Gitweb:
http://git.kernel.org/git/?p=linux/kernel/git/torvalds/linux-2.6.git;a=commit;h=d835dfecd00fd770288dcd9a46c0e0966d526fdf
Commit: d835dfecd00fd770288dcd9a46c0e0966d526fdf
Parent: 79539cec0c3c38d35a1e3e5310d2c562ae6e82b8
Author: Avi Kivity <[EMAIL PROTECTED]>
AuthorDate: Wed Nov 21 02:57:59 2007 +0200
Committer: Avi Kivity <[EMAIL PROTECTED]>
CommitDate: Wed Jan 30 17:53:10 2008 +0200
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 <[EMAIL PROTECTED]>
---
drivers/kvm/mmu.c | 2 +-
drivers/kvm/x86.c | 25 +++++++++++++++++++++++++
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 281dd5f..346aa65 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 ac09f38..15e1203 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 71f2477..b1528c9 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);
-
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