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Groups > linux.kernel > #1234036
| From | Paolo Bonzini <pbonzini@redhat.com> |
|---|---|
| Newsgroups | linux.kernel |
| Subject | [FYI PATCH 19/20] KVM: nVMX: nested VPID emulation |
| Date | 2015-09-28 12:50 +0200 |
| Message-ID | <qdEam-3iu-17@gated-at.bofh.it> (permalink) |
| References | <qdE0F-37c-5@gated-at.bofh.it> |
| Organization | linux.* mail to news gateway |
From: Wanpeng Li <wanpeng.li@hotmail.com>
VPID is used to tag address space and avoid a TLB flush. Currently L0 use
the same VPID to run L1 and all its guests. KVM flushes VPID when switching
between L1 and L2.
This patch advertises VPID to the L1 hypervisor, then address space of L1
and L2 can be separately treated and avoid TLB flush when swithing between
L1 and L2. For each nested vmentry, if vpid12 is changed, reuse shadow vpid
w/ an invvpid.
Performance:
run lmbench on L2 w/ 3.5 kernel.
Context switching - times in microseconds - smaller is better
-------------------------------------------------------------------------
Host OS 2p/0K 2p/16K 2p/64K 8p/16K 8p/64K 16p/16K 16p/64K
ctxsw ctxsw ctxsw ctxsw ctxsw ctxsw ctxsw
--------- ------------- ------ ------ ------ ------ ------ ------- -------
kernel Linux 3.5.0-1 1.2200 1.3700 1.4500 4.7800 2.3300 5.60000 2.88000 nested VPID
kernel Linux 3.5.0-1 1.2600 1.4300 1.5600 12.7 12.9 3.49000 7.46000 vanilla
Reviewed-by: Jan Kiszka <jan.kiszka@siemens.com>
Suggested-by: Wincy Van <fanwenyi0529@gmail.com>
Signed-off-by: Wanpeng Li <wanpeng.li@hotmail.com>
[Handle the case where vpid02 cannot be allocated. - Paolo]
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
---
arch/x86/kvm/vmx.c | 39 ++++++++++++++++++++++++++++++++-------
1 file changed, 32 insertions(+), 7 deletions(-)
diff --git a/arch/x86/kvm/vmx.c b/arch/x86/kvm/vmx.c
index bb7ae30caa13..75f3ee01f59b 100644
--- a/arch/x86/kvm/vmx.c
+++ b/arch/x86/kvm/vmx.c
@@ -424,6 +424,9 @@ struct nested_vmx {
/* to migrate it to L2 if VM_ENTRY_LOAD_DEBUG_CONTROLS is off */
u64 vmcs01_debugctl;
+ u16 vpid02;
+ u16 last_vpid;
+
u32 nested_vmx_procbased_ctls_low;
u32 nested_vmx_procbased_ctls_high;
u32 nested_vmx_true_procbased_ctls_low;
@@ -1157,6 +1160,11 @@ static inline bool nested_cpu_has_virt_x2apic_mode(struct vmcs12 *vmcs12)
return nested_cpu_has2(vmcs12, SECONDARY_EXEC_VIRTUALIZE_X2APIC_MODE);
}
+static inline bool nested_cpu_has_vpid(struct vmcs12 *vmcs12)
+{
+ return nested_cpu_has2(vmcs12, SECONDARY_EXEC_ENABLE_VPID);
+}
+
static inline bool nested_cpu_has_apic_reg_virt(struct vmcs12 *vmcs12)
{
return nested_cpu_has2(vmcs12, SECONDARY_EXEC_APIC_REGISTER_VIRT);
@@ -2471,6 +2479,7 @@ static void nested_vmx_setup_ctls_msrs(struct vcpu_vmx *vmx)
SECONDARY_EXEC_VIRTUALIZE_APIC_ACCESSES |
SECONDARY_EXEC_RDTSCP |
SECONDARY_EXEC_VIRTUALIZE_X2APIC_MODE |
+ SECONDARY_EXEC_ENABLE_VPID |
SECONDARY_EXEC_APIC_REGISTER_VIRT |
SECONDARY_EXEC_VIRTUAL_INTR_DELIVERY |
SECONDARY_EXEC_WBINVD_EXITING |
@@ -6670,6 +6679,7 @@ static void free_nested(struct vcpu_vmx *vmx)
return;
vmx->nested.vmxon = false;
+ free_vpid(vmx->nested.vpid02);
nested_release_vmcs12(vmx);
if (enable_shadow_vmcs)
free_vmcs(vmx->nested.current_shadow_vmcs);
@@ -7199,7 +7209,7 @@ static int handle_invvpid(struct kvm_vcpu *vcpu)
case VMX_VPID_EXTENT_INDIVIDUAL_ADDR:
case VMX_VPID_EXTENT_SINGLE_CONTEXT:
case VMX_VPID_EXTENT_ALL_CONTEXT:
- vmx_flush_tlb(vcpu);
+ __vmx_flush_tlb(vcpu, to_vmx(vcpu)->nested.vpid02);
nested_vmx_succeed(vcpu);
break;
default:
@@ -8575,8 +8585,10 @@ static struct kvm_vcpu *vmx_create_vcpu(struct kvm *kvm, unsigned int id)
goto free_vmcs;
}
- if (nested)
+ if (nested) {
nested_vmx_setup_ctls_msrs(vmx);
+ vmx->nested.vpid02 = allocate_vpid();
+ }
vmx->nested.posted_intr_nv = -1;
vmx->nested.current_vmptr = -1ull;
@@ -8597,6 +8609,7 @@ static struct kvm_vcpu *vmx_create_vcpu(struct kvm *kvm, unsigned int id)
return &vmx->vcpu;
free_vmcs:
+ free_vpid(vmx->nested.vpid02);
free_loaded_vmcs(vmx->loaded_vmcs);
free_msrs:
kfree(vmx->guest_msrs);
@@ -9458,12 +9471,24 @@ static void prepare_vmcs02(struct kvm_vcpu *vcpu, struct vmcs12 *vmcs12)
if (enable_vpid) {
/*
- * Trivially support vpid by letting L2s share their parent
- * L1's vpid. TODO: move to a more elaborate solution, giving
- * each L2 its own vpid and exposing the vpid feature to L1.
+ * There is no direct mapping between vpid02 and vpid12, the
+ * vpid02 is per-vCPU for L0 and reused while the value of
+ * vpid12 is changed w/ one invvpid during nested vmentry.
+ * The vpid12 is allocated by L1 for L2, so it will not
+ * influence global bitmap(for vpid01 and vpid02 allocation)
+ * even if spawn a lot of nested vCPUs.
*/
- vmcs_write16(VIRTUAL_PROCESSOR_ID, vmx->vpid);
- vmx_flush_tlb(vcpu);
+ if (nested_cpu_has_vpid(vmcs12) && vmx->nested.vpid02) {
+ vmcs_write16(VIRTUAL_PROCESSOR_ID, vmx->nested.vpid02);
+ if (vmcs12->virtual_processor_id != vmx->nested.last_vpid) {
+ vmx->nested.last_vpid = vmcs12->virtual_processor_id;
+ __vmx_flush_tlb(vcpu, to_vmx(vcpu)->nested.vpid02);
+ }
+ } else {
+ vmcs_write16(VIRTUAL_PROCESSOR_ID, vmx->vpid);
+ vmx_flush_tlb(vcpu);
+ }
+
}
if (nested_cpu_has_ept(vmcs12)) {
--
1.8.3.1
--
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[FYI PATCH 00/20] kvm/queue will be merged soon to kvm/next Paolo Bonzini <pbonzini@redhat.com> - 2015-09-28 12:40 +0200 [FYI PATCH 03/20] KVM: x86: replace vm_has_apicv hook with cpu_uses_apicv Paolo Bonzini <pbonzini@redhat.com> - 2015-09-28 12:40 +0200 [FYI PATCH 15/20] kvm/x86: Hyper-V HV_X64_MSR_VP_RUNTIME support Paolo Bonzini <pbonzini@redhat.com> - 2015-09-28 12:40 +0200 [FYI PATCH 12/20] kvm: add capability for any-length ioeventfds Paolo Bonzini <pbonzini@redhat.com> - 2015-09-28 12:40 +0200 [FYI PATCH 20/20] KVM: vmx: disable posted interrupts if no local APIC Paolo Bonzini <pbonzini@redhat.com> - 2015-09-28 12:50 +0200 [FYI PATCH 04/20] KVM: x86: introduce lapic_in_kernel Paolo Bonzini <pbonzini@redhat.com> - 2015-09-28 12:50 +0200 [FYI PATCH 11/20] kvm: add tracepoint for fast mmio Paolo Bonzini <pbonzini@redhat.com> - 2015-09-28 12:50 +0200 [FYI PATCH 17/20] KVM: VMX: introduce __vmx_flush_tlb to handle specific vpid Paolo Bonzini <pbonzini@redhat.com> - 2015-09-28 12:50 +0200 [FYI PATCH 09/20] KVM: x86: Add support for local interrupt requests from userspace Paolo Bonzini <pbonzini@redhat.com> - 2015-09-28 12:50 +0200 [FYI PATCH 10/20] kvm: use kmalloc() instead of kzalloc() during iodev register/unregister Paolo Bonzini <pbonzini@redhat.com> - 2015-09-28 12:50 +0200 [FYI PATCH 19/20] KVM: nVMX: nested VPID emulation Paolo Bonzini <pbonzini@redhat.com> - 2015-09-28 12:50 +0200 [FYI PATCH 18/20] KVM: nVMX: emulate the INVVPID instruction Paolo Bonzini <pbonzini@redhat.com> - 2015-09-28 12:50 +0200 [FYI PATCH 06/20] KVM: x86: Split the APIC from the rest of IRQCHIP. Paolo Bonzini <pbonzini@redhat.com> - 2015-09-28 12:50 +0200 [FYI PATCH 07/20] KVM: x86: Add KVM exit for IOAPIC EOIs Paolo Bonzini <pbonzini@redhat.com> - 2015-09-28 12:50 +0200 [FYI PATCH 05/20] KVM: x86: unify handling of interrupt window Paolo Bonzini <pbonzini@redhat.com> - 2015-09-28 12:50 +0200 [FYI PATCH 13/20] kvm/x86: Hyper-V HV_X64_MSR_RESET msr Paolo Bonzini <pbonzini@redhat.com> - 2015-09-28 12:50 +0200 [FYI PATCH 14/20] kvm/x86: Hyper-V HV_X64_MSR_VP_INDEX export for QEMU. Paolo Bonzini <pbonzini@redhat.com> - 2015-09-28 12:50 +0200 [FYI PATCH 02/20] KVM: x86: store IOAPIC-handled vectors in each VCPU Paolo Bonzini <pbonzini@redhat.com> - 2015-09-28 12:50 +0200 [FYI PATCH 01/20] KVM: x86: set TMR when the interrupt is accepted Paolo Bonzini <pbonzini@redhat.com> - 2015-09-28 12:50 +0200
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