[RFC PATCH 17/24] KVM: nSVM: Flush both L1 and L2 ASIDs on KVM_REQ_TLB_FLUSH
From: Yosry Ahmed
Date: Wed Mar 26 2025 - 15:43:02 EST
KVM_REQ_TLB_FLUSH is used to flush all TLB entries for all contexts
(e.g. in kvm_flush_remote_tlbs()). Flush both L1 and L2 ASIDs in
svm_flush_tlb_all() to handle it appropriately.
This is currently not required as nested transitions do unconditional
TLB flushes, but this is a step toward eliminating that.
Signed-off-by: Yosry Ahmed <yosry.ahmed@xxxxxxxxx>
---
arch/x86/kvm/svm/nested.c | 1 -
arch/x86/kvm/svm/svm.c | 10 ++--------
2 files changed, 2 insertions(+), 9 deletions(-)
diff --git a/arch/x86/kvm/svm/nested.c b/arch/x86/kvm/svm/nested.c
index c336ab63c6da3..56a4ff480bb3d 100644
--- a/arch/x86/kvm/svm/nested.c
+++ b/arch/x86/kvm/svm/nested.c
@@ -491,7 +491,6 @@ static void nested_svm_entry_tlb_flush(struct kvm_vcpu *vcpu)
* TODO: optimize unconditional TLB flush/MMU sync. A partial list of
* things to fix before this can be conditional:
*
- * - Flush TLBs for both L1 and L2 remote TLB flush
* - 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
diff --git a/arch/x86/kvm/svm/svm.c b/arch/x86/kvm/svm/svm.c
index fb6b9f88a1504..4cad1085936bb 100644
--- a/arch/x86/kvm/svm/svm.c
+++ b/arch/x86/kvm/svm/svm.c
@@ -4064,14 +4064,8 @@ static void svm_flush_tlb_all(struct kvm_vcpu *vcpu)
if (WARN_ON_ONCE(svm_hv_is_enlightened_tlb_enabled(vcpu)))
hv_flush_remote_tlbs(vcpu->kvm);
- /*
- * Flush only the current ASID even if the TLB flush was invoked via
- * kvm_flush_remote_tlbs(). Although flushing remote TLBs requires all
- * ASIDs to be flushed, KVM uses a single ASID for L1 and L2, and
- * unconditionally does a TLB flush on both nested VM-Enter and nested
- * VM-Exit (via kvm_mmu_reset_context()).
- */
- svm_flush_tlb_asid(vcpu, is_guest_mode(vcpu));
+ svm_flush_tlb_asid(vcpu, false);
+ svm_flush_tlb_asid(vcpu, true);
}
static void svm_flush_tlb_gva(struct kvm_vcpu *vcpu, gva_t gva)
--
2.49.0.395.g12beb8f557-goog