Re: [PATCH v9 2/8] KVM: arm/arm64: Re-factor setting the Stage 2 entry to exec on fault

On 03/12/2018 13:32, Anshuman Khandual wrote:

On 10/31/2018 11:27 PM, Punit Agrawal wrote:

quoted

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 <redacted>
Reviewed-by: Suzuki K Poulose <suzuki.poulose@arm.com>
Cc: Christoffer Dall <redacted>
Cc: Marc Zyngier <redacted>
---
  virt/kvm/arm/mmu.c | 28 +++++++++++++++-------------
  1 file changed, 15 insertions(+), 13 deletions(-)

diff --git a/virt/kvm/arm/mmu.c b/virt/kvm/arm/mmu.c
index 59595207c5e1..6912529946fb 100644
--- 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;

New line not required, still within 80 characters.

quoted

  	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

Coherent or invalidated with invalidate_icache_guest_page ?

We also do clean_dcache above if needed. So that makes sure
the data is coherent. Am I missing something here ?

quoted

+	 * mapping be executable.
+	 *
+	 * Write faults (!exec_fault && FSC_PERM) are orthogonal to
+	 * execute permissions, and we preserve whatever we have.
+	 */

Otherwise looks good.

Suzuki

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