Christoffer Dall <christoffer.d...@arm.com> writes:
> On Fri, Apr 20, 2018 at 03:54:06PM +0100, Punit Agrawal wrote:
>> 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 <punit.agra...@arm.com>
>> Cc: Christoffer Dall <christoffer.d...@arm.com>
>> Cc: Marc Zyngier <marc.zyng...@arm.com>
>> ---
>> virt/kvm/arm/mmu.c | 36 +++++++++++++++++++++---------------
>> 1 file changed, 21 insertions(+), 15 deletions(-)
>>
>> diff --git a/virt/kvm/arm/mmu.c b/virt/kvm/arm/mmu.c
>> index 7f6a944db23d..db382c7c7cd7 100644
>> --- a/virt/kvm/arm/mmu.c
>> +++ b/virt/kvm/arm/mmu.c
>> @@ -1428,7 +1428,7 @@ static int user_mem_abort(struct kvm_vcpu *vcpu,
>> phys_addr_t fault_ipa,
>> kvm_pfn_t pfn;
>> pgprot_t mem_type = PAGE_S2;
>> bool logging_active = memslot_is_logging(memslot);
>> - unsigned long flags = 0;
>> + unsigned long vma_pagesize, flags = 0;
>>
>> write_fault = kvm_is_write_fault(vcpu);
>> exec_fault = kvm_vcpu_trap_is_iabt(vcpu);
>> @@ -1448,7 +1448,8 @@ static int user_mem_abort(struct kvm_vcpu *vcpu,
>> phys_addr_t fault_ipa,
>> return -EFAULT;
>> }
>>
>> - if (vma_kernel_pagesize(vma) == PMD_SIZE && !logging_active) {
>> + vma_pagesize = vma_kernel_pagesize(vma);
>> + if (vma_pagesize == PMD_SIZE && !logging_active) {
>> hugetlb = true;
>> gfn = (fault_ipa & PMD_MASK) >> PAGE_SHIFT;
>> } else {
>> @@ -1517,23 +1518,33 @@ 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) {
>> + /*
>> + * Only PMD_SIZE transparent hugepages(THP) are
>> + * currently supported. This code will need to be
>> + * updated if other THP sizes are supported.
>> + */
>> hugetlb = transparent_hugepage_adjust(&pfn, &fault_ipa);
>> + vma_pagesize = PMD_SIZE;
>> + }
>> +
>> + 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) {
>> new_pmd = kvm_s2pmd_mkexec(new_pmd);
>> - invalidate_icache_guest_page(pfn, PMD_SIZE);
>> } else if (fault_status == FSC_PERM) {
>
> This could now be rewritten to:
>
> if (exec_fault ||
> (fault_status == FSC_PERM && stage2_is_exec(kvm,
> fault_ipa)))
> new_pmd = kvm_s2pmd_mkexec(new_pmd);
>
> which we could even consider making
>
> static bool stage2_should_exec(struct kvm *kvm, phys_addr_t addr,
> bool exec_fault, unsigned long fault_status)
> {
> /*
> * If we took an execution fault we will have made the
> * icache/dcache coherent 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.
> */
> return exec_fault ||
> (fault_status == FSC_PERM && stage2_is_exec(kvm, fault_ipa));
> }
>
> The benefit would be to have this documentation in a single place and
> slightly simply both the hugetlb and !hugetlb blocks.
Makes sense. And saves another copy when we introduce PUD handling in a
latter patch. I've rolled this in with minor changes.
>
>
>> /* Preserve execute if XN was already cleared */
>> if (stage2_is_exec(kvm, fault_ipa))
>> @@ -1546,16 +1557,11 @@ 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) {
>> 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))
>> --
>> 2.17.0
>>
>
> Notwithstanding my suggestion above:
>
> Reviewed-by: Christoffer Dall <christoffer.d...@arm.com>
Thanks,
Punit
