| Message ID | 20201027212346.23409-7-sean.j.christopherson@intel.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | KVM: VMX: Clean up Hyper-V PV TLB flush | expand |
Sean Christopherson <sean.j.christopherson@intel.com> writes: > Drop the dedicated 'ept_pointers_match' field in favor of stuffing > 'hv_tlb_eptp' with INVALID_PAGE to mark it as invalid, i.e. to denote > that there is at least one EPTP mismatch. Use a local variable to > track whether or not a mismatch is detected so that hv_tlb_eptp can be > used to skip redundant flushes. > > No functional change intended. > > Signed-off-by: Sean Christopherson <sean.j.christopherson@intel.com> > --- > arch/x86/kvm/vmx/vmx.c | 35 +++++++++++++++++++++++------------ > arch/x86/kvm/vmx/vmx.h | 7 ------- > 2 files changed, 23 insertions(+), 19 deletions(-) > > diff --git a/arch/x86/kvm/vmx/vmx.c b/arch/x86/kvm/vmx/vmx.c > index 17b228c4ba19..25a714cda662 100644 > --- a/arch/x86/kvm/vmx/vmx.c > +++ b/arch/x86/kvm/vmx/vmx.c > @@ -500,32 +500,44 @@ static int hv_remote_flush_tlb_with_range(struct kvm *kvm, > { > struct kvm_vmx *kvm_vmx = to_kvm_vmx(kvm); > struct kvm_vcpu *vcpu; > - int ret = 0, i; > + int ret = 0, i, nr_unique_valid_eptps; > u64 tmp_eptp; > > spin_lock(&kvm_vmx->ept_pointer_lock); > > - if (kvm_vmx->ept_pointers_match != EPT_POINTERS_MATCH) { > - kvm_vmx->ept_pointers_match = EPT_POINTERS_MATCH; > - kvm_vmx->hv_tlb_eptp = INVALID_PAGE; > + if (!VALID_PAGE(kvm_vmx->hv_tlb_eptp)) { > + nr_unique_valid_eptps = 0; > > + /* > + * Flush all valid EPTPs, and see if all vCPUs have converged > + * on a common EPTP, in which case future flushes can skip the > + * loop and flush the common EPTP. > + */ > kvm_for_each_vcpu(i, vcpu, kvm) { > tmp_eptp = to_vmx(vcpu)->ept_pointer; > if (!VALID_PAGE(tmp_eptp) || > tmp_eptp == kvm_vmx->hv_tlb_eptp) > continue; > > - if (!VALID_PAGE(kvm_vmx->hv_tlb_eptp)) > + /* > + * Set the tracked EPTP to the first valid EPTP. Keep > + * this EPTP for the entirety of the loop even if more > + * EPTPs are encountered as a low effort optimization > + * to avoid flushing the same (first) EPTP again. > + */ > + if (++nr_unique_valid_eptps == 1) > kvm_vmx->hv_tlb_eptp = tmp_eptp; > - else > - kvm_vmx->ept_pointers_match > - = EPT_POINTERS_MISMATCH; > > ret |= hv_remote_flush_eptp(tmp_eptp, range); > } > - if (kvm_vmx->ept_pointers_match == EPT_POINTERS_MISMATCH) > + > + /* > + * The optimized flush of a single EPTP can't be used if there > + * are multiple valid EPTPs (obviously). > + */ > + if (nr_unique_valid_eptps > 1) > kvm_vmx->hv_tlb_eptp = INVALID_PAGE; > - } else if (VALID_PAGE(kvm_vmx->hv_tlb_eptp)) { > + } else { > ret = hv_remote_flush_eptp(kvm_vmx->hv_tlb_eptp, range); > } > > @@ -3060,8 +3072,7 @@ static void vmx_load_mmu_pgd(struct kvm_vcpu *vcpu, hpa_t root_hpa, > if (kvm_x86_ops.tlb_remote_flush) { > spin_lock(&to_kvm_vmx(kvm)->ept_pointer_lock); > to_vmx(vcpu)->ept_pointer = eptp; > - to_kvm_vmx(kvm)->ept_pointers_match > - = EPT_POINTERS_CHECK; > + to_kvm_vmx(kvm)->hv_tlb_eptp = INVALID_PAGE; > spin_unlock(&to_kvm_vmx(kvm)->ept_pointer_lock); > } > > diff --git a/arch/x86/kvm/vmx/vmx.h b/arch/x86/kvm/vmx/vmx.h > index 9a25e83f8b96..cecc2a641e19 100644 > --- a/arch/x86/kvm/vmx/vmx.h > +++ b/arch/x86/kvm/vmx/vmx.h > @@ -288,12 +288,6 @@ struct vcpu_vmx { > } shadow_msr_intercept; > }; > > -enum ept_pointers_status { > - EPT_POINTERS_CHECK = 0, > - EPT_POINTERS_MATCH = 1, > - EPT_POINTERS_MISMATCH = 2 > -}; > - > struct kvm_vmx { > struct kvm kvm; > > @@ -302,7 +296,6 @@ struct kvm_vmx { > gpa_t ept_identity_map_addr; > > hpa_t hv_tlb_eptp; > - enum ept_pointers_status ept_pointers_match; > spinlock_t ept_pointer_lock; > }; This looks really neat and straighforward now, thanks! Reviewed-by: Vitaly Kuznetsov <vkuznets@redhat.com>
diff --git a/arch/x86/kvm/vmx/vmx.c b/arch/x86/kvm/vmx/vmx.c index 17b228c4ba19..25a714cda662 100644 --- a/arch/x86/kvm/vmx/vmx.c +++ b/arch/x86/kvm/vmx/vmx.c @@ -500,32 +500,44 @@ static int hv_remote_flush_tlb_with_range(struct kvm *kvm, { struct kvm_vmx *kvm_vmx = to_kvm_vmx(kvm); struct kvm_vcpu *vcpu; - int ret = 0, i; + int ret = 0, i, nr_unique_valid_eptps; u64 tmp_eptp; spin_lock(&kvm_vmx->ept_pointer_lock); - if (kvm_vmx->ept_pointers_match != EPT_POINTERS_MATCH) { - kvm_vmx->ept_pointers_match = EPT_POINTERS_MATCH; - kvm_vmx->hv_tlb_eptp = INVALID_PAGE; + if (!VALID_PAGE(kvm_vmx->hv_tlb_eptp)) { + nr_unique_valid_eptps = 0; + /* + * Flush all valid EPTPs, and see if all vCPUs have converged + * on a common EPTP, in which case future flushes can skip the + * loop and flush the common EPTP. + */ kvm_for_each_vcpu(i, vcpu, kvm) { tmp_eptp = to_vmx(vcpu)->ept_pointer; if (!VALID_PAGE(tmp_eptp) || tmp_eptp == kvm_vmx->hv_tlb_eptp) continue; - if (!VALID_PAGE(kvm_vmx->hv_tlb_eptp)) + /* + * Set the tracked EPTP to the first valid EPTP. Keep + * this EPTP for the entirety of the loop even if more + * EPTPs are encountered as a low effort optimization + * to avoid flushing the same (first) EPTP again. + */ + if (++nr_unique_valid_eptps == 1) kvm_vmx->hv_tlb_eptp = tmp_eptp; - else - kvm_vmx->ept_pointers_match - = EPT_POINTERS_MISMATCH; ret |= hv_remote_flush_eptp(tmp_eptp, range); } - if (kvm_vmx->ept_pointers_match == EPT_POINTERS_MISMATCH) + + /* + * The optimized flush of a single EPTP can't be used if there + * are multiple valid EPTPs (obviously). + */ + if (nr_unique_valid_eptps > 1) kvm_vmx->hv_tlb_eptp = INVALID_PAGE; - } else if (VALID_PAGE(kvm_vmx->hv_tlb_eptp)) { + } else { ret = hv_remote_flush_eptp(kvm_vmx->hv_tlb_eptp, range); } @@ -3060,8 +3072,7 @@ static void vmx_load_mmu_pgd(struct kvm_vcpu *vcpu, hpa_t root_hpa, if (kvm_x86_ops.tlb_remote_flush) { spin_lock(&to_kvm_vmx(kvm)->ept_pointer_lock); to_vmx(vcpu)->ept_pointer = eptp; - to_kvm_vmx(kvm)->ept_pointers_match - = EPT_POINTERS_CHECK; + to_kvm_vmx(kvm)->hv_tlb_eptp = INVALID_PAGE; spin_unlock(&to_kvm_vmx(kvm)->ept_pointer_lock); } diff --git a/arch/x86/kvm/vmx/vmx.h b/arch/x86/kvm/vmx/vmx.h index 9a25e83f8b96..cecc2a641e19 100644 --- a/arch/x86/kvm/vmx/vmx.h +++ b/arch/x86/kvm/vmx/vmx.h @@ -288,12 +288,6 @@ struct vcpu_vmx { } shadow_msr_intercept; }; -enum ept_pointers_status { - EPT_POINTERS_CHECK = 0, - EPT_POINTERS_MATCH = 1, - EPT_POINTERS_MISMATCH = 2 -}; - struct kvm_vmx { struct kvm kvm; @@ -302,7 +296,6 @@ struct kvm_vmx { gpa_t ept_identity_map_addr; hpa_t hv_tlb_eptp; - enum ept_pointers_status ept_pointers_match; spinlock_t ept_pointer_lock; };
Drop the dedicated 'ept_pointers_match' field in favor of stuffing 'hv_tlb_eptp' with INVALID_PAGE to mark it as invalid, i.e. to denote that there is at least one EPTP mismatch. Use a local variable to track whether or not a mismatch is detected so that hv_tlb_eptp can be used to skip redundant flushes. No functional change intended. Signed-off-by: Sean Christopherson <sean.j.christopherson@intel.com> --- arch/x86/kvm/vmx/vmx.c | 35 +++++++++++++++++++++++------------ arch/x86/kvm/vmx/vmx.h | 7 ------- 2 files changed, 23 insertions(+), 19 deletions(-)