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

>
>> + * 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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