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SubjectRe: [PATCH RFCv2 6/9] kvm/arm64: Export kvm_handle_user_mem_abort() with prefault mode
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Hi Mark,

On 5/26/20 8:58 PM, Mark Rutland wrote:
> On Fri, May 08, 2020 at 01:29:16PM +1000, Gavin Shan wrote:
>> This renames user_mem_abort() to kvm_handle_user_mem_abort(), and
>> then export it. The function will be used in asynchronous page fault
>> to populate a page table entry once the corresponding page is populated
>> from the backup device (e.g. swap partition):
>>
>> * Parameter @fault_status is replace by @esr.
>> * The parameters are reorder based on their importance.
>
> It seems like multiple changes are going on here, and it would be
> clearer with separate patches.
>
> Passing the ESR rather than the extracted fault status seems fine, but
> for clarirty it's be nicer to do this in its own patch.
>

Ok. I'll have a separate patch to do this.

> Why is it necessary to re-order the function parameters? Does that align
> with other function prototypes?
>

There are no explicit reasons for it. I can restore the order to what we
had previously if you like.

> What exactly is the `prefault` parameter meant to do? It doesn't do
> anything currently, so it'd be better to introduce it later when logic
> using it is instroduced, or where callers will pass distinct values.
>

Yes, fair enough. I will merge the logic with PATCH[7] then.

> Thanks,
> Mark.
>

Thanks,
Gavin

>>
>> This shouldn't cause any functional changes.
>>
>> Signed-off-by: Gavin Shan <gshan@redhat.com>
>> ---
>> arch/arm64/include/asm/kvm_host.h | 4 ++++
>> virt/kvm/arm/mmu.c | 14 ++++++++------
>> 2 files changed, 12 insertions(+), 6 deletions(-)
>>
>> diff --git a/arch/arm64/include/asm/kvm_host.h b/arch/arm64/include/asm/kvm_host.h
>> index 32c8a675e5a4..f77c706777ec 100644
>> --- a/arch/arm64/include/asm/kvm_host.h
>> +++ b/arch/arm64/include/asm/kvm_host.h
>> @@ -437,6 +437,10 @@ int __kvm_arm_vcpu_set_events(struct kvm_vcpu *vcpu,
>> struct kvm_vcpu_events *events);
>>
>> #define KVM_ARCH_WANT_MMU_NOTIFIER
>> +int kvm_handle_user_mem_abort(struct kvm_vcpu *vcpu, unsigned int esr,
>> + struct kvm_memory_slot *memslot,
>> + phys_addr_t fault_ipa, unsigned long hva,
>> + bool prefault);
>> int kvm_unmap_hva_range(struct kvm *kvm,
>> unsigned long start, unsigned long end);
>> int kvm_set_spte_hva(struct kvm *kvm, unsigned long hva, pte_t pte);
>> diff --git a/virt/kvm/arm/mmu.c b/virt/kvm/arm/mmu.c
>> index e462e0368fd9..95aaabb2b1fc 100644
>> --- a/virt/kvm/arm/mmu.c
>> +++ b/virt/kvm/arm/mmu.c
>> @@ -1656,12 +1656,12 @@ static bool fault_supports_stage2_huge_mapping(struct kvm_memory_slot *memslot,
>> (hva & ~(map_size - 1)) + map_size <= uaddr_end;
>> }
>>
>> -static int user_mem_abort(struct kvm_vcpu *vcpu, phys_addr_t fault_ipa,
>> - struct kvm_memory_slot *memslot, unsigned long hva,
>> - unsigned long fault_status)
>> +int kvm_handle_user_mem_abort(struct kvm_vcpu *vcpu, unsigned int esr,
>> + struct kvm_memory_slot *memslot,
>> + phys_addr_t fault_ipa, unsigned long hva,
>> + bool prefault)
>> {
>> - int ret;
>> - u32 esr = kvm_vcpu_get_esr(vcpu);
>> + unsigned int fault_status = kvm_vcpu_trap_get_fault_type(esr);
>> bool write_fault, writable, force_pte = false;
>> bool exec_fault, needs_exec;
>> unsigned long mmu_seq;
>> @@ -1674,6 +1674,7 @@ static int user_mem_abort(struct kvm_vcpu *vcpu, phys_addr_t fault_ipa,
>> pgprot_t mem_type = PAGE_S2;
>> bool logging_active = memslot_is_logging(memslot);
>> unsigned long vma_pagesize, flags = 0;
>> + int ret;
>>
>> write_fault = kvm_is_write_fault(esr);
>> exec_fault = kvm_vcpu_trap_is_iabt(esr);
>> @@ -1995,7 +1996,8 @@ int kvm_handle_guest_abort(struct kvm_vcpu *vcpu, struct kvm_run *run)
>> goto out_unlock;
>> }
>>
>> - ret = user_mem_abort(vcpu, fault_ipa, memslot, hva, fault_status);
>> + ret = kvm_handle_user_mem_abort(vcpu, esr, memslot,
>> + fault_ipa, hva, false);
>> if (ret == 0)
>> ret = 1;
>> out:
>> --
>> 2.23.0
>>
>

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