[RFC PATCH 15/17] KVM: arm64: Allow parallel calls to kvm_pgtable_stage2_map()

[Oliver Upton]

The map walker is now appraised of how to walk the tables in parallel
with another table walker. Take a parameter indicating whether or not a
walk is done in parallel so as to relax the atomicity/locking
requirements on ptes.

Defer actually using parallel walks to a later change.

Signed-off-by: Oliver Upton <oupton at google.com>
---
 arch/arm64/include/asm/kvm_pgtable.h  | 4 +++-
 arch/arm64/kvm/hyp/nvhe/mem_protect.c | 2 +-
 arch/arm64/kvm/hyp/pgtable.c          | 4 ++--
 arch/arm64/kvm/mmu.c                  | 6 +++---
 4 files changed, 9 insertions(+), 7 deletions(-)

diff --git a/arch/arm64/include/asm/kvm_pgtable.h b/arch/arm64/include/asm/kvm_pgtable.h
index 52e55e00f0ca..9830eea19de4 100644
--- a/arch/arm64/include/asm/kvm_pgtable.h
+++ b/arch/arm64/include/asm/kvm_pgtable.h
@@ -328,6 +328,8 @@ void kvm_pgtable_stage2_destroy(struct kvm_pgtable *pgt);
  * @prot:	Permissions and attributes for the mapping.
  * @mc:		Cache of pre-allocated and zeroed memory from which to allocate
  *		page-table pages.
+ * @shared:	true if multiple software walkers could be traversing the tables
+ *		in parallel
  *
  * The offset of @addr within a page is ignored, @size is rounded-up to
  * the next page boundary and @phys is rounded-down to the previous page
@@ -349,7 +351,7 @@ void kvm_pgtable_stage2_destroy(struct kvm_pgtable *pgt);
  */
 int kvm_pgtable_stage2_map(struct kvm_pgtable *pgt, u64 addr, u64 size,
 			   u64 phys, enum kvm_pgtable_prot prot,
-			   void *mc);
+			   void *mc, bool shared);
 
 /**
  * kvm_pgtable_stage2_set_owner() - Unmap and annotate pages in the IPA space to
diff --git a/arch/arm64/kvm/hyp/nvhe/mem_protect.c b/arch/arm64/kvm/hyp/nvhe/mem_protect.c
index 42a5f35cd819..53b172036c2a 100644
--- a/arch/arm64/kvm/hyp/nvhe/mem_protect.c
+++ b/arch/arm64/kvm/hyp/nvhe/mem_protect.c
@@ -251,7 +251,7 @@ static inline int __host_stage2_idmap(u64 start, u64 end,
 				      enum kvm_pgtable_prot prot)
 {
 	return kvm_pgtable_stage2_map(&host_kvm.pgt, start, end - start, start,
-				      prot, &host_s2_pool);
+				      prot, &host_s2_pool, false);
 }
 
 /*
diff --git a/arch/arm64/kvm/hyp/pgtable.c b/arch/arm64/kvm/hyp/pgtable.c
index a9a48edba63b..20ff198ebef7 100644
--- a/arch/arm64/kvm/hyp/pgtable.c
+++ b/arch/arm64/kvm/hyp/pgtable.c
@@ -1119,7 +1119,7 @@ static int stage2_map_walker(u64 addr, u64 end, u32 level, kvm_pte_t *ptep, kvm_
 
 int kvm_pgtable_stage2_map(struct kvm_pgtable *pgt, u64 addr, u64 size,
 			   u64 phys, enum kvm_pgtable_prot prot,
-			   void *mc)
+			   void *mc, bool shared)
 {
 	int ret;
 	struct stage2_map_data map_data = {
@@ -1144,7 +1144,7 @@ int kvm_pgtable_stage2_map(struct kvm_pgtable *pgt, u64 addr, u64 size,
 	if (ret)
 		return ret;
 
-	ret = kvm_pgtable_walk(pgt, addr, size, &walker, false);
+	ret = kvm_pgtable_walk(pgt, addr, size, &walker, shared);
 	dsb(ishst);
 	return ret;
 }
diff --git a/arch/arm64/kvm/mmu.c b/arch/arm64/kvm/mmu.c
index 6ecf37009c21..63cf18cdb978 100644
--- a/arch/arm64/kvm/mmu.c
+++ b/arch/arm64/kvm/mmu.c
@@ -832,7 +832,7 @@ int kvm_phys_addr_ioremap(struct kvm *kvm, phys_addr_t guest_ipa,
 
 		write_lock(&kvm->mmu_lock);
 		ret = kvm_pgtable_stage2_map(pgt, addr, PAGE_SIZE, pa, prot,
-					     &cache);
+					     &cache, false);
 		write_unlock(&kvm->mmu_lock);
 		if (ret)
 			break;
@@ -1326,7 +1326,7 @@ static int user_mem_abort(struct kvm_vcpu *vcpu, phys_addr_t fault_ipa,
 
 		ret = kvm_pgtable_stage2_map(pgt, fault_ipa, vma_pagesize,
 					     __pfn_to_phys(pfn), prot,
-					     mmu_caches);
+					     mmu_caches, true);
 	}
 
 	/* Mark the page dirty only if the fault is handled successfully */
@@ -1526,7 +1526,7 @@ bool kvm_set_spte_gfn(struct kvm *kvm, struct kvm_gfn_range *range)
 	 */
 	kvm_pgtable_stage2_map(kvm->arch.mmu.pgt, range->start << PAGE_SHIFT,
 			       PAGE_SIZE, __pfn_to_phys(pfn),
-			       KVM_PGTABLE_PROT_R, NULL);
+			       KVM_PGTABLE_PROT_R, NULL, false);
 
 	return false;
 }
-- 
2.36.0.rc0.470.gd361397f0d-goog