Suzuki K Poulose <suzuki.poulose@xxxxxxx> writes:
> Hi Punit,
>
>
> On 09/24/2018 06:45 PM, Punit Agrawal wrote:
>> KVM only supports PMD hugepages at stage 2. Now that the various page
>> handling routines are updated, extend the stage 2 fault handling to
>> map in PUD hugepages.
>>
>> Addition of PUD hugepage support enables additional page sizes (e.g.,
>> 1G with 4K granule) which can be useful on cores that support mapping
>> larger block sizes in the TLB entries.
>>
>> Signed-off-by: Punit Agrawal <punit.agrawal@xxxxxxx>
>> Cc: Christoffer Dall <christoffer.dall@xxxxxxx>
>> Cc: Marc Zyngier <marc.zyngier@xxxxxxx>
>> Cc: Russell King <linux@xxxxxxxxxxxxxxx>
>> Cc: Catalin Marinas <catalin.marinas@xxxxxxx>
>> Cc: Will Deacon <will.deacon@xxxxxxx>
>
>
>>
>> diff --git a/arch/arm/include/asm/kvm_mmu.h b/arch/arm/include/asm/kvm_mmu.h
>> index a42b9505c9a7..a8e86b926ee0 100644
>> --- a/arch/arm/include/asm/kvm_mmu.h
>> +++ b/arch/arm/include/asm/kvm_mmu.h
>> @@ -84,11 +84,14 @@ void kvm_clear_hyp_idmap(void);
>> #define kvm_pfn_pte(pfn, prot) pfn_pte(pfn, prot)
>> #define kvm_pfn_pmd(pfn, prot) pfn_pmd(pfn, prot)
>> +#define kvm_pfn_pud(pfn, prot) (__pud(0))
>> #define kvm_pud_pfn(pud) ({ BUG(); 0; })
>> #define kvm_pmd_mkhuge(pmd) pmd_mkhuge(pmd)
>> +/* No support for pud hugepages */
>> +#define kvm_pud_mkhuge(pud) (pud)
>>
>
> shouldn't this be BUG() like other PUD huge helpers for arm32 ?
>
>> /*
>> * The following kvm_*pud*() functions are provided strictly to allow
>> @@ -105,6 +108,23 @@ static inline bool kvm_s2pud_readonly(pud_t *pud)
>> return false;
>> }
>> +static inline void kvm_set_pud(pud_t *pud, pud_t new_pud)
>> +{
>> + BUG();
>> +}
>> +
>> +static inline pud_t kvm_s2pud_mkwrite(pud_t pud)
>> +{
>> + BUG();
>> + return pud;
>> +}
>> +
>> +static inline pud_t kvm_s2pud_mkexec(pud_t pud)
>> +{
>> + BUG();
>> + return pud;
>> +}
>> +
>
>
>> diff --git a/virt/kvm/arm/mmu.c b/virt/kvm/arm/mmu.c
>> index 3ff7ebb262d2..5b8163537bc2 100644
>> --- a/virt/kvm/arm/mmu.c
>> +++ b/virt/kvm/arm/mmu.c
>
> ...
>
>
>> @@ -1669,7 +1746,28 @@ static int user_mem_abort(struct kvm_vcpu *vcpu, phys_addr_t fault_ipa,
>> needs_exec = exec_fault ||
>> (fault_status == FSC_PERM && stage2_is_exec(kvm, fault_ipa));
>> - if (hugetlb && vma_pagesize == PMD_SIZE) {
>> + if (hugetlb && vma_pagesize == PUD_SIZE) {
>> + /*
>> + * Assuming that PUD level always exists at Stage 2 -
>> + * this is true for 4k pages with 40 bits IPA
>> + * currently supported.
>> + *
>> + * When using 64k pages, 40bits of IPA results in
>> + * using only 2-levels at Stage 2. Overlooking this
>> + * problem for now as a PUD hugepage with 64k pages is
>> + * too big (4TB) to be practical.
>> + */
>> + pud_t new_pud = kvm_pfn_pud(pfn, mem_type);
>
> Is this based on the Dynamic IPA series ? The cover letter seems
> to suggest that it is. But I don't see the check to make sure we have
> stage2 PUD level here before we go ahead and try PUD huge page at
> stage2. Also the comment above seems outdated in that case.
It is indeed based on the Dynamic IPA series but I seem to have lost the
actual changes introducing the checks for PUD level. Let me fix that up
and post an update.
Sorry for the noise.
Punit
>
>> +
>> + new_pud = kvm_pud_mkhuge(new_pud);
>> + if (writable)
>> + new_pud = kvm_s2pud_mkwrite(new_pud);
>> +
>> + if (needs_exec)
>> + new_pud = kvm_s2pud_mkexec(new_pud);
>> +
>> + ret = stage2_set_pud_huge(kvm, memcache, fault_ipa, &new_pud);
>> + } else if (hugetlb && vma_pagesize == PMD_SIZE) {
>> pmd_t new_pmd = kvm_pfn_pmd(pfn, mem_type);
>> new_pmd = kvm_pmd_mkhuge(new_pmd);
>>
>
>
> Suzuki
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