KVM: arm/arm64: Re-factor setting the Stage 2 entry to exec on fault

Stage 2 fault handler marks a page as executable if it is handling an
execution fault or if it was a permission fault in which case the
executable bit needs to be preserved.

The logic to decide if the page should be marked executable is
duplicated for PMD and PTE entries. To avoid creating another copy
when support for PUD hugepages is introduced refactor the code to
share the checks needed to mark a page table entry as executable.

Signed-off-by: Punit Agrawal <punit.agrawal@arm.com>
Reviewed-by: Suzuki K Poulose <suzuki.poulose@arm.com>
Reviewed-by: Christoffer Dall <christoffer.dall@arm.com>
Signed-off-by: Suzuki K Poulose <suzuki.poulose@arm.com>
Signed-off-by: Marc Zyngier <marc.zyngier@arm.com>

diff --git a/virt/kvm/arm/mmu.c b/virt/kvm/arm/mmu.c
index 59595207c5e134b14fd4add0f76b2b10bff3a039..6912529946fb712d26b0f21dad283f32de5f0f5c 100644 (file)
--- a/virt/kvm/arm/mmu.c
+++ b/virt/kvm/arm/mmu.c
@@ -1475,7 +1475,8 @@ static int user_mem_abort(struct kvm_vcpu *vcpu, phys_addr_t fault_ipa,
                          unsigned long fault_status)
 {
        int ret;
-       bool write_fault, exec_fault, writable, force_pte = false;
+       bool write_fault, writable, force_pte = false;
+       bool exec_fault, needs_exec;
        unsigned long mmu_seq;
        gfn_t gfn = fault_ipa >> PAGE_SHIFT;
        struct kvm *kvm = vcpu->kvm;
@@ -1598,19 +1599,25 @@ static int user_mem_abort(struct kvm_vcpu *vcpu, phys_addr_t fault_ipa,
        if (exec_fault)
                invalidate_icache_guest_page(pfn, vma_pagesize);
 
+       /*
+        * If we took an execution fault we have made the
+        * icache/dcache coherent above and should now let the s2
+        * mapping be executable.
+        *
+        * Write faults (!exec_fault && FSC_PERM) are orthogonal to
+        * execute permissions, and we preserve whatever we have.
+        */
+       needs_exec = exec_fault ||
+               (fault_status == FSC_PERM && stage2_is_exec(kvm, fault_ipa));
+
        if (vma_pagesize == PMD_SIZE) {
                pmd_t new_pmd = pfn_pmd(pfn, mem_type);
                new_pmd = pmd_mkhuge(new_pmd);
                if (writable)
                        new_pmd = kvm_s2pmd_mkwrite(new_pmd);
 
-               if (exec_fault) {
+               if (needs_exec)
                        new_pmd = kvm_s2pmd_mkexec(new_pmd);
-               } 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 {
@@ -1621,13 +1628,8 @@ static int user_mem_abort(struct kvm_vcpu *vcpu, phys_addr_t fault_ipa,
                        mark_page_dirty(kvm, gfn);
                }
 
-               if (exec_fault) {
+               if (needs_exec)
                        new_pte = kvm_s2pte_mkexec(new_pte);
-               } 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);
        }