Commit 1438921c authored Oct 08, 2018 by Liran Alon Committed by Paolo Bonzini Oct 13, 2018

KVM: nVMX: Flush TLB entries tagged by dest EPTP on L1<->L2 transitions



If L1 and L2 share VPID (because L1 don't use VPID or we haven't allocated
a vpid02), we need to flush TLB on L1<->L2 transitions.

Before this patch, this TLB flushing was done by vmx_flush_tlb().
If L0 use EPT, this will translate into INVEPT(active_eptp);
However, if L1 use EPT, in L1->L2 VMEntry, active EPTP is EPTP01 but
TLB entries populated by L2 are tagged with EPTP02.
Therefore we should delay vmx_flush_tlb() until active_eptp is EPTP02.

To achieve this, instead of directly calling vmx_flush_tlb() we request
it to be called by KVM_REQ_TLB_FLUSH which is evaluated after
KVM_REQ_LOAD_CR3 which sets the active_eptp to EPTP02 as required.

Similarly, on L2->L1 VMExit, active EPTP is EPTP02 but TLB entries
populated by L1 are tagged with EPTP01 and therefore we should delay
vmx_flush_tlb() until active_eptp is EPTP01.

Reviewed-by: Mihai Carabas <mihai.carabas@oracle.com>
Reviewed-by: Darren Kenny <darren.kenny@oracle.com>
Reviewed-by: Nikita Leshenko <nikita.leshchenko@oracle.com>
Signed-off-by: Liran Alon <liran.alon@oracle.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

parent 3de6347b

arch/x86/kvm/vmx.c

+14 −2

Original line number	Diff line number	Diff line
		@@ -12290,7 +12290,15 @@ static int prepare_vmcs02(struct kvm_vcpu vcpu, struct vmcs12 vmcs12,
		__vmx_flush_tlb(vcpu, vmx->nested.vpid02, true);
		}
		} else {
		vmx_flush_tlb(vcpu, true);
		/*
		* If L1 use EPT, then L0 needs to execute INVEPT on
		* EPTP02 instead of EPTP01. Therefore, delay TLB
		* flush until vmcs02->eptp is fully updated by
		* KVM_REQ_LOAD_CR3. Note that this assumes
		* KVM_REQ_TLB_FLUSH is evaluated after
		* KVM_REQ_LOAD_CR3 in vcpu_enter_guest().
		*/
		kvm_make_request(KVM_REQ_TLB_FLUSH, vcpu);
		}
		}

		@@ -13188,10 +13196,14 @@ static void load_vmcs12_host_state(struct kvm_vcpu *vcpu,
		* Therefore, flush TLB only in case vmcs01 uses VPID and
		* vmcs12 don't use VPID as in this case L1 & L2 TLB entries
		* are both tagged with vmx->vpid.
		*
		* If vmcs12 uses EPT, we need to execute this flush on EPTP01
		* and therefore we request the TLB flush to happen only after VMCS EPTP
		* has been set by KVM_REQ_LOAD_CR3.
		*/
		if (enable_vpid &&
		!(nested_cpu_has_vpid(vmcs12) && to_vmx(vcpu)->nested.vpid02)) {
		vmx_flush_tlb(vcpu, true);
		kvm_make_request(KVM_REQ_TLB_FLUSH, vcpu);
		}

		vmcs_write32(GUEST_SYSENTER_CS, vmcs12->host_ia32_sysenter_cs);