[PATCH 4/6] KVM MMU: optimize for writing cr4
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From: Xiao Guangrong on 12 Apr 2010 04:10 Usually, OS changes CR4.PGE bit to flush all global page, under this case, no need reset mmu and just flush tlb Signed-off-by: Xiao Guangrong <xiaoguangrong(a)cn.fujitsu.com> --- arch/x86/kvm/x86.c | 9 +++++++++ 1 files changed, 9 insertions(+), 0 deletions(-) diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c index fd5c3d3..2aaa6fb 100644 --- a/arch/x86/kvm/x86.c +++ b/arch/x86/kvm/x86.c @@ -463,6 +463,15 @@ void kvm_set_cr4(struct kvm_vcpu *vcpu, unsigned long cr4) unsigned long old_cr4 = kvm_read_cr4(vcpu); unsigned long pdptr_bits = X86_CR4_PGE | X86_CR4_PSE | X86_CR4_PAE; + if (cr4 == old_cr4) + return; + + if ((cr4 ^ old_cr4) == X86_CR4_PGE) { + kvm_mmu_sync_roots(vcpu); + kvm_mmu_flush_tlb(vcpu); + return; + } + if (cr4 & CR4_RESERVED_BITS) { kvm_inject_gp(vcpu, 0); return; -- 1.6.1.2 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo(a)vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/ |