diff options
author | David Matlack <dmatlack@google.com> | 2021-06-17 23:19:46 +0000 |
---|---|---|
committer | Paolo Bonzini <pbonzini@redhat.com> | 2021-06-18 06:45:46 -0400 |
commit | 0b873fd7fb53ed7343ee7ee166e1373aec02a9cb (patch) | |
tree | 0a8a768eaa17782bf54852d0b95f91f16c654de6 | |
parent | KVM: x86/mmu: Remove redundant is_tdp_mmu_root check (diff) | |
download | linux-dev-0b873fd7fb53ed7343ee7ee166e1373aec02a9cb.tar.xz linux-dev-0b873fd7fb53ed7343ee7ee166e1373aec02a9cb.zip |
KVM: x86/mmu: Remove redundant is_tdp_mmu_enabled check
This check is redundant because the root shadow page will only be a TDP
MMU page if is_tdp_mmu_enabled() returns true, and is_tdp_mmu_enabled()
never changes for the lifetime of a VM.
It's possible that this check was added for performance reasons but it
is unlikely that it is useful in practice since to_shadow_page() is
cheap. That being said, this patch also caches the return value of
is_tdp_mmu_root() in direct_page_fault() since there's no reason to
duplicate the call so many times, so performance is not a concern.
Suggested-by: Sean Christopherson <seanjc@google.com>
Signed-off-by: David Matlack <dmatlack@google.com>
Message-Id: <20210617231948.2591431-3-dmatlack@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
-rw-r--r-- | arch/x86/kvm/mmu/mmu.c | 11 | ||||
-rw-r--r-- | arch/x86/kvm/mmu/tdp_mmu.h | 4 |
2 files changed, 7 insertions, 8 deletions
diff --git a/arch/x86/kvm/mmu/mmu.c b/arch/x86/kvm/mmu/mmu.c index 7d3e57678d34..10c1c2029d35 100644 --- a/arch/x86/kvm/mmu/mmu.c +++ b/arch/x86/kvm/mmu/mmu.c @@ -3608,7 +3608,7 @@ static bool get_mmio_spte(struct kvm_vcpu *vcpu, u64 addr, u64 *sptep) return reserved; } - if (is_tdp_mmu_root(vcpu->kvm, vcpu->arch.mmu->root_hpa)) + if (is_tdp_mmu_root(vcpu->arch.mmu->root_hpa)) leaf = kvm_tdp_mmu_get_walk(vcpu, addr, sptes, &root); else leaf = get_walk(vcpu, addr, sptes, &root); @@ -3780,6 +3780,7 @@ static bool try_async_pf(struct kvm_vcpu *vcpu, bool prefault, gfn_t gfn, static int direct_page_fault(struct kvm_vcpu *vcpu, gpa_t gpa, u32 error_code, bool prefault, int max_level, bool is_tdp) { + bool is_tdp_mmu_fault = is_tdp_mmu_root(vcpu->arch.mmu->root_hpa); bool write = error_code & PFERR_WRITE_MASK; bool map_writable; @@ -3792,7 +3793,7 @@ static int direct_page_fault(struct kvm_vcpu *vcpu, gpa_t gpa, u32 error_code, if (page_fault_handle_page_track(vcpu, error_code, gfn)) return RET_PF_EMULATE; - if (!is_tdp_mmu_root(vcpu->kvm, vcpu->arch.mmu->root_hpa)) { + if (!is_tdp_mmu_fault) { r = fast_page_fault(vcpu, gpa, error_code); if (r != RET_PF_INVALID) return r; @@ -3814,7 +3815,7 @@ static int direct_page_fault(struct kvm_vcpu *vcpu, gpa_t gpa, u32 error_code, r = RET_PF_RETRY; - if (is_tdp_mmu_root(vcpu->kvm, vcpu->arch.mmu->root_hpa)) + if (is_tdp_mmu_fault) read_lock(&vcpu->kvm->mmu_lock); else write_lock(&vcpu->kvm->mmu_lock); @@ -3825,7 +3826,7 @@ static int direct_page_fault(struct kvm_vcpu *vcpu, gpa_t gpa, u32 error_code, if (r) goto out_unlock; - if (is_tdp_mmu_root(vcpu->kvm, vcpu->arch.mmu->root_hpa)) + if (is_tdp_mmu_fault) r = kvm_tdp_mmu_map(vcpu, gpa, error_code, map_writable, max_level, pfn, prefault); else @@ -3833,7 +3834,7 @@ static int direct_page_fault(struct kvm_vcpu *vcpu, gpa_t gpa, u32 error_code, prefault, is_tdp); out_unlock: - if (is_tdp_mmu_root(vcpu->kvm, vcpu->arch.mmu->root_hpa)) + if (is_tdp_mmu_fault) read_unlock(&vcpu->kvm->mmu_lock); else write_unlock(&vcpu->kvm->mmu_lock); diff --git a/arch/x86/kvm/mmu/tdp_mmu.h b/arch/x86/kvm/mmu/tdp_mmu.h index 78d8a296f0b6..f6e0667cf4b6 100644 --- a/arch/x86/kvm/mmu/tdp_mmu.h +++ b/arch/x86/kvm/mmu/tdp_mmu.h @@ -86,12 +86,10 @@ void kvm_mmu_uninit_tdp_mmu(struct kvm *kvm); static inline bool is_tdp_mmu_enabled(struct kvm *kvm) { return kvm->arch.tdp_mmu_enabled; } static inline bool is_tdp_mmu_page(struct kvm_mmu_page *sp) { return sp->tdp_mmu_page; } -static inline bool is_tdp_mmu_root(struct kvm *kvm, hpa_t hpa) +static inline bool is_tdp_mmu_root(hpa_t hpa) { struct kvm_mmu_page *sp; - if (!is_tdp_mmu_enabled(kvm)) - return false; if (WARN_ON(!VALID_PAGE(hpa))) return false; |