Re: cr3 OOS optimisation breaks 32-bit GNU/kFreeBSD guest

Marcelo Tosatti
2009-03-23T17:27:44Z

On Sun, Mar 22, 2009 at 11:35:00AM +0200, Avi Kivity wrote:
> Good catch, indeed. But is it sufficient? We could unlink a page
> through other means, for example by the guest zapping a page directory
> entry.

Yep.

> Maybe it's best to resync when relinking a global page?

How about this. It will shorten the unsync period of global pages,
unfortunately.

diff --git a/arch/x86/kvm/mmu.c b/arch/x86/kvm/mmu.c
index 2a36f7f..bccdcc7 100644
--- a/arch/x86/kvm/mmu.c
+++ b/arch/x86/kvm/mmu.c
@@ -1238,6 +1238,10 @@ static struct kvm_mmu_page *kvm_mmu_get_page(struct kvm_vcpu *vcpu,
set_bit(KVM_REQ_MMU_SYNC, &vcpu->requests);
kvm_mmu_mark_parents_unsync(vcpu, sp);
}
+ if (role.level != PT_PAGE_TABLE_LEVEL &&
+ !list_empty(&vcpu->kvm->arch.oos_global_pages))
+ set_bit(KVM_REQ_MMU_GLOBAL_SYNC, &vcpu->requests);
+
pgprintk("%s: found\n", __func__);
return sp;
}
diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
index 2ea8262..48169d7 100644
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -3109,6 +3109,8 @@ static int vcpu_enter_guest(struct kvm_vcpu *vcpu, struct kvm_run *kvm_run)
kvm_write_guest_time(vcpu);
if (test_and_clear_bit(KVM_REQ_MMU_SYNC, &vcpu->requests))
kvm_mmu_sync_roots(vcpu);
+ if (test_and_clear_bit(KVM_REQ_MMU_GLOBAL_SYNC, &vcpu->requests))
+ kvm_mmu_sync_global(vcpu);
if (test_and_clear_bit(KVM_REQ_TLB_FLUSH, &vcpu->requests))
kvm_x86_ops->tlb_flush(vcpu);
if (test_and_clear_bit(KVM_REQ_REPORT_TPR_ACCESS,
diff --git a/include/linux/kvm_host.h b/include/linux/kvm_host.h
index 11eb702..8efd6e3 100644
--- a/include/linux/kvm_host.h
+++ b/include/linux/kvm_host.h
@@ -37,7 +37,8 @@
#define KVM_REQ_PENDING_TIMER 5
#define KVM_REQ_UNHALT 6
#define KVM_REQ_MMU_SYNC 7
-#define KVM_REQ_KVMCLOCK_UPDATE 8
+#define KVM_REQ_MMU_GLOBAL_SYNC 8
+#define KVM_REQ_KVMCLOCK_UPDATE 9

#define KVM_USERSPACE_IRQ_SOURCE_ID 0