The per-VM ASID is currently shared by both L1 and L2 guests. That ASID
is currently flushed on every transition between L1 and L2.
Allocate and track a separate ASID per-VM for nested guests. This is in
preparation for doing fine-grained TLB flushes on nested transitions
instead of unconditional full flushes.
Nested ASIDs are still not fully maintained (e.g. a remote flush will
only flush the current ASID), so keep the TLB flush on every transition
until this is sorted out in following changes.
Add a helper to get the ASID associated with a specific VMCB and use it
instead of directly reading the VM's ASID. This transparently uses L2's
ASID when an L2 guest is being run.
L1's ASID is flushed on KVM_REQ_TLB_FLUSH_GUEST if it is the active
context, so remove the TODO in nested_svm_transition_tlb_flush() about
it.
Signed-off-by: Yosry Ahmed <yosry.ahmed@xxxxxxxxx>
---
arch/x86/kvm/svm/nested.c | 8 ++++++--
arch/x86/kvm/svm/svm.c | 13 +++++++++++--
arch/x86/kvm/svm/svm.h | 3 ++-
3 files changed, 19 insertions(+), 5 deletions(-)
diff --git a/arch/x86/kvm/svm/nested.c b/arch/x86/kvm/svm/nested.c
index 81184b2fb27fd..75223869aa8c6 100644
--- a/arch/x86/kvm/svm/nested.c
+++ b/arch/x86/kvm/svm/nested.c
@@ -495,7 +495,6 @@ static void nested_svm_transition_tlb_flush(struct kvm_vcpu *vcpu)
* - Honor L1's request to flush an ASID on nested VMRUN
* - Sync nested NPT MMU on VMRUN that flushes L2's ASID[*]
* - Don't crush a pending TLB flush in vmcb02 on nested VMRUN
- * - Flush L1's ASID on KVM_REQ_TLB_FLUSH_GUEST
*
* [*] Unlike nested EPT, SVM's ASID management can invalidate nested
* NPT guest-physical mappings on VMRUN.
@@ -677,7 +676,7 @@ static void nested_vmcb02_prepare_control(struct vcpu_svm *svm,
vmcb02->control.nested_ctl = vmcb01->control.nested_ctl;
vmcb02->control.iopm_base_pa = vmcb01->control.iopm_base_pa;
vmcb02->control.msrpm_base_pa = vmcb01->control.msrpm_base_pa;
- vmcb02->control.asid = svm_asid(vcpu->kvm);
+ vmcb02->control.asid = svm_nested_asid(vcpu->kvm);
/* Also overwritten later if necessary. */
vmcb_clr_flush_asid(vmcb02);
@@ -1179,6 +1178,7 @@ static void nested_svm_triple_fault(struct kvm_vcpu *vcpu)
int svm_allocate_nested(struct vcpu_svm *svm)
{
+ struct kvm_svm *kvm_svm = to_kvm_svm(svm->vcpu.kvm);
struct page *vmcb02_page;
if (svm->nested.initialized)
@@ -1196,6 +1196,10 @@ int svm_allocate_nested(struct vcpu_svm *svm)
svm_vcpu_init_msrpm(&svm->vcpu, svm->nested.msrpm);
svm->nested.initialized = true;
+
+ if (!kvm_svm->nested_asid)
+ kvm_svm->nested_asid = kvm_svm->asid;
+
return 0;
err_free_vmcb02:
diff --git a/arch/x86/kvm/svm/svm.c b/arch/x86/kvm/svm/svm.c
index f028d006f69dc..e664d8428c792 100644
--- a/arch/x86/kvm/svm/svm.c
+++ b/arch/x86/kvm/svm/svm.c
@@ -1225,17 +1225,26 @@ static inline void init_vmcb_after_set_cpuid(struct kvm_vcpu *vcpu)
}
}
-unsigned int svm_asid(struct kvm *kvm)
+unsigned int svm_nested_asid(struct kvm *kvm)
+{
+ return to_kvm_svm(kvm)->nested_asid;
+}
+
+static unsigned int svm_asid(struct kvm *kvm)
{
return to_kvm_svm(kvm)->asid;
}
static unsigned int svm_get_current_asid(struct vcpu_svm *svm)
{
- struct kvm *kvm = svm->vcpu.kvm;
+ struct kvm_vcpu *vcpu = &svm->vcpu;
+ struct kvm *kvm = vcpu->kvm;
if (sev_guest(kvm))
return sev_get_asid(kvm);
+ if (is_guest_mode(vcpu))
+ return svm_nested_asid(kvm);
+ WARN_ON_ONCE(svm->current_vmcb != &svm->vmcb01);
return svm_asid(kvm);
}
diff --git a/arch/x86/kvm/svm/svm.h b/arch/x86/kvm/svm/svm.h
index 436b7e83141b9..e67e3a64e92f7 100644
--- a/arch/x86/kvm/svm/svm.h
+++ b/arch/x86/kvm/svm/svm.h
@@ -118,6 +118,7 @@ struct kvm_svm {
struct kvm kvm;
unsigned int asid;
+ unsigned int nested_asid;
/* Struct members for AVIC */
u32 avic_vm_id;
@@ -651,7 +652,7 @@ void svm_complete_interrupt_delivery(struct kvm_vcpu *vcpu, int delivery_mode,
int trig_mode, int vec);
bool svm_register_asid(unsigned int asid);
void svm_unregister_asid(unsigned int asid);
-unsigned int svm_asid(struct kvm *kvm);
+unsigned int svm_nested_asid(struct kvm *kvm);
/* nested.c */
--
2.49.0.395.g12beb8f557-goog
