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| author | Avi Kivity <avi@redhat.com> | 2010-03-15 13:59:57 +0200 |
|---|---|---|
| committer | Avi Kivity <avi@redhat.com> | 2010-05-17 12:15:43 +0300 |
| commit | 08e850c6536db302050c0287649e68e3bbdfe2c7 (patch) | |
| tree | 9eb7e554b53ea9eb1cb408f81234f404a43a54ab /arch/x86/kvm/paging_tmpl.h | |
| parent | fbc5d139bb92e6822e4c000f97631a072d8babf9 (diff) | |
| download | linux-08e850c6536db302050c0287649e68e3bbdfe2c7.tar.gz linux-08e850c6536db302050c0287649e68e3bbdfe2c7.tar.bz2 linux-08e850c6536db302050c0287649e68e3bbdfe2c7.zip | |
KVM: MMU: Reinstate pte prefetch on invlpg
Commit fb341f57 removed the pte prefetch on guest invlpg, citing guest races.
However, the SDM is adamant that prefetch is allowed:
"The processor may create entries in paging-structure caches for
translations required for prefetches and for accesses that are a
result of speculative execution that would never actually occur
in the executed code path."
And, in fact, there was a race in the prefetch code: we picked up the pte
without the mmu lock held, so an older invlpg could install the pte over
a newer invlpg.
Reinstate the prefetch logic, but this time note whether another invlpg has
executed using a counter. If a race occured, do not install the pte.
Signed-off-by: Avi Kivity <avi@redhat.com>
Signed-off-by: Marcelo Tosatti <mtosatti@redhat.com>
Diffstat (limited to 'arch/x86/kvm/paging_tmpl.h')
| -rw-r--r-- | arch/x86/kvm/paging_tmpl.h | 15 |
1 files changed, 15 insertions, 0 deletions
diff --git a/arch/x86/kvm/paging_tmpl.h b/arch/x86/kvm/paging_tmpl.h index 4b37e1acd375..067797a72768 100644 --- a/arch/x86/kvm/paging_tmpl.h +++ b/arch/x86/kvm/paging_tmpl.h @@ -463,6 +463,7 @@ out_unlock: static void FNAME(invlpg)(struct kvm_vcpu *vcpu, gva_t gva) { struct kvm_shadow_walk_iterator iterator; + gpa_t pte_gpa = -1; int level; u64 *sptep; int need_flush = 0; @@ -476,6 +477,10 @@ static void FNAME(invlpg)(struct kvm_vcpu *vcpu, gva_t gva) if (level == PT_PAGE_TABLE_LEVEL || ((level == PT_DIRECTORY_LEVEL && is_large_pte(*sptep))) || ((level == PT_PDPE_LEVEL && is_large_pte(*sptep)))) { + struct kvm_mmu_page *sp = page_header(__pa(sptep)); + + pte_gpa = (sp->gfn << PAGE_SHIFT); + pte_gpa += (sptep - sp->spt) * sizeof(pt_element_t); if (is_shadow_present_pte(*sptep)) { rmap_remove(vcpu->kvm, sptep); @@ -493,7 +498,17 @@ static void FNAME(invlpg)(struct kvm_vcpu *vcpu, gva_t gva) if (need_flush) kvm_flush_remote_tlbs(vcpu->kvm); + + atomic_inc(&vcpu->kvm->arch.invlpg_counter); + spin_unlock(&vcpu->kvm->mmu_lock); + + if (pte_gpa == -1) + return; + + if (mmu_topup_memory_caches(vcpu)) + return; + kvm_mmu_pte_write(vcpu, pte_gpa, NULL, sizeof(pt_element_t), 0); } static gpa_t FNAME(gva_to_gpa)(struct kvm_vcpu *vcpu, gva_t vaddr, u32 access, |