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Revert "KVM: Avoid useless memory write when possible" 

This reverts commit a3c870bdce.  While it
does save useless updates, it (probably) defeats the fork detector, causing
a massive performance loss.

Signed-off-by: Avi Kivity <avi@qumranet.com>
This commit is contained in:
Avi Kivity 2007-07-23 18:33:14 +03:00
parent 5e58cfe41c
commit 7cfa4b0a43
1 changed files with 2 additions and 4 deletions
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6
drivers/kvm/kvm_main.c
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@ -1070,10 +1070,8 @@ static int emulator_write_phys(struct kvm_vcpu *vcpu, gpa_t gpa,
return 0;
mark_page_dirty(vcpu->kvm, gpa >> PAGE_SHIFT);
virt = kmap_atomic(page, KM_USER0);
if (memcmp(virt + offset_in_page(gpa), val, bytes)) {
kvm_mmu_pte_write(vcpu, gpa, virt + offset, val, bytes);
memcpy(virt + offset_in_page(gpa), val, bytes);
}
kvm_mmu_pte_write(vcpu, gpa, virt + offset, val, bytes);
memcpy(virt + offset_in_page(gpa), val, bytes);
kunmap_atomic(virt, KM_USER0);
return 1;
}