Messages in this thread | | | From | Lai Jiangshan <> | Subject | [PATCH 0/2] KVM: X86: Don't reset mmu context when changing PGE or PCID | Date | Sun, 19 Sep 2021 10:42:44 +0800 |
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From: Lai Jiangshan <laijs@linux.alibaba.com>
This patchset uses kvm_vcpu_flush_tlb_guest() instead of kvm_mmu_reset_context() when X86_CR4_PGE is changed or X86_CR4_PCIDE is changed 1->0.
Neither X86_CR4_PGE nor X86_CR4_PCIDE participates in kvm_mmu_role, so kvm_mmu_reset_context() is not required to be invoked. Only flushing tlb is required as SDM says.
The patchset has nothing to do with performance, because the overheads of kvm_mmu_reset_context() and kvm_vcpu_flush_tlb_guest() are the same. And even in the [near] future, kvm_vcpu_flush_tlb_guest() will be optimized, the code is not in the hot path.
This patchset makes the code more clear when to reset the mmu context. And it makes KVM_MMU_CR4_ROLE_BITS consistent with kvm_mmu_role.
Lai Jiangshan (2): KVM: X86: Don't reset mmu context when X86_CR4_PCIDE 1->0 KVM: X86: Don't reset mmu context when toggling X86_CR4_PGE
arch/x86/kvm/mmu.h | 5 ++--- arch/x86/kvm/x86.c | 7 +++++-- 2 files changed, 7 insertions(+), 5 deletions(-)
-- 2.19.1.6.gb485710b
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