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| author | Avi Kivity | 2007-11-21 01:57:59 +0100 |
|---|---|---|
| committer | Avi Kivity | 2008-01-30 16:53:10 +0100 |
| commit | d835dfecd00fd770288dcd9a46c0e0966d526fdf (patch) | |
| tree | 9e80c69f9024e45b39cf0d1eeda56ba4a57567a6 /drivers/kvm/x86.c | |
| parent | KVM: MMU: Avoid unnecessary remote tlb flushes when guest updates a pte (diff) | |
| download | kernel-qcow2-linux-d835dfecd00fd770288dcd9a46c0e0966d526fdf.tar.gz kernel-qcow2-linux-d835dfecd00fd770288dcd9a46c0e0966d526fdf.tar.xz kernel-qcow2-linux-d835dfecd00fd770288dcd9a46c0e0966d526fdf.zip | |
KVM: Don't bother the mmu if cr3 load doesn't change cr3
If the guest requests just a tlb flush, don't take the vm lock and
drop the mmu context pointlessly.
Signed-off-by: Avi Kivity <avi@qumranet.com>
Diffstat (limited to 'drivers/kvm/x86.c')
| -rw-r--r-- | drivers/kvm/x86.c | 25 |
1 files changed, 25 insertions, 0 deletions
diff --git a/drivers/kvm/x86.c b/drivers/kvm/x86.c index ac09f381f47f..15e1203faef0 100644 --- a/drivers/kvm/x86.c +++ b/drivers/kvm/x86.c @@ -166,6 +166,26 @@ out: return ret; } +static bool pdptrs_changed(struct kvm_vcpu *vcpu) +{ + u64 pdpte[ARRAY_SIZE(vcpu->pdptrs)]; + bool changed = true; + int r; + + if (is_long_mode(vcpu) || !is_pae(vcpu)) + return false; + + mutex_lock(&vcpu->kvm->lock); + r = kvm_read_guest(vcpu->kvm, vcpu->cr3 & ~31u, pdpte, sizeof(pdpte)); + if (r < 0) + goto out; + changed = memcmp(pdpte, vcpu->pdptrs, sizeof(pdpte)) != 0; +out: + mutex_unlock(&vcpu->kvm->lock); + + return changed; +} + void set_cr0(struct kvm_vcpu *vcpu, unsigned long cr0) { if (cr0 & CR0_RESERVED_BITS) { @@ -271,6 +291,11 @@ EXPORT_SYMBOL_GPL(set_cr4); void set_cr3(struct kvm_vcpu *vcpu, unsigned long cr3) { + if (cr3 == vcpu->cr3 && !pdptrs_changed(vcpu)) { + kvm_mmu_flush_tlb(vcpu); + return; + } + if (is_long_mode(vcpu)) { if (cr3 & CR3_L_MODE_RESERVED_BITS) { printk(KERN_DEBUG "set_cr3: #GP, reserved bits\n"); |