr + offset); + if (get_user(pte, ptep_user)) { present = false; break; } |