| Message ID | 20220407155645.940890-2-vkuznets@redhat.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | KVM: x86: hyper-v: Fine-grained TLB flush + Direct TLB flush feature | expand |
On Thu, Apr 07, 2022, Vitaly Kuznetsov wrote: > diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c > index e9647614dc8c..3c54f6804b7b 100644 > --- a/arch/x86/kvm/x86.c > +++ b/arch/x86/kvm/x86.c > @@ -3341,7 +3341,12 @@ void kvm_service_local_tlb_flush_requests(struct kvm_vcpu *vcpu) > if (kvm_check_request(KVM_REQ_TLB_FLUSH_CURRENT, vcpu)) > kvm_vcpu_flush_tlb_current(vcpu); > > - if (kvm_check_request(KVM_REQ_TLB_FLUSH_GUEST, vcpu)) > + if (kvm_check_request(KVM_REQ_TLB_FLUSH_GUEST, vcpu)) { > + kvm_vcpu_flush_tlb_guest(vcpu); > + kvm_clear_request(KVM_REQ_HV_TLB_FLUSH, vcpu); > + } > + > + if (kvm_check_request(KVM_REQ_HV_TLB_FLUSH, vcpu)) > kvm_vcpu_flush_tlb_guest(vcpu); It'd be slightly more performant to do: if (kvm_check_request(KVM_REQ_TLB_FLUSH_GUEST, vcpu)) { kvm_vcpu_flush_tlb_guest(vcpu); kvm_clear_request(KVM_REQ_HV_TLB_FLUSH, vcpu); } else if (kvm_check_request(KVM_REQ_HV_TLB_FLUSH, vcpu)) { kvm_hv_vcpu_flush_tlb(vcpu); } And then when the code becomes if (kvm_check_request(KVM_REQ_TLB_FLUSH_GUEST, vcpu)) { kvm_vcpu_flush_tlb_guest(vcpu); if (kvm_check_request(KVM_REQ_HV_TLB_FLUSH, vcpu)) kvm_hv_vcpu_empty_flush_tlb(vcpu); } else if (kvm_check_request(KVM_REQ_HV_TLB_FLUSH, vcpu)) { kvm_hv_vcpu_flush_tlb(vcpu); } the elif will help unsuspecting readers see that the HV_TLB_FLUSH request is cleared by kvm_check_request() in the TLB_FLUSH_GUEST path. The elif could result in having to bail from VM-Entry if the request becomes pending after the check/clear inside TLB_FLUSH_GUEST, but that should be a very rare case. > } > EXPORT_SYMBOL_GPL(kvm_service_local_tlb_flush_requests); > -- > 2.35.1 >
diff --git a/arch/x86/include/asm/kvm_host.h b/arch/x86/include/asm/kvm_host.h index 3460bcd75bf2..488934fadc3a 100644 --- a/arch/x86/include/asm/kvm_host.h +++ b/arch/x86/include/asm/kvm_host.h @@ -105,6 +105,8 @@ KVM_ARCH_REQ_FLAGS(30, KVM_REQUEST_WAIT | KVM_REQUEST_NO_WAKEUP) #define KVM_REQ_MMU_FREE_OBSOLETE_ROOTS \ KVM_ARCH_REQ_FLAGS(31, KVM_REQUEST_WAIT | KVM_REQUEST_NO_WAKEUP) +#define KVM_REQ_HV_TLB_FLUSH \ + KVM_ARCH_REQ_FLAGS(32, KVM_REQUEST_WAIT | KVM_REQUEST_NO_WAKEUP) #define CR0_RESERVED_BITS \ (~(unsigned long)(X86_CR0_PE | X86_CR0_MP | X86_CR0_EM | X86_CR0_TS \ diff --git a/arch/x86/kvm/hyperv.c b/arch/x86/kvm/hyperv.c index e235c1d43f83..b60bad29caf8 100644 --- a/arch/x86/kvm/hyperv.c +++ b/arch/x86/kvm/hyperv.c @@ -1876,11 +1876,11 @@ static u64 kvm_hv_flush_tlb(struct kvm_vcpu *vcpu, struct kvm_hv_hcall *hc) * analyze it here, flush TLB regardless of the specified address space. */ if (all_cpus) { - kvm_make_all_cpus_request(kvm, KVM_REQ_TLB_FLUSH_GUEST); + kvm_make_all_cpus_request(kvm, KVM_REQ_HV_TLB_FLUSH); } else { sparse_set_to_vcpu_mask(kvm, sparse_banks, valid_bank_mask, vcpu_mask); - kvm_make_vcpus_request_mask(kvm, KVM_REQ_TLB_FLUSH_GUEST, vcpu_mask); + kvm_make_vcpus_request_mask(kvm, KVM_REQ_HV_TLB_FLUSH, vcpu_mask); } ret_success: diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c index e9647614dc8c..3c54f6804b7b 100644 --- a/arch/x86/kvm/x86.c +++ b/arch/x86/kvm/x86.c @@ -3341,7 +3341,12 @@ void kvm_service_local_tlb_flush_requests(struct kvm_vcpu *vcpu) if (kvm_check_request(KVM_REQ_TLB_FLUSH_CURRENT, vcpu)) kvm_vcpu_flush_tlb_current(vcpu); - if (kvm_check_request(KVM_REQ_TLB_FLUSH_GUEST, vcpu)) + if (kvm_check_request(KVM_REQ_TLB_FLUSH_GUEST, vcpu)) { + kvm_vcpu_flush_tlb_guest(vcpu); + kvm_clear_request(KVM_REQ_HV_TLB_FLUSH, vcpu); + } + + if (kvm_check_request(KVM_REQ_HV_TLB_FLUSH, vcpu)) kvm_vcpu_flush_tlb_guest(vcpu); } EXPORT_SYMBOL_GPL(kvm_service_local_tlb_flush_requests);
In preparation to implementing fine-grained Hyper-V TLB flush and Direct TLB flush, resurrect dedicated KVM_REQ_HV_TLB_FLUSH request bit. As KVM_REQ_TLB_FLUSH_GUEST is a stronger operation, clear KVM_REQ_HV_TLB_FLUSH request in kvm_service_local_tlb_flush_requests() when KVM_REQ_TLB_FLUSH_GUEST was also requested. No functional change intended. Signed-off-by: Vitaly Kuznetsov <vkuznets@redhat.com> --- arch/x86/include/asm/kvm_host.h | 2 ++ arch/x86/kvm/hyperv.c | 4 ++-- arch/x86/kvm/x86.c | 7 ++++++- 3 files changed, 10 insertions(+), 3 deletions(-)