lkml.org 
[lkml]   [2018]   [Jul]   [11]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
SubjectRe: [PATCH v5 4/7] KVM: arm64: Support PUD hugepage in stage2_is_exec()
From
Date
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>

\
 
 \ /
  Last update: 2018-07-11 15:41    [W:0.083 / U:6.656 seconds]
©2003-2018 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site