| Message ID | 20180705140850.5801-5-punit.agrawal@arm.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
Hi Punit, On 05/07/18 15:08, 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 | 10 +++++++++- > 4 files changed, 22 insertions(+), 1 deletion(-) > > 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] */ > + The changes above look good to me. Please see below. > /* > * Memory Attribute override for Stage-2 (MemAttr[3:0]) > */ > diff --git a/virt/kvm/arm/mmu.c b/virt/kvm/arm/mmu.c > index db04b18218c1..ccdea0edabb3 100644 > --- a/virt/kvm/arm/mmu.c > +++ b/virt/kvm/arm/mmu.c > @@ -1040,10 +1040,18 @@ static int stage2_set_pmd_huge(struct kvm *kvm, struct kvm_mmu_memory_cache > > static bool stage2_is_exec(struct kvm *kvm, phys_addr_t addr) > { > + pud_t *pudp; > pmd_t *pmdp; > pte_t *ptep; > > - 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)) > + return kvm_s2pud_exec(pudp); > + > + pmdp = stage2_pmd_offset(pudp, addr); > if (!pmdp || pmd_none(*pmdp) || !pmd_present(*pmdp)) > return false; I am wondering if we need a slightly better way to deal with this kind of operation. We seem to duplicate the above operation (here and in the following patches), i.e, finding the "leaf entry" for a given address and follow the checks one level up at a time. So instead of doing, stage2_get_pud() and walking down everywhere this is needed, how about adding : /* Returns true if the leaf entry is found and updates the relevant pointer */ found = stage2_get_leaf_entry(kvm, NULL, addr, &pudp, &pmdp, &ptep) which could set the appropriate entry and we could check the result here. Cheers Suzuki
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 db04b18218c1..ccdea0edabb3 100644 --- a/virt/kvm/arm/mmu.c +++ b/virt/kvm/arm/mmu.c @@ -1040,10 +1040,18 @@ static int stage2_set_pmd_huge(struct kvm *kvm, struct kvm_mmu_memory_cache static bool stage2_is_exec(struct kvm *kvm, phys_addr_t addr) { + pud_t *pudp; pmd_t *pmdp; pte_t *ptep; - 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)) + return kvm_s2pud_exec(pudp); + + pmdp = stage2_pmd_offset(pudp, addr); if (!pmdp || pmd_none(*pmdp) || !pmd_present(*pmdp)) return false;
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 | 10 +++++++++- 4 files changed, 22 insertions(+), 1 deletion(-)