From: Lai Jiangshan <jiangshanlai@gmail.com>
To: linux-kernel@vger.kernel.org
Cc: Paolo Bonzini <pbonzini@redhat.com>,
Sean Christopherson <seanjc@google.com>,
Vitaly Kuznetsov <vkuznets@redhat.com>,
kvm@vger.kernel.org, Lai Jiangshan <laijs@linux.alibaba.com>
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 [thread overview]
Message-ID: <20210919024246.89230-1-jiangshanlai@gmail.com> (raw)
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
next reply other threads:[~2021-09-19 2:42 UTC|newest]
Thread overview: 8+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-09-19 2:42 Lai Jiangshan [this message]
2021-09-19 2:42 ` [PATCH 1/2] KVM: X86: Don't reset mmu context when X86_CR4_PCIDE 1->0 Lai Jiangshan
2021-10-14 18:47 ` Sean Christopherson
2021-10-14 18:48 ` Sean Christopherson
2021-09-19 2:42 ` [PATCH 2/2] KVM: X86: Don't reset mmu context when toggling X86_CR4_PGE Lai Jiangshan
2021-10-14 18:50 ` Sean Christopherson
2021-10-14 16:03 ` [PATCH 0/2] KVM: X86: Don't reset mmu context when changing PGE or PCID Lai Jiangshan
2021-10-15 16:02 ` Paolo Bonzini
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