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KVM: powerpc: Map guest userspace with TID=0 mappings

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When we use TID=N userspace mappings, we must ensure that kernel mappings have
been destroyed when entering userspace. Using TID=1/TID=0 for kernel/user
mappings and running userspace with PID=0 means that userspace can't access the
kernel mappings, but the kernel can directly access userspace.

The net is that we don't need to flush the TLB on privilege switches, but we do
on guest context switches (which are far more infrequent). Guest boot time
performance improvement: about 30%.

Signed-off-by: Hollis Blanchard <hollisb@us.ibm.com>
Signed-off-by: Avi Kivity <avi@qumranet.com>
This commit is contained in:
Hollis Blanchard
2008-07-25 13:54:53 -05:00
committed by Avi Kivity
parent 83aae4a809
commit 49dd2c4928
7 changed files with 40 additions and 18 deletions
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arch/powerpc/kernel/asm-offsets.c
+1 -1
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@@ -369,7 +369,7 @@ int main(void)
DEFINE(VCPU_SPRG5, offsetof(struct kvm_vcpu, arch.sprg5));
DEFINE(VCPU_SPRG6, offsetof(struct kvm_vcpu, arch.sprg6));
DEFINE(VCPU_SPRG7, offsetof(struct kvm_vcpu, arch.sprg7));
DEFINE(VCPU_PID, offsetof(struct kvm_vcpu, arch.pid));
DEFINE(VCPU_SHADOW_PID, offsetof(struct kvm_vcpu, arch.shadow_pid));
DEFINE(VCPU_LAST_INST, offsetof(struct kvm_vcpu, arch.last_inst));
DEFINE(VCPU_FAULT_DEAR, offsetof(struct kvm_vcpu, arch.fault_dear));