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Message-ID: <20180504113904.GE10191@C02W217FHV2R.local>
Date: Fri, 4 May 2018 13:39:04 +0200
From: Christoffer Dall <christoffer.dall@....com>
To: Punit Agrawal <punit.agrawal@....com>
Cc: kvmarm@...ts.cs.columbia.edu, linux-arm-kernel@...ts.infradead.org,
marc.zyngier@....com, linux-kernel@...r.kernel.org,
suzuki.poulose@....com, Russell King <linux@...linux.org.uk>,
Catalin Marinas <catalin.marinas@....com>,
Will Deacon <will.deacon@....com>
Subject: Re: [PATCH v2 4/4] KVM: arm64: Add support for PUD hugepages at
stage 2
On Tue, May 01, 2018 at 11:26:59AM +0100, Punit Agrawal wrote:
> KVM currently supports PMD hugepages at stage 2. Extend the stage 2
> fault handling to add support for PUD hugepages.
>
> Addition of pud hugepage support enables additional hugepage
> 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@....com>
> Cc: Christoffer Dall <christoffer.dall@....com>
> Cc: Marc Zyngier <marc.zyngier@....com>
> Cc: Russell King <linux@...linux.org.uk>
> Cc: Catalin Marinas <catalin.marinas@....com>
> Cc: Will Deacon <will.deacon@....com>
Reviewed-by: Christoffer Dall <christoffer.dall@....com>
> ---
> arch/arm/include/asm/kvm_mmu.h | 19 ++++++++++++
> arch/arm64/include/asm/kvm_mmu.h | 15 ++++++++++
> arch/arm64/include/asm/pgtable-hwdef.h | 4 +++
> arch/arm64/include/asm/pgtable.h | 2 ++
> virt/kvm/arm/mmu.c | 40 ++++++++++++++++++++++++--
> 5 files changed, 77 insertions(+), 3 deletions(-)
>
> diff --git a/arch/arm/include/asm/kvm_mmu.h b/arch/arm/include/asm/kvm_mmu.h
> index 224c22c0a69c..155916dbdd7e 100644
> --- a/arch/arm/include/asm/kvm_mmu.h
> +++ b/arch/arm/include/asm/kvm_mmu.h
> @@ -77,8 +77,11 @@ 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_pmd_mkhuge(pmd) pmd_mkhuge(pmd)
> +/* No support for pud hugepages */
> +#define kvm_pud_mkhuge(pud) (pud)
>
> /*
> * The following kvm_*pud*() functionas are provided strictly to allow
> @@ -95,6 +98,22 @@ 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;
> +}
>
> static inline void kvm_set_pmd(pmd_t *pmd, pmd_t new_pmd)
> {
> diff --git a/arch/arm64/include/asm/kvm_mmu.h b/arch/arm64/include/asm/kvm_mmu.h
> index f440cf216a23..f49a68fcbf26 100644
> --- a/arch/arm64/include/asm/kvm_mmu.h
> +++ b/arch/arm64/include/asm/kvm_mmu.h
> @@ -172,11 +172,14 @@ void kvm_clear_hyp_idmap(void);
>
> #define kvm_set_pte(ptep, pte) set_pte(ptep, pte)
> #define kvm_set_pmd(pmdp, pmd) set_pmd(pmdp, pmd)
> +#define kvm_set_pud(pudp, pud) set_pud(pudp, pud)
>
> #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) pfn_pud(pfn, prot)
>
> #define kvm_pmd_mkhuge(pmd) pmd_mkhuge(pmd)
> +#define kvm_pud_mkhuge(pud) pud_mkhuge(pud)
>
> static inline pte_t kvm_s2pte_mkwrite(pte_t pte)
> {
> @@ -190,6 +193,12 @@ static inline pmd_t kvm_s2pmd_mkwrite(pmd_t pmd)
> return pmd;
> }
>
> +static inline pud_t kvm_s2pud_mkwrite(pud_t pud)
> +{
> + pud_val(pud) |= PUD_S2_RDWR;
> + return pud;
> +}
> +
> static inline pte_t kvm_s2pte_mkexec(pte_t pte)
> {
> pte_val(pte) &= ~PTE_S2_XN;
> @@ -202,6 +211,12 @@ static inline pmd_t kvm_s2pmd_mkexec(pmd_t pmd)
> return pmd;
> }
>
> +static inline pud_t kvm_s2pud_mkexec(pud_t pud)
> +{
> + pud_val(pud) &= ~PUD_S2_XN;
> + return pud;
> +}
> +
> static inline void kvm_set_s2pte_readonly(pte_t *ptep)
> {
> pteval_t old_pteval, pteval;
> diff --git a/arch/arm64/include/asm/pgtable-hwdef.h b/arch/arm64/include/asm/pgtable-hwdef.h
> index fd208eac9f2a..e327665e94d1 100644
> --- a/arch/arm64/include/asm/pgtable-hwdef.h
> +++ b/arch/arm64/include/asm/pgtable-hwdef.h
> @@ -193,6 +193,10 @@
> #define PMD_S2_RDWR (_AT(pmdval_t, 3) << 6) /* HAP[2:1] */
> #define PMD_S2_XN (_AT(pmdval_t, 2) << 53) /* XN[1:0] */
>
> +#define PUD_S2_RDONLY (_AT(pudval_t, 1) << 6) /* HAP[2:1] */
> +#define PUD_S2_RDWR (_AT(pudval_t, 3) << 6) /* HAP[2:1] */
> +#define PUD_S2_XN (_AT(pudval_t, 2) << 53) /* XN[1:0] */
> +
> /*
> * Memory Attribute override for Stage-2 (MemAttr[3:0])
> */
> diff --git a/arch/arm64/include/asm/pgtable.h b/arch/arm64/include/asm/pgtable.h
> index 7c4c8f318ba9..31ea9fda07e3 100644
> --- a/arch/arm64/include/asm/pgtable.h
> +++ b/arch/arm64/include/asm/pgtable.h
> @@ -386,6 +386,8 @@ static inline int pmd_protnone(pmd_t pmd)
>
> #define pud_write(pud) pte_write(pud_pte(pud))
>
> +#define pud_mkhuge(pud) (__pud(pud_val(pud) & ~PUD_TABLE_BIT))
> +
> #define __pud_to_phys(pud) __pte_to_phys(pud_pte(pud))
> #define __phys_to_pud_val(phys) __phys_to_pte_val(phys)
> #define pud_pfn(pud) ((__pud_to_phys(pud) & PUD_MASK) >> PAGE_SHIFT)
> diff --git a/virt/kvm/arm/mmu.c b/virt/kvm/arm/mmu.c
> index 3afbf693e045..1fb108d47dbd 100644
> --- a/virt/kvm/arm/mmu.c
> +++ b/virt/kvm/arm/mmu.c
> @@ -1036,6 +1036,26 @@ static int stage2_set_pmd_huge(struct kvm *kvm, struct kvm_mmu_memory_cache
> return 0;
> }
>
> +static int stage2_set_pud_huge(struct kvm *kvm, struct kvm_mmu_memory_cache *cache,
> + phys_addr_t addr, const pud_t *new_pud)
> +{
> + pud_t *pud, old_pud;
> +
> + pud = stage2_get_pud(kvm, cache, addr);
> + VM_BUG_ON(!pud);
> +
> + old_pud = *pud;
> + if (pud_present(old_pud)) {
> + pud_clear(pud);
> + kvm_tlb_flush_vmid_ipa(kvm, addr);
> + } else {
> + get_page(virt_to_page(pud));
> + }
> +
> + kvm_set_pud(pud, *new_pud);
> + return 0;
> +}
> +
> static bool stage2_is_exec(struct kvm *kvm, phys_addr_t addr)
> {
> pmd_t *pmdp;
> @@ -1467,9 +1487,12 @@ static int user_mem_abort(struct kvm_vcpu *vcpu, phys_addr_t fault_ipa,
> }
>
> vma_pagesize = vma_kernel_pagesize(vma);
> - if (vma_pagesize == PMD_SIZE && !logging_active) {
> + if ((vma_pagesize == PMD_SIZE || vma_pagesize == PUD_SIZE) &&
> + !logging_active) {
> + struct hstate *h = hstate_vma(vma);
> +
> hugetlb = true;
> - gfn = (fault_ipa & PMD_MASK) >> PAGE_SHIFT;
> + gfn = (fault_ipa & huge_page_mask(h)) >> PAGE_SHIFT;
> } else {
> /*
> * Pages belonging to memslots that don't have the same
> @@ -1556,7 +1579,18 @@ 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 (hugetlb) {
> + if (vma_pagesize == PUD_SIZE) {
> + pud_t new_pud = kvm_pfn_pud(pfn, mem_type);
> +
> + new_pud = kvm_pud_mkhuge(new_pud);
> + if (writable)
> + new_pud = kvm_s2pud_mkwrite(new_pud);
> +
> + if (stage2_should_exec(kvm, fault_ipa, exec_fault, fault_status))
> + new_pud = kvm_s2pud_mkexec(new_pud);
> +
> + ret = stage2_set_pud_huge(kvm, memcache, fault_ipa, &new_pud);
> + } else if (vma_pagesize == PMD_SIZE) {
> pmd_t new_pmd = kvm_pfn_pmd(pfn, mem_type);
>
> new_pmd = kvm_pmd_mkhuge(new_pmd);
> --
> 2.17.0
>
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