Sean Christopherson <sean.j.christopherson@xxxxxxxxx> writes:
> On Fri, Aug 07, 2020 at 04:12:30PM +0200, Vitaly Kuznetsov wrote:
>> No functional change intended. Slot flags will need to be analyzed
>> prior to try_async_pf() when KVM_MEM_PCI_HOLE is implemented.
>
(Sorry it took me so long to reply. No, I wasn't hoping for Paolo's
magical "queued, thanks", I just tried to not read my email while on
vacation).
> Why? Wouldn't it be just as easy, and arguably more appropriate, to add
> KVM_PFN_ERR_PCI_HOLE and update handle_abornmal_pfn() accordinaly?
>
Yes, we can do that, but what I don't quite like here is that
try_async_pf() does much more than 'trying async PF'. In particular, it
extracts 'pfn' and this is far from being obvious. Maybe we can rename
try_async_pf() somewhat smartly (e.g. 'try_handle_pf()')? Your
suggestion will make perfect sense to me then.
>> Signed-off-by: Vitaly Kuznetsov <vkuznets@xxxxxxxxxx>
>> ---
>> arch/x86/kvm/mmu/mmu.c | 14 ++++++++------
>> arch/x86/kvm/mmu/paging_tmpl.h | 7 +++++--
>> 2 files changed, 13 insertions(+), 8 deletions(-)
>>
>> diff --git a/arch/x86/kvm/mmu/mmu.c b/arch/x86/kvm/mmu/mmu.c
>> index 862bf418214e..fef6956393f7 100644
>> --- a/arch/x86/kvm/mmu/mmu.c
>> +++ b/arch/x86/kvm/mmu/mmu.c
>> @@ -4042,11 +4042,10 @@ static bool kvm_arch_setup_async_pf(struct kvm_vcpu *vcpu, gpa_t cr2_or_gpa,
>> kvm_vcpu_gfn_to_hva(vcpu, gfn), &arch);
>> }
>>
>> -static bool try_async_pf(struct kvm_vcpu *vcpu, bool prefault, gfn_t gfn,
>> - gpa_t cr2_or_gpa, kvm_pfn_t *pfn, bool write,
>> - bool *writable)
>> +static bool try_async_pf(struct kvm_vcpu *vcpu, struct kvm_memory_slot *slot,
>> + bool prefault, gfn_t gfn, gpa_t cr2_or_gpa,
>> + kvm_pfn_t *pfn, bool write, bool *writable)
>> {
>> - struct kvm_memory_slot *slot = kvm_vcpu_gfn_to_memslot(vcpu, gfn);
>> bool async;
>>
>> /* Don't expose private memslots to L2. */
>> @@ -4082,7 +4081,7 @@ static int direct_page_fault(struct kvm_vcpu *vcpu, gpa_t gpa, u32 error_code,
>> bool exec = error_code & PFERR_FETCH_MASK;
>> bool lpage_disallowed = exec && is_nx_huge_page_enabled();
>> bool map_writable;
>> -
>> + struct kvm_memory_slot *slot;
>> gfn_t gfn = gpa >> PAGE_SHIFT;
>> unsigned long mmu_seq;
>> kvm_pfn_t pfn;
>> @@ -4104,7 +4103,10 @@ static int direct_page_fault(struct kvm_vcpu *vcpu, gpa_t gpa, u32 error_code,
>> mmu_seq = vcpu->kvm->mmu_notifier_seq;
>> smp_rmb();
>>
>> - if (try_async_pf(vcpu, prefault, gfn, gpa, &pfn, write, &map_writable))
>> + slot = kvm_vcpu_gfn_to_memslot(vcpu, gfn);
>> +
>> + if (try_async_pf(vcpu, slot, prefault, gfn, gpa, &pfn, write,
>> + &map_writable))
>> return RET_PF_RETRY;
>>
>> if (handle_abnormal_pfn(vcpu, is_tdp ? 0 : gpa, gfn, pfn, ACC_ALL, &r))
>> diff --git a/arch/x86/kvm/mmu/paging_tmpl.h b/arch/x86/kvm/mmu/paging_tmpl.h
>> index 0172a949f6a7..5c6a895f67c3 100644
>> --- a/arch/x86/kvm/mmu/paging_tmpl.h
>> +++ b/arch/x86/kvm/mmu/paging_tmpl.h
>> @@ -779,6 +779,7 @@ static int FNAME(page_fault)(struct kvm_vcpu *vcpu, gpa_t addr, u32 error_code,
>> int write_fault = error_code & PFERR_WRITE_MASK;
>> int user_fault = error_code & PFERR_USER_MASK;
>> struct guest_walker walker;
>> + struct kvm_memory_slot *slot;
>> int r;
>> kvm_pfn_t pfn;
>> unsigned long mmu_seq;
>> @@ -833,8 +834,10 @@ static int FNAME(page_fault)(struct kvm_vcpu *vcpu, gpa_t addr, u32 error_code,
>> mmu_seq = vcpu->kvm->mmu_notifier_seq;
>> smp_rmb();
>>
>> - if (try_async_pf(vcpu, prefault, walker.gfn, addr, &pfn, write_fault,
>> - &map_writable))
>> + slot = kvm_vcpu_gfn_to_memslot(vcpu, walker.gfn);
>> +
>> + if (try_async_pf(vcpu, slot, prefault, walker.gfn, addr, &pfn,
>> + write_fault, &map_writable))
>> return RET_PF_RETRY;
>>
>> if (handle_abnormal_pfn(vcpu, addr, walker.gfn, pfn, walker.pte_access, &r))
>> --
>> 2.25.4
>>
>
--
Vitaly
