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SubjectRe: [PATCH v9 2/8] KVM: arm/arm64: Re-factor setting the Stage 2 entry to exec on fault
On Wed, Dec 05, 2018 at 10:47:10AM +0000, Suzuki K Poulose wrote:
>
>
> On 03/12/2018 13:32, Anshuman Khandual wrote:
> >
> >
> >On 10/31/2018 11:27 PM, Punit Agrawal wrote:
> >>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>
> >>Cc: Christoffer Dall <christoffer.dall@arm.com>
> >>Cc: Marc Zyngier <marc.zyngier@arm.com>
> >>---
> >> 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.
> >
> >> 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 ?
>

I think you've got it right. We have made the icache coherent with the
data/instructions in the page by invalidating the icache. I think the
comment is ok either way.

Thanks,

Christoffer

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