[PATCH v2 1/4] KVM: arm/arm64: Share common code in user_mem_abort()

Christoffer Dall [off-list ref] writes:

On Tue, May 01, 2018 at 11:26:56AM +0100, Punit Agrawal wrote:

quoted

The code for operations such as marking the pfn as dirty, and
dcache/icache maintenance during stage 2 fault handling is duplicated
between normal pages and PMD hugepages.

Instead of creating another copy of the operations when we introduce
PUD hugepages, let's share them across the different pagesizes.

Signed-off-by: Punit Agrawal <redacted>
Reviewed-by: Christoffer Dall <redacted>
Cc: Marc Zyngier <redacted>
---
 virt/kvm/arm/mmu.c | 66 +++++++++++++++++++++++++++-------------------
 1 file changed, 39 insertions(+), 27 deletions(-)

diff --git a/virt/kvm/arm/mmu.c b/virt/kvm/arm/mmu.c
index 7f6a944db23d..686fc6a4b866 100644
--- a/virt/kvm/arm/mmu.c
+++ b/virt/kvm/arm/mmu.c

[...]

quoted

@@ -1517,28 +1533,34 @@ static int user_mem_abort(struct kvm_vcpu *vcpu, phys_addr_t fault_ipa,
 	if (mmu_notifier_retry(kvm, mmu_seq))
 		goto out_unlock;
 
-	if (!hugetlb && !force_pte)
+	if (!hugetlb && !force_pte) {
 		hugetlb = transparent_hugepage_adjust(&pfn, &fault_ipa);
+		/*
+		 * Only PMD_SIZE transparent hugepages(THP) are
+		 * currently supported. This code will need to be
+		 * updated to support other THP sizes.
+		 */
+		if (hugetlb)
+			vma_pagesize = PMD_SIZE;

nit: this is a bit of a trap waiting to happen, as the suggested
semantics of hugetlb is now hugetlbfs and not THP.

It may be slightly nicer to do do:

		if (transparent_hugepage_adjust(&pfn, &fault_ipa))
			vma_pagesize = PMD_SIZE;

I should've noticed this.

I'll incorporate your suggestion and update the condition below using
hugetlb to rely on vma_pagesize instead.

Thanks,
Punit

quoted

+	}
+
+	if (writable)
+		kvm_set_pfn_dirty(pfn);
+
+	if (fault_status != FSC_PERM)
+		clean_dcache_guest_page(pfn, vma_pagesize);
+
+	if (exec_fault)
+		invalidate_icache_guest_page(pfn, vma_pagesize);
 
 	if (hugetlb) {
 		pmd_t new_pmd = pfn_pmd(pfn, mem_type);
 		new_pmd = pmd_mkhuge(new_pmd);
-		if (writable) {
+		if (writable)
 			new_pmd = kvm_s2pmd_mkwrite(new_pmd);
-			kvm_set_pfn_dirty(pfn);
-		}
 
-		if (fault_status != FSC_PERM)
-			clean_dcache_guest_page(pfn, PMD_SIZE);
-
-		if (exec_fault) {
+		if (stage2_should_exec(kvm, fault_ipa, exec_fault, fault_status))
 			new_pmd = kvm_s2pmd_mkexec(new_pmd);
-			invalidate_icache_guest_page(pfn, PMD_SIZE);
-		} else if (fault_status == FSC_PERM) {
-			/* Preserve execute if XN was already cleared */
-			if (stage2_is_exec(kvm, fault_ipa))
-				new_pmd = kvm_s2pmd_mkexec(new_pmd);
-		}
 
 		ret = stage2_set_pmd_huge(kvm, memcache, fault_ipa, &new_pmd);
 	} else {

@@ -1546,21 +1568,11 @@ static int user_mem_abort(struct kvm_vcpu *vcpu, phys_addr_t fault_ipa,
 
 		if (writable) {
 			new_pte = kvm_s2pte_mkwrite(new_pte);
-			kvm_set_pfn_dirty(pfn);
 			mark_page_dirty(kvm, gfn);
 		}
 
-		if (fault_status != FSC_PERM)
-			clean_dcache_guest_page(pfn, PAGE_SIZE);
-
-		if (exec_fault) {
+		if (stage2_should_exec(kvm, fault_ipa, exec_fault, fault_status))
 			new_pte = kvm_s2pte_mkexec(new_pte);
-			invalidate_icache_guest_page(pfn, PAGE_SIZE);
-		} else if (fault_status == FSC_PERM) {
-			/* Preserve execute if XN was already cleared */
-			if (stage2_is_exec(kvm, fault_ipa))
-				new_pte = kvm_s2pte_mkexec(new_pte);
-		}
 
 		ret = stage2_set_pte(kvm, memcache, fault_ipa, &new_pte, flags);
 	}

-- 
2.17.0

Otherwise looks good.

Thanks,
-Christoffer
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