Messages in this thread | | | Subject | Re: [PATCH v5 4/7] KVM: arm64: Support PUD hugepage in stage2_is_exec() | From | Suzuki K Poulose <> | Date | Wed, 11 Jul 2018 14:41:29 +0100 |
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On 09/07/18 15:41, Punit Agrawal wrote: > In preparation for creating PUD hugepages at stage 2, add support for > detecting execute permissions on PUD page table entries. Faults due to > lack of execute permissions on page table entries is used to perform > i-cache invalidation on first execute. > > Provide trivial implementations of arm32 helpers to allow sharing of > code. > > Signed-off-by: Punit Agrawal <punit.agrawal@arm.com> > Cc: Christoffer Dall <christoffer.dall@arm.com> > Cc: Marc Zyngier <marc.zyngier@arm.com> > Cc: Russell King <linux@armlinux.org.uk> > Cc: Catalin Marinas <catalin.marinas@arm.com> > Cc: Will Deacon <will.deacon@arm.com> > --- > arch/arm/include/asm/kvm_mmu.h | 6 ++++ > arch/arm64/include/asm/kvm_mmu.h | 5 +++ > arch/arm64/include/asm/pgtable-hwdef.h | 2 ++ > virt/kvm/arm/mmu.c | 49 +++++++++++++++++++++++--- > 4 files changed, 57 insertions(+), 5 deletions(-) > > diff --git a/arch/arm/include/asm/kvm_mmu.h b/arch/arm/include/asm/kvm_mmu.h > index c23722f75d5c..d05c8986e495 100644 > --- a/arch/arm/include/asm/kvm_mmu.h > +++ b/arch/arm/include/asm/kvm_mmu.h > @@ -96,6 +96,12 @@ static inline bool kvm_s2pud_readonly(pud_t *pud) > } > > > +static inline bool kvm_s2pud_exec(pud_t *pud) > +{ > + BUG(); > + return false; > +} > + > static inline void kvm_set_pmd(pmd_t *pmd, pmd_t new_pmd) > { > *pmd = new_pmd; > diff --git a/arch/arm64/include/asm/kvm_mmu.h b/arch/arm64/include/asm/kvm_mmu.h > index 84051930ddfe..15bc1be8f82f 100644 > --- a/arch/arm64/include/asm/kvm_mmu.h > +++ b/arch/arm64/include/asm/kvm_mmu.h > @@ -249,6 +249,11 @@ static inline bool kvm_s2pud_readonly(pud_t *pudp) > return kvm_s2pte_readonly((pte_t *)pudp); > } > > +static inline bool kvm_s2pud_exec(pud_t *pudp) > +{ > + return !(READ_ONCE(pud_val(*pudp)) & PUD_S2_XN); > +} > + > static inline bool kvm_page_empty(void *ptr) > { > struct page *ptr_page = virt_to_page(ptr); > diff --git a/arch/arm64/include/asm/pgtable-hwdef.h b/arch/arm64/include/asm/pgtable-hwdef.h > index fd208eac9f2a..10ae592b78b8 100644 > --- a/arch/arm64/include/asm/pgtable-hwdef.h > +++ b/arch/arm64/include/asm/pgtable-hwdef.h > @@ -193,6 +193,8 @@ > #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_XN (_AT(pudval_t, 2) << 53) /* XN[1:0] */ > + > /* > * Memory Attribute override for Stage-2 (MemAttr[3:0]) > */ > diff --git a/virt/kvm/arm/mmu.c b/virt/kvm/arm/mmu.c > index ed8f8271c389..e73909a31e02 100644 > --- a/virt/kvm/arm/mmu.c > +++ b/virt/kvm/arm/mmu.c > @@ -1038,23 +1038,62 @@ static int stage2_set_pmd_huge(struct kvm *kvm, struct kvm_mmu_memory_cache > return 0; > } > > -static bool stage2_is_exec(struct kvm *kvm, phys_addr_t addr) > +/* > + * stage2_get_leaf_entry - walk the stage2 VM page tables and return > + * true if a valid and present leaf-entry is found. A pointer to the > + * leaf-entry is returned in the appropriate level variable - pudpp, > + * pmdpp, ptepp. > + */ > +static bool stage2_get_leaf_entry(struct kvm *kvm, phys_addr_t addr, > + pud_t **pudpp, pmd_t **pmdpp, pte_t **ptepp) > { > + pud_t *pudp; > pmd_t *pmdp; > pte_t *ptep;
nit: As mentioned in the other thread, you may initialize the reference pointers to NULL to make sure we start clean and avoid the initialization everywhere this is called.
> > - pmdp = stage2_get_pmd(kvm, NULL, addr); > + pudp = stage2_get_pud(kvm, NULL, addr); > + if (!pudp || pud_none(*pudp) || !pud_present(*pudp)) > + return false; > + > + if (pud_huge(*pudp)) { > + *pudpp = pudp; > + return true; > + } > + > + pmdp = stage2_pmd_offset(pudp, addr); > if (!pmdp || pmd_none(*pmdp) || !pmd_present(*pmdp)) > return false; > > - if (pmd_thp_or_huge(*pmdp)) > - return kvm_s2pmd_exec(pmdp); > + if (pmd_thp_or_huge(*pmdp)) { > + *pmdpp = pmdp; > + return true; > + } > > ptep = pte_offset_kernel(pmdp, addr); > if (!ptep || pte_none(*ptep) || !pte_present(*ptep)) > return false; > > - return kvm_s2pte_exec(ptep); > + *ptepp = ptep; > + return true; > +} > + > +static bool stage2_is_exec(struct kvm *kvm, phys_addr_t addr) > +{ > + pud_t *pudp = NULL; > + pmd_t *pmdp = NULL; > + pte_t *ptep = NULL; > + bool found; > + > + found = stage2_get_leaf_entry(kvm, addr, &pudp, &pmdp, &ptep); > + if (!found) > + return false; > + > + if (pudp) > + return kvm_s2pud_exec(pudp); > + else if (pmdp) > + return kvm_s2pmd_exec(pmdp); > + else > + return kvm_s2pte_exec(ptep); > }
Reviewed-by: Suzuki K Poulose <suzuki.poulose@arm.com>
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