diff options
| author | Avi Kivity <avi@qumranet.com> | 2007-11-21 02:57:59 +0200 |
|---|---|---|
| committer | Avi Kivity <avi@qumranet.com> | 2008-01-30 17:53:10 +0200 |
| commit | d835dfecd00fd770288dcd9a46c0e0966d526fdf (patch) | |
| tree | 9e80c69f9024e45b39cf0d1eeda56ba4a57567a6 | |
| parent | 79539cec0c3c38d35a1e3e5310d2c562ae6e82b8 (diff) | |
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>
| -rw-r--r-- | drivers/kvm/mmu.c | 2 | ||||
| -rw-r--r-- | drivers/kvm/x86.c | 25 | ||||
| -rw-r--r-- | drivers/kvm/x86.h | 1 |
3 files changed, 27 insertions, 1 deletions
diff --git a/drivers/kvm/mmu.c b/drivers/kvm/mmu.c index 281dd5f9310c..346aa65a08d5 100644 --- a/drivers/kvm/mmu.c +++ b/drivers/kvm/mmu.c @@ -1086,7 +1086,7 @@ static int nonpaging_init_context(struct kvm_vcpu *vcpu) return 0; } -static void kvm_mmu_flush_tlb(struct kvm_vcpu *vcpu) +void kvm_mmu_flush_tlb(struct kvm_vcpu *vcpu) { ++vcpu->stat.tlb_flush; kvm_x86_ops->tlb_flush(vcpu); 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"); diff --git a/drivers/kvm/x86.h b/drivers/kvm/x86.h index 71f2477d03fd..b1528c9f566f 100644 --- a/drivers/kvm/x86.h +++ b/drivers/kvm/x86.h @@ -299,6 +299,7 @@ int emulator_write_emulated(unsigned long addr, unsigned long segment_base(u16 selector); +void kvm_mmu_flush_tlb(struct kvm_vcpu *vcpu); void kvm_mmu_pte_write(struct kvm_vcpu *vcpu, gpa_t gpa, const u8 *new, int bytes); int kvm_mmu_unprotect_page_virt(struct kvm_vcpu *vcpu, gva_t gva); |