[PATCH 4/7] KVM: arm/arm64: Condition TLB maintenance on unmap with a flag

[Marc Zyngier <maz@kernel.org>]

In order to allow the elision of TLB maintenance operations
on unmap, add a new flag (KVM_UNMAP_ELIDE_TBLI) that a caller
can use to indicate that TLB invalidation is not required.

Nobody is passing this flag yet, hence no functional change.

Signed-off-by: Marc Zyngier <maz@kernel.org>
---
 virt/kvm/arm/mmu.c | 19 +++++++++++++------
 1 file changed, 13 insertions(+), 6 deletions(-)

diff --git a/virt/kvm/arm/mmu.c b/virt/kvm/arm/mmu.c
index ebf8c87cc007..4399866842dc 100644
--- a/virt/kvm/arm/mmu.c
+++ b/virt/kvm/arm/mmu.c
@@ -37,6 +37,7 @@ static unsigned long io_map_base;
 
 /* Flags controlling S2 unmapping */
 #define KVM_UNMAP_ELIDE_CMO		(1UL << 0)
+#define KVM_UNMAP_ELIDE_TBLI		(1UL << 1)
 
 #define KVM_S2PTE_FLAG_IS_IOMAP		(1UL << 0)
 #define KVM_S2_FLAG_LOGGING_ACTIVE	(1UL << 1)
@@ -160,7 +161,8 @@ static void clear_stage2_pgd_entry(struct kvm *kvm, pgd_t *pgd, phys_addr_t addr
 {
 	pud_t *pud_table __maybe_unused = stage2_pud_offset(kvm, pgd, 0UL);
 	stage2_pgd_clear(kvm, pgd);
-	kvm_tlb_flush_vmid_ipa(kvm, addr);
+	if (!(flags & KVM_UNMAP_ELIDE_TBLI))
+		kvm_tlb_flush_vmid_ipa(kvm, addr);
 	stage2_pud_free(kvm, pud_table);
 	put_page(virt_to_page(pgd));
 }
@@ -171,7 +173,8 @@ static void clear_stage2_pud_entry(struct kvm *kvm, pud_t *pud, phys_addr_t addr
 	pmd_t *pmd_table __maybe_unused = stage2_pmd_offset(kvm, pud, 0);
 	VM_BUG_ON(stage2_pud_huge(kvm, *pud));
 	stage2_pud_clear(kvm, pud);
-	kvm_tlb_flush_vmid_ipa(kvm, addr);
+	if (!(flags & KVM_UNMAP_ELIDE_TBLI))
+		kvm_tlb_flush_vmid_ipa(kvm, addr);
 	stage2_pmd_free(kvm, pmd_table);
 	put_page(virt_to_page(pud));
 }
@@ -182,7 +185,8 @@ static void clear_stage2_pmd_entry(struct kvm *kvm, pmd_t *pmd, phys_addr_t addr
 	pte_t *pte_table = pte_offset_kernel(pmd, 0);
 	VM_BUG_ON(pmd_thp_or_huge(*pmd));
 	pmd_clear(pmd);
-	kvm_tlb_flush_vmid_ipa(kvm, addr);
+	if (!(flags & KVM_UNMAP_ELIDE_TBLI))
+		kvm_tlb_flush_vmid_ipa(kvm, addr);
 	free_page((unsigned long)pte_table);
 	put_page(virt_to_page(pmd));
 }
@@ -253,7 +257,8 @@ static void unmap_stage2_ptes(struct kvm *kvm, pmd_t *pmd,
 			pte_t old_pte = *pte;
 
 			kvm_set_pte(pte, __pte(0));
-			kvm_tlb_flush_vmid_ipa(kvm, addr);
+			if (!(flags & KVM_UNMAP_ELIDE_TBLI))
+				kvm_tlb_flush_vmid_ipa(kvm, addr);
 
 			/* No need to invalidate the cache for device mappings */
 			if (!kvm_is_device_pfn(pte_pfn(old_pte)) &&
@@ -283,7 +288,8 @@ static void unmap_stage2_pmds(struct kvm *kvm, pud_t *pud,
 				pmd_t old_pmd = *pmd;
 
 				pmd_clear(pmd);
-				kvm_tlb_flush_vmid_ipa(kvm, addr);
+				if (!(flags & KVM_UNMAP_ELIDE_TBLI))
+					kvm_tlb_flush_vmid_ipa(kvm, addr);
 
 				if (!(flags & KVM_UNMAP_ELIDE_CMO))
 					kvm_flush_dcache_pmd(old_pmd);
@@ -314,7 +320,8 @@ static void unmap_stage2_puds(struct kvm *kvm, pgd_t *pgd,
 				pud_t old_pud = *pud;
 
 				stage2_pud_clear(kvm, pud);
-				kvm_tlb_flush_vmid_ipa(kvm, addr);
+				if (!(flags & KVM_UNMAP_ELIDE_TBLI))
+					kvm_tlb_flush_vmid_ipa(kvm, addr);
 				if (!(flags & KVM_UNMAP_ELIDE_CMO))
 					kvm_flush_dcache_pud(old_pud);
 				put_page(virt_to_page(pud));
-- 
2.20.1